/**

  * $Id: texcache.c,v 1.9 2007-01-11 06:51:11 nkeynes Exp $

  *

  * 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 "pvr2/pvr2.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 64

 /**

  * 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 0xFF

 static texcache_entry_index texcache_free_ptr = 0;

 static GLuint texcache_free_list[MAX_TEXTURES];

 typedef struct texcache_entry {

     uint32_t texture_addr;

     int width, height, mode;

     GLuint texture_id;

     texcache_entry_index next;

     uint32_t lru_count;

 } *texcache_entry_t;

 static uint8_t texcache_page_lookup[PVR2_RAM_PAGES];

 static uint32_t texcache_ref_counter;

 static struct texcache_entry texcache_active_list[MAX_TEXTURES];

 /**

  * 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_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];

     glGenTextures( MAX_TEXTURES, texids );

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

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

     }

 }

 /**

  * 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_free_ptr = 0;

     texcache_ref_counter = 0;

 }

 /**

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

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

  * switching GL targets.

  */    

 void texcache_shutdown( )

 {

     GLuint texids[MAX_TEXTURES];

     int i;

     texcache_flush();

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

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

     }

     glDeleteTextures( MAX_TEXTURES, texids );

 }

 /**

  * 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];	

 	/* 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;

 }

 /**

  * Evict a single texture from the cache.

  * @return the slot of the evicted texture.

  */

 static texcache_entry_index texcache_evict( 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;

 	}

     }

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

     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].next = EMPTY_ENTRY; /* Just for safety */

     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 ) {

 		texcache_active_list[idx].next = replace_next;

 		break;

 	    }

 	    idx = next;

 	} while( next != EMPTY_ENTRY );

     }

     return slot;

 }

 static void detwiddle_pal8_to_32(int x1, int y1, int size, int totsize,

 				 char **in, uint32_t *out, uint32_t *pal) {

     if (size == 1) {

 	out[y1 * totsize + x1] = pal[**in];

 	(*in)++;

     } else {

 	int ns = size>>1;

 	detwiddle_pal8_to_32(x1, y1, ns, totsize, in, out, pal);

 	detwiddle_pal8_to_32(x1, y1+ns, ns, totsize, in, out, pal);

 	detwiddle_pal8_to_32(x1+ns, y1, ns, totsize, in, out, pal);

 	detwiddle_pal8_to_32(x1+ns, y1+ns, ns, totsize, in, out, pal);

     }

 }

 static void detwiddle_pal8_to_16(int x1, int y1, int size, int totsize,

 				 char **in, uint16_t *out, uint16_t *pal) {

     if (size == 1) {

 	out[y1 * totsize + x1] = pal[**in];

 	(*in)++;

     } else {

 	int ns = size>>1;

 	detwiddle_pal8_to_16(x1, y1, ns, totsize, in, out, pal);

 	detwiddle_pal8_to_16(x1, y1+ns, ns, totsize, in, out, pal);

 	detwiddle_pal8_to_16(x1+ns, y1, ns, totsize, in, out, pal);

 	detwiddle_pal8_to_16(x1+ns, y1+ns, ns, totsize, in, out, pal);

     }

 }

 static void detwiddle_16_to_16(int x1, int y1, int size, int totsize,

 			       uint16_t **in, uint16_t *out ) {

     if (size == 1) {

 	out[y1 * totsize + x1] = **in;

 	(*in)++;

     } else {

 	int ns = size>>1;

 	detwiddle_16_to_16(x1, y1, ns, totsize, in, out);

 	detwiddle_16_to_16(x1, y1+ns, ns, totsize, in, out);

 	detwiddle_16_to_16(x1+ns, y1, ns, totsize, in, out);

 	detwiddle_16_to_16(x1+ns, y1+ns, ns, totsize, in, out);

     }

 }

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

 struct vq_codebook {

     uint16_t quad[256][4];

 };

 static void detwiddle_vq_to_16(int x1, int y1, int size, int totsize,

 		   uint8_t **in, uint16_t *out, struct vq_codebook *codebook ) {

     if( size == 2 ) {

 	uint8_t code = **in;

