Added MesaLib-7.6

1 files changed, 1795 insertions, 0 deletions

diff --git a/mesalib/src/mesa/swrast/s_span.c b/mesalib/src/mesa/swrast/s_span.c
new file mode 100644
index 000000000..0e2793b47
--- /dev/null
+++ b/mesalib/src/mesa/swrast/s_span.c
@@ -0,0 +1,1795 @@
+/*
+ * Mesa 3-D graphics library
+ * Version:  7.5
+ *
+ * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
+ * Copyright (C) 2009  VMware, Inc.  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.
+ */
+
+
+/**
+ * \file swrast/s_span.c
+ * \brief Span processing functions used by all rasterization functions.
+ * This is where all the per-fragment tests are performed
+ * \author Brian Paul
+ */
+
+#include "main/glheader.h"
+#include "main/colormac.h"
+#include "main/context.h"
+#include "main/macros.h"
+#include "main/imports.h"
+#include "main/image.h"
+
+#include "s_atifragshader.h"
+#include "s_alpha.h"
+#include "s_blend.h"
+#include "s_context.h"
+#include "s_depth.h"
+#include "s_fog.h"
+#include "s_logic.h"
+#include "s_masking.h"
+#include "s_fragprog.h"
+#include "s_span.h"
+#include "s_stencil.h"
+#include "s_texcombine.h"
+
+
+/**
+ * Set default fragment attributes for the span using the
+ * current raster values.  Used prior to glDraw/CopyPixels
+ * and glBitmap.
+ */
+void
+_swrast_span_default_attribs(GLcontext *ctx, SWspan *span)
+{
+   /* Z*/
+   {
+      const GLfloat depthMax = ctx->DrawBuffer->_DepthMaxF;
+      if (ctx->DrawBuffer->Visual.depthBits <= 16)
+         span->z = FloatToFixed(ctx->Current.RasterPos[2] * depthMax + 0.5F);
+      else {
+         GLfloat tmpf = ctx->Current.RasterPos[2] * depthMax; 
+         tmpf = MIN2(tmpf, depthMax);
+         span->z = (GLint)tmpf;
+      }
+      span->zStep = 0;
+      span->interpMask |= SPAN_Z;
+   }
+
+   /* W (for perspective correction) */
+   span->attrStart[FRAG_ATTRIB_WPOS][3] = 1.0;
+   span->attrStepX[FRAG_ATTRIB_WPOS][3] = 0.0;
+   span->attrStepY[FRAG_ATTRIB_WPOS][3] = 0.0;
+
+   /* primary color, or color index */
+   if (ctx->Visual.rgbMode) {
+      GLchan r, g, b, a;
+      UNCLAMPED_FLOAT_TO_CHAN(r, ctx->Current.RasterColor[0]);
+      UNCLAMPED_FLOAT_TO_CHAN(g, ctx->Current.RasterColor[1]);
+      UNCLAMPED_FLOAT_TO_CHAN(b, ctx->Current.RasterColor[2]);
+      UNCLAMPED_FLOAT_TO_CHAN(a, ctx->Current.RasterColor[3]);
+#if CHAN_TYPE == GL_FLOAT
+      span->red = r;
+      span->green = g;
+      span->blue = b;
+      span->alpha = a;
+#else
+      span->red   = IntToFixed(r);
+      span->green = IntToFixed(g);
+      span->blue  = IntToFixed(b);
+      span->alpha = IntToFixed(a);
+#endif
+      span->redStep = 0;
+      span->greenStep = 0;
+      span->blueStep = 0;
+      span->alphaStep = 0;
+      span->interpMask |= SPAN_RGBA;
+
+      COPY_4V(span->attrStart[FRAG_ATTRIB_COL0], ctx->Current.RasterColor);
+      ASSIGN_4V(span->attrStepX[FRAG_ATTRIB_COL0], 0.0, 0.0, 0.0, 0.0);
+      ASSIGN_4V(span->attrStepY[FRAG_ATTRIB_COL0], 0.0, 0.0, 0.0, 0.0);
+   }
+   else {
+      span->index = FloatToFixed(ctx->Current.RasterIndex);
+      span->indexStep = 0;
+      span->interpMask |= SPAN_INDEX;
+   }
+
+   /* Secondary color */
+   if (ctx->Visual.rgbMode && (ctx->Light.Enabled || ctx->Fog.ColorSumEnabled))
+   {
+      COPY_4V(span->attrStart[FRAG_ATTRIB_COL1], ctx->Current.RasterSecondaryColor);
+      ASSIGN_4V(span->attrStepX[FRAG_ATTRIB_COL1], 0.0, 0.0, 0.0, 0.0);
+      ASSIGN_4V(span->attrStepY[FRAG_ATTRIB_COL1], 0.0, 0.0, 0.0, 0.0);
+   }
+
+   /* fog */
+   {
+      const SWcontext *swrast = SWRAST_CONTEXT(ctx);
+      GLfloat fogVal; /* a coord or a blend factor */
+      if (swrast->_PreferPixelFog) {
+         /* fog blend factors will be computed from fog coordinates per pixel */
+         fogVal = ctx->Current.RasterDistance;
+      }
+      else {
+         /* fog blend factor should be computed from fogcoord now */
+         fogVal = _swrast_z_to_fogfactor(ctx, ctx->Current.RasterDistance);
+      }
+      span->attrStart[FRAG_ATTRIB_FOGC][0] = fogVal;
+      span->attrStepX[FRAG_ATTRIB_FOGC][0] = 0.0;
+      span->attrStepY[FRAG_ATTRIB_FOGC][0] = 0.0;
+   }
+
+   /* texcoords */
+   {
+      GLuint i;
+      for (i = 0; i < ctx->Const.MaxTextureCoordUnits; i++) {
+         const GLuint attr = FRAG_ATTRIB_TEX0 + i;
+         const GLfloat *tc = ctx->Current.RasterTexCoords[i];
+         if (ctx->FragmentProgram._Current || ctx->ATIFragmentShader._Enabled) {
+            COPY_4V(span->attrStart[attr], tc);
+         }
+         else if (tc[3] > 0.0F) {
+            /* use (s/q, t/q, r/q, 1) */
+            span->attrStart[attr][0] = tc[0] / tc[3];
+            span->attrStart[attr][1] = tc[1] / tc[3];
+            span->attrStart[attr][2] = tc[2] / tc[3];
+            span->attrStart[attr][3] = 1.0;
+         }
+         else {
+            ASSIGN_4V(span->attrStart[attr], 0.0F, 0.0F, 0.0F, 1.0F);
+         }
+         ASSIGN_4V(span->attrStepX[attr], 0.0F, 0.0F, 0.0F, 0.0F);
+         ASSIGN_4V(span->attrStepY[attr], 0.0F, 0.0F, 0.0F, 0.0F);
+      }
+   }
+}
+
+
+/**
+ * Interpolate the active attributes (and'd with attrMask) to
+ * fill in span->array->attribs[].
+ * Perspective correction will be done.  The point/line/triangle function
+ * should have computed attrStart/Step values for FRAG_ATTRIB_WPOS[3]!
+ */
+static INLINE void
+interpolate_active_attribs(GLcontext *ctx, SWspan *span, GLbitfield attrMask)
+{
+   const SWcontext *swrast = SWRAST_CONTEXT(ctx);
+
+   /*
+    * Don't overwrite existing array values, such as colors that may have
+    * been produced by glDraw/CopyPixels.
