/**

  * $Id$

  *

  * PVR2 Tile Accelerator implementation

  *

  * 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 <string.h>

 #include "lxdream.h"

 #include "pvr2/pvr2.h"

 #include "pvr2/pvr2mmio.h"

 #include "asic.h"

 #include "dream.h"

 #define STATE_IDLE                 0

 #define STATE_IN_LIST              1

 #define STATE_IN_POLYGON           2

 #define STATE_EXPECT_POLY_BLOCK2   3

 #define STATE_EXPECT_VERTEX_BLOCK2 4

 #define STATE_ERROR                5

 #define STATE_EXPECT_END_VERTEX_BLOCK2 7

 #define TA_CMD(i) ( (i) >> 29 )

 #define TA_CMD_END_LIST 0

 #define TA_CMD_CLIP 1

 #define TA_CMD_POLYGON_CONTEXT 4

 #define TA_CMD_SPRITE_CONTEXT 5

 #define TA_CMD_VERTEX 7

 #define TA_LIST_NONE -1

 #define TA_LIST_OPAQUE 0

 #define TA_LIST_OPAQUE_MOD 1

 #define TA_LIST_TRANS 2

 #define TA_LIST_TRANS_MOD 3

 #define TA_LIST_PUNCH_OUT 4

 #define TA_IS_MODIFIER_LIST(list) (list == TA_LIST_OPAQUE_MOD || list == TA_LIST_TRANS_MOD)

 #define TA_GROW_UP 0

 #define TA_GROW_DOWN 1

 #define TA_VERTEX_NONE                        -1

 #define TA_VERTEX_PACKED                      0x00

 #define TA_VERTEX_TEX_PACKED                  0x08

 #define TA_VERTEX_TEX_SPEC_PACKED             0x0C

 #define TA_VERTEX_TEX_UV16_PACKED             0x09

 #define TA_VERTEX_TEX_UV16_SPEC_PACKED        0x0D

 #define TA_VERTEX_FLOAT                       0x10

 #define TA_VERTEX_TEX_FLOAT                   0x18

 #define TA_VERTEX_TEX_SPEC_FLOAT              0x1C

 #define TA_VERTEX_TEX_UV16_FLOAT              0x19

 #define TA_VERTEX_TEX_UV16_SPEC_FLOAT         0x1D

 #define TA_VERTEX_INTENSITY                   0x20

 #define TA_VERTEX_TEX_INTENSITY               0x28

 #define TA_VERTEX_TEX_SPEC_INTENSITY          0x2C

 #define TA_VERTEX_TEX_UV16_INTENSITY          0x29

 #define TA_VERTEX_TEX_UV16_SPEC_INTENSITY     0x2D

 #define TA_VERTEX_PACKED_MOD                  0x40

 #define TA_VERTEX_TEX_PACKED_MOD              0x48

 #define TA_VERTEX_TEX_SPEC_PACKED_MOD         0x4C

 #define TA_VERTEX_TEX_UV16_PACKED_MOD         0x49

 #define TA_VERTEX_TEX_UV16_SPEC_PACKED_MOD    0x4D

 #define TA_VERTEX_INTENSITY_MOD               0x60

 #define TA_VERTEX_TEX_INTENSITY_MOD           0x68

 #define TA_VERTEX_TEX_SPEC_INTENSITY_MOD      0x6C

 #define TA_VERTEX_TEX_UV16_INTENSITY_MOD      0x69

 #define TA_VERTEX_TEX_UV16_SPEC_INTENSITY_MOD 0x6D

 #define TA_VERTEX_SPRITE                      0x80

 #define TA_VERTEX_TEX_SPRITE                  0x88

 #define TA_VERTEX_MOD_VOLUME                  0x81

 #define TA_VERTEX_LISTLESS                    0xFF

 #define TA_IS_NORMAL_POLY() (ta_status.current_vertex_type < TA_VERTEX_SPRITE)

 static int strip_lengths[4] = {3,4,6,8}; /* in vertexes */

 #define TA_POLYCMD_LISTTYPE(i) ( ((i) >> 24) & 0x0F )

 #define TA_POLYCMD_USELENGTH(i) ( i & 0x00800000 )

 #define TA_POLYCMD_LENGTH(i)  strip_lengths[((i >> 18) & 0x03)]

 #define TA_POLYCMD_CLIP(i)  ((i>>16)&0x03)

 #define TA_POLYCMD_CLIP_NONE 0

 #define TA_POLYCMD_CLIP_INSIDE 2

 #define TA_POLYCMD_CLIP_OUTSIDE 3

 #define TA_POLYCMD_COLOURFMT(i)  (i & 0x00000030)

 #define TA_POLYCMD_COLOURFMT_ARGB32 0x00000000

 #define TA_POLYCMD_COLOURFMT_FLOAT 0x00000010

 #define TA_POLYCMD_COLOURFMT_INTENSITY 0x00000020

 #define TA_POLYCMD_COLOURFMT_LASTINT 0x00000030

 #define TA_POLYCMD_MODIFIED 0x00000080

 #define TA_POLYCMD_FULLMOD  0x00000040

 #define TA_POLYCMD_TEXTURED 0x00000008

 #define TA_POLYCMD_SPECULAR 0x00000004

 #define TA_POLYCMD_SHADED 0x00000002

 #define TA_POLYCMD_UV16 0x00000001

 #define TA_POLYCMD_IS_SPECULAR(i) ((i & 0x0000000C)==0x0000000C) /* Only applies to textured polys */

 #define TA_POLYCMD_IS_FULLMOD(i) ((i & 0x000000C0)==0x000000C0)

 #define TA_IS_END_VERTEX(i) (i & 0x10000000)

 /** Note these are not the IEEE 754 definitions - the TA treats NANs

  * as if they were INFs of the appropriate sign.

