xref: /openbmc/linux/arch/alpha/include/uapi/asm/swab.h (revision 275876e2)
1 #ifndef _ALPHA_SWAB_H
2 #define _ALPHA_SWAB_H
3 
4 #include <linux/types.h>
5 #include <linux/compiler.h>
6 #include <asm/compiler.h>
7 
8 #ifdef __GNUC__
9 
10 static 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 */
43