swizzle.c

   1 #include <caml/fail.h>
   2 #include <caml/alloc.h>
   3 #include <caml/memory.h>
   4
   5 /* Following is just a rehash of the code in here:
   6    http://playstation2-linux.com/download/p2lsd/sparkys_swizzle_code.html
   7 */
   8 static void unswizzle_32_to_8 (void *dst, unsigned char *src, void *pal, int w, int h)
   9 {
  10     int x, y;
  11     int width = w;
  12     int height = h;
  13     uint32 *rgba = dst;
  14     uint32 *palD = pal;
  15
  16     for (y = 0; y < height; ++y) {
  17         for (x = 0; x < w; ++x ) {
  18             int block_location = (y&(~0xf))*width + (x&(~0xf))*2;
  19             int swap_selector = (((y+2)>>2)&0x1)*4;
  20             int posY = (((y&(~3))>>1) + (y&1))&0x7;
  21             int column_location = posY*width*2 + ((x+swap_selector)&0x7)*4;
  22             int byte_num = ((y>>1)&1) + ((x>>2)&2);
  23             *rgba++ = palD[src[block_location + column_location + byte_num]];
  24         }
  25     }
  26 }
  27
  28 static void unswizzle_32_to_4 (void *dst, unsigned char *src, void *pal, int w, int h)
  29 {
  30     int x, y;
  31     int width = w;
  32     int height = h;
  33     uint32 *rgba = dst;
  34     uint32 *palD = pal;
  35
  36     for (y=0; y<height; y++) {
  37         for (x=0; x<width; x++) {
  38             int pageX = x & (~0x7f);
  39             int pageY = y & (~0x7f);
  40
  41             int pages_horz = (width+127)/128;
  42             int pages_vert = (height+127)/128;
  43
  44             int page_number = (pageY/128)*pages_horz + (pageX/128);
  45
  46             int page32Y = (page_number/pages_vert)*32;
  47             int page32X = (page_number%pages_vert)*64;
  48
  49             int page_location = page32Y*height*2 + page32X*4;
  50
  51             int locX = x & 0x7f;
  52             int locY = y & 0x7f;
  53
  54             int block_location = ((locX&(~0x1f))>>1)*height + (locY&(~0xf))*2;
  55             int swap_selector = (((y+2)>>2)&0x1)*4;
  56             int posY = (((y&(~3))>>1) + (y&1))&0x7;
  57
  58             int column_location = posY*height*2 + ((x+swap_selector)&0x7)*4;
  59
  60             int byte_num = (x>>3)&3; /* 0,1,2,3 */
  61             int bits_set = (y>>1)&1; /* 0,1            (lower/upper 4 bits) */
  62
  63             unsigned char v =
  64                 src[page_location + block_location + column_location + byte_num];
  65
  66             /* bits_set = !bits_set; */
  67             v = (v >> (bits_set * 4)) & 0x0f;
  68             *rgba++ = palD[v];
  69         }
  70     }
  71 }
  72
  73 CAMLprim value ml_to_rgba (value data_v, value positions_v,
  74                            value dim_v, value type_v)
  75 {
  76     CAMLparam4 (data_v, positions_v, dim_v, type_v);
  77     CAMLlocal1 (rgba_v);
  78     uint32 *rgba;
  79     char *data = String_val (data_v);
  80     int pix_pos = Int_val (Field (positions_v, 0));
  81     int pal_pos = Int_val (Field (positions_v, 1));
  82     int w = Int_val (Field (dim_v, 0));
  83     int h = Int_val (Field (dim_v, 1));
  84     int size = w * h;
  85     int i;
  86     uint32 *pal = (uint32 *) (data + pal_pos);
  87     unsigned char *pix = (unsigned char *) (data + pix_pos);
  88
  89     rgba_v = caml_alloc_string (size << 2);
  90     rgba = (uint32 *) String_val (rgba_v);
  91
  92     switch (Int_val (type_v)) {
  93         case 0:
  94             for (i = 0; i < size; ++i)
  95                 rgba[i] = pal[pix[i]];
  96             break;
  97
  98         case 1:
  99             for (i = 0; i < (size >> 1); ++i) {
 100                 unsigned char v = pix[i];
 101                 rgba[i*2] = pal[v >> 4];
 102                 rgba[i*2+1] = pal[v & 0x0f];
 103             }
 104             break;
 105
 106         case 2:
 107             unswizzle_32_to_8 (rgba, pix, pal, w, h);
 108             break;
 109
 110         case 3:
 111             unswizzle_32_to_4 (rgba, pix, pal, w, h);
 112             break;
 113     }
 114
 115     CAMLreturn (rgba_v);
 116 }