 	(*in)++;

 	out[y1 * totsize + x1] = codebook->quad[code][0];

 	out[y1 * totsize + x1 + 1] = codebook->quad[code][1];

 	out[(y1+1) * totsize + x1] = codebook->quad[code][2];

 	out[(y1+1) * totsize + x1 + 1] = codebook->quad[code][3];

     } else {

 	int ns = size>>1;

 	detwiddle_vq_to_16(x1, y1, ns, totsize, in, out, codebook);

 	detwiddle_vq_to_16(x1, y1+ns, ns, totsize, in, out, codebook);

 	detwiddle_vq_to_16(x1+ns, y1, ns, totsize, in, out, codebook);

 	detwiddle_vq_to_16(x1+ns, y1+ns, ns, totsize, in, out, codebook);

     }	

 }

 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( int width, int height, char *input, uint16_t *output,

 		       struct vq_codebook *codebook, int twiddled ) {

     int i,j;

     uint8_t *c = (uint8_t *)input;

     if( twiddled ) {

 	detwiddle_vq_to_16( 0, 0, width, width, &c, output, codebook );

     } else {

 	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];

 	    }

 	}

     }

 }

 /**

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

  * bound OpenGL texture.

  */

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

 			      int mode ) {

     uint32_t bytes = width * height;

     int shift = 1;

     GLint intFormat, format, type;

     int tex_format = mode & PVR2_TEX_FORMAT_MASK;

     struct vq_codebook codebook;

     GLint filter = GL_LINEAR;

     /* Decode the format parameters */

     switch( tex_format ) {

     case PVR2_TEX_FORMAT_IDX4:

 	ERROR( "4-bit indexed textures not supported" );

     case PVR2_TEX_FORMAT_IDX8:

 	switch( MMIO_READ( PVR2, RENDER_PALETTE ) & 0x03 ) {

 	case 0: /* ARGB1555 */

 	    intFormat = GL_RGB5_A1;

 	    format = GL_RGBA;

 	    type = GL_UNSIGNED_SHORT_1_5_5_5_REV;

 	    break;

 	case 1: 

 	    intFormat = GL_RGB;

 	    format = GL_RGB;

 	    type = GL_UNSIGNED_SHORT_5_6_5_REV;

 	    break;

 	case 2:

 	    intFormat = GL_RGBA4;

 	    format = GL_BGRA;

 	    type = GL_UNSIGNED_SHORT_4_4_4_4_REV;

 	    break;

 	case 3:

 	    intFormat = GL_RGBA8;

 	    format = GL_BGRA;

 	    type = GL_UNSIGNED_INT_8_8_8_8_REV;

 	    shift = 2;

 	    break;

 	}

 	bytes <<= shift;

 	break;

     case PVR2_TEX_FORMAT_ARGB1555:

 	bytes <<= 1;

 	intFormat = GL_RGB5_A1;

 	format = GL_RGBA;

 	type = GL_UNSIGNED_SHORT_1_5_5_5_REV;

 	break;

     case PVR2_TEX_FORMAT_RGB565:

 	bytes <<= 1;

 	intFormat = GL_RGB;

 	format = GL_RGB;

 	type = GL_UNSIGNED_SHORT_5_6_5_REV;

 	break;

     case PVR2_TEX_FORMAT_ARGB4444:

 	bytes <<= 1;

 	intFormat = GL_RGBA4;

 	format = GL_BGRA;

 	type = GL_UNSIGNED_SHORT_4_4_4_4_REV;

 	break;

     case PVR2_TEX_FORMAT_YUV422:

 	ERROR( "YUV textures not supported" );

 	break;

     case PVR2_TEX_FORMAT_BUMPMAP:

 	ERROR( "Bumpmap not supported" );

 	break;

     }

     int level=0, last_level = 0, mip_width = width, mip_height = height, mip_bytes = bytes;

     if( PVR2_TEX_IS_MIPMAPPED(mode) ) {

 	int i;

 	for( i=0; 1<<(i+1) < width; i++ );

 	last_level = i;

 	mip_width = width >> i;

 	mip_height= height >> i;

 	mip_bytes = bytes >> (i*2);

 	filter = GL_LINEAR_MIPMAP_LINEAR;

     }

     if( PVR2_TEX_IS_COMPRESSED(mode) ) {

 	uint16_t tmp[VQ_CODEBOOK_SIZE];

