154 lines
2.6 KiB
C
154 lines
2.6 KiB
C
/*
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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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