svn merge ^/branches/released . --username marha

1 files changed, 2209 insertions, 0 deletions

diff --git a/mesalib/src/mesa/main/renderbuffer.c b/mesalib/src/mesa/main/renderbuffer.c
new file mode 100644
index 000000000..38be8266e
--- /dev/null
+++ b/mesalib/src/mesa/main/renderbuffer.c
@@ -0,0 +1,2209 @@
+/*
+ * Mesa 3-D graphics library
+ * Version:  6.5
+ *
+ * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/**
+ * Functions for allocating/managing renderbuffers.
+ * Also, routines for reading/writing software-based renderbuffer data as
+ * ubytes, ushorts, uints, etc.
+ *
+ * The 'alpha8' renderbuffer is interesting.  It's used to add a software-based
+ * alpha channel to RGB renderbuffers.  This is done by wrapping the RGB
+ * renderbuffer with the alpha renderbuffer.  We can do this because of the
+ * OO-nature of renderbuffers.
+ *
+ * Down the road we'll use this for run-time support of 8, 16 and 32-bit
+ * color channels.  For example, Mesa may use 32-bit/float color channels
+ * internally (swrast) and use wrapper renderbuffers to convert 32-bit
+ * values down to 16 or 8-bit values for whatever kind of framebuffer we have.
+ */
+
+
+#include "glheader.h"
+#include "imports.h"
+#include "context.h"
+#include "mtypes.h"
+#include "fbobject.h"
+#include "renderbuffer.h"
+
+#include "rbadaptors.h"
+
+
+/* 32-bit color index format.  Not a public format. */
+#define COLOR_INDEX32 0x424243
+
+
+/*
+ * Routines for get/put values in common buffer formats follow.
+ * Someday add support for arbitrary row stride to make them more
+ * flexible.
+ */
+
+/**********************************************************************
+ * Functions for buffers of 1 X GLubyte values.
+ * Typically stencil.
+ */
+
+static void *
+get_pointer_ubyte(GLcontext *ctx, struct gl_renderbuffer *rb,
+                  GLint x, GLint y)
+{
+   if (!rb->Data)
+      return NULL;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   /* Can't assert _ActualFormat since these funcs may be used for serveral
+    * different formats (GL_ALPHA8, GL_STENCIL_INDEX8, etc).
+    */
+   return (GLubyte *) rb->Data + y * rb->Width + x;
+}
+
+
+static void
+get_row_ubyte(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+              GLint x, GLint y, void *values)
+{
+   const GLubyte *src = (const GLubyte *) rb->Data + y * rb->Width + x;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   _mesa_memcpy(values, src, count * sizeof(GLubyte));
+}
+
+
+static void
+get_values_ubyte(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                 const GLint x[], const GLint y[], void *values)
+{
+   GLubyte *dst = (GLubyte *) values;
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   for (i = 0; i < count; i++) {
+      const GLubyte *src = (GLubyte *) rb->Data + y[i] * rb->Width + x[i];
+      dst[i] = *src;
+   }
+}
+
+
+static void
+put_row_ubyte(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+              GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   const GLubyte *src = (const GLubyte *) values;
+   GLubyte *dst = (GLubyte *) rb->Data + y * rb->Width + x;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            dst[i] = src[i];
+         }
+      }
+   }
+   else {
+      _mesa_memcpy(dst, values, count * sizeof(GLubyte));
+   }
+}
+
+
+static void
+put_mono_row_ubyte(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                   GLint x, GLint y, const void *value, const GLubyte *mask)
+{
+   const GLubyte val = *((const GLubyte *) value);
+   GLubyte *dst = (GLubyte *) rb->Data + y * rb->Width + x;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            dst[i] = val;
+         }
+      }
+   }
+   else {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         dst[i] = val;
+      }
+   }
+}
+
+
+static void
+put_values_ubyte(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                 const GLint x[], const GLint y[],
+                 const void *values, const GLubyte *mask)
+{
+   const GLubyte *src = (const GLubyte *) values;
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLubyte *dst = (GLubyte *) rb->Data + y[i] * rb->Width + x[i];
+         *dst = src[i];
+      }
+   }
+}
+
+
+static void
+put_mono_values_ubyte(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                      const GLint x[], const GLint y[],
+                      const void *value, const GLubyte *mask)
+{
+   const GLubyte val = *((const GLubyte *) value);
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLubyte *dst = (GLubyte *) rb->Data + y[i] * rb->Width + x[i];
+         *dst = val;
+      }
+   }
+}
+
+
+/**********************************************************************
+ * Functions for buffers of 1 X GLushort values.
+ * Typically depth/Z.
+ */
+
+static void *
+get_pointer_ushort(GLcontext *ctx, struct gl_renderbuffer *rb,
+                   GLint x, GLint y)
+{
+   if (!rb->Data)
+      return NULL;
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT);
+   ASSERT(rb->Width > 0);
+   return (GLushort *) rb->Data + y * rb->Width + x;
+}
+
+
+static void
+get_row_ushort(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+               GLint x, GLint y, void *values)
+{
+   const void *src = rb->GetPointer(ctx, rb, x, y);
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT);
+   _mesa_memcpy(values, src, count * sizeof(GLushort));
+}
+
+
+static void
+get_values_ushort(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                  const GLint x[], const GLint y[], void *values)
+{
+   GLushort *dst = (GLushort *) values;
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT);
+   for (i = 0; i < count; i++) {
+      const GLushort *src = (GLushort *) rb->Data + y[i] * rb->Width + x[i];
+      dst[i] = *src;
+   }
+}
+
+
+static void
+put_row_ushort(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+               GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   const GLushort *src = (const GLushort *) values;
+   GLushort *dst = (GLushort *) rb->Data + y * rb->Width + x;
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT);
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            dst[i] = src[i];
+         }
+      }
+   }
+   else {
+      _mesa_memcpy(dst, src, count * sizeof(GLushort));
+   }
+}
+
+
+static void
+put_mono_row_ushort(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                    GLint x, GLint y, const void *value, const GLubyte *mask)
+{
+   const GLushort val = *((const GLushort *) value);
+   GLushort *dst = (GLushort *) rb->Data + y * rb->Width + x;
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT);
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            dst[i] = val;
+         }
+      }
+   }
+   else {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         dst[i] = val;
+      }
+   }
+}
+
+
+static void
+put_values_ushort(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                  const GLint x[], const GLint y[], const void *values,
+                  const GLubyte *mask)
+{
+   const GLushort *src = (const GLushort *) values;
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLushort *dst = (GLushort *) rb->Data + y[i] * rb->Width + x[i];
+         *dst = src[i];
+      }
+   }
+}
+ 
+
+static void
+put_mono_values_ushort(GLcontext *ctx, struct gl_renderbuffer *rb,
+                       GLuint count, const GLint x[], const GLint y[],
+                       const void *value, const GLubyte *mask)
+{
+   const GLushort val = *((const GLushort *) value);
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT);
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            GLushort *dst = (GLushort *) rb->Data + y[i] * rb->Width + x[i];
+            *dst = val;
+         }
+      }
+   }
+   else {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         GLushort *dst = (GLushort *) rb->Data + y[i] * rb->Width + x[i];
+         *dst = val;
+      }
+   }
+}
+ 
+
+/**********************************************************************
+ * Functions for buffers of 1 X GLuint values.
+ * Typically depth/Z or color index.
+ */
+
+static void *
+get_pointer_uint(GLcontext *ctx, struct gl_renderbuffer *rb,
+                 GLint x, GLint y)
+{
+   if (!rb->Data)
+      return NULL;
+   ASSERT(rb->DataType == GL_UNSIGNED_INT ||
+          rb->DataType == GL_UNSIGNED_INT_24_8_EXT);
+   return (GLuint *) rb->Data + y * rb->Width + x;
+}
+
+
+static void
+get_row_uint(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+             GLint x, GLint y, void *values)
+{
+   const void *src = rb->GetPointer(ctx, rb, x, y);
+   ASSERT(rb->DataType == GL_UNSIGNED_INT ||
+          rb->DataType == GL_UNSIGNED_INT_24_8_EXT);
+   _mesa_memcpy(values, src, count * sizeof(GLuint));
+}
+
+
+static void
+get_values_uint(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                const GLint x[], const GLint y[], void *values)
+{
+   GLuint *dst = (GLuint *) values;
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_INT ||
+          rb->DataType == GL_UNSIGNED_INT_24_8_EXT);
+   for (i = 0; i < count; i++) {
+      const GLuint *src = (GLuint *) rb->Data + y[i] * rb->Width + x[i];
+      dst[i] = *src;
+   }
+}
+
+
+static void
+put_row_uint(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+             GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   const GLuint *src = (const GLuint *) values;
+   GLuint *dst = (GLuint *) rb->Data + y * rb->Width + x;
+   ASSERT(rb->DataType == GL_UNSIGNED_INT ||
+          rb->DataType == GL_UNSIGNED_INT_24_8_EXT);
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            dst[i] = src[i];
+         }
+      }
+   }
+   else {
+      _mesa_memcpy(dst, src, count * sizeof(GLuint));
+   }
+}
+
+
+static void
+put_mono_row_uint(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                  GLint x, GLint y, const void *value, const GLubyte *mask)
+{
+   const GLuint val = *((const GLuint *) value);
+   GLuint *dst = (GLuint *) rb->Data + y * rb->Width + x;
+   ASSERT(rb->DataType == GL_UNSIGNED_INT ||
+          rb->DataType == GL_UNSIGNED_INT_24_8_EXT);
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            dst[i] = val;
+         }
+      }
+   }
+   else {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         dst[i] = val;
+      }
+   }
+}
+
+
+static void
+put_values_uint(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                const GLint x[], const GLint y[], const void *values,
+                const GLubyte *mask)
+{
+   const GLuint *src = (const GLuint *) values;
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_INT ||
+          rb->DataType == GL_UNSIGNED_INT_24_8_EXT);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLuint *dst = (GLuint *) rb->Data + y[i] * rb->Width + x[i];
+         *dst = src[i];
+      }
+   }
+}
+
+
+static void
+put_mono_values_uint(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                     const GLint x[], const GLint y[], const void *value,
+                     const GLubyte *mask)
+{
+   const GLuint val = *((const GLuint *) value);
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_INT ||
+          rb->DataType == GL_UNSIGNED_INT_24_8_EXT);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLuint *dst = (GLuint *) rb->Data + y[i] * rb->Width + x[i];
+         *dst = val;
+      }
+   }
+}
+
+
+/**********************************************************************
+ * Functions for buffers of 3 X GLubyte (or GLbyte) values.
