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/*
* Fast C2P (Chunky-to-Planar) Conversion
*
* Copyright (C) 2003-2008 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/build_bug.h>
/*
* Basic transpose step
*/
static inline void _transp(u32 d[], unsigned int i1, unsigned int i2,
unsigned int shift, u32 mask)
{
u32 t = (d[i1] ^ (d[i2] >> shift)) & mask;
d[i1] ^= t;
d[i2] ^= t << shift;
}
static __always_inline u32 get_mask(unsigned int n)
{
switch (n) {
case 1:
return 0x55555555;
case 2:
return 0x33333333;
case 4:
return 0x0f0f0f0f;
case 8:
return 0x00ff00ff;
case 16:
return 0x0000ffff;
}
BUILD_BUG();
return 0;
}
/*
* Transpose operations on 8 32-bit words
*/
static __always_inline void transp8(u32 d[], unsigned int n, unsigned int m)
{
u32 mask = get_mask(n);
switch (m) {
case 1:
/* First n x 1 block */
_transp(d, 0, 1, n, mask);
/* Second n x 1 block */
_transp(d, 2, 3, n, mask);
/* Third n x 1 block */
_transp(d, 4, 5, n, mask);
/* Fourth n x 1 block */
_transp(d, 6, 7, n, mask);
return;
case 2:
/* First n x 2 block */
_transp(d, 0, 2, n, mask);
_transp(d, 1, 3, n, mask);
/* Second n x 2 block */
_transp(d, 4, 6, n, mask);
_transp(d, 5, 7, n, mask);
return;
case 4:
/* Single n x 4 block */
_transp(d, 0, 4, n, mask);
_transp(d, 1, 5, n, mask);
_transp(d, 2, 6, n, mask);
_transp(d, 3, 7, n, mask);
return;
}
BUILD_BUG();
}
/*
* Transpose operations on 4 32-bit words
*/
static __always_inline void transp4(u32 d[], unsigned int n, unsigned int m)
{
u32 mask = get_mask(n);
switch (m) {
case 1:
/* First n x 1 block */
_transp(d, 0, 1, n, mask);
/* Second n x 1 block */
_transp(d, 2, 3, n, mask);
return;
case 2:
/* Single n x 2 block */
_transp(d, 0, 2, n, mask);
_transp(d, 1, 3, n, mask);
return;
}
BUILD_BUG();
}
/*
* Transpose operations on 4 32-bit words (reverse order)
*/
static __always_inline void transp4x(u32 d[], unsigned int n, unsigned int m)
{
u32 mask = get_mask(n);
switch (m) {
case 2:
/* Single n x 2 block */
_transp(d, 2, 0, n, mask);
_transp(d, 3, 1, n, mask);
return;
}
BUILD_BUG();
}
/*
* Compose two values, using a bitmask as decision value
* This is equivalent to (a & mask) | (b & ~mask)
*/
static inline u32 comp(u32 a, u32 b, u32 mask)
{
return ((a ^ b) & mask) ^ b;
}