  */

 #define TA_IS_INF(f) (((*((uint32_t *)&f)) & 0xFF800000) == 0x7F800000)

 #define TA_IS_NINF(f) (((*((uint32_t *)&f)) & 0xFF800000) == 0xFF800000)

 #define MIN3( x1, x2, x3 ) ( (x1)<(x2)? ((x1)<(x3)?(x1):(x3)) : ((x2)<(x3)?(x2):(x3)) )

 #define MAX3( x1, x2, x3 ) ( (x1)>(x2)? ((x1)>(x3)?(x1):(x3)) : ((x2)>(x3)?(x2):(x3)) )

 #define TILESLOT( x, y ) (ta_status.current_tile_matrix + (ta_status.current_tile_size * (y * ta_status.width+ x) << 2))

 extern char *video_base;

 #define PVRRAM(addr) (*(uint32_t *)(video_base + ((addr)&PVR2_RAM_MASK)))

 struct pvr2_ta_vertex {

     float x,y,z;

     uint32_t detail[8]; /* 0-8 detail words */

 };

 struct tile_bounds {

     int32_t x1, y1, x2, y2;

 };

 struct pvr2_ta_status {

     int32_t state;

     int32_t width, height; /* Tile resolution, ie 20x15 */

     int32_t tilelist_dir; /* Growth direction of the tilelist, 0 = up, 1 = down */

     uint32_t tilelist_size; /* Size of the tilelist segments */

     uint32_t tilelist_start; /* Initial address of the tilelist */

     uint32_t polybuf_start; /* Initial bank address of the polygon buffer (ie &0x00F00000) */

     int32_t current_vertex_type;

     uint32_t accept_vertexes; /* 0 = NO, 1 = YES */

     int32_t vertex_count; /* index of last start-vertex seen, or -1 if no vertexes 

      * are present

      */

     uint32_t max_vertex;     /* Maximum number of vertexes in the current polygon (3/4/6/8) */

     uint32_t current_list_type;

     uint32_t current_tile_matrix; /* Memory location of the first tile for the current list. */

     uint32_t current_tile_size; /* Size of the tile matrix space  in 32-bit words (0/8/16/32)*/

     uint32_t intensity1, intensity2;

     struct tile_bounds clip;

     int32_t clip_mode;

     /**

      * Current working object

      */

     int32_t poly_context_size;

     int32_t poly_vertex_size;

     int32_t poly_parity;

     uint32_t poly_context[5];

     uint32_t poly_pointer;

     struct tile_bounds last_triangle_bounds;

     struct pvr2_ta_vertex poly_vertex[8];

     uint32_t debug_output;

 };

 static struct pvr2_ta_status ta_status;

 static int tilematrix_sizes[4] = {0,8,16,32};

 /**

  * Convenience union - ta data is either 32-bit integer or 32-bit float.

  */

 union ta_data {

     unsigned int i;

     float f;

 };

 void pvr2_ta_reset() {

     ta_status.state = STATE_ERROR; /* State not valid until initialized */

     ta_status.debug_output = 0;

 }

 void pvr2_ta_save_state( FILE *f )

 {

     fwrite( &ta_status, sizeof(ta_status), 1, f );

 }

 int pvr2_ta_load_state( FILE *f )

 {

     if( fread( &ta_status, sizeof(ta_status), 1, f ) != 1 )

         return 1;

     return 0;

 }

 void pvr2_ta_init() {

     ta_status.state = STATE_IDLE;

     ta_status.current_list_type = -1;

     ta_status.current_vertex_type = -1;

     ta_status.poly_parity = 0;

     ta_status.vertex_count = 0;

     ta_status.max_vertex = 3;

     ta_status.current_vertex_type = TA_VERTEX_LISTLESS;

     ta_status.poly_vertex_size = 0;

     memset(&ta_status.poly_context[1], 0, 4);

     ta_status.last_triangle_bounds.x1 = -1;

     ta_status.accept_vertexes = TRUE;

     ta_status.clip.x1 = 0;

     ta_status.clip.y1 = 0;

     ta_status.clip_mode = TA_POLYCMD_CLIP_NONE;

     uint32_t size = MMIO_READ( PVR2, TA_TILESIZE );

     ta_status.width = (size & 0xFFFF) + 1;

     ta_status.height = (size >> 16) + 1;

     ta_status.clip.x2 = ta_status.width-1;

     ta_status.clip.y2 = ta_status.height-1;

     uint32_t control = MMIO_READ( PVR2, TA_TILECFG );

     ta_status.tilelist_dir = (control >> 20) & 0x01;

     ta_status.tilelist_size = tilematrix_sizes[ (control & 0x03) ];

     MMIO_WRITE( PVR2, TA_POLYPOS, MMIO_READ( PVR2, TA_POLYBASE ) );

     uint32_t plistpos = MMIO_READ( PVR2, TA_LISTBASE ) >> 2;

     if( ta_status.tilelist_dir == TA_GROW_DOWN ) {

         plistpos -= ta_status.tilelist_size;

     }

     MMIO_WRITE( PVR2, TA_LISTPOS, plistpos );

     ta_status.tilelist_start = plistpos;

     ta_status.polybuf_start = MMIO_READ( PVR2, TA_POLYBASE ) & 0x00F00000;

 }

 static uint32_t parse_float_colour( float a, float r, float g, float b ) {

     int ai,ri,gi,bi;

     if( TA_IS_INF(a) ) {

         ai = 255;

     } else {

         ai = 256 * CLAMP(a,0.0,1.0) - 1;

         if( ai < 0 ) ai = 0;

     }

     if( TA_IS_INF(r) ) {

         ri = 255;

     } else {

         ri = 256 * CLAMP(r,0.0,1.0) - 1;

         if( ri < 0 ) ri = 0;

     }

     if( TA_IS_INF(g) ) {

         gi = 255;

     } else {

         gi = 256 * CLAMP(g,0.0,1.0) - 1;

         if( gi < 0 ) gi = 0;

     }

     if( TA_IS_INF(b) ) {

         bi = 255;

     } else {

         bi = 256 * CLAMP(b,0.0,1.0) - 1;

         if( bi < 0 ) bi = 0;

     }

     return (ai << 24) | (ri << 16) | (gi << 8) | bi;

 }

 static uint32_t parse_intensity_colour( uint32_t base, float intensity )

 {

     unsigned int i = (unsigned int)(256 * CLAMP(intensity, 0.0,1.0));

     return

     (((((base & 0xFF) * i) & 0xFF00) |

             (((base & 0xFF00) * i) & 0xFF0000) |

             (((base & 0xFF0000) * i) & 0xFF000000)) >> 8) |

             (base & 0xFF000000);

 }

 /**

  * Initialize the specified TA list.

  */

 static void ta_init_list( unsigned int listtype ) {

     int config = MMIO_READ( PVR2, TA_TILECFG );

     int tile_matrix = MMIO_READ( PVR2, TA_TILEBASE );

     int list_end = MMIO_READ( PVR2, TA_LISTEND );

     ta_status.current_tile_matrix = tile_matrix;

     /* If the list grows down, the end must be < tile matrix start. 

      * If it grows up, the end must be > tile matrix start.

      * Don't ask me why, it just does...