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

 	texture_addr += VQ_CODEBOOK_SIZE;

 	vq_get_codebook( &codebook, tmp );

     }

     for( level=last_level; level>= 0; level-- ) {

 	char data[mip_bytes];

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

 	if( tex_format == PVR2_TEX_FORMAT_IDX8 ) {

 	    int inputlength = mip_bytes >> shift;

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

 	    char *palette = mmio_region_PVR2PAL.mem + (bank * (256 << shift));

 	    char tmp[inputlength];

 	    char *p = tmp;

 	    pvr2_vram64_read( tmp, texture_addr, inputlength );

 	    if( shift == 2 ) {

 		detwiddle_pal8_to_32( 0, 0, mip_width, mip_width, &p, 

 				      (uint32_t *)data, (uint32_t *)palette );

 	    } else {

 		detwiddle_pal8_to_16( 0, 0, mip_width, mip_width, &p,

 				      (uint16_t *)data, (uint16_t *)palette );

 	    }

 	} else if( PVR2_TEX_IS_COMPRESSED(mode) ) {

 	    int inputlength = ((mip_width*mip_height) >> 2);

 	    char tmp[inputlength];

 	    pvr2_vram64_read( tmp, texture_addr, inputlength );

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

 		       PVR2_TEX_IS_TWIDDLED(mode) );

 	} else if( PVR2_TEX_IS_TWIDDLED(mode) ) {

 	    char tmp[mip_bytes];

 	    uint16_t *p = (uint16_t *)tmp;

 	    pvr2_vram64_read( tmp, texture_addr, mip_bytes );

 	    /* Untwiddle */

 	    detwiddle_16_to_16( 0, 0, mip_width, mip_width, &p, (uint16_t *)&data );

 	} else {

 	    pvr2_vram64_read( data, texture_addr, mip_bytes );

 	}

 	if( PVR2_TEX_IS_MIPMAPPED(mode) && mip_width == 2 ) {

 	    /* Opengl requires a 1x1 texture, but the PVR2 doesn't. This should

 	     * strictly speaking be the average of the 2x2 texture, but we're

 	     * lazy at the moment */

 	    glTexImage2D( GL_TEXTURE_2D, level+1, intFormat, 1, 1, 0, format, type, data );

 	}

 	/* Pass to GL */

 	glTexImage2D( GL_TEXTURE_2D, level, intFormat, mip_width, mip_height, 0, format, type,

 		      data );

 	texture_addr += mip_bytes;

 	mip_width <<= 1;

 	mip_height <<= 1;

 	mip_bytes <<= 2;

     }

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, filter);

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

 }

 /**

  * 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. The texture

  * will be bound to the GL_TEXTURE_2D target before being returned.

  * 

  * 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.

  */

 GLuint texcache_get_texture( uint32_t texture_addr, int width, int height,

 			     int mode )

 {

     uint32_t texture_page = texture_addr >> 12;

     texcache_entry_index idx = texcache_page_lookup[texture_page];

     while( idx != EMPTY_ENTRY ) {

 	texcache_entry_t entry = &texcache_active_list[idx];

 	if( entry->texture_addr == texture_addr &&

 	    entry->mode == mode &&

 	    entry->width == width &&

 	    entry->height == height ) {

 	    entry->lru_count = texcache_ref_counter++;

 	    glBindTexture( GL_TEXTURE_2D, entry->texture_id );

 	    return entry->texture_id;

 	}

         idx = entry->next;

     }

     /* Not found - check the free list */

     int slot = 0;

     if( texcache_free_ptr < MAX_TEXTURES ) {

 	slot = texcache_free_list[texcache_free_ptr++];

     } else {

 	slot = texcache_evict();

     }

     /* Construct new entry */

     texcache_active_list[slot].texture_addr = texture_addr;

     texcache_active_list[slot].width = width;

     texcache_active_list[slot].height = height;

     texcache_active_list[slot].mode = mode;

     texcache_active_list[slot].lru_count = texcache_ref_counter++;

     /* Add entry to the lookup table */

     texcache_active_list[slot].next = texcache_page_lookup[texture_page];

     texcache_page_lookup[texture_page] = slot;

     /* Construct the GL texture */

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

     texcache_load_texture( texture_addr, width, height, mode );

     return texcache_active_list[slot].texture_id;

 }