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153 lines
2.6 KiB
153 lines
2.6 KiB
/* |
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* Fast C2P (Chunky-to-Planar) Conversion |
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* |
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* Copyright (C) 2003-2008 Geert Uytterhoeven |
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* |
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* NOTES: |
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* - This code was inspired by Scout's C2P tutorial |
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* - It assumes to run on a big endian system |
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* |
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* This file is subject to the terms and conditions of the GNU General Public |
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* License. See the file COPYING in the main directory of this archive |
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* for more details. |
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*/ |
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#include <linux/build_bug.h> |
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/* |
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* Basic transpose step |
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*/ |
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static inline void _transp(u32 d[], unsigned int i1, unsigned int i2, |
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unsigned int shift, u32 mask) |
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{ |
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u32 t = (d[i1] ^ (d[i2] >> shift)) & mask; |
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d[i1] ^= t; |
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d[i2] ^= t << shift; |
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} |
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static __always_inline u32 get_mask(unsigned int n) |
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{ |
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switch (n) { |
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case 1: |
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return 0x55555555; |
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case 2: |
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return 0x33333333; |
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case 4: |
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return 0x0f0f0f0f; |
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case 8: |
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return 0x00ff00ff; |
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case 16: |
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return 0x0000ffff; |
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} |
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BUILD_BUG(); |
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return 0; |
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} |
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/* |
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* Transpose operations on 8 32-bit words |
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*/ |
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static __always_inline void transp8(u32 d[], unsigned int n, unsigned int m) |
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{ |
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u32 mask = get_mask(n); |
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switch (m) { |
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case 1: |
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/* First n x 1 block */ |
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_transp(d, 0, 1, n, mask); |
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/* Second n x 1 block */ |
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_transp(d, 2, 3, n, mask); |
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/* Third n x 1 block */ |
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_transp(d, 4, 5, n, mask); |
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/* Fourth n x 1 block */ |
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_transp(d, 6, 7, n, mask); |
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return; |
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case 2: |
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/* First n x 2 block */ |
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_transp(d, 0, 2, n, mask); |
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_transp(d, 1, 3, n, mask); |
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/* Second n x 2 block */ |
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_transp(d, 4, 6, n, mask); |
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_transp(d, 5, 7, n, mask); |
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return; |
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case 4: |
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/* Single n x 4 block */ |
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_transp(d, 0, 4, n, mask); |
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_transp(d, 1, 5, n, mask); |
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_transp(d, 2, 6, n, mask); |
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_transp(d, 3, 7, n, mask); |
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return; |
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} |
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BUILD_BUG(); |
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} |
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/* |
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* Transpose operations on 4 32-bit words |
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*/ |
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static __always_inline void transp4(u32 d[], unsigned int n, unsigned int m) |
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{ |
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u32 mask = get_mask(n); |
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switch (m) { |
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case 1: |
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/* First n x 1 block */ |
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_transp(d, 0, 1, n, mask); |
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/* Second n x 1 block */ |
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_transp(d, 2, 3, n, mask); |
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return; |
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case 2: |
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/* Single n x 2 block */ |
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_transp(d, 0, 2, n, mask); |
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_transp(d, 1, 3, n, mask); |
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return; |
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} |
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BUILD_BUG(); |
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} |
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/* |
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* Transpose operations on 4 32-bit words (reverse order) |
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*/ |
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static __always_inline void transp4x(u32 d[], unsigned int n, unsigned int m) |
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{ |
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u32 mask = get_mask(n); |
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switch (m) { |
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case 2: |
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/* Single n x 2 block */ |
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_transp(d, 2, 0, n, mask); |
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_transp(d, 3, 1, n, mask); |
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return; |
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} |
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BUILD_BUG(); |
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} |
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/* |
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* Compose two values, using a bitmask as decision value |
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* This is equivalent to (a & mask) | (b & ~mask) |
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*/ |
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static inline u32 comp(u32 a, u32 b, u32 mask) |
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{ |
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return ((a ^ b) & mask) ^ b; |
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}
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