+    */
+   attrMask &= ~span->arrayAttribs;
+
+   ATTRIB_LOOP_BEGIN
+      if (attrMask & (1 << attr)) {
+         const GLfloat dwdx = span->attrStepX[FRAG_ATTRIB_WPOS][3];
+         GLfloat w = span->attrStart[FRAG_ATTRIB_WPOS][3];
+         const GLfloat dv0dx = span->attrStepX[attr][0];
+         const GLfloat dv1dx = span->attrStepX[attr][1];
+         const GLfloat dv2dx = span->attrStepX[attr][2];
+         const GLfloat dv3dx = span->attrStepX[attr][3];
+         GLfloat v0 = span->attrStart[attr][0] + span->leftClip * dv0dx;
+         GLfloat v1 = span->attrStart[attr][1] + span->leftClip * dv1dx;
+         GLfloat v2 = span->attrStart[attr][2] + span->leftClip * dv2dx;
+         GLfloat v3 = span->attrStart[attr][3] + span->leftClip * dv3dx;
+         GLuint k;
+         for (k = 0; k < span->end; k++) {
+            const GLfloat invW = 1.0f / w;
+            span->array->attribs[attr][k][0] = v0 * invW;
+            span->array->attribs[attr][k][1] = v1 * invW;
+            span->array->attribs[attr][k][2] = v2 * invW;
+            span->array->attribs[attr][k][3] = v3 * invW;
+            v0 += dv0dx;
+            v1 += dv1dx;
+            v2 += dv2dx;
+            v3 += dv3dx;
+            w += dwdx;
+         }
+         ASSERT((span->arrayAttribs & (1 << attr)) == 0);
+         span->arrayAttribs |= (1 << attr);
+      }
+   ATTRIB_LOOP_END
+}
+
+
+/**
+ * Interpolate primary colors to fill in the span->array->rgba8 (or rgb16)
+ * color array.
+ */
+static INLINE void
+interpolate_int_colors(GLcontext *ctx, SWspan *span)
+{
+   const GLuint n = span->end;
+   GLuint i;
+
+#if CHAN_BITS != 32
+   ASSERT(!(span->arrayMask & SPAN_RGBA));
+#endif
+
+   switch (span->array->ChanType) {
+#if CHAN_BITS != 32
+   case GL_UNSIGNED_BYTE:
+      {
+         GLubyte (*rgba)[4] = span->array->rgba8;
+         if (span->interpMask & SPAN_FLAT) {
+            GLubyte color[4];
+            color[RCOMP] = FixedToInt(span->red);
+            color[GCOMP] = FixedToInt(span->green);
+            color[BCOMP] = FixedToInt(span->blue);
+            color[ACOMP] = FixedToInt(span->alpha);
+            for (i = 0; i < n; i++) {
+               COPY_4UBV(rgba[i], color);
+            }
+         }
+         else {
+            GLfixed r = span->red;
+            GLfixed g = span->green;
+            GLfixed b = span->blue;
+            GLfixed a = span->alpha;
+            GLint dr = span->redStep;
+            GLint dg = span->greenStep;
+            GLint db = span->blueStep;
+            GLint da = span->alphaStep;
+            for (i = 0; i < n; i++) {
+               rgba[i][RCOMP] = FixedToChan(r);
+               rgba[i][GCOMP] = FixedToChan(g);
+               rgba[i][BCOMP] = FixedToChan(b);
+               rgba[i][ACOMP] = FixedToChan(a);
+               r += dr;
+               g += dg;
+               b += db;
+               a += da;
+            }
+         }
+      }
+      break;
+   case GL_UNSIGNED_SHORT:
+      {
+         GLushort (*rgba)[4] = span->array->rgba16;
+         if (span->interpMask & SPAN_FLAT) {
+            GLushort color[4];
+            color[RCOMP] = FixedToInt(span->red);
+            color[GCOMP] = FixedToInt(span->green);
+            color[BCOMP] = FixedToInt(span->blue);
+            color[ACOMP] = FixedToInt(span->alpha);
+            for (i = 0; i < n; i++) {
+               COPY_4V(rgba[i], color);
+            }
+         }
+         else {
+            GLushort (*rgba)[4] = span->array->rgba16;
+            GLfixed r, g, b, a;
+            GLint dr, dg, db, da;
+            r = span->red;
+            g = span->green;
+            b = span->blue;
+            a = span->alpha;
+            dr = span->redStep;
+            dg = span->greenStep;
+            db = span->blueStep;
+            da = span->alphaStep;
+            for (i = 0; i < n; i++) {
+               rgba[i][RCOMP] = FixedToChan(r);
+               rgba[i][GCOMP] = FixedToChan(g);
+               rgba[i][BCOMP] = FixedToChan(b);
+               rgba[i][ACOMP] = FixedToChan(a);
+               r += dr;
+               g += dg;
+               b += db;
+               a += da;
+            }
+         }
+      }
+      break;
+#endif
+   case GL_FLOAT:
+      interpolate_active_attribs(ctx, span, FRAG_BIT_COL0);
+      break;
+   default:
+      _mesa_problem(NULL, "bad datatype in interpolate_int_colors");
+   }
+   span->arrayMask |= SPAN_RGBA;
+}
+
+
+/**
+ * Populate the FRAG_ATTRIB_COL0 array.
+ */
+static INLINE void
+interpolate_float_colors(SWspan *span)
+{
+   GLfloat (*col0)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
+   const GLuint n = span->end;
+   GLuint i;
+
+   assert(!(span->arrayAttribs & FRAG_BIT_COL0));
+
+   if (span->arrayMask & SPAN_RGBA) {
+      /* convert array of int colors */
+      for (i = 0; i < n; i++) {
+         col0[i][0] = UBYTE_TO_FLOAT(span->array->rgba8[i][0]);
+         col0[i][1] = UBYTE_TO_FLOAT(span->array->rgba8[i][1]);
+         col0[i][2] = UBYTE_TO_FLOAT(span->array->rgba8[i][2]);
+         col0[i][3] = UBYTE_TO_FLOAT(span->array->rgba8[i][3]);
+      }
+   }
+   else {
+      /* interpolate red/green/blue/alpha to get float colors */
+      ASSERT(span->interpMask & SPAN_RGBA);
+      if (span->interpMask & SPAN_FLAT) {
+         GLfloat r = FixedToFloat(span->red);
+         GLfloat g = FixedToFloat(span->green);
+         GLfloat b = FixedToFloat(span->blue);
+         GLfloat a = FixedToFloat(span->alpha);
+         for (i = 0; i < n; i++) {
+            ASSIGN_4V(col0[i], r, g, b, a);
+         }
+      }
+      else {
+         GLfloat r = FixedToFloat(span->red);
+         GLfloat g = FixedToFloat(span->green);
+         GLfloat b = FixedToFloat(span->blue);
+         GLfloat a = FixedToFloat(span->alpha);
+         GLfloat dr = FixedToFloat(span->redStep);
+         GLfloat dg = FixedToFloat(span->greenStep);
+         GLfloat db = FixedToFloat(span->blueStep);
+         GLfloat da = FixedToFloat(span->alphaStep);
+         for (i = 0; i < n; i++) {
+            col0[i][0] = r;
+            col0[i][1] = g;
+            col0[i][2] = b;
+            col0[i][3] = a;
+            r += dr;
+            g += dg;
+            b += db;
+            a += da;
+         }
+      }
+   }
+
+   span->arrayAttribs |= FRAG_BIT_COL0;
+   span->array->ChanType = GL_FLOAT;
+}
+
+
+
+/* Fill in the span.color.index array from the interpolation values */
+static INLINE void
+interpolate_indexes(GLcontext *ctx, SWspan *span)
+{
+   GLfixed index = span->index;
+   const GLint indexStep = span->indexStep;
+   const GLuint n = span->end;
+   GLuint *indexes = span->array->index;
+   GLuint i;
+   (void) ctx;
+
+   ASSERT(!(span->arrayMask & SPAN_INDEX));
+
+   if ((span->interpMask & SPAN_FLAT) || (indexStep == 0)) {
+      /* constant color */
+      index = FixedToInt(index);
+      for (i = 0; i < n; i++) {
+         indexes[i] = index;
+      }
+   }
+   else {
+      /* interpolate */
+      for (i = 0; i < n; i++) {
+         indexes[i] = FixedToInt(index);
+         index += indexStep;
+      }
+   }
+   span->arrayMask |= SPAN_INDEX;
+   span->interpMask &= ~SPAN_INDEX;
+}
+
+
+/**
+ * Fill in the span.zArray array from the span->z, zStep values.
+ */
+void
+_swrast_span_interpolate_z( const GLcontext *ctx, SWspan *span )
+{
+   const GLuint n = span->end;
+   GLuint i;
+
+   ASSERT(!(span->arrayMask & SPAN_Z));
+
+   if (ctx->DrawBuffer->Visual.depthBits <= 16) {
+      GLfixed zval = span->z;
+      GLuint *z = span->array->z; 
+      for (i = 0; i < n; i++) {
+         z[i] = FixedToInt(zval);
+         zval += span->zStep;
+      }
+   }
+   else {
+      /* Deep Z buffer, no fixed->int shift */
+      GLuint zval = span->z;
+      GLuint *z = span->array->z;
+      for (i = 0; i < n; i++) {
+         z[i] = zval;
+         zval += span->zStep;
+      }
+   }
+   span->interpMask &= ~SPAN_Z;
+   span->arrayMask |= SPAN_Z;
+}
+
+
+/**
+ * Compute mipmap LOD from partial derivatives.
