path: root/nx-X11/extras/Mesa/src/mesa/drivers/dri/i830/i830_texstate.c

/**************************************************************************

Copyright 2001 2d3d Inc., Delray Beach, FL

All Rights Reserved.

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/* $XFree86: xc/lib/GL/mesa/src/drv/i830/i830_texstate.c,v 1.3 2002/12/10 01:26:53 dawes Exp $ */

/**
 * \file i830_texstate.c
 * 
 * Heavily based on the I810 driver, which was written by Keith Whitwell.
 *
 * \author Jeff Hartmann <jhartmann@2d3d.com>
 * \author Keith Whitwell <keithw@tungstengraphics.com>
 */

#include "glheader.h"
#include "macros.h"
#include "mtypes.h"
#include "simple_list.h"
#include "enums.h"
#include "texformat.h"
#include "texstore.h"

#include "mm.h"

#include "i830_screen.h"
#include "i830_dri.h"

#include "i830_context.h"
#include "i830_tex.h"
#include "i830_state.h"
#include "i830_ioctl.h"

#define I830_TEX_UNIT_ENABLED(unit)		(1<<unit)

static void i830SetTexImages( i830ContextPtr imesa, 
			      struct gl_texture_object *tObj )
{
   GLuint total_height, pitch, i, textureFormat;
   i830TextureObjectPtr t = (i830TextureObjectPtr) tObj->DriverData;
   const struct gl_texture_image *baseImage = tObj->Image[0][tObj->BaseLevel];
   GLint numLevels;

   switch( baseImage->TexFormat->MesaFormat ) {
   case MESA_FORMAT_L8:
      t->texelBytes = 1;
      textureFormat = MAPSURF_8BIT | MT_8BIT_L8;
      break;

   case MESA_FORMAT_I8:
      t->texelBytes = 1;
      textureFormat = MAPSURF_8BIT | MT_8BIT_I8;
      break;

   case MESA_FORMAT_AL88:
      t->texelBytes = 2;
      textureFormat = MAPSURF_16BIT | MT_16BIT_AY88;
      break;

   case MESA_FORMAT_RGB565:
      t->texelBytes = 2;
      textureFormat = MAPSURF_16BIT | MT_16BIT_RGB565;
      break;

   case MESA_FORMAT_ARGB1555:
      t->texelBytes = 2;
      textureFormat = MAPSURF_16BIT | MT_16BIT_ARGB1555;
      break;

   case MESA_FORMAT_ARGB4444:
      t->texelBytes = 2;
      textureFormat = MAPSURF_16BIT | MT_16BIT_ARGB4444;
      break;

   case MESA_FORMAT_ARGB8888:
      t->texelBytes = 4;
      textureFormat = MAPSURF_32BIT | MT_32BIT_ARGB8888;
      break;

   case MESA_FORMAT_YCBCR_REV:
      t->texelBytes = 2;
      textureFormat = (MAPSURF_422 | MT_422_YCRCB_NORMAL | 
		       TM0S1_COLORSPACE_CONVERSION);
      break;

   case MESA_FORMAT_YCBCR:
      t->texelBytes = 2;
      textureFormat = (MAPSURF_422 | MT_422_YCRCB_SWAPY | /* ??? */
		       TM0S1_COLORSPACE_CONVERSION);
      break;
      
   case MESA_FORMAT_RGB_FXT1:
   case MESA_FORMAT_RGBA_FXT1:
     t->texelBytes = 2;
     textureFormat = (MAPSURF_COMPRESSED | MT_COMPRESS_FXT1);
     break;
   case MESA_FORMAT_RGBA_DXT1:
   case MESA_FORMAT_RGB_DXT1:
     /*
      * DXTn pitches are Width/4 * blocksize in bytes
      * for DXT1: blocksize=8 so Width/4*8 = Width * 2
      * for DXT3/5: blocksize=16 so Width/4*16 = Width * 4
      */
     t->texelBytes = 2;
     textureFormat = (MAPSURF_COMPRESSED | MT_COMPRESS_DXT1);
     break;
   case MESA_FORMAT_RGBA_DXT3:
     t->texelBytes = 4;
     textureFormat = (MAPSURF_COMPRESSED | MT_COMPRESS_DXT2_3);
     break;
   case MESA_FORMAT_RGBA_DXT5:
     t->texelBytes = 4;
     textureFormat = (MAPSURF_COMPRESSED | MT_COMPRESS_DXT4_5);
     break;
   default:
      fprintf(stderr, "%s: bad image format\n", __FUNCTION__);
      free( t );
      return;
   }