      */

     if( ((ta_status.tilelist_dir == TA_GROW_DOWN && list_end <= tile_matrix) ||

             (ta_status.tilelist_dir == TA_GROW_UP && list_end >= tile_matrix )) &&

             listtype <= TA_LIST_PUNCH_OUT ) {

         int i;

         uint32_t *p;

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

             int size = tilematrix_sizes[(config & 0x03)] << 2;

             ta_status.current_tile_matrix += ta_status.width * ta_status.height * size;

             config >>= 4;

         }

         ta_status.current_tile_size = tilematrix_sizes[(config & 0x03)];

         /* Initialize each tile to 0xF0000000 */

         if( ta_status.current_tile_size != 0 ) {

             p = (uint32_t *)(video_base + ta_status.current_tile_matrix);

             for( i=0; i< ta_status.width * ta_status.height; i++ ) {

                 *p = 0xF0000000;

                 p += ta_status.current_tile_size;

             }

         }

     } else {

         ta_status.current_tile_size = 0;

     }

     if( tile_matrix == list_end ) {

         ta_status.current_tile_size = 0;

     }

     ta_status.state = STATE_IN_LIST;

     ta_status.current_list_type = listtype;

     ta_status.last_triangle_bounds.x1 = -1;

 }

 static int list_events[5] = {EVENT_PVR_OPAQUE_DONE, EVENT_PVR_OPAQUEMOD_DONE, 

         EVENT_PVR_TRANS_DONE, EVENT_PVR_TRANSMOD_DONE,

         EVENT_PVR_PUNCHOUT_DONE };

 static void ta_end_list() {

     if( ta_status.current_list_type != TA_LIST_NONE ) {

         asic_event( list_events[ta_status.current_list_type] );

     }

     ta_status.current_list_type = TA_LIST_NONE;

     ta_status.current_vertex_type = TA_VERTEX_LISTLESS;

     ta_status.poly_vertex_size = 0;

     memset(&ta_status.poly_context[1], 0, 4);

     ta_status.state = STATE_IDLE;

 }

 static void ta_bad_input_error() {

     asic_event( EVENT_PVR_BAD_INPUT );

 }

 /**

  * Write data out to the polygon buffer.

  * If the end-of-buffer is reached, asserts EVENT_PVR_PRIM_ALLOC_FAIL

  * @param data to be written

  * @param length Number of 32-bit words to write.

  * @return number of words actually written

  */

 static int ta_write_polygon_buffer( uint32_t *data, int length )

 {

     int rv;

     int posn = MMIO_READ( PVR2, TA_POLYPOS );

     int end = MMIO_READ( PVR2, TA_POLYEND );

     uint32_t *target = (uint32_t *)(video_base + posn);

     for( rv=0; rv < length; rv++ ) {

         if( posn == end ) {

             asic_event( EVENT_PVR_PRIM_ALLOC_FAIL );

             //	    ta_status.state = STATE_ERROR;

             break;

         }

         if( posn < PVR2_RAM_SIZE ) {

             *target++ = *data++;

         }

         posn += 4;

     }

     MMIO_WRITE( PVR2, TA_POLYPOS, posn );

     return rv;

 }

 #define TA_NO_ALLOC 0xFFFFFFFF

 /**

  * Allocate a new tile list block from the grow space and update the

  * word at reference to be a link to the new block.

  */

 static uint32_t ta_alloc_tilelist( uint32_t reference ) {

     uint32_t posn = MMIO_READ( PVR2, TA_LISTPOS );

     uint32_t limit = MMIO_READ( PVR2, TA_LISTEND ) >> 2;

     uint32_t newposn;

     if( ta_status.tilelist_dir == TA_GROW_DOWN ) {

         newposn = posn - ta_status.tilelist_size;

         if( posn == limit ) {

             PVRRAM(posn<<2) = 0xF0000000;

             PVRRAM(reference) = 0xE0000000 | (posn<<2);

             return TA_NO_ALLOC;

         } else if( posn < limit ) {

             PVRRAM(reference) = 0xE0000000 | (posn<<2);

             return TA_NO_ALLOC;

         } else if( newposn <= limit ) {

         } else if( newposn <= (limit + ta_status.tilelist_size) ) {

             asic_event( EVENT_PVR_MATRIX_ALLOC_FAIL );

             MMIO_WRITE( PVR2, TA_LISTPOS, newposn );

         } else {

             MMIO_WRITE( PVR2, TA_LISTPOS, newposn );

         }

         PVRRAM(reference) = 0xE0000000 | (posn<<2);

         return posn << 2;

     } else {

         newposn = posn + ta_status.tilelist_size;

         if( posn == limit ) {

             PVRRAM(posn<<2) = 0xF0000000;

             PVRRAM(reference) = 0xE0000000 | (posn<<2);

             return TA_NO_ALLOC;

         } else if ( posn > limit ) {

             PVRRAM(reference) = 0xE0000000 | (posn<<2);

             return TA_NO_ALLOC;

         } else if( newposn >= limit ) {

         } else if( newposn >= (limit - ta_status.tilelist_size) ) {

             asic_event( EVENT_PVR_MATRIX_ALLOC_FAIL );

             MMIO_WRITE( PVR2, TA_LISTPOS, newposn );

         } else {

             MMIO_WRITE( PVR2, TA_LISTPOS, newposn );

         }	    

         PVRRAM(reference) = 0xE0000000 | (posn<<2);

         return posn << 2;

     }

 }

 /**

  * Write a tile entry out to the matrix.

  */

 static void ta_write_tile_entry( int x, int y, uint32_t tile_entry ) {

     uint32_t tile = TILESLOT(x,y);

     uint32_t tilestart = tile;

     uint32_t value;

     uint32_t lasttri = 0;

     int i;

     if( ta_status.clip_mode == TA_POLYCMD_CLIP_OUTSIDE &&

             x >= ta_status.clip.x1 && x <= ta_status.clip.x2 &&

             y >= ta_status.clip.y1 && y <= ta_status.clip.y2 ) {

         /* Tile clipped out */

         return;

     }

     if( (tile_entry & 0x80000000) && 

             ta_status.last_triangle_bounds.x1 != -1 &&

             ta_status.last_triangle_bounds.x1 <= x &&

             ta_status.last_triangle_bounds.x2 >= x &&

             ta_status.last_triangle_bounds.y1 <= y &&

             ta_status.last_triangle_bounds.y2 >= y ) {

         /* potential for triangle stacking */

         lasttri = tile_entry & 0xE1E00000;

     }

     if( PVRRAM(tile) == 0xF0000000 ) {

         PVRRAM(tile) = tile_entry;

         PVRRAM(tile+4) = 0xF0000000;

         return;

     }

     while(1) {

         value = PVRRAM(tile);

         for( i=1; i<ta_status.current_tile_size; i++ ) {

             tile += 4;

             uint32_t nextval = PVRRAM(tile);

             if( nextval == 0xF0000000 ) {

                 if( lasttri != 0 && lasttri == (value&0xE1E00000) ) {

                     int count = (value & 0x1E000000) + 0x02000000;

                     if( count < 0x20000000 ) {

                         PVRRAM(tile-4) = (value & 0xE1FFFFFF) | count;