+ * This the ideal solution, as given in the OpenGL spec.
+ */
+GLfloat
+_swrast_compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,
+                       GLfloat dqdx, GLfloat dqdy, GLfloat texW, GLfloat texH,
+                       GLfloat s, GLfloat t, GLfloat q, GLfloat invQ)
+{
+   GLfloat dudx = texW * ((s + dsdx) / (q + dqdx) - s * invQ);
+   GLfloat dvdx = texH * ((t + dtdx) / (q + dqdx) - t * invQ);
+   GLfloat dudy = texW * ((s + dsdy) / (q + dqdy) - s * invQ);
+   GLfloat dvdy = texH * ((t + dtdy) / (q + dqdy) - t * invQ);
+   GLfloat x = SQRTF(dudx * dudx + dvdx * dvdx);
+   GLfloat y = SQRTF(dudy * dudy + dvdy * dvdy);
+   GLfloat rho = MAX2(x, y);
+   GLfloat lambda = LOG2(rho);
+   return lambda;
+}
+
+
+/**
+ * Compute mipmap LOD from partial derivatives.
+ * This is a faster approximation than above function.
+ */
+#if 0
+GLfloat
+_swrast_compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,
+                     GLfloat dqdx, GLfloat dqdy, GLfloat texW, GLfloat texH,
+                     GLfloat s, GLfloat t, GLfloat q, GLfloat invQ)
+{
+   GLfloat dsdx2 = (s + dsdx) / (q + dqdx) - s * invQ;
+   GLfloat dtdx2 = (t + dtdx) / (q + dqdx) - t * invQ;
+   GLfloat dsdy2 = (s + dsdy) / (q + dqdy) - s * invQ;
+   GLfloat dtdy2 = (t + dtdy) / (q + dqdy) - t * invQ;
+   GLfloat maxU, maxV, rho, lambda;
+   dsdx2 = FABSF(dsdx2);
+   dsdy2 = FABSF(dsdy2);
+   dtdx2 = FABSF(dtdx2);
+   dtdy2 = FABSF(dtdy2);
+   maxU = MAX2(dsdx2, dsdy2) * texW;
+   maxV = MAX2(dtdx2, dtdy2) * texH;
+   rho = MAX2(maxU, maxV);
+   lambda = LOG2(rho);
+   return lambda;
+}
+#endif
+
+
+/**
+ * Fill in the span.array->attrib[FRAG_ATTRIB_TEXn] arrays from the
+ * using the attrStart/Step values.
+ *
+ * This function only used during fixed-function fragment processing.
+ *
+ * Note: in the places where we divide by Q (or mult by invQ) we're
+ * really doing two things: perspective correction and texcoord
+ * projection.  Remember, for texcoord (s,t,r,q) we need to index
+ * texels with (s/q, t/q, r/q).
+ */
+static void
+interpolate_texcoords(GLcontext *ctx, SWspan *span)
+{
+   const GLuint maxUnit
+      = (ctx->Texture._EnabledCoordUnits > 1) ? ctx->Const.MaxTextureUnits : 1;
+   GLuint u;
+
+   /* XXX CoordUnits vs. ImageUnits */
+   for (u = 0; u < maxUnit; u++) {
+      if (ctx->Texture._EnabledCoordUnits & (1 << u)) {
+         const GLuint attr = FRAG_ATTRIB_TEX0 + u;
+         const struct gl_texture_object *obj = ctx->Texture.Unit[u]._Current;
+         GLfloat texW, texH;
+         GLboolean needLambda;
+         GLfloat (*texcoord)[4] = span->array->attribs[attr];
+         GLfloat *lambda = span->array->lambda[u];
+         const GLfloat dsdx = span->attrStepX[attr][0];
+         const GLfloat dsdy = span->attrStepY[attr][0];
+         const GLfloat dtdx = span->attrStepX[attr][1];
+         const GLfloat dtdy = span->attrStepY[attr][1];
+         const GLfloat drdx = span->attrStepX[attr][2];
+         const GLfloat dqdx = span->attrStepX[attr][3];
+         const GLfloat dqdy = span->attrStepY[attr][3];
+         GLfloat s = span->attrStart[attr][0] + span->leftClip * dsdx;
+         GLfloat t = span->attrStart[attr][1] + span->leftClip * dtdx;
+         GLfloat r = span->attrStart[attr][2] + span->leftClip * drdx;
+         GLfloat q = span->attrStart[attr][3] + span->leftClip * dqdx;
+
+         if (obj) {
+            const struct gl_texture_image *img = obj->Image[0][obj->BaseLevel];
+            needLambda = (obj->MinFilter != obj->MagFilter)
+               || ctx->FragmentProgram._Current;
+            texW = img->WidthScale;
+            texH = img->HeightScale;
+         }
+         else {
+            /* using a fragment program */
+            texW = 1.0;
+            texH = 1.0;
+            needLambda = GL_FALSE;
+         }
+
+         if (needLambda) {
+            GLuint i;
+            if (ctx->FragmentProgram._Current
+                || ctx->ATIFragmentShader._Enabled) {
+               /* do perspective correction but don't divide s, t, r by q */
+               const GLfloat dwdx = span->attrStepX[FRAG_ATTRIB_WPOS][3];
+               GLfloat w = span->attrStart[FRAG_ATTRIB_WPOS][3] + span->leftClip * dwdx;
+               for (i = 0; i < span->end; i++) {
+                  const GLfloat invW = 1.0F / w;
+                  texcoord[i][0] = s * invW;
+                  texcoord[i][1] = t * invW;
+                  texcoord[i][2] = r * invW;
+                  texcoord[i][3] = q * invW;
+                  lambda[i] = _swrast_compute_lambda(dsdx, dsdy, dtdx, dtdy,
+                                                     dqdx, dqdy, texW, texH,
+                                                     s, t, q, invW);
+                  s += dsdx;
+                  t += dtdx;
+                  r += drdx;
+                  q += dqdx;
+                  w += dwdx;
+               }
+            }
+            else {
+               for (i = 0; i < span->end; i++) {
+                  const GLfloat invQ = (q == 0.0F) ? 1.0F : (1.0F / q);
+                  texcoord[i][0] = s * invQ;
+                  texcoord[i][1] = t * invQ;
+                  texcoord[i][2] = r * invQ;
+                  texcoord[i][3] = q;
+                  lambda[i] = _swrast_compute_lambda(dsdx, dsdy, dtdx, dtdy,
+                                                     dqdx, dqdy, texW, texH,
+                                                     s, t, q, invQ);
+                  s += dsdx;
+                  t += dtdx;
+                  r += drdx;
+                  q += dqdx;
+               }
+            }
+            span->arrayMask |= SPAN_LAMBDA;
+         }
+         else {
+            GLuint i;
+            if (ctx->FragmentProgram._Current ||
+                ctx->ATIFragmentShader._Enabled) {
+               /* do perspective correction but don't divide s, t, r by q */
+               const GLfloat dwdx = span->attrStepX[FRAG_ATTRIB_WPOS][3];
+               GLfloat w = span->attrStart[FRAG_ATTRIB_WPOS][3] + span->leftClip * dwdx;
+               for (i = 0; i < span->end; i++) {
+                  const GLfloat invW = 1.0F / w;
+                  texcoord[i][0] = s * invW;
+                  texcoord[i][1] = t * invW;
+                  texcoord[i][2] = r * invW;
+                  texcoord[i][3] = q * invW;
+                  lambda[i] = 0.0;
+                  s += dsdx;
+                  t += dtdx;
+                  r += drdx;
+                  q += dqdx;
+                  w += dwdx;
+               }
+            }
+            else if (dqdx == 0.0F) {
+               /* Ortho projection or polygon's parallel to window X axis */
+               const GLfloat invQ = (q == 0.0F) ? 1.0F : (1.0F / q);
+               for (i = 0; i < span->end; i++) {
+                  texcoord[i][0] = s * invQ;
+                  texcoord[i][1] = t * invQ;
+                  texcoord[i][2] = r * invQ;
+                  texcoord[i][3] = q;
+                  lambda[i] = 0.0;
+                  s += dsdx;
+                  t += dtdx;
+                  r += drdx;
+               }
+            }
+            else {
+               for (i = 0; i < span->end; i++) {
+                  const GLfloat invQ = (q == 0.0F) ? 1.0F : (1.0F / q);
+                  texcoord[i][0] = s * invQ;
+                  texcoord[i][1] = t * invQ;
+                  texcoord[i][2] = r * invQ;
+                  texcoord[i][3] = q;
+                  lambda[i] = 0.0;
+                  s += dsdx;
+                  t += dtdx;
+                  r += drdx;
+                  q += dqdx;
+               }
+            }
+         } /* lambda */
+      } /* if */
+   } /* for */
+}
+
+
+/**
+ * Fill in the arrays->attribs[FRAG_ATTRIB_WPOS] array.