+ * Typically color buffers.
+ * NOTE: the incoming and outgoing colors are RGBA!  We ignore incoming
+ * alpha values and return 255 for outgoing alpha values.
+ */
+
+static void *
+get_pointer_ubyte3(GLcontext *ctx, struct gl_renderbuffer *rb,
+                   GLint x, GLint y)
+{
+   ASSERT(rb->_ActualFormat == GL_RGB8);
+   /* No direct access since this buffer is RGB but caller will be
+    * treating it as if it were RGBA.
+    */
+   return NULL;
+}
+
+
+static void
+get_row_ubyte3(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+               GLint x, GLint y, void *values)
+{
+   const GLubyte *src = (const GLubyte *) rb->Data + 3 * (y * rb->Width + x);
+   GLubyte *dst = (GLubyte *) values;
+   GLuint i;
+   ASSERT(rb->_ActualFormat == GL_RGB8);
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   for (i = 0; i < count; i++) {
+      dst[i * 4 + 0] = src[i * 3 + 0];
+      dst[i * 4 + 1] = src[i * 3 + 1];
+      dst[i * 4 + 2] = src[i * 3 + 2];
+      dst[i * 4 + 3] = 255;
+   }
+}
+
+
+static void
+get_values_ubyte3(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                  const GLint x[], const GLint y[], void *values)
+{
+   GLubyte *dst = (GLubyte *) values;
+   GLuint i;
+   ASSERT(rb->_ActualFormat == GL_RGB8);
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   for (i = 0; i < count; i++) {
+      const GLubyte *src
+         = (GLubyte *) rb->Data + 3 * (y[i] * rb->Width + x[i]);
+      dst[i * 4 + 0] = src[0];
+      dst[i * 4 + 1] = src[1];
+      dst[i * 4 + 2] = src[2];
+      dst[i * 4 + 3] = 255;
+   }
+}
+
+
+static void
+put_row_ubyte3(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+               GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   /* note: incoming values are RGB+A! */
+   const GLubyte *src = (const GLubyte *) values;
+   GLubyte *dst = (GLubyte *) rb->Data + 3 * (y * rb->Width + x);
+   GLuint i;
+   ASSERT(rb->_ActualFormat == GL_RGB8);
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         dst[i * 3 + 0] = src[i * 4 + 0];
+         dst[i * 3 + 1] = src[i * 4 + 1];
+         dst[i * 3 + 2] = src[i * 4 + 2];
+      }
+   }
+}
+
+
+static void
+put_row_rgb_ubyte3(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                   GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   /* note: incoming values are RGB+A! */
+   const GLubyte *src = (const GLubyte *) values;
+   GLubyte *dst = (GLubyte *) rb->Data + 3 * (y * rb->Width + x);
+   GLuint i;
+   ASSERT(rb->_ActualFormat == GL_RGB8);
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         dst[i * 3 + 0] = src[i * 3 + 0];
+         dst[i * 3 + 1] = src[i * 3 + 1];
+         dst[i * 3 + 2] = src[i * 3 + 2];
+      }
+   }
+}
+
+
+static void
+put_mono_row_ubyte3(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                    GLint x, GLint y, const void *value, const GLubyte *mask)
+{
+   /* note: incoming value is RGB+A! */
+   const GLubyte val0 = ((const GLubyte *) value)[0];
+   const GLubyte val1 = ((const GLubyte *) value)[1];
+   const GLubyte val2 = ((const GLubyte *) value)[2];
+   GLubyte *dst = (GLubyte *) rb->Data + 3 * (y * rb->Width + x);
+   ASSERT(rb->_ActualFormat == GL_RGB8);
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   if (!mask && val0 == val1 && val1 == val2) {
+      /* optimized case */
+      _mesa_memset(dst, val0, 3 * count);
+   }
+   else {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (!mask || mask[i]) {
+            dst[i * 3 + 0] = val0;
+            dst[i * 3 + 1] = val1;
+            dst[i * 3 + 2] = val2;
+         }
+      }
+   }
+}
+
+
+static void
+put_values_ubyte3(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                  const GLint x[], const GLint y[], const void *values,
+                  const GLubyte *mask)
+{
+   /* note: incoming values are RGB+A! */
+   const GLubyte *src = (const GLubyte *) values;
+   GLuint i;
+   ASSERT(rb->_ActualFormat == GL_RGB8);
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLubyte *dst = (GLubyte *) rb->Data + 3 * (y[i] * rb->Width + x[i]);
+         dst[0] = src[i * 4 + 0];
+         dst[1] = src[i * 4 + 1];
+         dst[2] = src[i * 4 + 2];
+      }
+   }
+}
+
+
+static void
+put_mono_values_ubyte3(GLcontext *ctx, struct gl_renderbuffer *rb,
+                       GLuint count, const GLint x[], const GLint y[],
+                       const void *value, const GLubyte *mask)
+{
+   /* note: incoming value is RGB+A! */
+   const GLubyte val0 = ((const GLubyte *) value)[0];
+   const GLubyte val1 = ((const GLubyte *) value)[1];
+   const GLubyte val2 = ((const GLubyte *) value)[2];
+   GLuint i;
+   ASSERT(rb->_ActualFormat == GL_RGB8);
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLubyte *dst = (GLubyte *) rb->Data + 3 * (y[i] * rb->Width + x[i]);
+         dst[0] = val0;
+         dst[1] = val1;
+         dst[2] = val2;
+      }
+   }
+}
+
+
+/**********************************************************************
+ * Functions for buffers of 4 X GLubyte (or GLbyte) values.
+ * Typically color buffers.
+ */
+
+static void *
+get_pointer_ubyte4(GLcontext *ctx, struct gl_renderbuffer *rb,
+                   GLint x, GLint y)
+{
+   if (!rb->Data)
+      return NULL;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   ASSERT(rb->_ActualFormat == GL_RGBA8);
+   return (GLubyte *) rb->Data + 4 * (y * rb->Width + x);
+}
+
+
+static void
+get_row_ubyte4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+               GLint x, GLint y, void *values)
+{
+   const GLubyte *src = (const GLubyte *) rb->Data + 4 * (y * rb->Width + x);
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   ASSERT(rb->_ActualFormat == GL_RGBA8);
+   _mesa_memcpy(values, src, 4 * count * sizeof(GLubyte));
+}
+
+
+static void
+get_values_ubyte4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                  const GLint x[], const GLint y[], void *values)
+{
+   /* treat 4*GLubyte as 1*GLuint */
+   GLuint *dst = (GLuint *) values;
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   ASSERT(rb->_ActualFormat == GL_RGBA8);
+   for (i = 0; i < count; i++) {
+      const GLuint *src = (GLuint *) rb->Data + (y[i] * rb->Width + x[i]);
+      dst[i] = *src;
+   }
+}
+
+
+static void
+put_row_ubyte4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+               GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   /* treat 4*GLubyte as 1*GLuint */
+   const GLuint *src = (const GLuint *) values;
+   GLuint *dst = (GLuint *) rb->Data + (y * rb->Width + x);
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   ASSERT(rb->_ActualFormat == GL_RGBA8);
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            dst[i] = src[i];
+         }
+      }
+   }
+   else {
+      _mesa_memcpy(dst, src, 4 * count * sizeof(GLubyte));
+   }
+}
+
+
+static void
+put_row_rgb_ubyte4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                   GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   /* Store RGB values in RGBA buffer */
+   const GLubyte *src = (const GLubyte *) values;
+   GLubyte *dst = (GLubyte *) rb->Data + 4 * (y * rb->Width + x);
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   ASSERT(rb->_ActualFormat == GL_RGBA8);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         dst[i * 4 + 0] = src[i * 3 + 0];
+         dst[i * 4 + 1] = src[i * 3 + 1];
+         dst[i * 4 + 2] = src[i * 3 + 2];
+         dst[i * 4 + 3] = 0xff;
+      }
+   }
+}
+
+
+static void
+put_mono_row_ubyte4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                    GLint x, GLint y, const void *value, const GLubyte *mask)
+{
+   /* treat 4*GLubyte as 1*GLuint */
+   const GLuint val = *((const GLuint *) value);
+   GLuint *dst = (GLuint *) rb->Data + (y * rb->Width + x);
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   ASSERT(rb->_ActualFormat == GL_RGBA8);
+   if (!mask && val == 0) {
+      /* common case */
+      _mesa_bzero(dst, count * 4 * sizeof(GLubyte));
+   }
+   else {
+      /* general case */
+      if (mask) {
+         GLuint i;
+         for (i = 0; i < count; i++) {
+            if (mask[i]) {
+               dst[i] = val;
+            }
+         }
+      }
+      else {
+         GLuint i;
+         for (i = 0; i < count; i++) {
+            dst[i] = val;
+         }
+      }
+   }
+}
+
+
+static void
+put_values_ubyte4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                  const GLint x[], const GLint y[], const void *values,
+                  const GLubyte *mask)
+{
+   /* treat 4*GLubyte as 1*GLuint */
+   const GLuint *src = (const GLuint *) values;
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   ASSERT(rb->_ActualFormat == GL_RGBA8);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLuint *dst = (GLuint *) rb->Data + (y[i] * rb->Width + x[i]);
+         *dst = src[i];
+      }
+   }
+}
+
+
+static void
+put_mono_values_ubyte4(GLcontext *ctx, struct gl_renderbuffer *rb,
+                       GLuint count, const GLint x[], const GLint y[],
+                       const void *value, const GLubyte *mask)
+{
+   /* treat 4*GLubyte as 1*GLuint */
+   const GLuint val = *((const GLuint *) value);
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_BYTE);
+   ASSERT(rb->_ActualFormat == GL_RGBA8);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLuint *dst = (GLuint *) rb->Data + (y[i] * rb->Width + x[i]);
+         *dst = val;
+      }
+   }
+}
+
+
+/**********************************************************************
+ * Functions for buffers of 4 X GLushort (or GLshort) values.
