/**

  * $Id$

  *

  * Texture cache. Responsible for maintaining a working set of OpenGL 

  * textures. 

  *

  *

  * Copyright (c) 2005 Nathan Keynes.

  *

  * This program is free software; you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation; either version 2 of the License, or

  * (at your option) any later version.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  * GNU General Public License for more details.

  */

 #include <assert.h>

 #include <string.h>

 #include "pvr2/pvr2.h"

 #include "pvr2/pvr2mmio.h"

 #include "pvr2/glutil.h"

 /** Specifies the maximum number of OpenGL

  * textures we're willing to have open at a time. If more are

  * needed, textures will be evicted in LRU order.

  */

 #define MAX_TEXTURES 256

 /**

  * Data structure:

  *

  * Main operations:

  *    find entry by texture_addr

  *    add new entry

  *    move entry to tail of lru list

  *    remove entry

  */

 typedef signed short texcache_entry_index;

 #define EMPTY_ENTRY -1

 static texcache_entry_index texcache_free_ptr = 0;

 static GLuint texcache_free_list[MAX_TEXTURES];

 typedef struct texcache_entry {

     uint32_t texture_addr;

     uint32_t poly2_mode, tex_mode;

     GLuint texture_id;

     render_buffer_t buffer;

     texcache_entry_index next;

     uint32_t lru_count;

 } *texcache_entry_t;

 static texcache_entry_index texcache_page_lookup[PVR2_RAM_PAGES];

 static uint32_t texcache_ref_counter;

 static struct texcache_entry texcache_active_list[MAX_TEXTURES];

 static uint32_t texcache_palette_mode;

 static uint32_t texcache_stride_width;

 static gboolean texcache_have_palette_shader;

 static gboolean texcache_palette_valid;

 static GLuint texcache_palette_texid;

 /**

  * Initialize the texture cache.

  */

 void texcache_init( )

 {

     int i;

     for( i=0; i<PVR2_RAM_PAGES; i++ ) {

         texcache_page_lookup[i] = EMPTY_ENTRY;

     }

     for( i=0; i<MAX_TEXTURES; i++ ) {

         texcache_free_list[i] = i;

         texcache_active_list[i].texture_addr = -1;

         texcache_active_list[i].buffer = NULL;

         texcache_active_list[i].next = EMPTY_ENTRY;

     }

     texcache_free_ptr = 0;

     texcache_ref_counter = 0;

     texcache_palette_mode = -1;

     texcache_stride_width = 0;

 }

 void texcache_release_render_buffer( render_buffer_t buffer )

 {

     if( !buffer->flushed )

         pvr2_render_buffer_copy_to_sh4(buffer);

     pvr2_destroy_render_buffer(buffer);

 }

 /**

  * Flush all textures from the cache, returning them to the free list.

  */

 void texcache_flush( )

 {

     int i;

     /* clear structures */

     for( i=0; i<PVR2_RAM_PAGES; i++ ) {

         texcache_page_lookup[i] = EMPTY_ENTRY;

     }

     for( i=0; i<MAX_TEXTURES; i++ ) {

         texcache_free_list[i] = i;

         texcache_active_list[i].next = EMPTY_ENTRY;

         texcache_active_list[i].texture_addr = -1;

         if( texcache_active_list[i].buffer != NULL ) {

             texcache_release_render_buffer(texcache_active_list[i].buffer);

             texcache_active_list[i].buffer = NULL;

         }

     }

     texcache_free_ptr = 0;

     texcache_ref_counter = 0;

 }

 /**

  * Setup the initial texture ids (must be called after the GL context is

  * prepared)

  */

 void texcache_gl_init( )

 {

     int i;

     GLuint texids[MAX_TEXTURES];

     if( display_driver->capabilities.has_sl ) {

         texcache_have_palette_shader = TRUE;

         texcache_palette_valid = FALSE;

         glGenTextures(1, &texcache_palette_texid );

         /* Bind the texture and set the params */

         glActiveTexture(GL_TEXTURE1);

         glBindTexture(GL_TEXTURE_2D, texcache_palette_texid);

         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

         glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );

         glActiveTexture(GL_TEXTURE0);

     } else {

         texcache_have_palette_shader = FALSE;

     }

     glGenTextures( MAX_TEXTURES, texids );

     for( i=0; i<MAX_TEXTURES; i++ ) {

         texcache_active_list[i].texture_id = texids[i];

     }

     INFO( "Texcache initialized (%s, %s)", (texcache_have_palette_shader ? "Palette shader" : "No palette support"),

             (display_driver->capabilities.has_bgra ? "BGRA" : "RGBA") );

 }

 /**

  * Flush all textures and delete. The cache will be non-functional until

  * the next call to texcache_gl_init(). This would typically be done if

  * switching GL targets.