+ */
+static INLINE void
+interpolate_wpos(GLcontext *ctx, SWspan *span)
+{
+   GLfloat (*wpos)[4] = span->array->attribs[FRAG_ATTRIB_WPOS];
+   GLuint i;
+   const GLfloat zScale = 1.0 / ctx->DrawBuffer->_DepthMaxF;
+   GLfloat w, dw;
+
+   if (span->arrayMask & SPAN_XY) {
+      for (i = 0; i < span->end; i++) {
+         wpos[i][0] = (GLfloat) span->array->x[i];
+         wpos[i][1] = (GLfloat) span->array->y[i];
+      }
+   }
+   else {
+      for (i = 0; i < span->end; i++) {
+         wpos[i][0] = (GLfloat) span->x + i;
+         wpos[i][1] = (GLfloat) span->y;
+      }
+   }
+
+   dw = span->attrStepX[FRAG_ATTRIB_WPOS][3];
+   w = span->attrStart[FRAG_ATTRIB_WPOS][3] + span->leftClip * dw;
+   for (i = 0; i < span->end; i++) {
+      wpos[i][2] = (GLfloat) span->array->z[i] * zScale;
+      wpos[i][3] = w;
+      w += dw;
+   }
+}
+
+
+/**
+ * Apply the current polygon stipple pattern to a span of pixels.
+ */
+static INLINE void
+stipple_polygon_span(GLcontext *ctx, SWspan *span)
+{
+   GLubyte *mask = span->array->mask;
+
+   ASSERT(ctx->Polygon.StippleFlag);
+
+   if (span->arrayMask & SPAN_XY) {
+      /* arrays of x/y pixel coords */
+      GLuint i;
+      for (i = 0; i < span->end; i++) {
+         const GLint col = span->array->x[i] % 32;
+         const GLint row = span->array->y[i] % 32;
+         const GLuint stipple = ctx->PolygonStipple[row];
+         if (((1 << col) & stipple) == 0) {
+            mask[i] = 0;
+         }
+      }
+   }
+   else {
+      /* horizontal span of pixels */
+      const GLuint highBit = 1 << 31;
+      const GLuint stipple = ctx->PolygonStipple[span->y % 32];
+      GLuint i, m = highBit >> (GLuint) (span->x % 32);
+      for (i = 0; i < span->end; i++) {
+         if ((m & stipple) == 0) {
+            mask[i] = 0;
+         }
+         m = m >> 1;
+         if (m == 0) {
+            m = highBit;
+         }
+      }
+   }
+   span->writeAll = GL_FALSE;
+}
+
+
+/**
+ * Clip a pixel span to the current buffer/window boundaries:
+ * DrawBuffer->_Xmin, _Xmax, _Ymin, _Ymax.  This will accomplish
+ * window clipping and scissoring.
+ * Return:   GL_TRUE   some pixels still visible
+ *           GL_FALSE  nothing visible
+ */
+static INLINE GLuint
+clip_span( GLcontext *ctx, SWspan *span )
+{
+   const GLint xmin = ctx->DrawBuffer->_Xmin;
+   const GLint xmax = ctx->DrawBuffer->_Xmax;
+   const GLint ymin = ctx->DrawBuffer->_Ymin;
+   const GLint ymax = ctx->DrawBuffer->_Ymax;
+
+   span->leftClip = 0;
+
+   if (span->arrayMask & SPAN_XY) {
+      /* arrays of x/y pixel coords */
+      const GLint *x = span->array->x;
+      const GLint *y = span->array->y;
+      const GLint n = span->end;
+      GLubyte *mask = span->array->mask;
+      GLint i;
+      if (span->arrayMask & SPAN_MASK) {
+         /* note: using & intead of && to reduce branches */
+         for (i = 0; i < n; i++) {
+            mask[i] &= (x[i] >= xmin) & (x[i] < xmax)
+                     & (y[i] >= ymin) & (y[i] < ymax);
+         }
+      }
+      else {
+         /* note: using & intead of && to reduce branches */
+         for (i = 0; i < n; i++) {
+            mask[i] = (x[i] >= xmin) & (x[i] < xmax)
+                    & (y[i] >= ymin) & (y[i] < ymax);
+         }
+      }
+      return GL_TRUE;  /* some pixels visible */
+   }
+   else {
+      /* horizontal span of pixels */
+      const GLint x = span->x;
+      const GLint y = span->y;
+      GLint n = span->end;
+
+      /* Trivial rejection tests */
+      if (y < ymin || y >= ymax || x + n <= xmin || x >= xmax) {
+         span->end = 0;
+         return GL_FALSE;  /* all pixels clipped */
+      }
+
+      /* Clip to right */
+      if (x + n > xmax) {
+         ASSERT(x < xmax);
+         n = span->end = xmax - x;
+      }
+
+      /* Clip to the left */
+      if (x < xmin) {
+         const GLint leftClip = xmin - x;
+         GLuint i;
+
+         ASSERT(leftClip > 0);
+         ASSERT(x + n > xmin);
+
+         /* Clip 'leftClip' pixels from the left side.
+          * The span->leftClip field will be applied when we interpolate
+          * fragment attributes.
+          * For arrays of values, shift them left.
+          */
+         for (i = 0; i < FRAG_ATTRIB_MAX; i++) {
+            if (span->arrayAttribs & (1 << i)) {
+               /* shift array elements left by 'leftClip' */
+               _mesa_memcpy(span->array->attribs[i],
+                            span->array->attribs[i] + leftClip,
+                            (n - leftClip) * 4 * sizeof(GLfloat));
+            }
+         }
+
+         span->leftClip = leftClip;
+         span->x = xmin;
+         span->end -= leftClip;
+         span->writeAll = GL_FALSE;
+      }
+
+      ASSERT(span->x >= xmin);
+      ASSERT(span->x + span->end <= xmax);
+      ASSERT(span->y >= ymin);
+      ASSERT(span->y < ymax);
+
+      return GL_TRUE;  /* some pixels visible */
+   }
+}
+
+
+/**
+ * Apply all the per-fragment opertions to a span of color index fragments
+ * and write them to the enabled color drawbuffers.
+ * The 'span' parameter can be considered to be const.  Note that
+ * span->interpMask and span->arrayMask may be changed but will be restored
+ * to their original values before returning.