                         return;

                     }

                 }

                 if( i < ta_status.current_tile_size-1 ) {

                     PVRRAM(tile) = tile_entry;

                     PVRRAM(tile+4) = 0xF0000000;

                     return;

                 }

             }

             value = nextval;

         }

         if( value == 0xF0000000 ) {

             tile = ta_alloc_tilelist(tile);

             if( tile != TA_NO_ALLOC ) {

                 PVRRAM(tile) = tile_entry;

                 PVRRAM(tile+4) = 0xF0000000;

             }

             return;

         } else if( (value & 0xFF000000) == 0xE0000000 ) {

             value &= 0x00FFFFFF;

             if( value == tilestart )

                 return; /* Loop */

             tilestart = tile = value;

         } else {

             /* This should never happen */

             return;

         }

     }

 }

 /**

  * Write a completed polygon out to the memory buffers 

  * OPTIMIZEME: This is not terribly efficient at the moment.

  */

 static void ta_commit_polygon( ) {

     int i, x, y;

     int tx[ta_status.vertex_count], ty[ta_status.vertex_count];

     struct tile_bounds triangle_bound[ta_status.vertex_count - 2];

     struct tile_bounds polygon_bound;

     uint32_t poly_context[5];

     memcpy( poly_context, ta_status.poly_context, ta_status.poly_context_size * 4 );

     /* Compute the tile coordinates for each vertex (need to be careful with

      * clamping here)

      */

     for( i=0; i<ta_status.vertex_count; i++ ) {

         if( ta_status.poly_vertex[i].x < 0.0 || TA_IS_NINF(ta_status.poly_vertex[i].x) ) {

             tx[i] = -1;

         } else if( ta_status.poly_vertex[i].x > (float)INT_MAX || TA_IS_INF(ta_status.poly_vertex[i].x) ) {

             tx[i] = INT_MAX/32;

         } else {

             tx[i] = (int)(ta_status.poly_vertex[i].x / 32.0);

         }

         if( ta_status.poly_vertex[i].y < 0.0 || TA_IS_NINF(ta_status.poly_vertex[i].y)) {

             ty[i] = -1;

         } else if( ta_status.poly_vertex[i].y > (float)INT_MAX || TA_IS_INF(ta_status.poly_vertex[i].y) ) {

             ty[i] = INT_MAX/32;

         } else {

             ty[i] = (int)(ta_status.poly_vertex[i].y / 32.0);

         }

     }

     /* Compute bounding box for each triangle individually, as well

      * as the overall polygon.

      */

     for( i=0; i<ta_status.vertex_count-2; i++ ) {

         triangle_bound[i].x1 = MIN3(tx[i],tx[i+1],tx[i+2]);

         triangle_bound[i].x2 = MAX3(tx[i],tx[i+1],tx[i+2]);

         triangle_bound[i].y1 = MIN3(ty[i],ty[i+1],ty[i+2]);

         triangle_bound[i].y2 = MAX3(ty[i],ty[i+1],ty[i+2]);

         if( i == 0 ) {

             polygon_bound.x1 = triangle_bound[0].x1;

             polygon_bound.y1 = triangle_bound[0].y1;

             polygon_bound.x2 = triangle_bound[0].x2;

             polygon_bound.y2 = triangle_bound[0].y2;

         } else {

             polygon_bound.x1 = MIN(polygon_bound.x1, triangle_bound[i].x1);

             polygon_bound.x2 = MAX(polygon_bound.x2, triangle_bound[i].x2);

             polygon_bound.y1 = MIN(polygon_bound.y1, triangle_bound[i].y1);

             polygon_bound.y2 = MAX(polygon_bound.y2, triangle_bound[i].y2);

         }

     }

     /* Clamp the polygon bounds to the frustum */

     if( polygon_bound.x1 < 0 ) polygon_bound.x1 = 0;

     if( polygon_bound.x2 >= ta_status.width ) polygon_bound.x2 = ta_status.width-1;

     if( polygon_bound.y1 < 0 ) polygon_bound.y1 = 0;

     if( polygon_bound.y2 >= ta_status.width ) polygon_bound.y2 = ta_status.height-1;

     /* Set the "single tile" flag if it's entirely contained in 1 tile */

     if( polygon_bound.x1 == polygon_bound.x2 &&

             polygon_bound.y1 == polygon_bound.y2 ) {

         poly_context[0] |= 0x00200000;

     }

     /* If the polygon is entirely clipped, don't even write the polygon data */

     switch( ta_status.clip_mode ) {

     case TA_POLYCMD_CLIP_NONE:

         if( polygon_bound.x2 < 0 || polygon_bound.x1 >= ta_status.width ||

                 polygon_bound.y2 < 0 || polygon_bound.y1 >= ta_status.height ) {

             return;

         }

         break;

     case TA_POLYCMD_CLIP_INSIDE:

         if( polygon_bound.x2 < ta_status.clip.x1 || polygon_bound.x1 > ta_status.clip.x2 ||

                 polygon_bound.y2 < ta_status.clip.y1 || polygon_bound.y1 > ta_status.clip.y2 ) {

             return;

         } else {

             /* Clamp to clip bounds */

             if( polygon_bound.x1 < ta_status.clip.x1 ) polygon_bound.x1 = ta_status.clip.x1;

             if( polygon_bound.x2 > ta_status.clip.x2 ) polygon_bound.x2 = ta_status.clip.x2;

             if( polygon_bound.y1 < ta_status.clip.y1 ) polygon_bound.y1 = ta_status.clip.y1;

             if( polygon_bound.y2 > ta_status.clip.y2 ) polygon_bound.y2 = ta_status.clip.y2;

         }

         break;

     case TA_POLYCMD_CLIP_OUTSIDE:

         if( polygon_bound.x1 >= ta_status.clip.x1 && polygon_bound.x2 <= ta_status.clip.x2 &&

                 polygon_bound.y1 >= ta_status.clip.y1 && polygon_bound.y2 <= ta_status.clip.y2 ) {

             return;

         }

         break;

     }

     /* Ok, we're good to go - write out the polygon first */

     uint32_t tile_entry = (MMIO_READ( PVR2, TA_POLYPOS ) - ta_status.polybuf_start) >> 2 | 

     ta_status.poly_pointer;

     int status = ta_write_polygon_buffer( poly_context, ta_status.poly_context_size );

     if( status == 0 ) {

         /* No memory available - abort */

         return;