+ * Typically accum buffer.
+ */
+
+static void *
+get_pointer_ushort4(GLcontext *ctx, struct gl_renderbuffer *rb,
+                    GLint x, GLint y)
+{
+   if (!rb->Data)
+      return NULL;
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT || rb->DataType == GL_SHORT);
+   return (GLushort *) rb->Data + 4 * (y * rb->Width + x);
+}
+
+
+static void
+get_row_ushort4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                GLint x, GLint y, void *values)
+{
+   const GLshort *src = (const GLshort *) rb->Data + 4 * (y * rb->Width + x);
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT || rb->DataType == GL_SHORT);
+   _mesa_memcpy(values, src, 4 * count * sizeof(GLshort));
+}
+
+
+static void
+get_values_ushort4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                   const GLint x[], const GLint y[], void *values)
+{
+   GLushort *dst = (GLushort *) values;
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT || rb->DataType == GL_SHORT);
+   for (i = 0; i < count; i++) {
+      const GLushort *src
+         = (GLushort *) rb->Data + 4 * (y[i] * rb->Width + x[i]);
+      dst[i] = *src;
+   }
+}
+
+
+static void
+put_row_ushort4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   const GLushort *src = (const GLushort *) values;
+   GLushort *dst = (GLushort *) rb->Data + 4 * (y * rb->Width + x);
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT || rb->DataType == GL_SHORT);
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            dst[i * 4 + 0] = src[i * 4 + 0];
+            dst[i * 4 + 1] = src[i * 4 + 1];
+            dst[i * 4 + 2] = src[i * 4 + 2];
+            dst[i * 4 + 3] = src[i * 4 + 3];
+         }
+      }
+   }
+   else {
+      _mesa_memcpy(dst, src, 4 * count * sizeof(GLushort));
+   }
+}
+
+
+static void
+put_row_rgb_ushort4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                    GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   /* Put RGB values in RGBA buffer */
+   const GLushort *src = (const GLushort *) values;
+   GLushort *dst = (GLushort *) rb->Data + 4 * (y * rb->Width + x);
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT || rb->DataType == GL_SHORT);
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            dst[i * 4 + 0] = src[i * 3 + 0];
+            dst[i * 4 + 1] = src[i * 3 + 1];
+            dst[i * 4 + 2] = src[i * 3 + 2];
+            dst[i * 4 + 3] = 0xffff;
+         }
+      }
+   }
+   else {
+      _mesa_memcpy(dst, src, 4 * count * sizeof(GLushort));
+   }
+}
+
+
+static void
+put_mono_row_ushort4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                     GLint x, GLint y, const void *value, const GLubyte *mask)
+{
+   const GLushort val0 = ((const GLushort *) value)[0];
+   const GLushort val1 = ((const GLushort *) value)[1];
+   const GLushort val2 = ((const GLushort *) value)[2];
+   const GLushort val3 = ((const GLushort *) value)[3];
+   GLushort *dst = (GLushort *) rb->Data + 4 * (y * rb->Width + x);
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT || rb->DataType == GL_SHORT);
+   if (!mask && val0 == 0 && val1 == 0 && val2 == 0 && val3 == 0) {
+      /* common case for clearing accum buffer */
+      _mesa_bzero(dst, count * 4 * sizeof(GLushort));
+   }
+   else {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (!mask || mask[i]) {
+            dst[i * 4 + 0] = val0;
+            dst[i * 4 + 1] = val1;
+            dst[i * 4 + 2] = val2;
+            dst[i * 4 + 3] = val3;
+         }
+      }
+   }
+}
+
+
+static void
+put_values_ushort4(GLcontext *ctx, struct gl_renderbuffer *rb, GLuint count,
+                   const GLint x[], const GLint y[], const void *values,
+                   const GLubyte *mask)
+{
+   const GLushort *src = (const GLushort *) values;
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT || rb->DataType == GL_SHORT);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLushort *dst = (GLushort *) rb->Data + 4 * (y[i] * rb->Width + x[i]);
+         dst[0] = src[i * 4 + 0];
+         dst[1] = src[i * 4 + 1];
+         dst[2] = src[i * 4 + 2];
+         dst[3] = src[i * 4 + 3];
+      }
+   }
+}
+
+
+static void
+put_mono_values_ushort4(GLcontext *ctx, struct gl_renderbuffer *rb,
+                        GLuint count, const GLint x[], const GLint y[],
+                        const void *value, const GLubyte *mask)
+{
+   const GLushort val0 = ((const GLushort *) value)[0];
+   const GLushort val1 = ((const GLushort *) value)[1];
+   const GLushort val2 = ((const GLushort *) value)[2];
+   const GLushort val3 = ((const GLushort *) value)[3];
+   GLuint i;
+   ASSERT(rb->DataType == GL_UNSIGNED_SHORT || rb->DataType == GL_SHORT);
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLushort *dst = (GLushort *) rb->Data + 4 * (y[i] * rb->Width + x[i]);
+         dst[0] = val0;
+         dst[1] = val1;
+         dst[2] = val2;
+         dst[3] = val3;
+      }
+   }
+}
+
+
+
+/**
+ * This is a software fallback for the gl_renderbuffer->AllocStorage
+ * function.
+ * Device drivers will typically override this function for the buffers
+ * which it manages (typically color buffers, Z and stencil).
+ * Other buffers (like software accumulation and aux buffers) which the driver
+ * doesn't manage can be handled with this function.
+ *
+ * This one multi-purpose function can allocate stencil, depth, accum, color
+ * or color-index buffers!
+ *
+ * This function also plugs in the appropriate GetPointer, Get/PutRow and
+ * Get/PutValues functions.