   /* Compute which mipmap levels we really want to send to the hardware.
    */

   driCalculateTextureFirstLastLevel( (driTextureObject *) t );


   /* Figure out the amount of memory required to hold all the mipmap
    * levels.  Choose the smallest pitch to accomodate the largest
    * mipmap:
    */
   numLevels = t->base.lastLevel - t->base.firstLevel + 1;

   /* Pitch would be subject to additional rules if texture memory were
    * tiled.  Currently it isn't. 
    */
   if (0) {
      pitch = 128;
      while (pitch < tObj->Image[0][t->base.firstLevel]->Width * t->texelBytes)
	 pitch *= 2;
   }
   else {
      pitch = tObj->Image[0][t->base.firstLevel]->Width * t->texelBytes;
      pitch = (pitch + 3) & ~3;
   }


   /* All images must be loaded at this pitch.  Count the number of
    * lines required:
    */
   for ( total_height = i = 0 ; i < numLevels ; i++ ) {
      t->image[0][i].image = tObj->Image[0][t->base.firstLevel + i];
      if (!t->image[0][i].image) 
	 break;
      
      t->image[0][i].offset = total_height * pitch;
      if (t->image[0][i].image->IsCompressed)
	{
	  if (t->image[0][i].image->Height > 4)
	    total_height += t->image[0][i].image->Height/4;
	  else
	    total_height += 1;
	}
      else
	total_height += t->image[0][i].image->Height;
      t->image[0][i].internalFormat = baseImage->Format;
   }

   t->Pitch = pitch;
   t->base.totalSize = total_height*pitch;
   t->Setup[I830_TEXREG_TM0S1] = 
      (((tObj->Image[0][t->base.firstLevel]->Height - 1) << TM0S1_HEIGHT_SHIFT) |
       ((tObj->Image[0][t->base.firstLevel]->Width - 1) << TM0S1_WIDTH_SHIFT) |
       textureFormat);
   t->Setup[I830_TEXREG_TM0S2] = 
      ((((pitch / 4) - 1) << TM0S2_PITCH_SHIFT));   
   t->Setup[I830_TEXREG_TM0S3] &= ~TM0S3_MAX_MIP_MASK;
   t->Setup[I830_TEXREG_TM0S3] &= ~TM0S3_MIN_MIP_MASK;
   t->Setup[I830_TEXREG_TM0S3] |= ((numLevels - 1)*4) << TM0S3_MIN_MIP_SHIFT;
   t->dirty = I830_UPLOAD_TEX0 | I830_UPLOAD_TEX1 
	| I830_UPLOAD_TEX2 | I830_UPLOAD_TEX3;

   LOCK_HARDWARE( imesa );
   i830UploadTexImagesLocked( imesa, t );
   UNLOCK_HARDWARE( imesa );
}

/* ================================================================
 * Texture combine functions
 */


/**
 * Calculate the hardware instuctions to setup the current texture enviromnemt
 * settings.  Since \c gl_texture_unit::_CurrentCombine is used, both
 * "classic" texture enviroments and GL_ARB_texture_env_combine type texture
 * environments are treated identically.
 *
 * \todo
 * This function should return \c GLboolean.  When \c GL_FALSE is returned,
 * it means that an environment is selected that the hardware cannot do.  This
 * is the way the Radeon and R200 drivers work.
 * 
 * \todo
 * Looking at i830_3d_regs.h, it seems the i830 can do part of
 * GL_ATI_texture_env_combine3.  It can handle using \c GL_ONE and
 * \c GL_ZERO as combine inputs (which the code already supports).  It can
 * also handle the \c GL_MODULATE_ADD_ATI mode.  Is it worth investigating
 * partial support for the extension?
 * 
 * \todo
 * Some thought needs to be put into the way combiners work.  The driver
 * treats the hardware as if there's a specific combine unit tied to each
 * texture unit.  That's why there's the special case for a disabled texture
 * unit.  That's not the way the hardware works.  In reality, there are 4
 * texture units and four general instruction slots.  Each instruction slot
 * can use any texture as an input.  There's no need for this wierd "no-op"
 * stuff.  If texture units 0 and 3 are enabled, the  instructions to combine
 * them should be in slots 0 and 1, not 0 and 3 with two no-ops inbetween.
 */