     } else {

         for( i=0; i<ta_status.vertex_count && status != 0; i++ ) {

             status = ta_write_polygon_buffer( (uint32_t *)(&ta_status.poly_vertex[i]), 3 + ta_status.poly_vertex_size );

         }

     }

     if( ta_status.current_tile_size == 0 ) {

         /* No memory for tile entry, so don't write anything */

         return;

     }

     /* And now the tile entries. Triangles are different from everything else */

     if( ta_status.vertex_count == 3 ) {

         tile_entry |= 0x80000000;

         for( y=polygon_bound.y1; y<=polygon_bound.y2; y++ ) {

             for( x=polygon_bound.x1; x<=polygon_bound.x2; x++ ) {

                 ta_write_tile_entry( x,y,tile_entry );

             }

         }

         ta_status.last_triangle_bounds.x1 = polygon_bound.x1;

         ta_status.last_triangle_bounds.y1 = polygon_bound.y1;

         ta_status.last_triangle_bounds.x2 = polygon_bound.x2;

         ta_status.last_triangle_bounds.y2 = polygon_bound.y2;

     } else if( ta_status.current_vertex_type == TA_VERTEX_SPRITE ||

             ta_status.current_vertex_type == TA_VERTEX_TEX_SPRITE ) {

         tile_entry |= 0xA0000000;

         for( y=polygon_bound.y1; y<=polygon_bound.y2; y++ ) {

             for( x=polygon_bound.x1; x<=polygon_bound.x2; x++ ) {

                 ta_write_tile_entry( x,y,tile_entry );

             }

         }

         ta_status.last_triangle_bounds.x1 = polygon_bound.x1;

         ta_status.last_triangle_bounds.y1 = polygon_bound.y1;

         ta_status.last_triangle_bounds.x2 = polygon_bound.x2;

         ta_status.last_triangle_bounds.y2 = polygon_bound.y2;

     } else {

         for( y=polygon_bound.y1; y<=polygon_bound.y2; y++ ) {

             for( x=polygon_bound.x1; x<=polygon_bound.x2; x++ ) {

                 uint32_t entry = tile_entry;

                 for( i=0; i<ta_status.vertex_count-2; i++ ) {

                     if( triangle_bound[i].x1 <= x && triangle_bound[i].x2 >= x &&

                             triangle_bound[i].y1 <= y && triangle_bound[i].y2 >= y ) {

                         entry |= (0x40000000>>i);

                     }

                 }

                 ta_write_tile_entry( x, y, entry );

             }

         }

         ta_status.last_triangle_bounds.x1 = -1;

     }

 }

 /**

  * Variant of ta_split_polygon called when vertex_count == max_vertex, but 

  * the client hasn't sent the LAST VERTEX flag. Commit the poly as normal

  * first, then start a new poly with the first 2 vertexes taken from the 

  * current one.

  */

 static void ta_split_polygon() {

     ta_commit_polygon();

     if( TA_IS_NORMAL_POLY() ) { 

         /* This only applies to ordinary polys - Sprites + modifier lists are

          * handled differently

          */

         if( ta_status.vertex_count == 3 ) {

             /* Triangles use an odd/even scheme */

             if( ta_status.poly_parity == 0 ) {

                 memcpy( &ta_status.poly_vertex[0], &ta_status.poly_vertex[2], 

                         sizeof(struct pvr2_ta_vertex) );

                 ta_status.poly_parity = 1;

             } else {

                 memcpy( &ta_status.poly_vertex[1], &ta_status.poly_vertex[2],

                         sizeof(struct pvr2_ta_vertex) );

                 ta_status.poly_parity = 0;

             }

         } else {

             /* Everything else just uses the last 2 vertexes in order */

             memcpy( &ta_status.poly_vertex[0], &ta_status.poly_vertex[ta_status.vertex_count-2], 

                     sizeof(struct pvr2_ta_vertex)*2 );

             ta_status.poly_parity = 0;

         }

         ta_status.vertex_count = 2;

     } else {

         ta_status.vertex_count = 0;

     }

 }

 /**

  * Parse the polygon context block and setup the internal state to receive

  * vertexes.

  * @param data 32 bytes of parameter data.

  */

 static void ta_parse_polygon_context( union ta_data *data ) {

     int colourfmt = TA_POLYCMD_COLOURFMT(data[0].i);

     if( TA_POLYCMD_USELENGTH(data[0].i) ) {

         ta_status.max_vertex = TA_POLYCMD_LENGTH(data[0].i);

     }

     ta_status.clip_mode = TA_POLYCMD_CLIP(data[0].i);

     if( ta_status.clip_mode == 1 ) { /* Reserved - treat as CLIP_INSIDE */

         ta_status.clip_mode = TA_POLYCMD_CLIP_INSIDE;

     }

     ta_status.vertex_count = 0;

     ta_status.poly_context[0] = 

         (data[1].i & 0xFC1FFFFF) | ((data[0].i & 0x0B) << 22);

     ta_status.poly_context[1] = data[2].i;

     ta_status.poly_context[3] = data[4].i;

     ta_status.poly_parity = 0;

     if( data[0].i & TA_POLYCMD_TEXTURED ) {

         ta_status.current_vertex_type = data[0].i & 0x0D;

         ta_status.poly_context[2] = data[3].i;

         ta_status.poly_context[4] = data[5].i;

         if( data[0].i & TA_POLYCMD_SPECULAR ) {

             ta_status.poly_context[0] |= 0x01000000;

             ta_status.poly_vertex_size = 4;

         } else {

             ta_status.poly_vertex_size = 3;

         }

         if( data[0].i & TA_POLYCMD_UV16 ) {

             ta_status.poly_vertex_size--;

         }

     } else {

         ta_status.current_vertex_type = 0;

         ta_status.poly_vertex_size = 1;

         ta_status.poly_context[2] = 0;

         ta_status.poly_context[4] = 0;

     }

     ta_status.poly_pointer = (ta_status.poly_vertex_size << 21);

     ta_status.poly_context_size = 3;

     if( data[0].i & TA_POLYCMD_MODIFIED ) {

         ta_status.poly_pointer |= 0x01000000;

         if( data[0].i & TA_POLYCMD_FULLMOD ) {

             ta_status.poly_context_size = 5;

             ta_status.poly_vertex_size <<= 1;

             ta_status.current_vertex_type |= 0x40;

             /* Modified/float not supported - behaves as per last intensity */

             if( colourfmt == TA_POLYCMD_COLOURFMT_FLOAT ) {

                 colourfmt = TA_POLYCMD_COLOURFMT_LASTINT;

             }

         }

     }

     if( colourfmt == TA_POLYCMD_COLOURFMT_INTENSITY ) {

         if( TA_POLYCMD_IS_FULLMOD(data[0].i) ||

                 TA_POLYCMD_IS_SPECULAR(data[0].i) ) {

             ta_status.state = STATE_EXPECT_POLY_BLOCK2;

         } else {

             ta_status.intensity1 = 

                 parse_float_colour( data[4].f, data[5].f, data[6].f, data[7].f );

         }

     } else if( colourfmt == TA_POLYCMD_COLOURFMT_LASTINT ) {

         colourfmt = TA_POLYCMD_COLOURFMT_INTENSITY;

     }

     ta_status.current_vertex_type |= colourfmt;

 }

 /**

  * Parse the modifier volume context block and setup the internal state to 

  * receive modifier vertexes.

