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1/*2 * Fast C2P (Chunky-to-Planar) Conversion3 *4 * Copyright (C) 2003-2008 Geert Uytterhoeven5 *6 * NOTES:7 * - This code was inspired by Scout's C2P tutorial8 * - It assumes to run on a big endian system9 *10 * This file is subject to the terms and conditions of the GNU General Public11 * License. See the file COPYING in the main directory of this archive12 * for more details.13 */14 15#include <linux/build_bug.h>16 17 18 /*19 * Basic transpose step20 */21 22static inline void _transp(u32 d[], unsigned int i1, unsigned int i2,23 unsigned int shift, u32 mask)24{25 u32 t = (d[i1] ^ (d[i2] >> shift)) & mask;26 27 d[i1] ^= t;28 d[i2] ^= t << shift;29}30 31 32static __always_inline u32 get_mask(unsigned int n)33{34 switch (n) {35 case 1:36 return 0x55555555;37 38 case 2:39 return 0x33333333;40 41 case 4:42 return 0x0f0f0f0f;43 44 case 8:45 return 0x00ff00ff;46 47 case 16:48 return 0x0000ffff;49 }50 51 BUILD_BUG();52 return 0;53}54 55 56 /*57 * Transpose operations on 8 32-bit words58 */59 60static __always_inline void transp8(u32 d[], unsigned int n, unsigned int m)61{62 u32 mask = get_mask(n);63 64 switch (m) {65 case 1:66 /* First n x 1 block */67 _transp(d, 0, 1, n, mask);68 /* Second n x 1 block */69 _transp(d, 2, 3, n, mask);70 /* Third n x 1 block */71 _transp(d, 4, 5, n, mask);72 /* Fourth n x 1 block */73 _transp(d, 6, 7, n, mask);74 return;75 76 case 2:77 /* First n x 2 block */78 _transp(d, 0, 2, n, mask);79 _transp(d, 1, 3, n, mask);80 /* Second n x 2 block */81 _transp(d, 4, 6, n, mask);82 _transp(d, 5, 7, n, mask);83 return;84 85 case 4:86 /* Single n x 4 block */87 _transp(d, 0, 4, n, mask);88 _transp(d, 1, 5, n, mask);89 _transp(d, 2, 6, n, mask);90 _transp(d, 3, 7, n, mask);91 return;92 }93 94 BUILD_BUG();95}96 97 98 /*99 * Transpose operations on 4 32-bit words100 */101 102static __always_inline void transp4(u32 d[], unsigned int n, unsigned int m)103{104 u32 mask = get_mask(n);105 106 switch (m) {107 case 1:108 /* First n x 1 block */109 _transp(d, 0, 1, n, mask);110 /* Second n x 1 block */111 _transp(d, 2, 3, n, mask);112 return;113 114 case 2:115 /* Single n x 2 block */116 _transp(d, 0, 2, n, mask);117 _transp(d, 1, 3, n, mask);118 return;119 }120 121 BUILD_BUG();122}123 124 125 /*126 * Transpose operations on 4 32-bit words (reverse order)127 */128 129static __always_inline void transp4x(u32 d[], unsigned int n, unsigned int m)130{131 u32 mask = get_mask(n);132 133 switch (m) {134 case 2:135 /* Single n x 2 block */136 _transp(d, 2, 0, n, mask);137 _transp(d, 3, 1, n, mask);138 return;139 }140 141 BUILD_BUG();142}143 144 145 /*146 * Compose two values, using a bitmask as decision value147 * This is equivalent to (a & mask) | (b & ~mask)148 */149 150static inline u32 comp(u32 a, u32 b, u32 mask)151{152 return ((a ^ b) & mask) ^ b;153}154