  */    

 void texcache_gl_shutdown( )

 {

     GLuint texids[MAX_TEXTURES];

     int i;

     texcache_flush();

     if( texcache_have_palette_shader ) {

         glDeleteTextures( 1, &texcache_palette_texid );

         texcache_palette_texid = -1;

     }

     for( i=0; i<MAX_TEXTURES; i++ ) {

         texids[i] = texcache_active_list[i].texture_id;

         texcache_active_list[i].texture_id = -1;

     }

     glDeleteTextures( MAX_TEXTURES, texids );

 }

 static void texcache_evict( int slot )

 {

     /* Remove the selected slot from the lookup table */

     assert( texcache_active_list[slot].texture_addr != -1 );

     uint32_t evict_page = texcache_active_list[slot].texture_addr >> 12;

     texcache_entry_index replace_next = texcache_active_list[slot].next;

     texcache_active_list[slot].texture_addr = -1;

     texcache_active_list[slot].next = EMPTY_ENTRY; /* Just for safety */

     if( texcache_active_list[slot].buffer != NULL ) {

         texcache_release_render_buffer(texcache_active_list[slot].buffer);

         texcache_active_list[slot].buffer = NULL;

     }

     if( texcache_page_lookup[evict_page] == slot ) {

         texcache_page_lookup[evict_page] = replace_next;

     } else {

         texcache_entry_index idx = texcache_page_lookup[evict_page];

         texcache_entry_index next;

         do {

             next = texcache_active_list[idx].next;

             if( next == slot ) {

                 assert( idx != replace_next );

                 texcache_active_list[idx].next = replace_next;

                 break;

             }

             idx = next;

         } while( next != EMPTY_ENTRY );

     }

 }

 /**

  * Evict a single texture from the cache.

  * @return the slot of the evicted texture.

  */

 static texcache_entry_index texcache_evict_lru( void )

 {

     /* Full table scan - take over the entry with the lowest lru value */

     texcache_entry_index slot = 0;

     int lru_value = texcache_active_list[0].lru_count;

     int i;

     for( i=1; i<MAX_TEXTURES; i++ ) {

         /* FIXME: account for rollover */

         if( texcache_active_list[i].lru_count < lru_value ) {

             slot = i;

             lru_value = texcache_active_list[i].lru_count;

         }

     }

     texcache_evict(slot);

     return slot;

 }

 /**

  * Evict all textures contained in the page identified by a texture address.

  */

 void texcache_invalidate_page( uint32_t texture_addr ) {

     uint32_t texture_page = texture_addr >> 12;

     texcache_entry_index idx = texcache_page_lookup[texture_page];

     if( idx == EMPTY_ENTRY )

         return;

     assert( texcache_free_ptr >= 0 );

     do {

         texcache_entry_t entry = &texcache_active_list[idx];

         entry->texture_addr = -1;

         if( entry->buffer != NULL ) {

             texcache_release_render_buffer(entry->buffer);

             entry->buffer = NULL;

         }

         /* release entry */

         texcache_free_ptr--;

         texcache_free_list[texcache_free_ptr] = idx;

         idx = entry->next;

         entry->next = EMPTY_ENTRY;

     } while( idx != EMPTY_ENTRY );

     texcache_page_lookup[texture_page] = EMPTY_ENTRY;

 }

 /**

  * Load the palette into 4 textures of 256 entries each. This mirrors the

  * banking done by the PVR2 for 8-bit textures, and also ensures that we

  * can use 8-bit paletted textures ourselves.