static void i830UpdateTexEnv( GLcontext *ctx, GLuint unit )
{
   i830ContextPtr imesa = I830_CONTEXT(ctx);
   const struct gl_texture_unit *texUnit = &ctx->Texture.Unit[unit];
   const GLuint numColorArgs = texUnit->_CurrentCombine->_NumArgsRGB;
   const GLuint numAlphaArgs = texUnit->_CurrentCombine->_NumArgsA;

   GLboolean need_constant_color = GL_FALSE;
   GLuint blendop;
   GLuint ablendop;
   GLuint args_RGB[3];
   GLuint args_A[3];
   GLuint rgb_shift = texUnit->Combine.ScaleShiftRGB;
   GLuint alpha_shift = texUnit->Combine.ScaleShiftA;
   int i;
   unsigned used;
   static const GLuint tex_blend_rgb[3] = {
      TEXPIPE_COLOR | TEXBLEND_ARG1 | TEXBLENDARG_MODIFY_PARMS,
      TEXPIPE_COLOR | TEXBLEND_ARG2 | TEXBLENDARG_MODIFY_PARMS,
      TEXPIPE_COLOR | TEXBLEND_ARG0 | TEXBLENDARG_MODIFY_PARMS,
   };
   static const GLuint tex_blend_a[3] = {
      TEXPIPE_ALPHA | TEXBLEND_ARG1 | TEXBLENDARG_MODIFY_PARMS,
      TEXPIPE_ALPHA | TEXBLEND_ARG2 | TEXBLENDARG_MODIFY_PARMS,
      TEXPIPE_ALPHA | TEXBLEND_ARG0 | TEXBLENDARG_MODIFY_PARMS,
   };
   static const GLuint op_rgb[4] = {
      0,
      TEXBLENDARG_INV_ARG,
      TEXBLENDARG_REPLICATE_ALPHA,
      TEXBLENDARG_REPLICATE_ALPHA | TEXBLENDARG_INV_ARG,
   };



   imesa->TexBlendWordsUsed[unit] = 0;

   if(I830_DEBUG&DEBUG_TEXTURE)
       fprintf(stderr, "[%s:%u] env. mode = %s\n",  __FUNCTION__, __LINE__, 
	       _mesa_lookup_enum_by_nr(texUnit->EnvMode));


