/* * Fast C2P (Chunky-to-Planar) Conversion * * Copyright (C) 2003 Geert Uytterhoeven * * NOTES: * - This code was inspired by Scout's C2P tutorial * - It assumes to run on a big endian system * * This file is subject to the terms and conditions of the GNU General Public * License. See the file COPYING in the main directory of this archive * for more details. */ #include <linux/string.h> #include "c2p.h" /* * Basic transpose step */ #define _transp(d, i1, i2, shift, mask) \ do { \ u32 t = (d[i1] ^ (d[i2] >> shift)) & mask; \ d[i1] ^= t; \ d[i2] ^= t << shift; \ } while (0) static inline u32 get_mask(int n) { switch (n) { case 1: return 0x55555555; break; case 2: return 0x33333333; break; case 4: return 0x0f0f0f0f; break; case 8: return 0x00ff00ff; break; case 16: return 0x0000ffff; break; } return 0; } #define transp_nx1(d, n) \ do { \ u32 mask = get_mask(n); \ /* First block */ \ _transp(d, 0, 1, n, mask); \ /* Second block */ \ _transp(d, 2, 3, n, mask); \ /* Third block */ \ _transp(d, 4, 5, n, mask); \ /* Fourth block */ \ _transp(d, 6, 7, n, mask); \ } while (0) #define transp_nx2(d, n) \ do { \ u32 mask = get_mask(n); \ /* First block */ \ _transp(d, 0, 2, n, mask); \ _transp(d, 1, 3, n, mask); \ /* Second block */ \ _transp(d, 4, 6, n, mask); \ _transp(d, 5, 7, n, mask); \ } while (0) #define transp_nx4(d, n) \ do { \ u32 mask = get_mask(n); \ _transp(d, 0, 4, n, mask); \ _transp(d, 1, 5, n, mask); \ _transp(d, 2, 6, n, mask); \ _transp(d, 3, 7, n, mask); \ } while (0) #define transp(d, n, m) transp_nx ## m(d, n) /* * Perform a full C2P step on 32 8-bit pixels, stored in 8 32-bit words * containing * - 32 8-bit chunky pixels on input * - permuted planar data on output */ static void c2p_8bpp(u32 d[8]) { transp(d, 16, 4); transp(d, 8, 2); transp(d, 4, 1); transp(d, 2, 4); transp(d, 1, 2); } /* * Array containing the permution indices of the planar data after c2p */ static const int perm_c2p_8bpp[8] = { 7, 5, 3, 1, 6, 4, 2, 0 }; /* * Compose two values, using a bitmask as decision value * This is equivalent to (a & mask) | (b & ~mask) */ static inline unsigned long comp(unsigned long a, unsigned long b, unsigned long mask) { return ((a ^ b) & mask) ^ b; } /* * Store a full block of planar data after c2p conversion */ static inline void store_planar(char *dst, u32 dst_inc, u32 bpp, u32 d[8]) { int i; for (i = 0; i < bpp; i++, dst += dst_inc) *(u32 *)dst = d[perm_c2p_8bpp[i]]; } /* * Store a partial block of planar data after c2p conversion */ static inline void store_planar_masked(char *dst, u32 dst_inc, u32 bpp, u32 d[8], u32 mask) { int i; for (i = 0; i < bpp; i++, dst += dst_inc) *(u32 *)dst = comp(d[perm_c2p_8bpp[i]], *(u32 *)dst, mask); } /* * c2p - Copy 8-bit chunky image data to a planar frame buffer * @dst: Starting address of the planar frame buffer * @dx: Horizontal destination offset (in pixels) * @dy: Vertical destination offset (in pixels) * @width: Image width (in pixels) * @height: Image height (in pixels) * @dst_nextline: Frame buffer offset to the next line (in bytes) * @dst_nextplane: Frame buffer offset to the next plane (in bytes) * @src_nextline: Image offset to the next line (in bytes) * @bpp: Bits per pixel of the planar frame buffer (1-8) */ void c2p(u8 *dst, const u8 *src, u32 dx, u32 dy, u32 width, u32 height, u32 dst_nextline, u32 dst_nextplane, u32 src_nextline, u32 bpp) { int dst_idx; u32 d[8], first, last, w; const u8 *c; u8 *p; dst += dy*dst_nextline+(dx & ~31); dst_idx = dx % 32; first = ~0UL >> dst_idx; last = ~(~0UL >> ((dst_idx+width) % 32)); while (height--) { c = src; p = dst; w = width; if (dst_idx+width <= 32) { /* Single destination word */ first &= last; memset(d, 0, sizeof(d)); memcpy((u8 *)d+dst_idx, c, width); c += width; c2p_8bpp(d); store_planar_masked(p, dst_nextplane, bpp, d, first); p += 4; } else { /* Multiple destination words */ w = width; /* Leading bits */ if (dst_idx) { w = 32 - dst_idx; memset(d, 0, dst_idx); memcpy((u8 *)d+dst_idx, c, w); c += w; c2p_8bpp(d); store_planar_masked(p, dst_nextplane, bpp, d, first); p += 4; w = width-w; } /* Main chunk */ while (w >= 32) { memcpy(d, c, 32); c += 32; c2p_8bpp(d); store_planar(p, dst_nextplane, bpp, d); p += 4; w -= 32; } /* Trailing bits */ w %= 32; if (w > 0) { memcpy(d, c, w); memset((u8 *)d+w, 0, 32-w); c2p_8bpp(d); store_planar_masked(p, dst_nextplane, bpp, d, last); } } src += src_nextline; dst += dst_nextline; } }