+ */
+void
+_swrast_write_index_span( GLcontext *ctx, SWspan *span)
+{
+   const SWcontext *swrast = SWRAST_CONTEXT(ctx);
+   const GLbitfield origInterpMask = span->interpMask;
+   const GLbitfield origArrayMask = span->arrayMask;
+   struct gl_framebuffer *fb = ctx->DrawBuffer;
+
+   ASSERT(span->end <= MAX_WIDTH);
+   ASSERT(span->primitive == GL_POINT  ||  span->primitive == GL_LINE ||
+	  span->primitive == GL_POLYGON  ||  span->primitive == GL_BITMAP);
+   ASSERT((span->interpMask | span->arrayMask) & SPAN_INDEX);
+   /*
+   ASSERT((span->interpMask & span->arrayMask) == 0);
+   */
+
+   if (span->arrayMask & SPAN_MASK) {
+      /* mask was initialized by caller, probably glBitmap */
+      span->writeAll = GL_FALSE;
+   }
+   else {
+      _mesa_memset(span->array->mask, 1, span->end);
+      span->writeAll = GL_TRUE;
+   }
+
+   /* Clipping */
+   if ((swrast->_RasterMask & CLIP_BIT) || (span->primitive != GL_POLYGON)) {
+      if (!clip_span(ctx, span)) {
+         return;
+      }
+   }
+
+   if (!(span->arrayMask & SPAN_MASK)) {
+      /* post-clip sanity check */
+      assert(span->x >= 0);
+      assert(span->y >= 0);
+   }
+
+   /* Depth bounds test */
+   if (ctx->Depth.BoundsTest && fb->Visual.depthBits > 0) {
+      if (!_swrast_depth_bounds_test(ctx, span)) {
+         return;
+      }
+   }
+
+#ifdef DEBUG
+   /* Make sure all fragments are within window bounds */
+   if (span->arrayMask & SPAN_XY) {
+      GLuint i;
+      for (i = 0; i < span->end; i++) {
+         if (span->array->mask[i]) {
+            assert(span->array->x[i] >= fb->_Xmin);
+            assert(span->array->x[i] < fb->_Xmax);
+            assert(span->array->y[i] >= fb->_Ymin);
+            assert(span->array->y[i] < fb->_Ymax);
+         }
+      }
+   }
+#endif
+
+   /* Polygon Stippling */
+   if (ctx->Polygon.StippleFlag && span->primitive == GL_POLYGON) {
+      stipple_polygon_span(ctx, span);
+   }
+
+   /* Stencil and Z testing */
+   if (ctx->Stencil._Enabled || ctx->Depth.Test) {
+      if (!(span->arrayMask & SPAN_Z))
+         _swrast_span_interpolate_z(ctx, span);
+
+      if (ctx->Stencil._Enabled) {
+         if (!_swrast_stencil_and_ztest_span(ctx, span)) {
+            span->arrayMask = origArrayMask;
+            return;
+         }
+      }
+      else {
+         ASSERT(ctx->Depth.Test);
+         if (!_swrast_depth_test_span(ctx, span)) {
+            span->interpMask = origInterpMask;
+            span->arrayMask = origArrayMask;
+            return;
+         }
+      }
+   }
+
+#if FEATURE_ARB_occlusion_query
+   if (ctx->Query.CurrentOcclusionObject) {
+      /* update count of 'passed' fragments */
+      struct gl_query_object *q = ctx->Query.CurrentOcclusionObject;
+      GLuint i;
+      for (i = 0; i < span->end; i++)
+         q->Result += span->array->mask[i];
+   }
+#endif
+
+   /* we have to wait until after occlusion to do this test */
+   if (ctx->Color.IndexMask == 0) {
+      /* write no pixels */
+      span->arrayMask = origArrayMask;
+      return;
+   }
+
+   /* Interpolate the color indexes if needed */
+   if (swrast->_FogEnabled ||
+       ctx->Color.IndexLogicOpEnabled ||
+       ctx->Color.IndexMask != 0xffffffff ||
+       (span->arrayMask & SPAN_COVERAGE)) {
+      if (!(span->arrayMask & SPAN_INDEX) /*span->interpMask & SPAN_INDEX*/) {
+         interpolate_indexes(ctx, span);
+      }
+   }
+
+   /* Fog */
+   if (swrast->_FogEnabled) {
+      _swrast_fog_ci_span(ctx, span);
+   }
+
+   /* Antialias coverage application */
+   if (span->arrayMask & SPAN_COVERAGE) {
+      const GLfloat *coverage = span->array->coverage;
+      GLuint *index = span->array->index;
+      GLuint i;
+      for (i = 0; i < span->end; i++) {
+         ASSERT(coverage[i] < 16);
+         index[i] = (index[i] & ~0xf) | ((GLuint) coverage[i]);
+      }
+   }
+
+   /*
+    * Write to renderbuffers
+    */
+   {
+      const GLuint numBuffers = fb->_NumColorDrawBuffers;
+      GLuint buf;
+
+      for (buf = 0; buf < numBuffers; buf++) {
+         struct gl_renderbuffer *rb = fb->_ColorDrawBuffers[buf];
+         GLuint indexSave[MAX_WIDTH];
+
+         ASSERT(rb->_BaseFormat == GL_COLOR_INDEX);
+
+         if (numBuffers > 1) {
+            /* save indexes for second, third renderbuffer writes */
+            _mesa_memcpy(indexSave, span->array->index,
+                         span->end * sizeof(indexSave[0]));
+         }
+
+         if (ctx->Color.IndexLogicOpEnabled) {
+            _swrast_logicop_ci_span(ctx, rb, span);
+         }
+
+         if (ctx->Color.IndexMask != 0xffffffff) {
+            _swrast_mask_ci_span(ctx, rb, span);
+         }
+
+         if (!(span->arrayMask & SPAN_INDEX) && span->indexStep == 0) {
+            /* all fragments have same color index */
+            GLubyte index8;
+            GLushort index16;
+            GLuint index32;
+            void *value;
+
+            if (rb->DataType == GL_UNSIGNED_BYTE) {
+               index8 = FixedToInt(span->index);
+               value = &index8;
+            }
+            else if (rb->DataType == GL_UNSIGNED_SHORT) {
+               index16 = FixedToInt(span->index);
+               value = &index16;
+            }
+            else {
+               ASSERT(rb->DataType == GL_UNSIGNED_INT);
+               index32 = FixedToInt(span->index);
+               value = &index32;
+            }
+
+            if (span->arrayMask & SPAN_XY) {
+               rb->PutMonoValues(ctx, rb, span->end, span->array->x, 
+                                 span->array->y, value, span->array->mask);
+            }
+            else {
+               rb->PutMonoRow(ctx, rb, span->end, span->x, span->y,
+                              value, span->array->mask);
+            }
+         }
+         else {
+            /* each fragment is a different color */
+            GLubyte index8[MAX_WIDTH];
+            GLushort index16[MAX_WIDTH];
+            void *values;
+
+            if (rb->DataType == GL_UNSIGNED_BYTE) {
+               GLuint k;
+               for (k = 0; k < span->end; k++) {
+                  index8[k] = (GLubyte) span->array->index[k];
+               }
+               values = index8;
+            }
+            else if (rb->DataType == GL_UNSIGNED_SHORT) {
+               GLuint k;
+               for (k = 0; k < span->end; k++) {
+                  index16[k] = (GLushort) span->array->index[k];
+               }
+               values = index16;
+            }
+            else {
+               ASSERT(rb->DataType == GL_UNSIGNED_INT);
+               values = span->array->index;
+            }
+
+            if (span->arrayMask & SPAN_XY) {
+               rb->PutValues(ctx, rb, span->end,
+                             span->array->x, span->array->y,
+                             values, span->array->mask);
+            }
+            else {
+               rb->PutRow(ctx, rb, span->end, span->x, span->y,
+                          values, span->array->mask);
+            }
+         }
+
+         if (buf + 1 < numBuffers) {
+            /* restore original span values */
+            _mesa_memcpy(span->array->index, indexSave,
+                         span->end * sizeof(indexSave[0]));
+         }
+      } /* for buf */
+   }
+
+   span->interpMask = origInterpMask;
+   span->arrayMask = origArrayMask;
+}
+
+
+/**
+ * Add specular colors to primary colors.
+ * Only called during fixed-function operation.
+ * Result is float color array (FRAG_ATTRIB_COL0).
+ */
+static INLINE void
+add_specular(GLcontext *ctx, SWspan *span)
+{
+   const SWcontext *swrast = SWRAST_CONTEXT(ctx);
+   const GLubyte *mask = span->array->mask;
+   GLfloat (*col0)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
+   GLfloat (*col1)[4] = span->array->attribs[FRAG_ATTRIB_COL1];
+   GLuint i;
+
+   ASSERT(!ctx->FragmentProgram._Current);
+   ASSERT(span->arrayMask & SPAN_RGBA);
+   ASSERT(swrast->_ActiveAttribMask & FRAG_BIT_COL1);
+   (void) swrast; /* silence warning */
+
+   if (span->array->ChanType == GL_FLOAT) {
+      if ((span->arrayAttribs & FRAG_BIT_COL0) == 0) {
+         interpolate_active_attribs(ctx, span, FRAG_BIT_COL0);
+      }
+   }
+   else {
+      /* need float colors */
+      if ((span->arrayAttribs & FRAG_BIT_COL0) == 0) {
+         interpolate_float_colors(span);
+      }
+   }
+
+   if ((span->arrayAttribs & FRAG_BIT_COL1) == 0) {
+      /* XXX could avoid this and interpolate COL1 in the loop below */
+      interpolate_active_attribs(ctx, span, FRAG_BIT_COL1);
+   }
+
+   ASSERT(span->arrayAttribs & FRAG_BIT_COL0);
+   ASSERT(span->arrayAttribs & FRAG_BIT_COL1);
+
+   for (i = 0; i < span->end; i++) {
+      if (mask[i]) {
+         col0[i][0] += col1[i][0];
+         col0[i][1] += col1[i][1];
+         col0[i][2] += col1[i][2];
+      }
+   }
+
+   span->array->ChanType = GL_FLOAT;
+}
+
+
+/**
+ * Apply antialiasing coverage value to alpha values.