  * @param data 32 bytes of parameter data.

  */

 static void ta_parse_modifier_context( union ta_data *data ) {

     ta_status.current_vertex_type = TA_VERTEX_MOD_VOLUME;

     ta_status.poly_vertex_size = 0;

     ta_status.clip_mode = TA_POLYCMD_CLIP(data[0].i);

     if( ta_status.clip_mode == 1 ) { /* Reserved - treat as CLIP_INSIDE */

         ta_status.clip_mode = TA_POLYCMD_CLIP_INSIDE;

     }

     ta_status.poly_context_size = 3;

     ta_status.poly_context[0] = (data[1].i & 0xFC1FFFFF) |

     ((data[0].i & 0x0B)<<22);

     if( TA_POLYCMD_IS_SPECULAR(data[0].i) ) {

         ta_status.poly_context[0] |= 0x01000000;

     }

     ta_status.poly_context[1] = 0;

     ta_status.poly_context[2] = 0;

     ta_status.vertex_count = 0;

     ta_status.max_vertex = 3;

     ta_status.poly_pointer = 0;

 }

 /**

  * Parse the sprite context block and setup the internal state to receive

  * vertexes.

  * @param data 32 bytes of parameter data.

  */

 static void ta_parse_sprite_context( union ta_data *data ) {

     ta_status.poly_context_size = 3;

     ta_status.poly_context[0] = (data[1].i & 0xFC1FFFFF) |

     ((data[0].i & 0x0B)<<22) | 0x00400000;

     ta_status.clip_mode = TA_POLYCMD_CLIP(data[0].i);

     if( ta_status.clip_mode == 1 ) { /* Reserved - treat as CLIP_INSIDE */

         ta_status.clip_mode = TA_POLYCMD_CLIP_INSIDE;

     }

     if( TA_POLYCMD_IS_SPECULAR(data[0].i) ) {

         ta_status.poly_context[0] |= 0x01000000;

     }

     ta_status.poly_context[1] = data[2].i;

     ta_status.poly_context[2] = data[3].i;

     if( data[0].i & TA_POLYCMD_TEXTURED ) {

         ta_status.poly_vertex_size = 2;

         ta_status.poly_vertex[2].detail[1] = data[4].i;

         ta_status.current_vertex_type = TA_VERTEX_TEX_SPRITE;

     } else {

         ta_status.poly_vertex_size = 1;

         ta_status.poly_vertex[2].detail[0] = data[4].i;

         ta_status.current_vertex_type = TA_VERTEX_SPRITE;

     }

     ta_status.vertex_count = 0;

     ta_status.max_vertex = 4;

     ta_status.poly_pointer = (ta_status.poly_vertex_size << 21);

 }

 /**

  * Copy the last read vertex into all vertexes up to max_vertex. Used for

  * Aborted polygons under some circumstances.

  */

 static void ta_fill_vertexes( ) {

     int i;

     for( i=ta_status.vertex_count; i<ta_status.max_vertex; i++ ) {

         memcpy( &ta_status.poly_vertex[i], &ta_status.poly_vertex[ta_status.vertex_count-1],

                 sizeof( struct pvr2_ta_vertex ) );

     }

 }

 static void ta_parse_vertex( union ta_data *data ) {

     struct pvr2_ta_vertex *vertex = &ta_status.poly_vertex[ta_status.vertex_count];

     vertex->x = data[1].f;

     vertex->y = data[2].f;

     vertex->z = data[3].f;

     switch( ta_status.current_vertex_type ) {

     case TA_VERTEX_PACKED:

         vertex->detail[0] = data[6].i;

         break;

     case TA_VERTEX_FLOAT:

         vertex->detail[0] = parse_float_colour( data[4].f, data[5].f, data[6].f, data[7].f );

         break;

     case TA_VERTEX_INTENSITY:

         vertex->detail[0] = parse_intensity_colour( ta_status.intensity1, data[6].f );

         break;

     case TA_VERTEX_TEX_SPEC_PACKED:

         vertex->detail[3] = data[7].i; /* ARGB */

         /* Fallthrough */

     case TA_VERTEX_TEX_PACKED:

         vertex->detail[0] = data[4].i; /* U */

         vertex->detail[1] = data[5].i; /* V */

         vertex->detail[2] = data[6].i; /* ARGB */

         break;

     case TA_VERTEX_TEX_UV16_SPEC_PACKED:

         vertex->detail[2] = data[7].i; /* ARGB */

         /* Fallthrough */

     case TA_VERTEX_TEX_UV16_PACKED:

         vertex->detail[0] = data[4].i; /* UV */

         vertex->detail[1] = data[6].i; /* ARGB */

         break;

     case TA_VERTEX_TEX_FLOAT:

     case TA_VERTEX_TEX_SPEC_FLOAT:

         vertex->detail[0] = data[4].i; /* U */

         vertex->detail[1] = data[5].i; /* UV */

         ta_status.state = STATE_EXPECT_VERTEX_BLOCK2;

         break;

     case TA_VERTEX_TEX_UV16_FLOAT:

     case TA_VERTEX_TEX_UV16_SPEC_FLOAT:

         vertex->detail[0] = data[4].i; /* UV */

         ta_status.state = STATE_EXPECT_VERTEX_BLOCK2;

         break;

     case TA_VERTEX_TEX_SPEC_INTENSITY:

         vertex->detail[3] = parse_intensity_colour( ta_status.intensity2, data[7].f );

         /* Fallthrough */

     case TA_VERTEX_TEX_INTENSITY:

         vertex->detail[0] = data[4].i; /* U */

         vertex->detail[1] = data[5].i; /* V */

         vertex->detail[2] = parse_intensity_colour( ta_status.intensity1, data[6].f );

         break;

     case TA_VERTEX_TEX_UV16_SPEC_INTENSITY:

         vertex->detail[2] = parse_intensity_colour( ta_status.intensity2, data[7].f );