+ */
+GLboolean
+_mesa_soft_renderbuffer_storage(GLcontext *ctx, struct gl_renderbuffer *rb,
+                                GLenum internalFormat,
+                                GLuint width, GLuint height)
+{
+   GLuint pixelSize;
+
+   /* first clear these fields */
+   rb->RedBits =
+   rb->GreenBits =
+   rb->BlueBits =
+   rb->AlphaBits =
+   rb->IndexBits =
+   rb->DepthBits =
+   rb->StencilBits = 0;
+
+   switch (internalFormat) {
+   case GL_RGB:
+   case GL_R3_G3_B2:
+   case GL_RGB4:
+   case GL_RGB5:
+   case GL_RGB8:
+   case GL_RGB10:
+   case GL_RGB12:
+   case GL_RGB16:
+      rb->_ActualFormat = GL_RGB8;
+      rb->_BaseFormat = GL_RGB;
+      rb->DataType = GL_UNSIGNED_BYTE;
+      rb->GetPointer = get_pointer_ubyte3;
+      rb->GetRow = get_row_ubyte3;
+      rb->GetValues = get_values_ubyte3;
+      rb->PutRow = put_row_ubyte3;
+      rb->PutRowRGB = put_row_rgb_ubyte3;
+      rb->PutMonoRow = put_mono_row_ubyte3;
+      rb->PutValues = put_values_ubyte3;
+      rb->PutMonoValues = put_mono_values_ubyte3;
+      rb->RedBits   = 8 * sizeof(GLubyte);
+      rb->GreenBits = 8 * sizeof(GLubyte);
+      rb->BlueBits  = 8 * sizeof(GLubyte);
+      rb->AlphaBits = 0;
+      pixelSize = 3 * sizeof(GLubyte);
+      break;
+   case GL_RGBA:
+   case GL_RGBA2:
+   case GL_RGBA4:
+   case GL_RGB5_A1:
+   case GL_RGBA8:
+      rb->_ActualFormat = GL_RGBA8;
+      rb->_BaseFormat = GL_RGBA;
+      rb->DataType = GL_UNSIGNED_BYTE;
+      rb->GetPointer = get_pointer_ubyte4;
+      rb->GetRow = get_row_ubyte4;
+      rb->GetValues = get_values_ubyte4;
+      rb->PutRow = put_row_ubyte4;
+      rb->PutRowRGB = put_row_rgb_ubyte4;
+      rb->PutMonoRow = put_mono_row_ubyte4;
+      rb->PutValues = put_values_ubyte4;
+      rb->PutMonoValues = put_mono_values_ubyte4;
+      rb->RedBits   = 8 * sizeof(GLubyte);
+      rb->GreenBits = 8 * sizeof(GLubyte);
+      rb->BlueBits  = 8 * sizeof(GLubyte);
+      rb->AlphaBits = 8 * sizeof(GLubyte);
+      pixelSize = 4 * sizeof(GLubyte);
+      break;
+   case GL_RGB10_A2:
+   case GL_RGBA12:
+   case GL_RGBA16:
+      rb->_ActualFormat = GL_RGBA16;
+      rb->_BaseFormat = GL_RGBA;
+      rb->DataType = GL_UNSIGNED_SHORT;
+      rb->GetPointer = get_pointer_ushort4;
+      rb->GetRow = get_row_ushort4;
+      rb->GetValues = get_values_ushort4;
+      rb->PutRow = put_row_ushort4;
+      rb->PutRowRGB = put_row_rgb_ushort4;
+      rb->PutMonoRow = put_mono_row_ushort4;
+      rb->PutValues = put_values_ushort4;
+      rb->PutMonoValues = put_mono_values_ushort4;
+      rb->RedBits   = 8 * sizeof(GLushort);
+      rb->GreenBits = 8 * sizeof(GLushort);
+      rb->BlueBits  = 8 * sizeof(GLushort);
+      rb->AlphaBits = 8 * sizeof(GLushort);
+      pixelSize = 4 * sizeof(GLushort);
+      break;
+#if 00
+   case GL_ALPHA8:
+      rb->_ActualFormat = GL_ALPHA8;
+      rb->_BaseFormat = GL_RGBA; /* Yes, not GL_ALPHA! */
+      rb->DataType = GL_UNSIGNED_BYTE;
+      rb->GetPointer = get_pointer_alpha8;
+      rb->GetRow = get_row_alpha8;
+      rb->GetValues = get_values_alpha8;
+      rb->PutRow = put_row_alpha8;
+      rb->PutRowRGB = NULL;
+      rb->PutMonoRow = put_mono_row_alpha8;
+      rb->PutValues = put_values_alpha8;
+      rb->PutMonoValues = put_mono_values_alpha8;
+      rb->RedBits   = 0; /*red*/
+      rb->GreenBits = 0; /*green*/
+      rb->BlueBits  = 0; /*blue*/
+      rb->AlphaBits = 8 * sizeof(GLubyte);
+      pixelSize = sizeof(GLubyte);
+      break;
+#endif
+   case GL_STENCIL_INDEX:
+   case GL_STENCIL_INDEX1_EXT:
+   case GL_STENCIL_INDEX4_EXT:
+   case GL_STENCIL_INDEX8_EXT:
+      rb->_ActualFormat = GL_STENCIL_INDEX8_EXT;
+      rb->_BaseFormat = GL_STENCIL_INDEX;
+      rb->DataType = GL_UNSIGNED_BYTE;
+      rb->GetPointer = get_pointer_ubyte;
+      rb->GetRow = get_row_ubyte;
+      rb->GetValues = get_values_ubyte;
+      rb->PutRow = put_row_ubyte;
+      rb->PutRowRGB = NULL;
+      rb->PutMonoRow = put_mono_row_ubyte;
+      rb->PutValues = put_values_ubyte;
+      rb->PutMonoValues = put_mono_values_ubyte;
+      rb->StencilBits = 8 * sizeof(GLubyte);
+      pixelSize = sizeof(GLubyte);
+      break;
+   case GL_STENCIL_INDEX16_EXT:
+      rb->_ActualFormat = GL_STENCIL_INDEX16_EXT;
+      rb->_BaseFormat = GL_STENCIL_INDEX;
+      rb->DataType = GL_UNSIGNED_SHORT;
+      rb->GetPointer = get_pointer_ushort;
+      rb->GetRow = get_row_ushort;
+      rb->GetValues = get_values_ushort;
+      rb->PutRow = put_row_ushort;
+      rb->PutRowRGB = NULL;
+      rb->PutMonoRow = put_mono_row_ushort;
+      rb->PutValues = put_values_ushort;
+      rb->PutMonoValues = put_mono_values_ushort;
+      rb->StencilBits = 8 * sizeof(GLushort);
+      pixelSize = sizeof(GLushort);
+      break;
+   case GL_DEPTH_COMPONENT:
+   case GL_DEPTH_COMPONENT16:
+      rb->_ActualFormat = GL_DEPTH_COMPONENT16;
+      rb->_BaseFormat = GL_DEPTH_COMPONENT;
+      rb->DataType = GL_UNSIGNED_SHORT;
+      rb->GetPointer = get_pointer_ushort;
+      rb->GetRow = get_row_ushort;
+      rb->GetValues = get_values_ushort;
+      rb->PutRow = put_row_ushort;
+      rb->PutRowRGB = NULL;
+      rb->PutMonoRow = put_mono_row_ushort;
+      rb->PutValues = put_values_ushort;
+      rb->PutMonoValues = put_mono_values_ushort;
+      rb->DepthBits = 8 * sizeof(GLushort);
+      pixelSize = sizeof(GLushort);
+      break;
+   case GL_DEPTH_COMPONENT24:
+   case GL_DEPTH_COMPONENT32:
+      rb->_BaseFormat = GL_DEPTH_COMPONENT;
+      rb->DataType = GL_UNSIGNED_INT;
+      rb->GetPointer = get_pointer_uint;
+      rb->GetRow = get_row_uint;
+      rb->GetValues = get_values_uint;
+      rb->PutRow = put_row_uint;
+      rb->PutRowRGB = NULL;
+      rb->PutMonoRow = put_mono_row_uint;
+      rb->PutValues = put_values_uint;
+      rb->PutMonoValues = put_mono_values_uint;
+      if (internalFormat == GL_DEPTH_COMPONENT24) {
+         rb->_ActualFormat = GL_DEPTH_COMPONENT24;
+         rb->DepthBits = 24;
+      }
+      else {
+         rb->_ActualFormat = GL_DEPTH_COMPONENT32;
+         rb->DepthBits = 32;
+      }
+      pixelSize = sizeof(GLuint);
+      break;
+   case GL_DEPTH_STENCIL_EXT:
+   case GL_DEPTH24_STENCIL8_EXT:
+      rb->_ActualFormat = GL_DEPTH24_STENCIL8_EXT;
+      rb->_BaseFormat = GL_DEPTH_STENCIL_EXT;
+      rb->DataType = GL_UNSIGNED_INT_24_8_EXT;
+      rb->GetPointer = get_pointer_uint;
+      rb->GetRow = get_row_uint;
+      rb->GetValues = get_values_uint;
+      rb->PutRow = put_row_uint;
+      rb->PutRowRGB = NULL;
+      rb->PutMonoRow = put_mono_row_uint;
+      rb->PutValues = put_values_uint;
+      rb->PutMonoValues = put_mono_values_uint;
+      rb->DepthBits = 24;
+      rb->StencilBits = 8;
+      pixelSize = sizeof(GLuint);
+      break;
+   case GL_COLOR_INDEX8_EXT:
+      rb->_ActualFormat = GL_COLOR_INDEX8_EXT;
+      rb->_BaseFormat = GL_COLOR_INDEX;
+      rb->DataType = GL_UNSIGNED_BYTE;
+      rb->GetPointer = get_pointer_ubyte;
+      rb->GetRow = get_row_ubyte;
+      rb->GetValues = get_values_ubyte;
+      rb->PutRow = put_row_ubyte;
+      rb->PutRowRGB = NULL;
+      rb->PutMonoRow = put_mono_row_ubyte;
+      rb->PutValues = put_values_ubyte;
+      rb->PutMonoValues = put_mono_values_ubyte;
+      rb->IndexBits = 8 * sizeof(GLubyte);
+      pixelSize = sizeof(GLubyte);
+      break;
+   case GL_COLOR_INDEX16_EXT:
+      rb->_ActualFormat = GL_COLOR_INDEX16_EXT;
+      rb->_BaseFormat = GL_COLOR_INDEX;
+      rb->DataType = GL_UNSIGNED_SHORT;
+      rb->GetPointer = get_pointer_ushort;
+      rb->GetRow = get_row_ushort;
+      rb->GetValues = get_values_ushort;
+      rb->PutRow = put_row_ushort;
+      rb->PutRowRGB = NULL;
+      rb->PutMonoRow = put_mono_row_ushort;
+      rb->PutValues = put_values_ushort;
+      rb->PutMonoValues = put_mono_values_ushort;
+      rb->IndexBits = 8 * sizeof(GLushort);
+      pixelSize = sizeof(GLushort);
+      break;
+   case COLOR_INDEX32:
+      rb->_ActualFormat = COLOR_INDEX32;
+      rb->_BaseFormat = GL_COLOR_INDEX;
+      rb->DataType = GL_UNSIGNED_INT;
+      rb->GetPointer = get_pointer_uint;
+      rb->GetRow = get_row_uint;
+      rb->GetValues = get_values_uint;
+      rb->PutRow = put_row_uint;
+      rb->PutRowRGB = NULL;
+      rb->PutMonoRow = put_mono_row_uint;
+      rb->PutValues = put_values_uint;
+      rb->PutMonoValues = put_mono_values_uint;
+      rb->IndexBits = 8 * sizeof(GLuint);
+      pixelSize = sizeof(GLuint);
+      break;
+   default:
+      _mesa_problem(ctx, "Bad internalFormat in _mesa_soft_renderbuffer_storage");
+      return GL_FALSE;
+   }
+
+   ASSERT(rb->DataType);
+   ASSERT(rb->GetPointer);
+   ASSERT(rb->GetRow);
+   ASSERT(rb->GetValues);
+   ASSERT(rb->PutRow);
+   ASSERT(rb->PutMonoRow);
+   ASSERT(rb->PutValues);
+   ASSERT(rb->PutMonoValues);
+
+   /* free old buffer storage */
+   if (rb->Data) {
+      _mesa_free(rb->Data);
+      rb->Data = NULL;
+   }
+
+   if (width > 0 && height > 0) {
+      /* allocate new buffer storage */
+      rb->Data = malloc(width * height * pixelSize);
+
+      if (rb->Data == NULL) {
+         rb->Width = 0;
+         rb->Height = 0;
+         _mesa_error(ctx, GL_OUT_OF_MEMORY,
+                     "software renderbuffer allocation (%d x %d x %d)",
+                     width, height, pixelSize);
+         return GL_FALSE;
+      }
+   }
+
+   rb->Width = width;
+   rb->Height = height;
+
+   return GL_TRUE;
+}
+
+
+
+/**********************************************************************/
+/**********************************************************************/
+/**********************************************************************/
+
+
+/**
+ * Here we utilize the gl_renderbuffer->Wrapper field to put an alpha
+ * buffer wrapper around an existing RGB renderbuffer (hw or sw).