+ */
+static INLINE void
+apply_aa_coverage(SWspan *span)
+{
+   const GLfloat *coverage = span->array->coverage;
+   GLuint i;
+   if (span->array->ChanType == GL_UNSIGNED_BYTE) {
+      GLubyte (*rgba)[4] = span->array->rgba8;
+      for (i = 0; i < span->end; i++) {
+         const GLfloat a = rgba[i][ACOMP] * coverage[i];
+         rgba[i][ACOMP] = (GLubyte) CLAMP(a, 0.0, 255.0);
+         ASSERT(coverage[i] >= 0.0);
+         ASSERT(coverage[i] <= 1.0);
+      }
+   }
+   else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
+      GLushort (*rgba)[4] = span->array->rgba16;
+      for (i = 0; i < span->end; i++) {
+         const GLfloat a = rgba[i][ACOMP] * coverage[i];
+         rgba[i][ACOMP] = (GLushort) CLAMP(a, 0.0, 65535.0);
+      }
+   }
+   else {
+      GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
+      for (i = 0; i < span->end; i++) {
+         rgba[i][ACOMP] = rgba[i][ACOMP] * coverage[i];
+         /* clamp later */
+      }
+   }
+}
+
+
+/**
+ * Clamp span's float colors to [0,1]
+ */
+static INLINE void
+clamp_colors(SWspan *span)
+{
+   GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL0];
+   GLuint i;
+   ASSERT(span->array->ChanType == GL_FLOAT);
+   for (i = 0; i < span->end; i++) {
+      rgba[i][RCOMP] = CLAMP(rgba[i][RCOMP], 0.0F, 1.0F);
+      rgba[i][GCOMP] = CLAMP(rgba[i][GCOMP], 0.0F, 1.0F);
+      rgba[i][BCOMP] = CLAMP(rgba[i][BCOMP], 0.0F, 1.0F);
+      rgba[i][ACOMP] = CLAMP(rgba[i][ACOMP], 0.0F, 1.0F);
+   }
+}
+
+
+/**
+ * Convert the span's color arrays to the given type.
+ * The only way 'output' can be greater than zero is when we have a fragment
+ * program that writes to gl_FragData[1] or higher.
+ * \param output  which fragment program color output is being processed
+ */
+static INLINE void
+convert_color_type(SWspan *span, GLenum newType, GLuint output)
+{
+   GLvoid *src, *dst;
+
+   if (output > 0 || span->array->ChanType == GL_FLOAT) {
+      src = span->array->attribs[FRAG_ATTRIB_COL0 + output];
+      span->array->ChanType = GL_FLOAT;
+   }
+   else if (span->array->ChanType == GL_UNSIGNED_BYTE) {
+      src = span->array->rgba8;
+   }
+   else {
+      ASSERT(span->array->ChanType == GL_UNSIGNED_SHORT);
+      src = span->array->rgba16;
+   }
+
+   if (newType == GL_UNSIGNED_BYTE) {
+      dst = span->array->rgba8;
+   }
+   else if (newType == GL_UNSIGNED_SHORT) {
+      dst = span->array->rgba16;
+   }
+   else {
+      dst = span->array->attribs[FRAG_ATTRIB_COL0];
+   }
+
+   _mesa_convert_colors(span->array->ChanType, src,
+                        newType, dst,
+                        span->end, span->array->mask);
+
+   span->array->ChanType = newType;
+   span->array->rgba = dst;
+}
+
+
+
+/**
+ * Apply fragment shader, fragment program or normal texturing to span.
+ */
+static INLINE void
+shade_texture_span(GLcontext *ctx, SWspan *span)
+{
+   GLbitfield inputsRead;
+
+   /* Determine which fragment attributes are actually needed */
+   if (ctx->FragmentProgram._Current) {
+      inputsRead = ctx->FragmentProgram._Current->Base.InputsRead;
+   }
+   else {
+      /* XXX we could be a bit smarter about this */
+      inputsRead = ~0;
+   }
+
+   if (ctx->FragmentProgram._Current ||
+       ctx->ATIFragmentShader._Enabled) {
+      /* programmable shading */
+      if (span->primitive == GL_BITMAP && span->array->ChanType != GL_FLOAT) {
+         convert_color_type(span, GL_FLOAT, 0);
+      }
+      if (span->primitive != GL_POINT ||
+	  (span->interpMask & SPAN_RGBA) ||
+	  ctx->Point.PointSprite) {
+         /* for single-pixel points, we populated the arrays already */
+         interpolate_active_attribs(ctx, span, ~0);
+      }
+      span->array->ChanType = GL_FLOAT;
+
+      if (!(span->arrayMask & SPAN_Z))
+         _swrast_span_interpolate_z (ctx, span);
+
+#if 0
+      if (inputsRead & FRAG_BIT_WPOS)
+#else
+      /* XXX always interpolate wpos so that DDX/DDY work */
+#endif
+         interpolate_wpos(ctx, span);
+
+      /* Run fragment program/shader now */
+      if (ctx->FragmentProgram._Current) {
+         _swrast_exec_fragment_program(ctx, span);
+      }
+      else {
+         ASSERT(ctx->ATIFragmentShader._Enabled);
+         _swrast_exec_fragment_shader(ctx, span);
+      }
+   }
+   else if (ctx->Texture._EnabledCoordUnits) {
+      /* conventional texturing */
+
+#if CHAN_BITS == 32
+      if ((span->arrayAttribs & FRAG_BIT_COL0) == 0) {
+         interpolate_int_colors(ctx, span);
+      }
+#else
+      if (!(span->arrayMask & SPAN_RGBA))
+         interpolate_int_colors(ctx, span);
+#endif
+      if ((span->arrayAttribs & FRAG_BITS_TEX_ANY) == 0x0)
+         interpolate_texcoords(ctx, span);
+
+      _swrast_texture_span(ctx, span);
+   }
+}
+
+
+
+/**
+ * Apply all the per-fragment operations to a span.
+ * This now includes texturing (_swrast_write_texture_span() is history).
+ * This function may modify any of the array values in the span.
+ * span->interpMask and span->arrayMask may be changed but will be restored
+ * to their original values before returning.
+ */
+void
+_swrast_write_rgba_span( GLcontext *ctx, SWspan *span)
+{
+   const SWcontext *swrast = SWRAST_CONTEXT(ctx);
+   const GLuint colorMask = *((GLuint *) ctx->Color.ColorMask);
+   const GLbitfield origInterpMask = span->interpMask;
+   const GLbitfield origArrayMask = span->arrayMask;
+   const GLbitfield origArrayAttribs = span->arrayAttribs;
+   const GLenum origChanType = span->array->ChanType;
+   void * const origRgba = span->array->rgba;
+   const GLboolean shader = (ctx->FragmentProgram._Current
+                             || ctx->ATIFragmentShader._Enabled);
+   const GLboolean shaderOrTexture = shader || ctx->Texture._EnabledCoordUnits;
+   struct gl_framebuffer *fb = ctx->DrawBuffer;
+
+   /*
+   printf("%s()  interp 0x%x  array 0x%x\n", __FUNCTION__,
+          span->interpMask, span->arrayMask);
+   */
+
+   ASSERT(span->primitive == GL_POINT ||
+          span->primitive == GL_LINE ||
+	  span->primitive == GL_POLYGON ||
+          span->primitive == GL_BITMAP);
+
+   /* Fragment write masks */
+   if (span->arrayMask & SPAN_MASK) {
+      /* mask was initialized by caller, probably glBitmap */
+      span->writeAll = GL_FALSE;
+   }
+   else {
+      _mesa_memset(span->array->mask, 1, span->end);
+      span->writeAll = GL_TRUE;
+   }
+
+   /* Clip to window/scissor box */
+   if (!clip_span(ctx, span)) {
+      return;
+   }
+
+   ASSERT(span->end <= MAX_WIDTH);
+
+#ifdef DEBUG
+   /* Make sure all fragments are within window bounds */
+   if (span->arrayMask & SPAN_XY) {
+      /* array of pixel locations */
+      GLuint i;
+      for (i = 0; i < span->end; i++) {
+         if (span->array->mask[i]) {
+            assert(span->array->x[i] >= fb->_Xmin);
+            assert(span->array->x[i] < fb->_Xmax);
+            assert(span->array->y[i] >= fb->_Ymin);
+            assert(span->array->y[i] < fb->_Ymax);
+         }
+      }
+   }
+#endif
+
+   /* Polygon Stippling */
+   if (ctx->Polygon.StippleFlag && span->primitive == GL_POLYGON) {
+      stipple_polygon_span(ctx, span);
+   }
+
+   /* This is the normal place to compute the fragment color/Z
+    * from texturing or shading.
