diff options
Diffstat (limited to 'kernel/arch/alpha/include/uapi/asm/swab.h')
| -rw-r--r-- | kernel/arch/alpha/include/uapi/asm/swab.h | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/kernel/arch/alpha/include/uapi/asm/swab.h b/kernel/arch/alpha/include/uapi/asm/swab.h new file mode 100644 index 000000000..4d682b16c --- /dev/null +++ b/kernel/arch/alpha/include/uapi/asm/swab.h @@ -0,0 +1,42 @@ +#ifndef _ALPHA_SWAB_H +#define _ALPHA_SWAB_H + +#include <linux/types.h> +#include <linux/compiler.h> +#include <asm/compiler.h> + +#ifdef __GNUC__ + +static inline __attribute_const__ __u32 __arch_swab32(__u32 x) +{ + /* + * Unfortunately, we can't use the 6 instruction sequence + * on ev6 since the latency of the UNPKBW is 3, which is + * pretty hard to hide. Just in case a future implementation + * has a lower latency, here's the sequence (also by Mike Burrows) + * + * UNPKBW a0, v0 v0: 00AA00BB00CC00DD + * SLL v0, 24, a0 a0: BB00CC00DD000000 + * BIS v0, a0, a0 a0: BBAACCBBDDCC00DD + * EXTWL a0, 6, v0 v0: 000000000000BBAA + * ZAP a0, 0xf3, a0 a0: 00000000DDCC0000 + * ADDL a0, v0, v0 v0: ssssssssDDCCBBAA + */ + + __u64 t0, t1, t2, t3; + + t0 = __kernel_inslh(x, 7); /* t0 : 0000000000AABBCC */ + t1 = __kernel_inswl(x, 3); /* t1 : 000000CCDD000000 */ + t1 |= t0; /* t1 : 000000CCDDAABBCC */ + t2 = t1 >> 16; /* t2 : 0000000000CCDDAA */ + t0 = t1 & 0xFF00FF00; /* t0 : 00000000DD00BB00 */ + t3 = t2 & 0x00FF00FF; /* t3 : 0000000000CC00AA */ + t1 = t0 + t3; /* t1 : ssssssssDDCCBBAA */ + + return t1; +} +#define __arch_swab32 __arch_swab32 + +#endif /* __GNUC__ */ + +#endif /* _ALPHA_SWAB_H */ |