+ *
+ * When PutRow is called (for example), we store the alpha values in
+ * this buffer, then pass on the PutRow call to the wrapped RGB
+ * buffer.
+ */
+
+
+static GLboolean
+alloc_storage_alpha8(GLcontext *ctx, struct gl_renderbuffer *arb,
+                     GLenum internalFormat, GLuint width, GLuint height)
+{
+   ASSERT(arb != arb->Wrapped);
+   ASSERT(arb->_ActualFormat == GL_ALPHA8);
+
+   /* first, pass the call to the wrapped RGB buffer */
+   if (!arb->Wrapped->AllocStorage(ctx, arb->Wrapped, internalFormat,
+                                  width, height)) {
+      return GL_FALSE;
+   }
+
+   /* next, resize my alpha buffer */
+   if (arb->Data) {
+      _mesa_free(arb->Data);
+   }
+
+   arb->Data = _mesa_malloc(width * height * sizeof(GLubyte));
+   if (arb->Data == NULL) {
+      arb->Width = 0;
+      arb->Height = 0;
+      _mesa_error(ctx, GL_OUT_OF_MEMORY, "software alpha buffer allocation");
+      return GL_FALSE;
+   }
+
+   arb->Width = width;
+   arb->Height = height;
+
+   return GL_TRUE;
+}
+
+
+/**
+ * Delete an alpha_renderbuffer object, as well as the wrapped RGB buffer.
+ */
+static void
+delete_renderbuffer_alpha8(struct gl_renderbuffer *arb)
+{
+   if (arb->Data) {
+      _mesa_free(arb->Data);
+   }
+   ASSERT(arb->Wrapped);
+   ASSERT(arb != arb->Wrapped);
+   arb->Wrapped->Delete(arb->Wrapped);
+   arb->Wrapped = NULL;
+   _mesa_free(arb);
+}
+
+
+static void *
+get_pointer_alpha8(GLcontext *ctx, struct gl_renderbuffer *arb,
+                   GLint x, GLint y)
+{
+   return NULL;   /* don't allow direct access! */
+}
+
+
+static void
+get_row_alpha8(GLcontext *ctx, struct gl_renderbuffer *arb, GLuint count,
+               GLint x, GLint y, void *values)
+{
+   /* NOTE: 'values' is RGBA format! */
+   const GLubyte *src = (const GLubyte *) arb->Data + y * arb->Width + x;
+   GLubyte *dst = (GLubyte *) values;
+   GLuint i;
+   ASSERT(arb != arb->Wrapped);
+   ASSERT(arb->DataType == GL_UNSIGNED_BYTE);
+   /* first, pass the call to the wrapped RGB buffer */
+   arb->Wrapped->GetRow(ctx, arb->Wrapped, count, x, y, values);
+   /* second, fill in alpha values from this buffer! */
+   for (i = 0; i < count; i++) {
+      dst[i * 4 + 3] = src[i];
+   }
+}
+
+
+static void
+get_values_alpha8(GLcontext *ctx, struct gl_renderbuffer *arb, GLuint count,
+                  const GLint x[], const GLint y[], void *values)
+{
+   GLubyte *dst = (GLubyte *) values;
+   GLuint i;
+   ASSERT(arb != arb->Wrapped);
+   ASSERT(arb->DataType == GL_UNSIGNED_BYTE);
+   /* first, pass the call to the wrapped RGB buffer */
+   arb->Wrapped->GetValues(ctx, arb->Wrapped, count, x, y, values);
+   /* second, fill in alpha values from this buffer! */
+   for (i = 0; i < count; i++) {
+      const GLubyte *src = (GLubyte *) arb->Data + y[i] * arb->Width + x[i];
+      dst[i * 4 + 3] = *src;
+   }
+}
+
+
+static void
+put_row_alpha8(GLcontext *ctx, struct gl_renderbuffer *arb, GLuint count,
+               GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   const GLubyte *src = (const GLubyte *) values;
+   GLubyte *dst = (GLubyte *) arb->Data + y * arb->Width + x;
+   GLuint i;
+   ASSERT(arb != arb->Wrapped);
+   ASSERT(arb->DataType == GL_UNSIGNED_BYTE);
+   /* first, pass the call to the wrapped RGB buffer */
+   arb->Wrapped->PutRow(ctx, arb->Wrapped, count, x, y, values, mask);
+   /* second, store alpha in our buffer */
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         dst[i] = src[i * 4 + 3];
+      }
+   }
+}
+
+
+static void
+put_row_rgb_alpha8(GLcontext *ctx, struct gl_renderbuffer *arb, GLuint count,
+                   GLint x, GLint y, const void *values, const GLubyte *mask)
+{
+   const GLubyte *src = (const GLubyte *) values;
+   GLubyte *dst = (GLubyte *) arb->Data + y * arb->Width + x;
+   GLuint i;
+   ASSERT(arb != arb->Wrapped);
+   ASSERT(arb->DataType == GL_UNSIGNED_BYTE);
+   /* first, pass the call to the wrapped RGB buffer */
+   arb->Wrapped->PutRowRGB(ctx, arb->Wrapped, count, x, y, values, mask);
+   /* second, store alpha in our buffer */
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         dst[i] = src[i * 4 + 3];
+      }
+   }
+}
+
+
+static void
+put_mono_row_alpha8(GLcontext *ctx, struct gl_renderbuffer *arb, GLuint count,
+                    GLint x, GLint y, const void *value, const GLubyte *mask)
+{
+   const GLubyte val = ((const GLubyte *) value)[3];
+   GLubyte *dst = (GLubyte *) arb->Data + y * arb->Width + x;
+   ASSERT(arb != arb->Wrapped);
+   ASSERT(arb->DataType == GL_UNSIGNED_BYTE);
+   /* first, pass the call to the wrapped RGB buffer */
+   arb->Wrapped->PutMonoRow(ctx, arb->Wrapped, count, x, y, value, mask);
+   /* second, store alpha in our buffer */
+   if (mask) {
+      GLuint i;
+      for (i = 0; i < count; i++) {
+         if (mask[i]) {
+            dst[i] = val;
+         }
+      }
+   }
+   else {
+      _mesa_memset(dst, val, count);
+   }
+}
+
+
+static void
+put_values_alpha8(GLcontext *ctx, struct gl_renderbuffer *arb, GLuint count,
+                  const GLint x[], const GLint y[],
+                  const void *values, const GLubyte *mask)
+{
+   const GLubyte *src = (const GLubyte *) values;
+   GLuint i;
+   ASSERT(arb != arb->Wrapped);
+   ASSERT(arb->DataType == GL_UNSIGNED_BYTE);
+   /* first, pass the call to the wrapped RGB buffer */
+   arb->Wrapped->PutValues(ctx, arb->Wrapped, count, x, y, values, mask);
+   /* second, store alpha in our buffer */
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLubyte *dst = (GLubyte *) arb->Data + y[i] * arb->Width + x[i];
+         *dst = src[i * 4 + 3];
+      }
+   }
+}
+
+
+static void
+put_mono_values_alpha8(GLcontext *ctx, struct gl_renderbuffer *arb,
+                       GLuint count, const GLint x[], const GLint y[],
+                       const void *value, const GLubyte *mask)
+{
+   const GLubyte val = ((const GLubyte *) value)[3];
+   GLuint i;
+   ASSERT(arb != arb->Wrapped);
+   ASSERT(arb->DataType == GL_UNSIGNED_BYTE);
+   /* first, pass the call to the wrapped RGB buffer */
+   arb->Wrapped->PutValues(ctx, arb->Wrapped, count, x, y, value, mask);
+   /* second, store alpha in our buffer */
+   for (i = 0; i < count; i++) {
+      if (!mask || mask[i]) {
+         GLubyte *dst = (GLubyte *) arb->Data + y[i] * arb->Width + x[i];
+         *dst = val;
+      }
+   }
+}
+
+
+static void
+copy_buffer_alpha8(struct gl_renderbuffer* dst, struct gl_renderbuffer* src)
+{
+   ASSERT(dst->_ActualFormat == GL_ALPHA8);
+   ASSERT(src->_ActualFormat == GL_ALPHA8);
+   ASSERT(dst->Width == src->Width);
+   ASSERT(dst->Height == src->Height);
+
+   _mesa_memcpy(dst->Data, src->Data, dst->Width * dst->Height * sizeof(GLubyte));
+}
+
+
+/**********************************************************************/
+/**********************************************************************/
+/**********************************************************************/
+
+
+/**
+ * Default GetPointer routine.  Always return NULL to indicate that
+ * direct buffer access is not supported.