   if ( !texUnit->_ReallyEnabled ) {
      imesa->TexBlend[unit][0] = (STATE3D_MAP_BLEND_OP_CMD(unit) |
				  TEXPIPE_COLOR |
				  ENABLE_TEXOUTPUT_WRT_SEL |
				  TEXOP_OUTPUT_CURRENT |
				  DISABLE_TEX_CNTRL_STAGE |
				  TEXOP_SCALE_1X |
				  TEXOP_MODIFY_PARMS |
				  TEXBLENDOP_ARG1);
      imesa->TexBlend[unit][1] = (STATE3D_MAP_BLEND_OP_CMD(unit) |
				  TEXPIPE_ALPHA |
				  ENABLE_TEXOUTPUT_WRT_SEL |
				  TEXOP_OUTPUT_CURRENT |
				  TEXOP_SCALE_1X |
				  TEXOP_MODIFY_PARMS |
				  TEXBLENDOP_ARG1);
      imesa->TexBlend[unit][2] = (STATE3D_MAP_BLEND_ARG_CMD(unit) |
				  TEXPIPE_COLOR |
				  TEXBLEND_ARG1 |
				  TEXBLENDARG_MODIFY_PARMS |
				  TEXBLENDARG_CURRENT);
      imesa->TexBlend[unit][3] = (STATE3D_MAP_BLEND_ARG_CMD(unit) |
				  TEXPIPE_ALPHA |
				  TEXBLEND_ARG1 |
				  TEXBLENDARG_MODIFY_PARMS |
				  TEXBLENDARG_CURRENT);
      imesa->TexBlendWordsUsed[unit] = 4;
   }
   else {
      switch(texUnit->_CurrentCombine->ModeRGB) {
	  case GL_REPLACE: 
	 blendop = TEXBLENDOP_ARG1;
      break;
	  case GL_MODULATE: 
	 blendop = TEXBLENDOP_MODULATE;
	 break;
	  case GL_ADD: 
	 blendop = TEXBLENDOP_ADD;
	 break;
	  case GL_ADD_SIGNED:
	 blendop = TEXBLENDOP_ADDSIGNED; 
	 break;
	  case GL_INTERPOLATE:
	 blendop = TEXBLENDOP_BLEND; 
	 break;
	  case GL_SUBTRACT: 
	 blendop = TEXBLENDOP_SUBTRACT;
	 break;
	  case GL_DOT3_RGB_EXT:
	  case GL_DOT3_RGBA_EXT:
	 /* The EXT version of the DOT3 extension does not support the
	  * scale factor, but the ARB version (and the version in OpenGL
	  * 1.3) does.
	  */
	 rgb_shift = 0;
	 alpha_shift = 0;
	 /* FALLTHROUGH */

	  case GL_DOT3_RGB:
	  case GL_DOT3_RGBA:
	 blendop = TEXBLENDOP_DOT3;
	 break;
	  default: 
	 return;
      }

      blendop |= (rgb_shift << TEXOP_SCALE_SHIFT);

      switch(texUnit->_CurrentCombine->ModeA) {
	  case GL_REPLACE: 
	 ablendop = TEXBLENDOP_ARG1;
	 break;
	  case GL_MODULATE: 
	 ablendop = TEXBLENDOP_MODULATE;
	 break;
	  case GL_ADD: 
	 ablendop = TEXBLENDOP_ADD;
	 break;
	  case GL_ADD_SIGNED:
	 ablendop = TEXBLENDOP_ADDSIGNED; 
	 break;
	  case GL_INTERPOLATE:
	 ablendop = TEXBLENDOP_BLEND; 
	 break;
	  case GL_SUBTRACT: 
	 ablendop = TEXBLENDOP_SUBTRACT;
	 break;
	  default:
	 return;
      }

      if ( (texUnit->_CurrentCombine->ModeRGB == GL_DOT3_RGBA_EXT)
	   || (texUnit->_CurrentCombine->ModeRGB == GL_DOT3_RGBA) ) {
	 ablendop = TEXBLENDOP_DOT3;
      }

      ablendop |= (alpha_shift << TEXOP_SCALE_SHIFT);

      /* Handle RGB args */
      for( i = 0 ; i < numColorArgs ; i++ ) {
	 const int op = texUnit->_CurrentCombine->OperandRGB[i] - GL_SRC_COLOR;

	 assert( (op >= 0) && (op <= 3) );
	 switch(texUnit->_CurrentCombine->SourceRGB[i]) {
	     case GL_TEXTURE: 
	    args_RGB[i] = TEXBLENDARG_TEXEL0 + unit;
	    break;
	     case GL_TEXTURE0:
	     case GL_TEXTURE1: 
	     case GL_TEXTURE2: 
	     case GL_TEXTURE3:
	    args_RGB[i] = TEXBLENDARG_TEXEL0
		+ (texUnit->_CurrentCombine->SourceRGB[i] & 0x03);
	    break;
	     case GL_CONSTANT:
	    args_RGB[i] = TEXBLENDARG_FACTOR_N; 
	    need_constant_color = GL_TRUE;
	    break;
	     case GL_PRIMARY_COLOR:
	    args_RGB[i] = TEXBLENDARG_DIFFUSE;
	    break;
	     case GL_PREVIOUS:
	    args_RGB[i] = TEXBLENDARG_CURRENT; 
	    break;
	     case GL_ONE:
	    args_RGB[i] = TEXBLENDARG_ONE;
	    break;
	     case GL_ZERO:
	    args_RGB[i] = TEXBLENDARG_ONE | TEXBLENDARG_INV_ARG;
	    break;
	     default: 
	    return;
	 }