  */

 static void texcache_load_palette_texture( gboolean format_changed )

 {

     GLint format, type, intFormat = GL_RGBA;

     unsigned i;

     int bpp = 2;

     uint32_t *palette = (uint32_t *)mmio_region_PVR2PAL.mem;

     uint16_t packed_palette[1024];

     char *data = (char *)palette;

     switch( texcache_palette_mode ) {

     case 0: /* ARGB1555 */

         format = GL_BGRA;

         type = GL_UNSIGNED_SHORT_1_5_5_5_REV;

         break;

     case 1:  /* RGB565 */

         intFormat = GL_RGB;

         format = GL_RGB;

         type = GL_UNSIGNED_SHORT_5_6_5;

         break;

     case 2: /* ARGB4444 */

         format = GL_BGRA;

         type = GL_UNSIGNED_SHORT_4_4_4_4_REV;

         break;

     case 3: /* ARGB8888 */

         format = GL_BGRA;

         type = GL_UNSIGNED_BYTE;

         bpp = 4;

         break;

     default:

         break; /* Can't happen */

     }

     if( bpp == 2 ) {

         for( i=0; i<1024; i++ ) {

             packed_palette[i] = (uint16_t)palette[i];

         }

         data = (char *)packed_palette;

     }

     glActiveTexture(GL_TEXTURE1);

     if( format_changed )

         glTexImage2DBGRA(0, intFormat, 1024, 1, format, type, data, data == (char *)palette );

     else

         glTexSubImage2DBGRA(0, 0, 0, 1024, 1, format, type, data, data == (char *)palette);

     glActiveTexture(GL_TEXTURE0);

     texcache_palette_valid = TRUE;

 }

 /**

  * Mark the palette as having changed. If we have palette support (via shaders)

  * we just flag the palette, otherwise we have to invalidate all palette

  * textures.

  */

 void texcache_invalidate_palette( )

 {

     if( texcache_have_palette_shader ) {

         texcache_palette_valid = FALSE;

     } else {

         int i;

         for( i=0; i<MAX_TEXTURES; i++ ) {

             if( texcache_active_list[i].texture_addr != -1 &&

                     PVR2_TEX_IS_PALETTE(texcache_active_list[i].tex_mode) ) {

                 texcache_evict( i );

                 texcache_free_ptr--;

                 texcache_free_list[texcache_free_ptr] = i;

             }

         }

     }

 }

 /**

  * Mark all stride textures as needing a re-read (ie when the stride width

  * is changed).

  */

 void texcache_invalidate_stride( )

 {

     int i;

     for( i=0; i<MAX_TEXTURES; i++ ) {

         if( texcache_active_list[i].texture_addr != -1 &&

                 PVR2_TEX_IS_STRIDE(texcache_active_list[i].tex_mode) ) {

             texcache_evict( i );

             texcache_free_ptr--;

             texcache_free_list[texcache_free_ptr] = i;

         }

     }

 }

 void texcache_begin_scene( uint32_t palette_mode, uint32_t stride )

 {

     gboolean format_changed = FALSE;

     if( palette_mode != texcache_palette_mode ) {

         texcache_invalidate_palette();

         format_changed = TRUE;

     }

     if( stride != texcache_stride_width )

         texcache_invalidate_stride();

     texcache_palette_mode = palette_mode;

     texcache_stride_width = stride;

     if( !texcache_palette_valid && texcache_have_palette_shader )

         texcache_load_palette_texture(format_changed);

 }

 static void decode_pal8_to_32( uint32_t *out, uint8_t *in, int inbytes, uint32_t *pal )

 {

     int i;

     for( i=0; i<inbytes; i++ ) {

         *out++ = pal[*in++];

     }

 }

 static void decode_pal8_to_16( uint16_t *out, uint8_t *in, int inbytes, uint32_t *pal )

 {

     int i;

     for( i=0; i<inbytes; i++ ) {

         *out++ = (uint16_t)pal[*in++];

     }

 }

 static void decode_pal4_to_32( uint32_t *out, uint8_t *in, int inbytes, uint32_t *pal )

 {

     int i;

     for( i=0; i<inbytes; i++ ) {

         *out++ = pal[*in & 0x0F];

         *out++ = pal[(*in >> 4)];

         in++;

     }

 }

 static void decode_pal4_to_pal8( uint8_t *out, uint8_t *in, int inbytes )

 {

     int i;

     for( i=0; i<inbytes; i++ ) {

         *out++ = (uint8_t)(*in & 0x0F);

         *out++ = (uint8_t)(*in >> 4);

         in++;

     }

 }

 static void decode_pal4_to_16( uint16_t *out, uint8_t *in, int inbytes, uint32_t *pal )