         /* Fallthrough */

     case TA_VERTEX_TEX_UV16_INTENSITY:

         vertex->detail[0] = data[4].i; /* UV */

         vertex->detail[1] = parse_intensity_colour( ta_status.intensity1, data[6].f );

         break;

     case TA_VERTEX_PACKED_MOD:

         vertex->detail[0] = data[4].i; /* ARGB */

         vertex->detail[1] = data[5].i; /* ARGB */

         break;

     case TA_VERTEX_INTENSITY_MOD:

         vertex->detail[0] = parse_intensity_colour( ta_status.intensity1, data[4].f );

         vertex->detail[1] = parse_intensity_colour( ta_status.intensity2, data[5].f );

         break;

     case TA_VERTEX_TEX_SPEC_PACKED_MOD:

         vertex->detail[3] = data[7].i; /* ARGB0 */

         /* Fallthrough */

     case TA_VERTEX_TEX_PACKED_MOD:

         vertex->detail[0] = data[4].i; /* U0 */

         vertex->detail[1] = data[5].i; /* V0 */

         vertex->detail[2] = data[6].i; /* ARGB0 */

         ta_status.state = STATE_EXPECT_VERTEX_BLOCK2;

         break;

     case TA_VERTEX_TEX_UV16_SPEC_PACKED_MOD:

         vertex->detail[2] = data[7].i; /* ARGB0 */

         /* Fallthrough */

     case TA_VERTEX_TEX_UV16_PACKED_MOD:

         vertex->detail[0] = data[4].i; /* UV0 */

         vertex->detail[1] = data[6].i; /* ARGB0 */

         ta_status.state = STATE_EXPECT_VERTEX_BLOCK2;

         break;

     case TA_VERTEX_TEX_SPEC_INTENSITY_MOD:

         vertex->detail[3] = parse_intensity_colour( ta_status.intensity1, data[7].f );

         /* Fallthrough */

     case TA_VERTEX_TEX_INTENSITY_MOD:

         vertex->detail[0] = data[4].i; /* U0 */

         vertex->detail[1] = data[5].i; /* V0 */

         vertex->detail[2] = parse_intensity_colour( ta_status.intensity1, data[6].f );

         ta_status.state = STATE_EXPECT_VERTEX_BLOCK2;

         break;

     case TA_VERTEX_TEX_UV16_SPEC_INTENSITY_MOD:

         vertex->detail[2] = parse_intensity_colour( ta_status.intensity1, data[7].f );

         /* Fallthrough */

     case TA_VERTEX_TEX_UV16_INTENSITY_MOD:

         vertex->detail[0] = data[4].i; /* UV0 */

         vertex->detail[1] = parse_intensity_colour( ta_status.intensity1, data[6].f );

         ta_status.state = STATE_EXPECT_VERTEX_BLOCK2;

         break;

     case TA_VERTEX_SPRITE:

     case TA_VERTEX_TEX_SPRITE:

     case TA_VERTEX_MOD_VOLUME:

     case TA_VERTEX_LISTLESS:

         vertex++;

         vertex->x = data[4].f;

         vertex->y = data[5].f;

         vertex->z = data[6].f;

         vertex++;

         vertex->x = data[7].f;

         ta_status.vertex_count += 2;

         ta_status.state = STATE_EXPECT_VERTEX_BLOCK2;

         break;

     }

     ta_status.vertex_count++;

 }

 static void ta_parse_vertex_block2( union ta_data *data ) {

     struct pvr2_ta_vertex *vertex = &ta_status.poly_vertex[ta_status.vertex_count-1];

     switch( ta_status.current_vertex_type ) {

     case TA_VERTEX_TEX_SPEC_FLOAT:

         vertex->detail[3] = parse_float_colour( data[4].f, data[5].f, data[6].f, data[7].f );

         /* Fallthrough */

     case TA_VERTEX_TEX_FLOAT:

         vertex->detail[2] = parse_float_colour( data[0].f, data[1].f, data[2].f, data[3].f );

         break;

     case TA_VERTEX_TEX_UV16_SPEC_FLOAT:

         vertex->detail[2] = parse_float_colour( data[4].f, data[5].f, data[6].f, data[7].f );

         /* Fallthrough */

     case TA_VERTEX_TEX_UV16_FLOAT:

         vertex->detail[1] = parse_float_colour( data[0].f, data[1].f, data[2].f, data[3].f );

         break;

     case TA_VERTEX_TEX_PACKED_MOD:

         vertex->detail[3] = data[0].i; /* U1 */

         vertex->detail[4] = data[1].i; /* V1 */

         vertex->detail[5] = data[2].i; /* ARGB1 */

         break;

     case TA_VERTEX_TEX_SPEC_PACKED_MOD:

         vertex->detail[4] = data[0].i; /* U1 */

         vertex->detail[5] = data[1].i; /* V1 */

         vertex->detail[6] = data[2].i; /* ARGB1 */

         vertex->detail[7] = data[3].i; /* ARGB1 */

         break;

     case TA_VERTEX_TEX_UV16_PACKED_MOD:

         vertex->detail[2] = data[0].i; /* UV1 */

         vertex->detail[3] = data[2].i; /* ARGB1 */

         break;

     case TA_VERTEX_TEX_UV16_SPEC_PACKED_MOD:

         vertex->detail[3] = data[0].i; /* UV1 */

         vertex->detail[4] = data[2].i; /* ARGB1 */

         vertex->detail[5] = data[3].i; /* ARGB1 */

         break;

     case TA_VERTEX_TEX_INTENSITY_MOD:

         vertex->detail[3] = data[0].i; /* U1 */

         vertex->detail[4] = data[1].i; /* V1 */

         vertex->detail[5] = parse_intensity_colour( ta_status.intensity2, data[2].f ); /* ARGB1 */

         break;

     case TA_VERTEX_TEX_SPEC_INTENSITY_MOD:

         vertex->detail[4] = data[0].i; /* U1 */

         vertex->detail[5] = data[1].i; /* V1 */

         vertex->detail[6] = parse_intensity_colour( ta_status.intensity2, data[2].f ); /* ARGB1 */

         vertex->detail[7] = parse_intensity_colour( ta_status.intensity2, data[3].f ); /* ARGB1 */

         break;

     case TA_VERTEX_TEX_UV16_INTENSITY_MOD:

         vertex->detail[2] = data[0].i; /* UV1 */

         vertex->detail[3] = parse_intensity_colour( ta_status.intensity2, data[2].f ); /* ARGB1 */

         break;

     case TA_VERTEX_TEX_UV16_SPEC_INTENSITY_MOD:

         vertex->detail[3] = data[0].i; /* UV1 */

         vertex->detail[4] = parse_intensity_colour( ta_status.intensity2, data[2].f ); /* ARGB1 */