	 /* Xor is used so that GL_ONE_MINUS_SRC_COLOR with GL_ZERO
	  * works correctly.
	  */
	 args_RGB[i] ^= op_rgb[op];
      }

      /* Handle A args */
      for( i = 0 ; i < numAlphaArgs ; i++ ) {
	 const int op = texUnit->_CurrentCombine->OperandA[i] - GL_SRC_ALPHA;

	 assert( (op >= 0) && (op <= 1) );
	 switch(texUnit->_CurrentCombine->SourceA[i]) {
	     case GL_TEXTURE: 
	    args_A[i] = TEXBLENDARG_TEXEL0 + unit;
	    break;
	     case GL_TEXTURE0:
	     case GL_TEXTURE1: 
	     case GL_TEXTURE2: 
	     case GL_TEXTURE3:
	    args_A[i] = TEXBLENDARG_TEXEL0 
		+ (texUnit->_CurrentCombine->SourceA[i] & 0x03);
	    break;
	     case GL_CONSTANT:
	    args_A[i] = TEXBLENDARG_FACTOR_N; 
	    need_constant_color = GL_TRUE;
	    break;
	     case GL_PRIMARY_COLOR:
	    args_A[i] = TEXBLENDARG_DIFFUSE; 
	    break;
	     case GL_PREVIOUS:
	    args_A[i] = TEXBLENDARG_CURRENT; 
	    break;
	     case GL_ONE:
	    args_A[i] = TEXBLENDARG_ONE;
	    break;
	     case GL_ZERO:
	    args_A[i] = TEXBLENDARG_ONE | TEXBLENDARG_INV_ARG;
	    break;
	     default: 
	    return;
	 }

	 /* We cheat. :) The register values for this are the same as for
	  * RGB.  Xor is used so that GL_ONE_MINUS_SRC_ALPHA with GL_ZERO
	  * works correctly.
	  */
	 args_A[i] ^= op_rgb[op];
      }

      /* Native Arg1 == Arg0 in GL_EXT_texture_env_combine spec */
      /* Native Arg2 == Arg1 in GL_EXT_texture_env_combine spec */
      /* Native Arg0 == Arg2 in GL_EXT_texture_env_combine spec */

      /* Build color pipeline */

      used = 0;
      imesa->TexBlend[unit][used++] = (STATE3D_MAP_BLEND_OP_CMD(unit) |
				       TEXPIPE_COLOR |
				       ENABLE_TEXOUTPUT_WRT_SEL |
				       TEXOP_OUTPUT_CURRENT |
				       DISABLE_TEX_CNTRL_STAGE |
				       TEXOP_MODIFY_PARMS |
				       blendop);

      imesa->TexBlend[unit][used++] = (STATE3D_MAP_BLEND_OP_CMD(unit) |
				       TEXPIPE_ALPHA |
				       ENABLE_TEXOUTPUT_WRT_SEL |
				       TEXOP_OUTPUT_CURRENT |
				       TEXOP_MODIFY_PARMS |
				       ablendop);

      for ( i = 0 ; i < numColorArgs ; i++ ) {
	 imesa->TexBlend[unit][used++] = (STATE3D_MAP_BLEND_ARG_CMD(unit) |
					  tex_blend_rgb[i] |
					  args_RGB[i]);
      }

      for ( i = 0 ; i < numAlphaArgs ; i++ ) {
	 imesa->TexBlend[unit][used++] = (STATE3D_MAP_BLEND_ARG_CMD(unit) |
					  tex_blend_a[i] |
					  args_A[i]);
      }


      if ( need_constant_color ) {
	 GLubyte r, g, b, a;
	 const GLfloat * const fc = texUnit->EnvColor;