 {

     int i;

     for( i=0; i<inbytes; i++ ) {

         *out++ = (uint16_t)pal[*in & 0x0F];

         *out++ = (uint16_t)pal[(*in >> 4)];

         in++;

     }

 }

 #define VQ_CODEBOOK_SIZE 2048 /* 256 entries * 4 pixels per quad * 2 byte pixels */

 struct vq_codebook {

     uint16_t quad[256][4];

 };

 static void vq_get_codebook( struct vq_codebook *codebook, 

                              uint16_t *input )

 {

     /* Detwiddle the codebook, for the sake of my own sanity if nothing else */

     uint16_t *p = (uint16_t *)input;

     int i;

     for( i=0; i<256; i++ ) {

         codebook->quad[i][0] = *p++;

         codebook->quad[i][2] = *p++;

         codebook->quad[i][1] = *p++;

         codebook->quad[i][3] = *p++;

     }

 }    

 static void vq_decode( uint16_t *output, unsigned char *input, int width, int height, 

                        struct vq_codebook *codebook ) {

     int i,j;

     uint8_t *c = (uint8_t *)input;

     for( j=0; j<height; j+=2 ) {

         for( i=0; i<width; i+=2 ) {

             uint8_t code = *c++;

             output[i + j*width] = codebook->quad[code][0];

             output[i + 1 + j*width] = codebook->quad[code][1];

             output[i + (j+1)*width] = codebook->quad[code][2];

             output[i + 1 + (j+1)*width] = codebook->quad[code][3];

         }

     }

 }

 static inline uint32_t yuv_to_rgb32( float y, float u, float v )

 {

     u -= 128;

     v -= 128;

     int r = (int)(y + v*1.375);

     int g = (int)(y - u*0.34375 - v*0.6875);

     int b = (int)(y + u*1.71875);

     if( r > 255 ) { r = 255; } else if( r < 0 ) { r = 0; }

     if( g > 255 ) { g = 255; } else if( g < 0 ) { g = 0; }

     if( b > 255 ) { b = 255; } else if( b < 0 ) { b = 0; }

     return 0xFF000000 | (b<<16) | (g<<8) | (r);

 }

 /**

  * Convert raster YUV texture data into RGB32 data - most GL implementations don't

  * directly support this format unfortunately. The input data is formatted as

  * 32 bits = 2 horizontal pixels, UYVY. This is currently done rather inefficiently

  * in floating point.

  */

 static void yuv_decode( uint32_t *output, uint32_t *input, int width, int height )

 {

     int x, y;

     uint32_t *p = input;

     for( y=0; y<height; y++ ) {

         for( x=0; x<width; x+=2 ) {

             float u = (float)(*p & 0xFF);

             float y0 = (float)( (*p>>8)&0xFF );

             float v = (float)( (*p>>16)&0xFF );

             float y1 = (float)( (*p>>24)&0xFF );

             *output++ = yuv_to_rgb32( y0, u, v ); 

             *output++ = yuv_to_rgb32( y1, u, v );

             p++;

         }

     }

 }

 static gboolean is_npot_texture( int width )

 {

     while( width != 0 ) {

         if( width & 1 ) 

             return width != 1;

         width >>= 1;

     }

     return TRUE;

 }

 /**

  * Load texture data from the given address and parameters into the currently

  * bound OpenGL texture.

  */

 static void texcache_load_texture( uint32_t texture_addr, int width, int height,

                                    int mode ) {

     int bpp_shift = 1; /* bytes per (output) pixel as a power of 2 */

     GLint intFormat = GL_RGBA, format, type;

     int tex_format = mode & PVR2_TEX_FORMAT_MASK;

     struct vq_codebook codebook;

     GLint min_filter = GL_LINEAR;

     GLint max_filter = GL_LINEAR;

     GLint mipmapfilter = GL_LINEAR_MIPMAP_LINEAR;

     /* Decode the format parameters */

     switch( tex_format ) {

     case PVR2_TEX_FORMAT_IDX4:

     case PVR2_TEX_FORMAT_IDX8:

         if( texcache_have_palette_shader ) {

             intFormat = GL_ALPHA;

             format = GL_ALPHA;

             type = GL_UNSIGNED_BYTE;

             bpp_shift = 0;

             min_filter = max_filter = GL_NEAREST;

             mipmapfilter = GL_NEAREST_MIPMAP_NEAREST;

         } else {

             /* For indexed-colour modes, we need to lookup the palette control

              * word to determine the de-indexed texture format.

