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Harvey Harrisondd8b72c2009-01-06 14:56:29 -08001#ifndef _ALPHA_SWAB_H
2#define _ALPHA_SWAB_H
3
Jaswinder Singh Rajput3fd59062009-01-31 10:36:04 +05304#include <linux/types.h>
Harvey Harrisondd8b72c2009-01-06 14:56:29 -08005#include <linux/compiler.h>
6#include <asm/compiler.h>
7
8#ifdef __GNUC__
9
10static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
11{
12 /*
13 * Unfortunately, we can't use the 6 instruction sequence
14 * on ev6 since the latency of the UNPKBW is 3, which is
15 * pretty hard to hide. Just in case a future implementation
16 * has a lower latency, here's the sequence (also by Mike Burrows)
17 *
18 * UNPKBW a0, v0 v0: 00AA00BB00CC00DD
19 * SLL v0, 24, a0 a0: BB00CC00DD000000
20 * BIS v0, a0, a0 a0: BBAACCBBDDCC00DD
21 * EXTWL a0, 6, v0 v0: 000000000000BBAA
22 * ZAP a0, 0xf3, a0 a0: 00000000DDCC0000
23 * ADDL a0, v0, v0 v0: ssssssssDDCCBBAA
24 */
25
26 __u64 t0, t1, t2, t3;
27
28 t0 = __kernel_inslh(x, 7); /* t0 : 0000000000AABBCC */
29 t1 = __kernel_inswl(x, 3); /* t1 : 000000CCDD000000 */
30 t1 |= t0; /* t1 : 000000CCDDAABBCC */
31 t2 = t1 >> 16; /* t2 : 0000000000CCDDAA */
32 t0 = t1 & 0xFF00FF00; /* t0 : 00000000DD00BB00 */
33 t3 = t2 & 0x00FF00FF; /* t3 : 0000000000CC00AA */
34 t1 = t0 + t3; /* t1 : ssssssssDDCCBBAA */
35
36 return t1;
37}
38#define __arch_swab32 __arch_swab32
39
40#endif /* __GNUC__ */
41
42#endif /* _ALPHA_SWAB_H */