	 FLOAT_COLOR_TO_UBYTE_COLOR(r, fc[RCOMP]);
	 FLOAT_COLOR_TO_UBYTE_COLOR(g, fc[GCOMP]);
	 FLOAT_COLOR_TO_UBYTE_COLOR(b, fc[BCOMP]);
	 FLOAT_COLOR_TO_UBYTE_COLOR(a, fc[ACOMP]);

	 imesa->TexBlend[unit][used++] = STATE3D_COLOR_FACTOR_CMD(unit);
	 imesa->TexBlend[unit][used++] = ((a << 24) | (r << 16) | (g << 8) | b);
      }

      imesa->TexBlendWordsUsed[unit] = used;
   }

   I830_STATECHANGE( imesa, I830_UPLOAD_TEXBLEND_N(unit) );
}


/* This is bogus -- can't load the same texture object on two units.
 */
static void i830TexSetUnit( i830TextureObjectPtr t, GLuint unit )
{
   if(I830_DEBUG&DEBUG_TEXTURE)
      fprintf(stderr, "%s unit(%d)\n", __FUNCTION__, unit);
   
   t->Setup[I830_TEXREG_TM0LI] = (STATE3D_LOAD_STATE_IMMEDIATE_2 | 
				  (LOAD_TEXTURE_MAP0 << unit) | 4);

   I830_SET_FIELD(t->Setup[I830_TEXREG_MCS], MAP_UNIT_MASK, MAP_UNIT(unit));

   t->current_unit = unit;
   t->base.bound |= (1U << unit);
}

#define TEXCOORDTYPE_MASK	(~((1<<13)|(1<<12)|(1<<11)))


static GLboolean enable_tex_common( GLcontext *ctx, GLuint unit )
{
   i830ContextPtr imesa = I830_CONTEXT(ctx);
   struct gl_texture_unit *texUnit = &ctx->Texture.Unit[unit];
   struct gl_texture_object *tObj = texUnit->_Current;
   i830TextureObjectPtr t = (i830TextureObjectPtr)tObj->DriverData;

   /* Fallback if there's a texture border */
   if ( tObj->Image[0][tObj->BaseLevel]->Border > 0 ) {
      return GL_FALSE;
   }

   /* Upload teximages (not pipelined)
    */
   if (t->base.dirty_images[0]) {
      i830SetTexImages( imesa, tObj );
      if (!t->base.memBlock) {
	 return GL_FALSE;
      }
   }

   /* Update state if this is a different texture object to last
    * time.
    */
   if (imesa->CurrentTexObj[unit] != t) {

      if ( imesa->CurrentTexObj[unit] != NULL ) {
	 /* The old texture is no longer bound to this texture unit.
	  * Mark it as such.
	  */

	 imesa->CurrentTexObj[unit]->base.bound &= ~(1U << unit);
      }

      I830_STATECHANGE( imesa, I830_UPLOAD_TEX_N(unit) );
      imesa->CurrentTexObj[unit] = t;
      i830TexSetUnit(t, unit);
   }

   /* Update texture environment if texture object image format or 
    * texture environment state has changed. 
    *
    * KW: doesn't work -- change from tex0 only to tex0+tex1 gets
    * missed (need to update last stage flag?).  Call
    * i830UpdateTexEnv always.
    */
   if (tObj->Image[0][tObj->BaseLevel]->Format !=
       imesa->TexEnvImageFmt[unit]) {
      imesa->TexEnvImageFmt[unit] = tObj->Image[0][tObj->BaseLevel]->Format;
   }
   i830UpdateTexEnv( ctx, unit );
   imesa->TexEnabledMask |= I830_TEX_UNIT_ENABLED(unit);

   return GL_TRUE;
}

static GLboolean enable_tex_rect( GLcontext *ctx, GLuint unit )
{
   i830ContextPtr imesa = I830_CONTEXT(ctx);
   struct gl_texture_unit *texUnit = &ctx->Texture.Unit[unit];
   struct gl_texture_object *tObj = texUnit->_Current;
   i830TextureObjectPtr t = (i830TextureObjectPtr)tObj->DriverData;
   GLuint mcs = t->Setup[I830_TEXREG_MCS];