              */

             switch( texcache_palette_mode ) {

             case 0: /* ARGB1555 */

                 format = GL_BGRA;

                 type = GL_UNSIGNED_SHORT_1_5_5_5_REV;

                 break;

             case 1:  /* RGB565 */

                 intFormat = GL_RGB;

                 format = GL_RGB;

                 type = GL_UNSIGNED_SHORT_5_6_5;

                 break;

             case 2: /* ARGB4444 */

                 format = GL_BGRA;

                 type = GL_UNSIGNED_SHORT_4_4_4_4_REV;

                 break;

             case 3: /* ARGB8888 */

                 format = GL_BGRA;

                 type = GL_UNSIGNED_BYTE;

                 bpp_shift = 2;

                 break;

             default:

                 return; /* Can't happen, but it makes gcc stop complaining */

             }

         }

         break;

         default:

         case PVR2_TEX_FORMAT_ARGB1555:

             format = GL_BGRA;

             type = GL_UNSIGNED_SHORT_1_5_5_5_REV;

             break;

         case PVR2_TEX_FORMAT_RGB565:

             intFormat = GL_RGB;

             format = GL_RGB;

             type = GL_UNSIGNED_SHORT_5_6_5;

             break;

         case PVR2_TEX_FORMAT_ARGB4444:

             format = GL_BGRA;

             type = GL_UNSIGNED_SHORT_4_4_4_4_REV;

             break;

         case PVR2_TEX_FORMAT_YUV422:

             /* YUV422 isn't directly supported by most implementations, so decode

              * it to a (reasonably) standard RGBA8.

              */

             bpp_shift = 2;

             format = GL_RGBA;

             type = GL_UNSIGNED_BYTE;

             break;

         case PVR2_TEX_FORMAT_BUMPMAP:

             WARN( "Bumpmap not supported" );

             return;

     }

     if( PVR2_TEX_IS_STRIDE(mode) && tex_format != PVR2_TEX_FORMAT_IDX4 &&

             tex_format != PVR2_TEX_FORMAT_IDX8 ) {

         /* Stride textures cannot be mip-mapped, compressed, indexed or twiddled */

         unsigned char data[(width*height) << bpp_shift];

         if( tex_format == PVR2_TEX_FORMAT_YUV422 ) {

             unsigned char tmp[(width*height)<<1];

             pvr2_vram64_read_stride( tmp, width<<1, texture_addr, texcache_stride_width<<1, height );

             yuv_decode( (uint32_t *)data, (uint32_t *)tmp, width, height );

         } else {

             pvr2_vram64_read_stride( data, width<<bpp_shift, texture_addr, texcache_stride_width<<bpp_shift, height );

         }

         glTexImage2DBGRA( 0, intFormat, width, height, format, type, data, FALSE );

         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, min_filter);

         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, max_filter);

         return;

     } 

     if( PVR2_TEX_IS_COMPRESSED(mode) ) {

         uint16_t tmp[VQ_CODEBOOK_SIZE];

         pvr2_vram64_read( (unsigned char *)tmp, texture_addr, VQ_CODEBOOK_SIZE );

         texture_addr += VQ_CODEBOOK_SIZE;

         vq_get_codebook( &codebook, tmp );

     }

     int level=0, last_level = 0, mip_width = width, mip_height = height, src_bytes, dest_bytes;

     if( PVR2_TEX_IS_MIPMAPPED(mode) ) {

         uint32_t src_offset = 0;

         min_filter = mipmapfilter;

         mip_height = height = width;

         while( (1<<last_level) < width ) {

             last_level++;

             src_offset += ((width>>last_level)*(width>>last_level));

         }

         if( width != 1 ) {

             src_offset += 3;

         }

         if( PVR2_TEX_IS_COMPRESSED(mode) ) {

             src_offset >>= 2;

         } else if( tex_format == PVR2_TEX_FORMAT_IDX4 ) {

             src_offset >>= 1;

         } else if( tex_format == PVR2_TEX_FORMAT_YUV422 ) {

             src_offset <<= 1;

