drivers/video/c2p.c

   1 /*
   2  *  Fast C2P (Chunky-to-Planar) Conversion
   3  *
   4  *  Copyright (C) 2003 Geert Uytterhoeven
   5  *
   6  *  NOTES:
   7  *    - This code was inspired by Scout's C2P tutorial
   8  *    - It assumes to run on a big endian system
   9  *
  10  *  This file is subject to the terms and conditions of the GNU General Public
  11  *  License. See the file COPYING in the main directory of this archive
  12  *  for more details.
  13  */
  14
  15 #include <linux/string.h>
  16 #include "c2p.h"
  17
  18
  19     /*
  20      *  Basic transpose step
  21      */
  22
  23 #define _transp(d, i1, i2, shift, mask)                 \
  24     do {                                                \
  25         u32 t = (d[i1] ^ (d[i2] >> shift)) & mask;      \
  26         d[i1] ^= t;                                     \
  27         d[i2] ^= t << shift;                            \
  28     } while (0)
  29
  30 static inline u32 get_mask(int n)
  31 {
  32     switch (n) {
  33         case 1:
  34             return 0x55555555;
  35             break;
  36
  37         case 2:
  38             return 0x33333333;
  39             break;
  40
  41         case 4:
  42             return 0x0f0f0f0f;
  43             break;
  44
  45         case 8:
  46             return 0x00ff00ff;
  47             break;
  48
  49         case 16:
  50             return 0x0000ffff;
  51             break;
  52     }
  53     return 0;
  54 }
  55
  56 #define transp_nx1(d, n)                                \
  57     do {                                                \
  58         u32 mask = get_mask(n);                         \
  59         /* First block */                               \
  60         _transp(d, 0, 1, n, mask);                      \
  61         /* Second block */                              \
  62         _transp(d, 2, 3, n, mask);                      \
  63         /* Third block */                               \
  64         _transp(d, 4, 5, n, mask);                      \
  65         /* Fourth block */                              \
  66         _transp(d, 6, 7, n, mask);                      \
  67     } while (0)
  68
  69 #define transp_nx2(d, n)                                \
  70     do {                                                \
  71         u32 mask = get_mask(n);                         \
  72         /* First block */                               \
  73         _transp(d, 0, 2, n, mask);                      \
  74         _transp(d, 1, 3, n, mask);                      \
  75         /* Second block */                              \
  76         _transp(d, 4, 6, n, mask);                      \
  77         _transp(d, 5, 7, n, mask);                      \
  78     } while (0)
  79
  80 #define transp_nx4(d, n)                                \
  81     do {                                                \
  82         u32 mask = get_mask(n);                         \
  83         _transp(d, 0, 4, n, mask);                      \
  84         _transp(d, 1, 5, n, mask);                      \
  85         _transp(d, 2, 6, n, mask);                      \
  86         _transp(d, 3, 7, n, mask);                      \
  87     } while (0)
  88
  89 #define transp(d, n, m) transp_nx ## m(d, n)
  90
  91
  92     /*
  93      *  Perform a full C2P step on 32 8-bit pixels, stored in 8 32-bit words
  94      *  containing
  95      *    - 32 8-bit chunky pixels on input
  96      *    - permuted planar data on output
  97      */
  98
  99 static void c2p_8bpp(u32 d[8])
 100 {
 101     transp(d, 16, 4);
 102     transp(d, 8, 2);
 103     transp(d, 4, 1);
 104     transp(d, 2, 4);
 105     transp(d, 1, 2);
 106 }
 107
 108
 109     /*
 110      *  Array containing the permution indices of the planar data after c2p
 111      */
 112
 113 static const int perm_c2p_8bpp[8] = { 7, 5, 3, 1, 6, 4, 2, 0 };
