Add support for GLX_SGI_make_current_read.

[mesa.git] / src / mesa / drivers / dri / i830 / i830_texstate.c

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

Copyright 2001 2d3d Inc., Delray Beach, FL

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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;

   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;
      t->image[0][i].internalFormat = baseImage->Format;
      total_height += t->image[0][i].image->Height;
   }

   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->TexBlendColorPipeNum[unit] = 0;
      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 */

      /* When we render we need to figure out which is the last really enabled
       * tex unit, and put last stage on it
       */

      imesa->TexBlendColorPipeNum[unit] = 0;
      used = 0;

      /* Build color pipeline */

      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 {
      disable_tex( ctx, unit );
      return GL_TRUE;
   }
}



/* Only deal with unit 0 and 1 for right now */
void i830UpdateTextureState( GLcontext *ctx )
{
   i830ContextPtr imesa = I830_CONTEXT(ctx);
   int pipe_num = 0;
   GLboolean ok;

   ok = (i830UpdateTexUnit( ctx, 0 ) &&
         i830UpdateTexUnit( ctx, 1 ) &&
         i830UpdateTexUnit( ctx, 2 ) &&
         i830UpdateTexUnit( ctx, 3 ));

   FALLBACK( imesa, I830_FALLBACK_TEXTURE, !ok );


   /* Make sure last stage is set correctly */
   if(imesa->TexEnabledMask & I830_TEX_UNIT_ENABLED(3)) {
      pipe_num = imesa->TexBlendColorPipeNum[3];
      imesa->TexBlend[3][pipe_num] |= TEXOP_LAST_STAGE;
   } else if(imesa->TexEnabledMask & I830_TEX_UNIT_ENABLED(2)) {
      pipe_num = imesa->TexBlendColorPipeNum[2];
      imesa->TexBlend[2][pipe_num] |= TEXOP_LAST_STAGE;
   } else if(imesa->TexEnabledMask & I830_TEX_UNIT_ENABLED(1)) {
      pipe_num = imesa->TexBlendColorPipeNum[1];
      imesa->TexBlend[1][pipe_num] |= TEXOP_LAST_STAGE;
   } else {
      pipe_num = imesa->TexBlendColorPipeNum[0];
      imesa->TexBlend[0][pipe_num] |= TEXOP_LAST_STAGE;
   }
}