+ */
+static void *
+nop_get_pointer(GLcontext *ctx, struct gl_renderbuffer *rb, GLint x, GLint y)
+{
+   return NULL;
+}
+
+
+/**
+ * Initialize the fields of a gl_renderbuffer to default values.
+ */
+void
+_mesa_init_renderbuffer(struct gl_renderbuffer *rb, GLuint name)
+{
+   _glthread_INIT_MUTEX(rb->Mutex);
+
+   rb->Magic = RB_MAGIC;
+   rb->ClassID = 0;
+   rb->Name = name;
+   rb->RefCount = 0;
+   rb->Delete = _mesa_delete_renderbuffer;
+
+   /* The rest of these should be set later by the caller of this function or
+    * the AllocStorage method:
+    */
+   rb->AllocStorage = NULL;
+
+   rb->Width = 0;
+   rb->Height = 0;
+   rb->InternalFormat = GL_NONE;
+   rb->_ActualFormat = GL_NONE;
+   rb->_BaseFormat = GL_NONE;
+
+   rb->ComponentType = GL_UNSIGNED_NORMALIZED; /* ARB_fbo */
+   rb->ColorEncoding = GL_LINEAR; /* ARB_fbo */
+
+   rb->RedBits = rb->GreenBits = rb->BlueBits = rb->AlphaBits = 0;
+   rb->IndexBits = 0;
+   rb->DepthBits = 0;
+   rb->StencilBits = 0;
+
+   rb->DataType = GL_NONE;
+   rb->Data = NULL;
+
+   /* Point back to ourself so that we don't have to check for Wrapped==NULL
+    * all over the drivers.
+    */
+   rb->Wrapped = rb;
+
+   rb->GetPointer = nop_get_pointer;
+   rb->GetRow = NULL;
+   rb->GetValues = NULL;
+   rb->PutRow = NULL;
+   rb->PutRowRGB = NULL;
+   rb->PutMonoRow = NULL;
+   rb->PutValues = NULL;
+   rb->PutMonoValues = NULL;
+}
+
+
+/**
+ * Allocate a new gl_renderbuffer object.  This can be used for user-created
+ * renderbuffers or window-system renderbuffers.
+ */
+struct gl_renderbuffer *
+_mesa_new_renderbuffer(GLcontext *ctx, GLuint name)
+{
+   struct gl_renderbuffer *rb = CALLOC_STRUCT(gl_renderbuffer);
+   if (rb) {
+      _mesa_init_renderbuffer(rb, name);
+   }
+   return rb;
+}
+
+
+/**
+ * Delete a gl_framebuffer.
+ * This is the default function for renderbuffer->Delete().
+ */
+void
+_mesa_delete_renderbuffer(struct gl_renderbuffer *rb)
+{
+   if (rb->Data) {
+      _mesa_free(rb->Data);
+   }
+   _mesa_free(rb);
+}
+
+
+/**
+ * Allocate a software-based renderbuffer.  This is called via the
+ * ctx->Driver.NewRenderbuffer() function when the user creates a new
+ * renderbuffer.
+ * This would not be used for hardware-based renderbuffers.
+ */
+struct gl_renderbuffer *
+_mesa_new_soft_renderbuffer(GLcontext *ctx, GLuint name)
+{
+   struct gl_renderbuffer *rb = _mesa_new_renderbuffer(ctx, name);
+   if (rb) {
+      rb->AllocStorage = _mesa_soft_renderbuffer_storage;
+      /* Normally, one would setup the PutRow, GetRow, etc functions here.
+       * But we're doing that in the _mesa_soft_renderbuffer_storage() function
+       * instead.
+       */
+   }
+   return rb;
+}
+
+
+/**
+ * Add software-based color renderbuffers to the given framebuffer.
+ * This is a helper routine for device drivers when creating a
+ * window system framebuffer (not a user-created render/framebuffer).
+ * Once this function is called, you can basically forget about this
+ * renderbuffer; core Mesa will handle all the buffer management and
+ * rendering!
+ */
+GLboolean
+_mesa_add_color_renderbuffers(GLcontext *ctx, struct gl_framebuffer *fb,
+                              GLuint rgbBits, GLuint alphaBits,
+                              GLboolean frontLeft, GLboolean backLeft,
+                              GLboolean frontRight, GLboolean backRight)
+{
+   GLuint b;
+
+   if (rgbBits > 16 || alphaBits > 16) {
+      _mesa_problem(ctx,
+                    "Unsupported bit depth in _mesa_add_color_renderbuffers");
+      return GL_FALSE;
+   }
+
+   assert(MAX_COLOR_ATTACHMENTS >= 4);
+
+   for (b = BUFFER_FRONT_LEFT; b <= BUFFER_BACK_RIGHT; b++) {
+      struct gl_renderbuffer *rb;
+
+      if (b == BUFFER_FRONT_LEFT && !frontLeft)
+         continue;
+      else if (b == BUFFER_BACK_LEFT && !backLeft)
+         continue;
+      else if (b == BUFFER_FRONT_RIGHT && !frontRight)
+         continue;
+      else if (b == BUFFER_BACK_RIGHT && !backRight)
+         continue;
+
+      assert(fb->Attachment[b].Renderbuffer == NULL);
+
+      rb = _mesa_new_renderbuffer(ctx, 0);
+      if (!rb) {
+         _mesa_error(ctx, GL_OUT_OF_MEMORY, "Allocating color buffer");
+         return GL_FALSE;
+      }
+
+      if (rgbBits <= 8) {
+         if (alphaBits)
+            rb->_ActualFormat = GL_RGBA8;
+         else
+            rb->_ActualFormat = GL_RGB8;
+      }
+      else {
+         assert(rgbBits <= 16);
+         if (alphaBits)
+            rb->_ActualFormat = GL_RGBA16;
+         else
+            rb->_ActualFormat = GL_RGBA16; /* don't really have RGB16 yet */
+      }
+      rb->InternalFormat = rb->_ActualFormat;
+
+      rb->AllocStorage = _mesa_soft_renderbuffer_storage;
+      _mesa_add_renderbuffer(fb, b, rb);
+   }
+
+   return GL_TRUE;
+}
+
+
+/**
+ * Add software-based color index renderbuffers to the given framebuffer.
+ * This is a helper routine for device drivers when creating a
+ * window system framebuffer (not a user-created render/framebuffer).
+ * Once this function is called, you can basically forget about this
+ * renderbuffer; core Mesa will handle all the buffer management and
+ * rendering!
+ */
+GLboolean
+_mesa_add_color_index_renderbuffers(GLcontext *ctx, struct gl_framebuffer *fb,
+                                    GLuint indexBits,
+                                    GLboolean frontLeft, GLboolean backLeft,
+                                    GLboolean frontRight, GLboolean backRight)
+{
+   GLuint b;
+
+   if (indexBits > 8) {
+      _mesa_problem(ctx,
+                "Unsupported bit depth in _mesa_add_color_index_renderbuffers");
+      return GL_FALSE;
+   }
+
+   assert(MAX_COLOR_ATTACHMENTS >= 4);
+
+   for (b = BUFFER_FRONT_LEFT; b <= BUFFER_BACK_RIGHT; b++) {
+      struct gl_renderbuffer *rb;
+
+      if (b == BUFFER_FRONT_LEFT && !frontLeft)
+         continue;
+      else if (b == BUFFER_BACK_LEFT && !backLeft)
+         continue;
+      else if (b == BUFFER_FRONT_RIGHT && !frontRight)
+         continue;
+      else if (b == BUFFER_BACK_RIGHT && !backRight)
+         continue;
+
+      assert(fb->Attachment[b].Renderbuffer == NULL);
+
+      rb = _mesa_new_renderbuffer(ctx, 0);
+      if (!rb) {
+         _mesa_error(ctx, GL_OUT_OF_MEMORY, "Allocating color buffer");
+         return GL_FALSE;
+      }
+
+      if (indexBits <= 8) {
+         /* only support GLuint for now */
+         /*rb->InternalFormat = GL_COLOR_INDEX8_EXT;*/
+         rb->_ActualFormat = COLOR_INDEX32;
+      }
+      else {
+         rb->_ActualFormat = COLOR_INDEX32;
+      }
+      rb->InternalFormat = rb->_ActualFormat;
+
+      rb->AllocStorage = _mesa_soft_renderbuffer_storage;
+      _mesa_add_renderbuffer(fb, b, rb);
+   }
+
+   return GL_TRUE;
+}
+
+
+/**
+ * Add software-based alpha renderbuffers to the given framebuffer.
+ * This is a helper routine for device drivers when creating a
+ * window system framebuffer (not a user-created render/framebuffer).
+ * Once this function is called, you can basically forget about this
+ * renderbuffer; core Mesa will handle all the buffer management and
+ * rendering!
+ */
+GLboolean
+_mesa_add_alpha_renderbuffers(GLcontext *ctx, struct gl_framebuffer *fb,
+                              GLuint alphaBits,
+                              GLboolean frontLeft, GLboolean backLeft,
+                              GLboolean frontRight, GLboolean backRight)
+{
+   GLuint b;
+
+   /* for window system framebuffers only! */
+   assert(fb->Name == 0);
+
+   if (alphaBits > 8) {
+      _mesa_problem(ctx,
+                    "Unsupported bit depth in _mesa_add_alpha_renderbuffers");
+      return GL_FALSE;
+   }
+
+   assert(MAX_COLOR_ATTACHMENTS >= 4);
+
+   /* Wrap each of the RGB color buffers with an alpha renderbuffer.
