mirror of https://gitee.com/openkylin/linux.git
43 lines
1.2 KiB
C
43 lines
1.2 KiB
C
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#ifndef _ALPHA_SWAB_H
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#define _ALPHA_SWAB_H
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#include <asm/types.h>
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#include <linux/compiler.h>
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#include <asm/compiler.h>
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#ifdef __GNUC__
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static inline __attribute_const__ __u32 __arch_swab32(__u32 x)
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{
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/*
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* Unfortunately, we can't use the 6 instruction sequence
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* on ev6 since the latency of the UNPKBW is 3, which is
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* pretty hard to hide. Just in case a future implementation
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* has a lower latency, here's the sequence (also by Mike Burrows)
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*
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* UNPKBW a0, v0 v0: 00AA00BB00CC00DD
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* SLL v0, 24, a0 a0: BB00CC00DD000000
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* BIS v0, a0, a0 a0: BBAACCBBDDCC00DD
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* EXTWL a0, 6, v0 v0: 000000000000BBAA
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* ZAP a0, 0xf3, a0 a0: 00000000DDCC0000
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* ADDL a0, v0, v0 v0: ssssssssDDCCBBAA
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*/
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__u64 t0, t1, t2, t3;
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t0 = __kernel_inslh(x, 7); /* t0 : 0000000000AABBCC */
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t1 = __kernel_inswl(x, 3); /* t1 : 000000CCDD000000 */
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t1 |= t0; /* t1 : 000000CCDDAABBCC */
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t2 = t1 >> 16; /* t2 : 0000000000CCDDAA */
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t0 = t1 & 0xFF00FF00; /* t0 : 00000000DD00BB00 */
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t3 = t2 & 0x00FF00FF; /* t3 : 0000000000CC00AA */
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t1 = t0 + t3; /* t1 : ssssssssDDCCBBAA */
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return t1;
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}
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#define __arch_swab32 __arch_swab32
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#endif /* __GNUC__ */
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#endif /* _ALPHA_SWAB_H */
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