1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 #ifndef _ALPHA_SWAB_H
3 #define _ALPHA_SWAB_H
4
5 #include <linux/types.h>
6 #include <linux/compiler.h>
7 #include <asm/compiler.h>
8
9 #ifdef __GNUC__
10
11 static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
12 {
13 /*
14 * Unfortunately, we can't use the 6 instruction sequence
15 * on ev6 since the latency of the UNPKBW is 3, which is
16 * pretty hard to hide. Just in case a future implementation
17 * has a lower latency, here's the sequence (also by Mike Burrows)
18 *
19 * UNPKBW a0, v0 v0: 00AA00BB00CC00DD
20 * SLL v0, 24, a0 a0: BB00CC00DD000000
21 * BIS v0, a0, a0 a0: BBAACCBBDDCC00DD
22 * EXTWL a0, 6, v0 v0: 000000000000BBAA
23 * ZAP a0, 0xf3, a0 a0: 00000000DDCC0000
24 * ADDL a0, v0, v0 v0: ssssssssDDCCBBAA
25 */
26
27 __u64 t0, t1, t2, t3;
28
29 t0 = __kernel_inslh(x, 7); /* t0 : 0000000000AABBCC */
30 t1 = __kernel_inswl(x, 3); /* t1 : 000000CCDD000000 */
31 t1 |= t0; /* t1 : 000000CCDDAABBCC */
32 t2 = t1 >> 16; /* t2 : 0000000000CCDDAA */
33 t0 = t1 & 0xFF00FF00; /* t0 : 00000000DD00BB00 */
34 t3 = t2 & 0x00FF00FF; /* t3 : 0000000000CC00AA */
35 t1 = t0 + t3; /* t1 : ssssssssDDCCBBAA */
36
37 return t1;
38 }
39 #define __arch_swab32 __arch_swab32
40
41 #endif /* __GNUC__ */
42
43 #endif /* _ALPHA_SWAB_H */
44
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