         } else if( tex_format != PVR2_TEX_FORMAT_IDX8 ) {

             src_offset <<= bpp_shift;

         }

         texture_addr += src_offset;

     }

     dest_bytes = (mip_width * mip_height) << bpp_shift;

     src_bytes = dest_bytes; // Modes will change this (below)

     for( level=0; level<= last_level; level++ ) {

         unsigned char data[dest_bytes];

         /* load data from image, detwiddling/uncompressing as required */

         if( tex_format == PVR2_TEX_FORMAT_IDX8 ) {

             if( texcache_have_palette_shader ) {

                 pvr2_vram64_read_twiddled_8( data, texture_addr, mip_width, mip_height );

             } else {

                 src_bytes = (mip_width * mip_height);

                 int bank = (mode >> 25) &0x03;

                 uint32_t *palette = ((uint32_t *)mmio_region_PVR2PAL.mem) + (bank<<8);

                 unsigned char tmp[src_bytes];

                 pvr2_vram64_read_twiddled_8( tmp, texture_addr, mip_width, mip_height );

                 if( bpp_shift == 2 ) {

                     decode_pal8_to_32( (uint32_t *)data, tmp, src_bytes, palette );

                 } else {

                     decode_pal8_to_16( (uint16_t *)data, tmp, src_bytes, palette );

                 }

             }

         } else if( tex_format == PVR2_TEX_FORMAT_IDX4 ) {

             src_bytes = (mip_width * mip_height) >> 1;

             unsigned char tmp[src_bytes];

             if( texcache_have_palette_shader ) {

                 pvr2_vram64_read_twiddled_4( tmp, texture_addr, mip_width, mip_height );

                 decode_pal4_to_pal8( data, tmp, src_bytes );

             } else {

                 int bank = (mode >>21 ) & 0x3F;

                 uint32_t *palette = ((uint32_t *)mmio_region_PVR2PAL.mem) + (bank<<4);

                 pvr2_vram64_read_twiddled_4( tmp, texture_addr, mip_width, mip_height );

                 if( bpp_shift == 2 ) {

                     decode_pal4_to_32( (uint32_t *)data, tmp, src_bytes, palette );

                 } else {

                     decode_pal4_to_16( (uint16_t *)data, tmp, src_bytes, palette );

                 }

             }

         } else if( tex_format == PVR2_TEX_FORMAT_YUV422 ) {

             src_bytes = ((mip_width*mip_height)<<1);

             unsigned char tmp[src_bytes];

             if( PVR2_TEX_IS_TWIDDLED(mode) ) {

                 pvr2_vram64_read_twiddled_16( tmp, texture_addr, mip_width, mip_height );

             } else {

                 pvr2_vram64_read( tmp, texture_addr, src_bytes );

             }

             yuv_decode( (uint32_t *)data, (uint32_t *)tmp, mip_width, mip_height );

         } else if( PVR2_TEX_IS_COMPRESSED(mode) ) {

             src_bytes = ((mip_width*mip_height) >> 2);

             unsigned char tmp[src_bytes];

             if( PVR2_TEX_IS_TWIDDLED(mode) ) {

                 pvr2_vram64_read_twiddled_8( tmp, texture_addr, mip_width>>1, mip_height>>1 );

             } else {

                 pvr2_vram64_read( tmp, texture_addr, src_bytes );

             }

             vq_decode( (uint16_t *)data, tmp, mip_width, mip_height, &codebook );

         } else if( PVR2_TEX_IS_TWIDDLED(mode) ) {

             pvr2_vram64_read_twiddled_16( data, texture_addr, mip_width, mip_height );

         } else {

             pvr2_vram64_read( data, texture_addr, src_bytes );

         }

         /* Pass to GL */

         if( level == last_level && level != 0 ) { /* 1x1 stored within a 2x2 */

             glTexImage2DBGRA( level, intFormat, 1, 1, format, type,

                     data + (3 << bpp_shift), FALSE );

         } else {

             glTexImage2DBGRA( level, intFormat, mip_width, mip_height, format, type, data, FALSE );

             if( mip_width > 2 ) {

                 mip_width >>= 1;

                 mip_height >>= 1;

                 dest_bytes >>= 2;

                 src_bytes >>= 2;

             }

             texture_addr -= src_bytes;

         }

     }

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, min_filter);

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, max_filter);