+    */
+   for (b = BUFFER_FRONT_LEFT; b <= BUFFER_BACK_RIGHT; b++) {
+      struct gl_renderbuffer *arb;
+
+      if (b == BUFFER_FRONT_LEFT && !frontLeft)
+         continue;
+      else if (b == BUFFER_BACK_LEFT && !backLeft)
+         continue;
+      else if (b == BUFFER_FRONT_RIGHT && !frontRight)
+         continue;
+      else if (b == BUFFER_BACK_RIGHT && !backRight)
+         continue;
+
+      /* the RGB buffer to wrap must already exist!! */
+      assert(fb->Attachment[b].Renderbuffer);
+
+      /* only GLubyte supported for now */
+      assert(fb->Attachment[b].Renderbuffer->DataType == GL_UNSIGNED_BYTE);
+
+      /* allocate alpha renderbuffer */
+      arb = _mesa_new_renderbuffer(ctx, 0);
+      if (!arb) {
+         _mesa_error(ctx, GL_OUT_OF_MEMORY, "Allocating alpha buffer");
+         return GL_FALSE;
+      }
+
+      /* wrap the alpha renderbuffer around the RGB renderbuffer */
+      arb->Wrapped = fb->Attachment[b].Renderbuffer;
+
+      /* Set up my alphabuffer fields and plug in my functions.
+       * The functions will put/get the alpha values from/to RGBA arrays
+       * and then call the wrapped buffer's functions to handle the RGB
+       * values.
+       */
+      arb->InternalFormat = arb->Wrapped->InternalFormat;
+      arb->_ActualFormat  = GL_ALPHA8;
+      arb->_BaseFormat    = arb->Wrapped->_BaseFormat;
+      arb->DataType       = arb->Wrapped->DataType;
+      arb->AllocStorage   = alloc_storage_alpha8;
+      arb->Delete         = delete_renderbuffer_alpha8;
+      arb->GetPointer     = get_pointer_alpha8;
+      arb->GetRow         = get_row_alpha8;
+      arb->GetValues      = get_values_alpha8;
+      arb->PutRow         = put_row_alpha8;
+      arb->PutRowRGB      = put_row_rgb_alpha8;
+      arb->PutMonoRow     = put_mono_row_alpha8;
+      arb->PutValues      = put_values_alpha8;
+      arb->PutMonoValues  = put_mono_values_alpha8;
+
+      /* clear the pointer to avoid assertion/sanity check failure later */
+      fb->Attachment[b].Renderbuffer = NULL;
+
+      /* plug the alpha renderbuffer into the colorbuffer attachment */
+      _mesa_add_renderbuffer(fb, b, arb);
+   }
+
+   return GL_TRUE;
+}
+
+
+/**
+ * For framebuffers that use a software alpha channel wrapper
+ * created by _mesa_add_alpha_renderbuffer or _mesa_add_soft_renderbuffers,
+ * copy the back buffer alpha channel into the front buffer alpha channel.
+ */
+void
+_mesa_copy_soft_alpha_renderbuffers(GLcontext *ctx, struct gl_framebuffer *fb)
+{
+   if (fb->Attachment[BUFFER_FRONT_LEFT].Renderbuffer &&
+       fb->Attachment[BUFFER_BACK_LEFT].Renderbuffer)
+      copy_buffer_alpha8(fb->Attachment[BUFFER_FRONT_LEFT].Renderbuffer,
+                         fb->Attachment[BUFFER_BACK_LEFT].Renderbuffer);
+
+
+   if (fb->Attachment[BUFFER_FRONT_RIGHT].Renderbuffer &&
+       fb->Attachment[BUFFER_BACK_RIGHT].Renderbuffer)
+      copy_buffer_alpha8(fb->Attachment[BUFFER_FRONT_RIGHT].Renderbuffer,
+                         fb->Attachment[BUFFER_BACK_RIGHT].Renderbuffer);
+}
+
+
+/**
+ * Add a software-based depth renderbuffer to the given framebuffer.
+ * This is a helper routine for device drivers when creating a
+ * window system framebuffer (not a user-created render/framebuffer).
+ * Once this function is called, you can basically forget about this
+ * renderbuffer; core Mesa will handle all the buffer management and
+ * rendering!
+ */
+GLboolean
+_mesa_add_depth_renderbuffer(GLcontext *ctx, struct gl_framebuffer *fb,
+                             GLuint depthBits)
+{
+   struct gl_renderbuffer *rb;
+
+   if (depthBits > 32) {
+      _mesa_problem(ctx,
+                    "Unsupported depthBits in _mesa_add_depth_renderbuffer");
+      return GL_FALSE;
+   }
+
+   assert(fb->Attachment[BUFFER_DEPTH].Renderbuffer == NULL);
+
+   rb = _mesa_new_renderbuffer(ctx, 0);
+   if (!rb) {
+      _mesa_error(ctx, GL_OUT_OF_MEMORY, "Allocating depth buffer");
+      return GL_FALSE;
+   }
+
+   if (depthBits <= 16) {
+      rb->_ActualFormat = GL_DEPTH_COMPONENT16;
+   }
+   else if (depthBits <= 24) {
+      rb->_ActualFormat = GL_DEPTH_COMPONENT24;
+   }
+   else {
+      rb->_ActualFormat = GL_DEPTH_COMPONENT32;
+   }
+   rb->InternalFormat = rb->_ActualFormat;
+
+   rb->AllocStorage = _mesa_soft_renderbuffer_storage;
+   _mesa_add_renderbuffer(fb, BUFFER_DEPTH, rb);
+
+   return GL_TRUE;
+}
+
+
+/**
+ * Add a software-based stencil renderbuffer to the given framebuffer.
+ * This is a helper routine for device drivers when creating a
+ * window system framebuffer (not a user-created render/framebuffer).
+ * Once this function is called, you can basically forget about this
+ * renderbuffer; core Mesa will handle all the buffer management and
+ * rendering!
+ */
+GLboolean
+_mesa_add_stencil_renderbuffer(GLcontext *ctx, struct gl_framebuffer *fb,
+                               GLuint stencilBits)
+{
+   struct gl_renderbuffer *rb;
+
+   if (stencilBits > 16) {
+      _mesa_problem(ctx,
+                  "Unsupported stencilBits in _mesa_add_stencil_renderbuffer");
+      return GL_FALSE;
+   }
+
+   assert(fb->Attachment[BUFFER_STENCIL].Renderbuffer == NULL);
+
+   rb = _mesa_new_renderbuffer(ctx, 0);
+   if (!rb) {
+      _mesa_error(ctx, GL_OUT_OF_MEMORY, "Allocating stencil buffer");
+      return GL_FALSE;
+   }
+
+   if (stencilBits <= 8) {
+      rb->_ActualFormat = GL_STENCIL_INDEX8_EXT;
+   }
+   else {
+      /* not really supported (see s_stencil.c code) */
+      rb->_ActualFormat = GL_STENCIL_INDEX16_EXT;
+   }
+   rb->InternalFormat = rb->_ActualFormat;
+
+   rb->AllocStorage = _mesa_soft_renderbuffer_storage;
+   _mesa_add_renderbuffer(fb, BUFFER_STENCIL, rb);
+
+   return GL_TRUE;
+}
+
+
+/**
+ * Add a software-based accumulation renderbuffer to the given framebuffer.
+ * This is a helper routine for device drivers when creating a
+ * window system framebuffer (not a user-created render/framebuffer).
+ * Once this function is called, you can basically forget about this
+ * renderbuffer; core Mesa will handle all the buffer management and
+ * rendering!
+ */
+GLboolean
+_mesa_add_accum_renderbuffer(GLcontext *ctx, struct gl_framebuffer *fb,
+                             GLuint redBits, GLuint greenBits,
+                             GLuint blueBits, GLuint alphaBits)
+{
+   struct gl_renderbuffer *rb;
+
+   if (redBits > 16 || greenBits > 16 || blueBits > 16 || alphaBits > 16) {
+      _mesa_problem(ctx,
+                    "Unsupported accumBits in _mesa_add_accum_renderbuffer");
+      return GL_FALSE;
+   }
+
+   assert(fb->Attachment[BUFFER_ACCUM].Renderbuffer == NULL);
+
+   rb = _mesa_new_renderbuffer(ctx, 0);
+   if (!rb) {
+      _mesa_error(ctx, GL_OUT_OF_MEMORY, "Allocating accum buffer");
+      return GL_FALSE;
+   }
+
+   rb->_ActualFormat = GL_RGBA16;
+   rb->InternalFormat = GL_RGBA16;
+   rb->AllocStorage = _mesa_soft_renderbuffer_storage;
+   _mesa_add_renderbuffer(fb, BUFFER_ACCUM, rb);
+
+   return GL_TRUE;
+}
+
+
+
+/**
+ * Add a software-based accumulation renderbuffer to the given framebuffer.
+ * This is a helper routine for device drivers when creating a
+ * window system framebuffer (not a user-created render/framebuffer).
+ * Once this function is called, you can basically forget about this
+ * renderbuffer; core Mesa will handle all the buffer management and
+ * rendering!
+ *
+ * NOTE: color-index aux buffers not supported.