   mcs &= ~TEXCOORDS_ARE_NORMAL;
   mcs |= TEXCOORDS_ARE_IN_TEXELUNITS;

   if (mcs != t->Setup[I830_TEXREG_MCS]) {
      I830_STATECHANGE( imesa, I830_UPLOAD_TEX_N(unit) );
      t->Setup[I830_TEXREG_MCS] = mcs;
   }

   return GL_TRUE;
}


static GLboolean enable_tex_2d( GLcontext *ctx, GLuint unit )
{
   i830ContextPtr imesa = I830_CONTEXT(ctx);
   struct gl_texture_unit *texUnit = &ctx->Texture.Unit[unit];
   struct gl_texture_object *tObj = texUnit->_Current;
   i830TextureObjectPtr t = (i830TextureObjectPtr)tObj->DriverData;
   GLuint mcs = t->Setup[I830_TEXREG_MCS];

   mcs &= ~TEXCOORDS_ARE_IN_TEXELUNITS;
   mcs |= TEXCOORDS_ARE_NORMAL;

   if (mcs != t->Setup[I830_TEXREG_MCS]) {
      I830_STATECHANGE( imesa, I830_UPLOAD_TEX_N(unit) );
      t->Setup[I830_TEXREG_MCS] = mcs;
   }

   return GL_TRUE;
}

 
static GLboolean disable_tex( GLcontext *ctx, int unit )
{
   i830ContextPtr imesa = I830_CONTEXT(ctx);

   /* This is happening too often.  I need to conditionally send diffuse
    * state to the card.  Perhaps a diffuse dirty flag of some kind.
    * Will need to change this logic if more than 2 texture units are
    * used.  We need to only do this up to the last unit enabled, or unit
    * one if nothing is enabled.
    */

   if ( imesa->CurrentTexObj[unit] != NULL ) {
      /* The old texture is no longer bound to this texture unit.
       * Mark it as such.
       */

      imesa->CurrentTexObj[unit]->base.bound &= ~(1U << unit);
      imesa->CurrentTexObj[unit] = NULL;
   }

   imesa->TexEnvImageFmt[unit] = 0;
   imesa->dirty &= ~(I830_UPLOAD_TEX_N(unit));
   
   i830UpdateTexEnv( ctx, unit );

   return GL_TRUE;
}

static GLboolean i830UpdateTexUnit( GLcontext *ctx, GLuint unit )
{
   i830ContextPtr imesa = I830_CONTEXT(ctx);
   struct gl_texture_unit *texUnit = &ctx->Texture.Unit[unit];

   imesa->TexEnabledMask &= ~(I830_TEX_UNIT_ENABLED(unit));

   if (texUnit->_ReallyEnabled == TEXTURE_2D_BIT) {
      return (enable_tex_common( ctx, unit ) &&
	      enable_tex_2d( ctx, unit ));
   }
   else if (texUnit->_ReallyEnabled == TEXTURE_RECT_BIT) {      
      return (enable_tex_common( ctx, unit ) &&
	      enable_tex_rect( ctx, unit ));
   }
   else if (texUnit->_ReallyEnabled) {
      return GL_FALSE;
   }
   else {
      return disable_tex( ctx, unit );
   }
}



void i830UpdateTextureState( GLcontext *ctx )
{
   i830ContextPtr imesa = I830_CONTEXT(ctx);
   int i;
   int last_stage = 0;
   GLboolean ok;

   for ( i = 0 ; i < ctx->Const.MaxTextureUnits ; i++ ) {
      if ( (ctx->Texture.Unit[i]._ReallyEnabled == TEXTURE_2D_BIT)
	   || (ctx->Texture.Unit[i]._ReallyEnabled == TEXTURE_RECT_BIT) ) {
	 last_stage = i;
      }
   }

   ok = GL_TRUE;
   for ( i = 0 ; i <= last_stage ; i++ ) {
      ok = ok && i830UpdateTexUnit( ctx, i );
   }

   FALLBACK( imesa, I830_FALLBACK_TEXTURE, !ok );


   /* Make sure last stage is set correctly */
   imesa->TexBlend[last_stage][0] |= TEXOP_LAST_STAGE;
}