         vertex->detail[5] = parse_intensity_colour( ta_status.intensity2, data[3].f ); /* ARGB1 */

         break;

     case TA_VERTEX_SPRITE:

         vertex->y = data[0].f;

         vertex->z = data[1].f;

         vertex++;

         ta_status.vertex_count++;

         vertex->x = data[2].f;

         vertex->y = data[3].f;

         vertex->z = 0;

         vertex->detail[0] = 0;

         ta_status.poly_vertex[0].detail[0] = 0;

         ta_status.poly_vertex[1].detail[0] = 0;

         break;

     case TA_VERTEX_TEX_SPRITE:

         vertex->y = data[0].f;

         vertex->z = data[1].f;

         vertex++;

         ta_status.vertex_count++;

         vertex->x = data[2].f;

         vertex->y = data[3].f;

         vertex->z = 0;

         vertex->detail[0] = 0;

         vertex->detail[1] = 0;

         ta_status.poly_vertex[0].detail[0] = data[5].i;

         ta_status.poly_vertex[0].detail[1] = 0;

         ta_status.poly_vertex[1].detail[0] = data[6].i;

         ta_status.poly_vertex[1].detail[1] = 0;

         ta_status.poly_vertex[2].detail[0] = data[7].i;

         break;

     case TA_VERTEX_MOD_VOLUME:

     case TA_VERTEX_LISTLESS:

         vertex->y = data[0].f;

         vertex->z = data[1].f;

         break;

     }

     ta_status.state = STATE_IN_POLYGON;

 }

 /**

  * Process 1 32-byte block of ta data

  */

 void pvr2_ta_process_block( unsigned char *input ) {

     union ta_data *data = (union ta_data *)input;

     switch( ta_status.state ) {

     case STATE_ERROR:

         /* Fatal error raised - stop processing until reset */

         return;

     case STATE_EXPECT_POLY_BLOCK2:

         /* This is always a pair of floating-point colours */

         ta_status.intensity1 = 

             parse_float_colour( data[0].f, data[1].f, data[2].f, data[3].f );

         ta_status.intensity2 =

             parse_float_colour( data[4].f, data[5].f, data[6].f, data[7].f );

         ta_status.state = STATE_IN_LIST;

         break;

     case STATE_EXPECT_VERTEX_BLOCK2:

         ta_parse_vertex_block2( data );

         if( ta_status.vertex_count == ta_status.max_vertex ) {

             ta_split_polygon();

         }

         break;

     case STATE_EXPECT_END_VERTEX_BLOCK2:

         ta_parse_vertex_block2( data );

         if( ta_status.vertex_count < 3 ) {

             ta_bad_input_error();

         } else {

             ta_commit_polygon();

         }

         ta_status.vertex_count = 0;

         ta_status.poly_parity = 0;

         ta_status.state = STATE_IN_LIST;

         break;

     case STATE_IN_LIST:

     case STATE_IN_POLYGON:

     case STATE_IDLE:

         switch( TA_CMD( data->i ) ) {

         case TA_CMD_END_LIST:

             if( ta_status.state == STATE_IN_POLYGON ) {

                 ta_bad_input_error();

                 ta_end_list();

                 ta_status.state = STATE_ERROR; /* Abort further processing */

             } else {

                 ta_end_list();

             }

             break;

         case TA_CMD_CLIP:

             if( ta_status.state == STATE_IN_POLYGON ) {

                 ta_bad_input_error();

                 ta_status.accept_vertexes = FALSE;

                 /* Enter stuffed up mode */

             }

             ta_status.clip.x1 = data[4].i & 0x3F;

             ta_status.clip.y1 = data[5].i & 0x0F;

             ta_status.clip.x2 = data[6].i & 0x3F;

             ta_status.clip.y2 = data[7].i & 0x0F;

             if( ta_status.clip.x2 >= ta_status.width )

                 ta_status.clip.x2 = ta_status.width - 1;

             if( ta_status.clip.y2 >= ta_status.height )

                 ta_status.clip.y2 = ta_status.height - 1;

             break;

         case TA_CMD_POLYGON_CONTEXT:

             if( ta_status.state == STATE_IDLE ) {

                 ta_init_list( TA_POLYCMD_LISTTYPE( data->i ) );

             }

             if( ta_status.vertex_count != 0 ) {

                 /* Error, and not a very well handled one either */

                 ta_bad_input_error();

                 ta_status.accept_vertexes = FALSE;

             } else {

                 if( TA_IS_MODIFIER_LIST( ta_status.current_list_type ) ) {

                     ta_parse_modifier_context(data);

                 } else {

                     ta_parse_polygon_context(data);

                 }

             }

             break;

         case TA_CMD_SPRITE_CONTEXT:

             if( ta_status.state == STATE_IDLE ) {

                 ta_init_list( TA_POLYCMD_LISTTYPE( data->i ) );

             }

             if( ta_status.vertex_count != 0 ) {

                 ta_fill_vertexes();

                 ta_commit_polygon();

             }

             ta_parse_sprite_context(data);

             break;

         case TA_CMD_VERTEX:

             ta_status.state = STATE_IN_POLYGON;

             ta_parse_vertex(data);

             if( ta_status.state == STATE_EXPECT_VERTEX_BLOCK2 ) {

                 if( TA_IS_END_VERTEX(data[0].i) ) {

                     ta_status.state = STATE_EXPECT_END_VERTEX_BLOCK2;

                 }

             } else if( TA_IS_END_VERTEX(data->i) ) {

                 if( ta_status.vertex_count < 3 ) {

                     ta_bad_input_error();

                 } else {

                     ta_commit_polygon();

                 }

                 ta_status.vertex_count = 0;

                 ta_status.poly_parity = 0;

                 ta_status.state = STATE_IN_LIST;

             } else if( ta_status.vertex_count == ta_status.max_vertex ) {

                 ta_split_polygon();

             }

             break;

         default:

             if( ta_status.state == STATE_IN_POLYGON ) {

                 ta_bad_input_error();

             }

         }

         break;

     }

 }

 /**

  * Write a block of data to the tile accelerator, adding the data to the 

  * current scene. We don't make any particular attempt to interpret the data

  * at this stage, deferring that until render time.

  *

  * Currently copies the data verbatim to the vertex buffer, processing only

  * far enough to generate the correct end-of-list events. Tile buffer is

  * entirely ignored.

  */

 void pvr2_ta_write( unsigned char *buf, uint32_t length )

 {

     if( ta_status.debug_output ) {

         fwrite_dump32( (uint32_t *)buf, length, stderr );

     }

     for( ; length >=32; length -= 32 ) {

         pvr2_ta_process_block( buf );

         buf += 32;

     }

 }