 114
 115
 116     /*
 117      *  Compose two values, using a bitmask as decision value
 118      *  This is equivalent to (a & mask) | (b & ~mask)
 119      */
 120
 121 static inline unsigned long comp(unsigned long a, unsigned long b,
 122                                  unsigned long mask)
 123 {
 124         return ((a ^ b) & mask) ^ b;
 125 }
 126
 127
 128     /*
 129      *  Store a full block of planar data after c2p conversion
 130      */
 131
 132 static inline void store_planar(char *dst, u32 dst_inc, u32 bpp, u32 d[8])
 133 {
 134     int i;
 135
 136     for (i = 0; i < bpp; i++, dst += dst_inc)
 137         *(u32 *)dst = d[perm_c2p_8bpp[i]];
 138 }
 139
 140
 141     /*
 142      *  Store a partial block of planar data after c2p conversion
 143      */
 144
 145 static inline void store_planar_masked(char *dst, u32 dst_inc, u32 bpp,
 146                                        u32 d[8], u32 mask)
 147 {
 148     int i;
 149
 150     for (i = 0; i < bpp; i++, dst += dst_inc)
 151         *(u32 *)dst = comp(d[perm_c2p_8bpp[i]], *(u32 *)dst, mask);
 152 }
 153
 154
 155     /*
 156      *  c2p - Copy 8-bit chunky image data to a planar frame buffer
 157      *  @dst: Starting address of the planar frame buffer
 158      *  @dx: Horizontal destination offset (in pixels)
 159      *  @dy: Vertical destination offset (in pixels)
 160      *  @width: Image width (in pixels)
 161      *  @height: Image height (in pixels)
 162      *  @dst_nextline: Frame buffer offset to the next line (in bytes)
 163      *  @dst_nextplane: Frame buffer offset to the next plane (in bytes)
 164      *  @src_nextline: Image offset to the next line (in bytes)
 165      *  @bpp: Bits per pixel of the planar frame buffer (1-8)
 166      */
 167
 168 void c2p(u8 *dst, const u8 *src, u32 dx, u32 dy, u32 width, u32 height,
 169          u32 dst_nextline, u32 dst_nextplane, u32 src_nextline, u32 bpp)
 170 {
 171     int dst_idx;
 172     u32 d[8], first, last, w;
 173     const u8 *c;
 174     u8 *p;
 175
 176     dst += dy*dst_nextline+(dx & ~31);
 177     dst_idx = dx % 32;
 178     first = ~0UL >> dst_idx;
 179     last = ~(~0UL >> ((dst_idx+width) % 32));
 180     while (height--) {
 181         c = src;
 182         p = dst;
 183         w = width;
 184         if (dst_idx+width <= 32) {
 185             /* Single destination word */
 186             first &= last;
 187             memset(d, 0, sizeof(d));
 188             memcpy((u8 *)d+dst_idx, c, width);
 189             c += width;
 190             c2p_8bpp(d);
 191             store_planar_masked(p, dst_nextplane, bpp, d, first);
 192             p += 4;
 193         } else {
 194             /* Multiple destination words */
 195             w = width;
 196             /* Leading bits */
 197             if (dst_idx) {
 198                 w = 32 - dst_idx;
 199                 memset(d, 0, dst_idx);
 200                 memcpy((u8 *)d+dst_idx, c, w);
 201                 c += w;
 202                 c2p_8bpp(d);
 203                 store_planar_masked(p, dst_nextplane, bpp, d, first);
 204                 p += 4;
 205                 w = width-w;
 206             }
 207             /* Main chunk */
 208             while (w >= 32) {
 209                 memcpy(d, c, 32);
 210                 c += 32;
 211                 c2p_8bpp(d);
 212                 store_planar(p, dst_nextplane, bpp, d);
 213                 p += 4;
 214                 w -= 32;
 215             }
 216             /* Trailing bits */
 217             w %= 32;
 218             if (w > 0) {
 219                 memcpy(d, c, w);
 220                 memset((u8 *)d+w, 0, 32-w);
 221                 c2p_8bpp(d);
 222                 store_planar_masked(p, dst_nextplane, bpp, d, last);
 223             }
 224         }
 225         src += src_nextline;
 226         dst += dst_nextline;
 227     }
 228 }
 229