 }

 static int texcache_find_texture_slot( uint32_t poly2_masked_word, uint32_t texture_word )

 {

     uint32_t texture_addr = (texture_word & 0x000FFFFF)<<3;

     uint32_t texture_page = texture_addr >> 12;

     texcache_entry_index next;

     texcache_entry_index idx = texcache_page_lookup[texture_page];

     while( idx != EMPTY_ENTRY ) {

         texcache_entry_t entry = &texcache_active_list[idx];

         if( entry->tex_mode == texture_word &&

                 entry->poly2_mode == poly2_masked_word ) {

             entry->lru_count = texcache_ref_counter++;

             return idx;

         }

         idx = entry->next;

     }

     return -1;

 }

 static int texcache_alloc_texture_slot( uint32_t poly2_word, uint32_t texture_word )

 {

     uint32_t texture_addr = (texture_word & 0x000FFFFF)<<3;

     uint32_t texture_page = texture_addr >> 12;

     texcache_entry_index slot = 0;

     if( texcache_free_ptr < MAX_TEXTURES ) {

         slot = texcache_free_list[texcache_free_ptr++];

     } else {

         slot = texcache_evict_lru();

     }

     /* Construct new entry */

     assert( texcache_active_list[slot].texture_addr == -1 );

     texcache_active_list[slot].texture_addr = texture_addr;

     texcache_active_list[slot].tex_mode = texture_word;

     texcache_active_list[slot].poly2_mode = poly2_word;

     texcache_active_list[slot].lru_count = texcache_ref_counter++;

     /* Add entry to the lookup table */

     int next = texcache_page_lookup[texture_page];

     if( next == slot ) {

         int i;

         fprintf( stderr, "Active list: " );

         for( i=0; i<MAX_TEXTURES; i++ ) {

             fprintf( stderr, "%d, ", texcache_active_list[i].next );

         }

         fprintf( stderr, "\n" );

         assert( next != slot );

     }

     texcache_active_list[slot].next = next;

     texcache_page_lookup[texture_page] = slot;

     return slot;

 }

 /**

  * Return a texture ID for the texture specified at the supplied address

  * and given parameters (the same sequence of bytes could in theory have

  * multiple interpretations). We use the texture address as the primary

  * index, but allow for multiple instances at each address.

  * 

  * If the texture has already been bound, return the ID to which it was

  * bound. Otherwise obtain an unused texture ID and set it up appropriately.

  * The current GL_TEXTURE_2D binding will be changed in this case.

  */

 GLuint texcache_get_texture( uint32_t poly2_word, uint32_t texture_word )

 {

     poly2_word &= 0x000F803F; /* Get just the texture-relevant bits */

     uint32_t texture_lookup = texture_word;

     if( PVR2_TEX_IS_PALETTE(texture_lookup) ) {

         texture_lookup &= 0xF81FFFFF; /* Mask out the bank bits */

     }

     int slot = texcache_find_texture_slot( poly2_word, texture_lookup );

     if( slot == -1 ) {

         /* Not found - check the free list */

         slot = texcache_alloc_texture_slot( poly2_word, texture_lookup );

         /* Construct the GL texture */

         uint32_t texture_addr = (texture_word & 0x000FFFFF)<<3;

         unsigned width = POLY2_TEX_WIDTH(poly2_word);

         unsigned height = POLY2_TEX_HEIGHT(poly2_word);

         glBindTexture( GL_TEXTURE_2D, texcache_active_list[slot].texture_id );

         glGetError();

         texcache_load_texture( texture_addr, width, height, texture_word );

         INFO( "Loaded texture %d: %x %dx%d %x (%x)", texcache_active_list[slot].texture_id, texture_addr, width, height, texture_word,

                 glGetError() );

         /* Set texture parameters from the poly2 word */

         if( POLY2_TEX_CLAMP_U(poly2_word) ) {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );

         } else if( POLY2_TEX_MIRROR_U(poly2_word) ) {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT );

         } else {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );

         }

         if( POLY2_TEX_CLAMP_V(poly2_word) ) {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );

         } else if( POLY2_TEX_MIRROR_V(poly2_word) ) {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_MIRRORED_REPEAT );

         } else {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );

         }

     }

     return texcache_active_list[slot].texture_id;

 }

 #if 0

 render_buffer_t texcache_get_render_buffer( uint32_t texture_addr, int mode, int width, int height )