+    */
+   if (shaderOrTexture && !swrast->_DeferredTexture) {
+      shade_texture_span(ctx, span);
+   }
+
+   /* Do the alpha test */
+   if (ctx->Color.AlphaEnabled) {
+      if (!_swrast_alpha_test(ctx, span)) {
+         /* all fragments failed test */
+         goto end;
+      }
+   }
+
+   /* Stencil and Z testing */
+   if (ctx->Stencil._Enabled || ctx->Depth.Test) {
+      if (!(span->arrayMask & SPAN_Z))
+         _swrast_span_interpolate_z(ctx, span);
+      if (ctx->Stencil._Enabled) {
+         /* Combined Z/stencil tests */
+         if (!_swrast_stencil_and_ztest_span(ctx, span)) {
+            /* all fragments failed test */
+            goto end;
+         }
+      }
+      else if (fb->Visual.depthBits > 0) {
+         /* Just regular depth testing */
+         ASSERT(ctx->Depth.Test);
+         ASSERT(span->arrayMask & SPAN_Z);
+         if (!_swrast_depth_test_span(ctx, span)) {
+            /* all fragments failed test */
+            goto end;
+         }
+      }
+   }
+
+#if FEATURE_ARB_occlusion_query
+   if (ctx->Query.CurrentOcclusionObject) {
+      /* update count of 'passed' fragments */
+      struct gl_query_object *q = ctx->Query.CurrentOcclusionObject;
+      GLuint i;
+      for (i = 0; i < span->end; i++)
+         q->Result += span->array->mask[i];
+   }
+#endif
+
+   /* We had to wait until now to check for glColorMask(0,0,0,0) because of
+    * the occlusion test.
+    */
+   if (colorMask == 0x0) {
+      /* no colors to write */
+      goto end;
+   }
+
+   /* If we were able to defer fragment color computation to now, there's
+    * a good chance that many fragments will have already been killed by
+    * Z/stencil testing.
+    */
+   if (shaderOrTexture && swrast->_DeferredTexture) {
+      shade_texture_span(ctx, span);
+   }
+
+#if CHAN_BITS == 32
+   if ((span->arrayAttribs & FRAG_BIT_COL0) == 0) {
+      interpolate_active_attribs(ctx, span, FRAG_BIT_COL0);
+   }
+#else
+   if ((span->arrayMask & SPAN_RGBA) == 0) {
+      interpolate_int_colors(ctx, span);
+   }
+#endif
+
+   ASSERT(span->arrayMask & SPAN_RGBA);
+
+   if (span->primitive == GL_BITMAP || !swrast->SpecularVertexAdd) {
+      /* Add primary and specular (diffuse + specular) colors */
+      if (!shader) {
+         if (ctx->Fog.ColorSumEnabled ||
+             (ctx->Light.Enabled &&
+              ctx->Light.Model.ColorControl == GL_SEPARATE_SPECULAR_COLOR)) {
+            add_specular(ctx, span);
+         }
+      }
+   }
+
+   /* Fog */
+   if (swrast->_FogEnabled) {
+      _swrast_fog_rgba_span(ctx, span);
+   }
+
+   /* Antialias coverage application */
+   if (span->arrayMask & SPAN_COVERAGE) {
+      apply_aa_coverage(span);
+   }
+
+   /* Clamp color/alpha values over the range [0.0, 1.0] before storage */
+   if (ctx->Color.ClampFragmentColor == GL_TRUE &&
+       span->array->ChanType == GL_FLOAT) {
+      clamp_colors(span);
+   }
+
+   /*
+    * Write to renderbuffers.
+    * Depending on glDrawBuffer() state and the which color outputs are
+    * written by the fragment shader, we may either replicate one color to
+    * all renderbuffers or write a different color to each renderbuffer.
+    * multiFragOutputs=TRUE for the later case.
+    */
+   {
+      const GLuint numBuffers = fb->_NumColorDrawBuffers;
+      const struct gl_fragment_program *fp = ctx->FragmentProgram._Current;
+      const GLboolean multiFragOutputs = 
+         (fp && fp->Base.OutputsWritten >= (1 << FRAG_RESULT_DATA0));
+      GLuint buf;
+
+      for (buf = 0; buf < numBuffers; buf++) {
+         struct gl_renderbuffer *rb = fb->_ColorDrawBuffers[buf];
+
+         /* color[fragOutput] will be written to buffer[buf] */
+
+         if (rb) {
+            GLchan rgbaSave[MAX_WIDTH][4];
+            const GLuint fragOutput = multiFragOutputs ? buf : 0;
+
+            if (rb->DataType != span->array->ChanType || fragOutput > 0) {
+               convert_color_type(span, rb->DataType, fragOutput);
+            }
+
+            if (!multiFragOutputs && numBuffers > 1) {
+               /* save colors for second, third renderbuffer writes */
+               _mesa_memcpy(rgbaSave, span->array->rgba,
+                            4 * span->end * sizeof(GLchan));
+            }
+
+            ASSERT(rb->_BaseFormat == GL_RGBA || rb->_BaseFormat == GL_RGB);
+
+            if (ctx->Color._LogicOpEnabled) {
+               _swrast_logicop_rgba_span(ctx, rb, span);
+            }
+            else if (ctx->Color.BlendEnabled) {
+               _swrast_blend_span(ctx, rb, span);
+            }
+
+            if (colorMask != 0xffffffff) {
+               _swrast_mask_rgba_span(ctx, rb, span);
+            }
+
+            if (span->arrayMask & SPAN_XY) {
+               /* array of pixel coords */
+               ASSERT(rb->PutValues);
+               rb->PutValues(ctx, rb, span->end,
+                             span->array->x, span->array->y,
+                             span->array->rgba, span->array->mask);
+            }
+            else {
+               /* horizontal run of pixels */
+               ASSERT(rb->PutRow);
+               rb->PutRow(ctx, rb, span->end, span->x, span->y,
+                          span->array->rgba,
+                          span->writeAll ? NULL: span->array->mask);
+            }
+
+            if (!multiFragOutputs && numBuffers > 1) {
+               /* restore original span values */
+               _mesa_memcpy(span->array->rgba, rgbaSave,
+                            4 * span->end * sizeof(GLchan));
+            }
+
+         } /* if rb */
+      } /* for buf */
+   }
+
+end:
+   /* restore these values before returning */
+   span->interpMask = origInterpMask;
+   span->arrayMask = origArrayMask;
+   span->arrayAttribs = origArrayAttribs;
+   span->array->ChanType = origChanType;
+   span->array->rgba = origRgba;
+}
+
+
+/**
+ * Read RGBA pixels from a renderbuffer.  Clipping will be done to prevent
+ * reading ouside the buffer's boundaries.