+ */
+GLboolean
+_mesa_add_aux_renderbuffers(GLcontext *ctx, struct gl_framebuffer *fb,
+                            GLuint colorBits, GLuint numBuffers)
+{
+   GLuint i;
+
+   if (colorBits > 16) {
+      _mesa_problem(ctx,
+                    "Unsupported accumBits in _mesa_add_aux_renderbuffers");
+      return GL_FALSE;
+   }
+
+   assert(numBuffers < MAX_AUX_BUFFERS);
+
+   for (i = 0; i < numBuffers; i++) {
+      struct gl_renderbuffer *rb = _mesa_new_renderbuffer(ctx, 0);
+
+      assert(fb->Attachment[BUFFER_AUX0 + i].Renderbuffer == NULL);
+
+      if (!rb) {
+         _mesa_error(ctx, GL_OUT_OF_MEMORY, "Allocating accum buffer");
+         return GL_FALSE;
+      }
+
+      if (colorBits <= 8) {
+         rb->_ActualFormat = GL_RGBA8;
+      }
+      else {
+         rb->_ActualFormat = GL_RGBA16;
+      }
+      rb->InternalFormat = rb->_ActualFormat;
+
+      rb->AllocStorage = _mesa_soft_renderbuffer_storage;
+      _mesa_add_renderbuffer(fb, BUFFER_AUX0 + i, rb);
+   }
+   return GL_TRUE;
+}
+
+
+/**
+ * Create/attach software-based renderbuffers to the given framebuffer.
+ * This is a helper routine for device drivers.  Drivers can just as well
+ * call the individual _mesa_add_*_renderbuffer() routines directly.
+ */
+void
+_mesa_add_soft_renderbuffers(struct gl_framebuffer *fb,
+                             GLboolean color,
+                             GLboolean depth,
+                             GLboolean stencil,
+                             GLboolean accum,
+                             GLboolean alpha,
+                             GLboolean aux)
+{
+   GLboolean frontLeft = GL_TRUE;
+   GLboolean backLeft = fb->Visual.doubleBufferMode;
+   GLboolean frontRight = fb->Visual.stereoMode;
+   GLboolean backRight = fb->Visual.stereoMode && fb->Visual.doubleBufferMode;
+
+   if (color) {
+      if (fb->Visual.rgbMode) {
+         assert(fb->Visual.redBits == fb->Visual.greenBits);
+         assert(fb->Visual.redBits == fb->Visual.blueBits);
+         _mesa_add_color_renderbuffers(NULL, fb,
+                                       fb->Visual.redBits,
+                                       fb->Visual.alphaBits,
+                                       frontLeft, backLeft,
+                                       frontRight, backRight);
+      }
+      else {
+         _mesa_add_color_index_renderbuffers(NULL, fb,
+                                             fb->Visual.indexBits,
+                                             frontLeft, backLeft,
+                                             frontRight, backRight);
+      }
+   }
+
+   if (depth) {
+      assert(fb->Visual.depthBits > 0);
+      _mesa_add_depth_renderbuffer(NULL, fb, fb->Visual.depthBits);
+   }
+
+   if (stencil) {
+      assert(fb->Visual.stencilBits > 0);
+      _mesa_add_stencil_renderbuffer(NULL, fb, fb->Visual.stencilBits);
+   }
+
+   if (accum) {
+      assert(fb->Visual.rgbMode);
+      assert(fb->Visual.accumRedBits > 0);
+      assert(fb->Visual.accumGreenBits > 0);
+      assert(fb->Visual.accumBlueBits > 0);
+      _mesa_add_accum_renderbuffer(NULL, fb,
+                                   fb->Visual.accumRedBits,
+                                   fb->Visual.accumGreenBits,
+                                   fb->Visual.accumBlueBits,
+                                   fb->Visual.accumAlphaBits);
+   }
+
+   if (aux) {
+      assert(fb->Visual.rgbMode);
+      assert(fb->Visual.numAuxBuffers > 0);
+      _mesa_add_aux_renderbuffers(NULL, fb, fb->Visual.redBits,
+                                  fb->Visual.numAuxBuffers);
+   }
+
+   if (alpha) {
+      assert(fb->Visual.rgbMode);
+      assert(fb->Visual.alphaBits > 0);
+      _mesa_add_alpha_renderbuffers(NULL, fb, fb->Visual.alphaBits,
+                                    frontLeft, backLeft,
+                                    frontRight, backRight);
+   }
+
+#if 0
+   if (multisample) {
+      /* maybe someday */
+   }
+#endif
+}
+
+
+/**
+ * Attach a renderbuffer to a framebuffer.
+ */
+void
+_mesa_add_renderbuffer(struct gl_framebuffer *fb,
+                       GLuint bufferName, struct gl_renderbuffer *rb)
+{
+   assert(fb);
+   assert(rb);
+   assert(bufferName < BUFFER_COUNT);
+
+   /* There should be no previous renderbuffer on this attachment point,
+    * with the exception of depth/stencil since the same renderbuffer may
+    * be used for both.
+    */
+   assert(bufferName == BUFFER_DEPTH ||
+          bufferName == BUFFER_STENCIL ||
+          fb->Attachment[bufferName].Renderbuffer == NULL);
+
+   /* winsys vs. user-created buffer cross check */
+   if (fb->Name) {
+      assert(rb->Name);
+   }
+   else {
+      assert(!rb->Name);
+   }
+
+   /* If Mesa's compiled with deep color channels (16 or 32 bits / channel)
+    * and the device driver is expecting 8-bit values (GLubyte), we can
+    * use a "renderbuffer adaptor/wrapper" to do the necessary conversions.
+    */
+   if (rb->_BaseFormat == GL_RGBA) {
+      if (CHAN_BITS == 16 && rb->DataType == GL_UNSIGNED_BYTE) {
+         GET_CURRENT_CONTEXT(ctx);
+         rb = _mesa_new_renderbuffer_16wrap8(ctx, rb);
+      }
+      else if (CHAN_BITS == 32 && rb->DataType == GL_UNSIGNED_BYTE) {
+         GET_CURRENT_CONTEXT(ctx);
+         rb = _mesa_new_renderbuffer_32wrap8(ctx, rb);
+      }
+      else if (CHAN_BITS == 32 && rb->DataType == GL_UNSIGNED_SHORT) {
+         GET_CURRENT_CONTEXT(ctx);
+         rb = _mesa_new_renderbuffer_32wrap16(ctx, rb);
+      }
+   }
+
+   fb->Attachment[bufferName].Type = GL_RENDERBUFFER_EXT;
+   fb->Attachment[bufferName].Complete = GL_TRUE;
+   _mesa_reference_renderbuffer(&fb->Attachment[bufferName].Renderbuffer, rb);
+}
+
+
+/**
+ * Remove the named renderbuffer from the given framebuffer.
+ */
+void
+_mesa_remove_renderbuffer(struct gl_framebuffer *fb, GLuint bufferName)
+{
+   struct gl_renderbuffer *rb;
+
+   assert(bufferName < BUFFER_COUNT);
+
+   rb = fb->Attachment[bufferName].Renderbuffer;
+   if (!rb)
+      return;
+
+   _mesa_reference_renderbuffer(&rb, NULL);
+
+   fb->Attachment[bufferName].Renderbuffer = NULL;
+}
+
+
+/**
+ * Set *ptr to point to rb.  If *ptr points to another renderbuffer,
+ * dereference that buffer first.  The new renderbuffer's refcount will
+ * be incremented.  The old renderbuffer's refcount will be decremented.
+ */
+void
+_mesa_reference_renderbuffer(struct gl_renderbuffer **ptr,
+                             struct gl_renderbuffer *rb)
+{
+   assert(ptr);
+   if (*ptr == rb) {
+      /* no change */
+      return;
+   }
+
+   if (*ptr) {
+      /* Unreference the old renderbuffer */
+      GLboolean deleteFlag = GL_FALSE;
+      struct gl_renderbuffer *oldRb = *ptr;
+
+      assert(oldRb->Magic == RB_MAGIC);
+      _glthread_LOCK_MUTEX(oldRb->Mutex);
+      assert(oldRb->Magic == RB_MAGIC);
+      ASSERT(oldRb->RefCount > 0);
+      oldRb->RefCount--;
+      /*printf("RB DECR %p (%d) to %d\n", (void*) oldRb, oldRb->Name, oldRb->RefCount);*/
+      deleteFlag = (oldRb->RefCount == 0);
+      _glthread_UNLOCK_MUTEX(oldRb->Mutex);
+
+      if (deleteFlag) {
+         oldRb->Magic = 0; /* now invalid memory! */
+         oldRb->Delete(oldRb);
+      }
+
+      *ptr = NULL;
+   }
+   assert(!*ptr);
+
+   if (rb) {
+      assert(rb->Magic == RB_MAGIC);
+      /* reference new renderbuffer */
+      _glthread_LOCK_MUTEX(rb->Mutex);
+      rb->RefCount++;
+      /*printf("RB INCR %p (%d) to %d\n", (void*) rb, rb->Name, rb->RefCount);*/
+      _glthread_UNLOCK_MUTEX(rb->Mutex);
+      *ptr = rb;
+   }
+}
+
+
+/**
+ * Create a new combined depth/stencil renderbuffer for implementing
+ * the GL_EXT_packed_depth_stencil extension.
+ * \return new depth/stencil renderbuffer
+ */
+struct gl_renderbuffer *
+_mesa_new_depthstencil_renderbuffer(GLcontext *ctx, GLuint name)
+{
+   struct gl_renderbuffer *dsrb;
+
+   dsrb = _mesa_new_renderbuffer(ctx, name);
+   if (!dsrb)
+      return NULL;
+
+   /* init fields not covered by _mesa_new_renderbuffer() */
+   dsrb->InternalFormat = GL_DEPTH24_STENCIL8_EXT;
+   dsrb->_ActualFormat = GL_DEPTH24_STENCIL8_EXT;
+   dsrb->AllocStorage = _mesa_soft_renderbuffer_storage;
+
+   return dsrb;
+}