 {

     uint32_t texture_word = ((texture_addr >> 3) & 0x000FFFFF) | PVR2_TEX_UNTWIDDLED;

     switch( mode ) {

     case COLFMT_BGRA1555: texture_word |= PVR2_TEX_FORMAT_ARGB1555; break;

     case COLFMT_RGB565:   texture_word |= PVR2_TEX_FORMAT_RGB565; break;

     case COLFMT_BGRA4444: texture_word |= PVR2_TEX_FORMAT_ARGB4444; break;

     default:

         WARN( "Rendering to non-texture colour format" );

     }

     if( is_npot_texture(width) )

         texture_word |= PVR2_TEX_STRIDE;

     int slot = texcache_find_texture_slot( texture_word, width, height );

     if( slot == -1 ) {

         slot = texcache_alloc_texture_slot( texture_word, width, height );

     }

     texcache_entry_t entry = &texcache_active_list[slot];

     if( entry->buffer == NULL ) {

         entry->buffer = pvr2_create_render_buffer( texture_addr, width, height, entry->texture_id );

     } else if( entry->buffer->width != width || entry->buffer->height != height ) {        

         texcache_release_render_buffer(entry->buffer);

         entry->buffer = pvr2_create_render_buffer( texture_addr, width, height, entry->texture_id );

     }

     return entry->buffer;

 }

 #endif

 /**

  * Check the integrity of the texcache. Verifies that every cache slot

  * appears exactly once on either the free list or one page list. For 

  * active slots, the texture address must also match the page it appears on.

  * 

  */

 void texcache_integrity_check()

 {

     int i;

     int slot_found[MAX_TEXTURES];

     memset( slot_found, 0, sizeof(slot_found) );

     /* Check entries on the free list */

     for( i= texcache_free_ptr; i< MAX_TEXTURES; i++ ) {

         int slot = texcache_free_list[i];

         assert( slot_found[slot] == 0 );

         assert( texcache_active_list[slot].next == EMPTY_ENTRY );

         slot_found[slot] = 1;

     }

     /* Check entries on the active lists */

     for( i=0; i< PVR2_RAM_PAGES; i++ ) {

         int slot = texcache_page_lookup[i];

         while( slot != EMPTY_ENTRY ) {

             assert( slot_found[slot] == 0 );

             assert( (texcache_active_list[slot].texture_addr >> 12) == i );

             slot_found[slot] = 2;

             slot = texcache_active_list[slot].next;

         }

     }

     /* Make sure we didn't miss any entries */

     for( i=0; i<MAX_TEXTURES; i++ ) {

         assert( slot_found[i] != 0 );

     }

 }

 /**

  * Dump the contents of the texture cache

  */

 void texcache_dump()

 {

     unsigned i;

     GLboolean boolresult;

     for( i=0; i< PVR2_RAM_PAGES; i++ ) {

         int slot = texcache_page_lookup[i];

         while( slot != EMPTY_ENTRY ) {

             fprintf( stderr, "%-3d: %08X %dx%d (%08X %08X) %s\n", slot,

                     texcache_active_list[slot].texture_addr,

                     POLY2_TEX_WIDTH(texcache_active_list[slot].poly2_mode),

                     POLY2_TEX_HEIGHT(texcache_active_list[slot].poly2_mode),

                     texcache_active_list[slot].poly2_mode,

                     texcache_active_list[slot].tex_mode,

 #ifdef HAVE_OPENGL_TEX_RESIDENT

                     (glAreTexturesResident(1, &texcache_active_list[slot].texture_id, &boolresult) ? "[RESIDENT]" : "[NOT RESIDENT]")

 #else

                     ""

 #endif

                     );

             slot = texcache_active_list[slot].next;

         }

     }

 }

 void texcache_print_idx4( uint32_t texture_addr, int width )

 {

     unsigned x,y;

     int src_bytes = (width*width>>1);

     char tmp[src_bytes];

     char data[width*width];

     pvr2_vram64_read_twiddled_4( tmp, texture_addr, width, width );

     decode_pal4_to_pal8( data, tmp, src_bytes );

     for( y=0; y<width; y++ ) {

         for( x=0; x<width; x++ ) {

             printf( "%1x", data[y*width+x] );

         }

         printf( "\n" );

     }

 }