+ * \param dstType  datatype for returned colors
+ * \param rgba  the returned colors
+ */
+void
+_swrast_read_rgba_span( GLcontext *ctx, struct gl_renderbuffer *rb,
+                        GLuint n, GLint x, GLint y, GLenum dstType,
+                        GLvoid *rgba)
+{
+   const GLint bufWidth = (GLint) rb->Width;
+   const GLint bufHeight = (GLint) rb->Height;
+
+   if (y < 0 || y >= bufHeight || x + (GLint) n < 0 || x >= bufWidth) {
+      /* completely above, below, or right */
+      /* XXX maybe leave rgba values undefined? */
+      _mesa_bzero(rgba, 4 * n * sizeof(GLchan));
+   }
+   else {
+      GLint skip, length;
+      if (x < 0) {
+         /* left edge clipping */
+         skip = -x;
+         length = (GLint) n - skip;
+         if (length < 0) {
+            /* completely left of window */
+            return;
+         }
+         if (length > bufWidth) {
+            length = bufWidth;
+         }
+      }
+      else if ((GLint) (x + n) > bufWidth) {
+         /* right edge clipping */
+         skip = 0;
+         length = bufWidth - x;
+         if (length < 0) {
+            /* completely to right of window */
+            return;
+         }
+      }
+      else {
+         /* no clipping */
+         skip = 0;
+         length = (GLint) n;
+      }
+
+      ASSERT(rb);
+      ASSERT(rb->GetRow);
+      ASSERT(rb->_BaseFormat == GL_RGB || rb->_BaseFormat == GL_RGBA);
+
+      if (rb->DataType == dstType) {
+         rb->GetRow(ctx, rb, length, x + skip, y,
+                    (GLubyte *) rgba + skip * RGBA_PIXEL_SIZE(rb->DataType));
+      }
+      else {
+         GLuint temp[MAX_WIDTH * 4];
+         rb->GetRow(ctx, rb, length, x + skip, y, temp);
+         _mesa_convert_colors(rb->DataType, temp,
+                   dstType, (GLubyte *) rgba + skip * RGBA_PIXEL_SIZE(dstType),
+                   length, NULL);
+      }
+   }
+}
+
+
+/**
+ * Read CI pixels from a renderbuffer.  Clipping will be done to prevent
+ * reading ouside the buffer's boundaries.
+ */
+void
+_swrast_read_index_span( GLcontext *ctx, struct gl_renderbuffer *rb,
+                         GLuint n, GLint x, GLint y, GLuint index[] )
+{
+   const GLint bufWidth = (GLint) rb->Width;
+   const GLint bufHeight = (GLint) rb->Height;
+
+   if (y < 0 || y >= bufHeight || x + (GLint) n < 0 || x >= bufWidth) {
+      /* completely above, below, or right */
+      _mesa_bzero(index, n * sizeof(GLuint));
+   }
+   else {
+      GLint skip, length;
+      if (x < 0) {
+         /* left edge clipping */
+         skip = -x;
+         length = (GLint) n - skip;
+         if (length < 0) {
+            /* completely left of window */
+            return;
+         }
+         if (length > bufWidth) {
+            length = bufWidth;
+         }
+      }
+      else if ((GLint) (x + n) > bufWidth) {
+         /* right edge clipping */
+         skip = 0;
+         length = bufWidth - x;
+         if (length < 0) {
+            /* completely to right of window */
+            return;
+         }
+      }
+      else {
+         /* no clipping */
+         skip = 0;
+         length = (GLint) n;
+      }
+
+      ASSERT(rb->GetRow);
+      ASSERT(rb->_BaseFormat == GL_COLOR_INDEX);
+
+      if (rb->DataType == GL_UNSIGNED_BYTE) {
+         GLubyte index8[MAX_WIDTH];
+         GLint i;
+         rb->GetRow(ctx, rb, length, x + skip, y, index8);
+         for (i = 0; i < length; i++)
+            index[skip + i] = index8[i];
+      }
+      else if (rb->DataType == GL_UNSIGNED_SHORT) {
+         GLushort index16[MAX_WIDTH];
+         GLint i;
+         rb->GetRow(ctx, rb, length, x + skip, y, index16);
+         for (i = 0; i < length; i++)
+            index[skip + i] = index16[i];
+      }
+      else if (rb->DataType == GL_UNSIGNED_INT) {
+         rb->GetRow(ctx, rb, length, x + skip, y, index + skip);
+      }
+   }
+}
+
+
+/**
+ * Wrapper for gl_renderbuffer::GetValues() which does clipping to avoid
+ * reading values outside the buffer bounds.
+ * We can use this for reading any format/type of renderbuffer.
+ * \param valueSize is the size in bytes of each value (pixel) put into the
+ *                  values array.
+ */
+void
+_swrast_get_values(GLcontext *ctx, struct gl_renderbuffer *rb,
+                   GLuint count, const GLint x[], const GLint y[],
+                   void *values, GLuint valueSize)
+{
+   GLuint i, inCount = 0, inStart = 0;
+
+   for (i = 0; i < count; i++) {
+      if (x[i] >= 0 && y[i] >= 0 &&
+	  x[i] < (GLint) rb->Width && y[i] < (GLint) rb->Height) {
+         /* inside */
+         if (inCount == 0)
+            inStart = i;
+         inCount++;
+      }
+      else {
+         if (inCount > 0) {
+            /* read [inStart, inStart + inCount) */
+            rb->GetValues(ctx, rb, inCount, x + inStart, y + inStart,
+                          (GLubyte *) values + inStart * valueSize);
+            inCount = 0;
+         }
+      }
+   }
+   if (inCount > 0) {
+      /* read last values */
+      rb->GetValues(ctx, rb, inCount, x + inStart, y + inStart,
+                    (GLubyte *) values + inStart * valueSize);
+   }
+}
+
+
+/**
+ * Wrapper for gl_renderbuffer::PutRow() which does clipping.
+ * \param valueSize  size of each value (pixel) in bytes
+ */
+void
+_swrast_put_row(GLcontext *ctx, struct gl_renderbuffer *rb,
+                GLuint count, GLint x, GLint y,
+                const GLvoid *values, GLuint valueSize)
+{
+   GLint skip = 0;
+
+   if (y < 0 || y >= (GLint) rb->Height)
+      return; /* above or below */
+
+   if (x + (GLint) count <= 0 || x >= (GLint) rb->Width)
+      return; /* entirely left or right */
+
+   if ((GLint) (x + count) > (GLint) rb->Width) {
+      /* right clip */
+      GLint clip = x + count - rb->Width;
+      count -= clip;
+   }
+
+   if (x < 0) {
+      /* left clip */
+      skip = -x;
+      x = 0;
+      count -= skip;
+   }
+
+   rb->PutRow(ctx, rb, count, x, y,
+              (const GLubyte *) values + skip * valueSize, NULL);
+}
+
+
+/**
+ * Wrapper for gl_renderbuffer::GetRow() which does clipping.
+ * \param valueSize  size of each value (pixel) in bytes
+ */
+void
+_swrast_get_row(GLcontext *ctx, struct gl_renderbuffer *rb,
+                GLuint count, GLint x, GLint y,
+                GLvoid *values, GLuint valueSize)
+{
+   GLint skip = 0;
+
+   if (y < 0 || y >= (GLint) rb->Height)
+      return; /* above or below */
+
+   if (x + (GLint) count <= 0 || x >= (GLint) rb->Width)
+      return; /* entirely left or right */
+
+   if (x + count > rb->Width) {
+      /* right clip */
+      GLint clip = x + count - rb->Width;
+      count -= clip;
+   }
+
+   if (x < 0) {
+      /* left clip */
+      skip = -x;
+      x = 0;
+      count -= skip;
+   }
+
+   rb->GetRow(ctx, rb, count, x, y, (GLubyte *) values + skip * valueSize);
+}
+
+
+/**
+ * Get RGBA pixels from the given renderbuffer.  Put the pixel colors into
+ * the span's specular color arrays.  The specular color arrays should no
+ * longer be needed by time this function is called.
+ * Used by blending, logicop and masking functions.
+ * \return pointer to the colors we read.
+ */
+void *
+_swrast_get_dest_rgba(GLcontext *ctx, struct gl_renderbuffer *rb,
+                      SWspan *span)
+{
+   const GLuint pixelSize = RGBA_PIXEL_SIZE(span->array->ChanType);
+   void *rbPixels;
+
+   /*
+    * Point rbPixels to a temporary space (use specular color arrays).
+    */
+   rbPixels = span->array->attribs[FRAG_ATTRIB_COL1];
+
+   /* Get destination values from renderbuffer */
+   if (span->arrayMask & SPAN_XY) {
+      _swrast_get_values(ctx, rb, span->end, span->array->x, span->array->y,
+                         rbPixels, pixelSize);
+   }
+   else {
+      _swrast_get_row(ctx, rb, span->end, span->x, span->y,
+                      rbPixels, pixelSize);
+   }
+
+   return rbPixels;
+}