mirror of
https://github.com/torvalds/linux.git
synced 2024-12-30 06:41:43 +00:00
8989aa4ada
Use cmpb which compares each byte in two 64 bit values and for each matching byte places 0xff in the target and 0x00 otherwise. A simple hash_name microbenchmark: http://ozlabs.org/~anton/junkcode/hash_name_bench.c shows this version to be 10-20% faster than running the x86 version on POWER8, depending on the length. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
204 lines
4.7 KiB
C
204 lines
4.7 KiB
C
#ifndef _ASM_WORD_AT_A_TIME_H
|
|
#define _ASM_WORD_AT_A_TIME_H
|
|
|
|
/*
|
|
* Word-at-a-time interfaces for PowerPC.
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <asm/asm-compat.h>
|
|
|
|
#ifdef __BIG_ENDIAN__
|
|
|
|
struct word_at_a_time {
|
|
const unsigned long high_bits, low_bits;
|
|
};
|
|
|
|
#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0xfe) + 1, REPEAT_BYTE(0x7f) }
|
|
|
|
/* Bit set in the bytes that have a zero */
|
|
static inline long prep_zero_mask(unsigned long val, unsigned long rhs, const struct word_at_a_time *c)
|
|
{
|
|
unsigned long mask = (val & c->low_bits) + c->low_bits;
|
|
return ~(mask | rhs);
|
|
}
|
|
|
|
#define create_zero_mask(mask) (mask)
|
|
|
|
static inline long find_zero(unsigned long mask)
|
|
{
|
|
long leading_zero_bits;
|
|
|
|
asm (PPC_CNTLZL "%0,%1" : "=r" (leading_zero_bits) : "r" (mask));
|
|
return leading_zero_bits >> 3;
|
|
}
|
|
|
|
static inline bool has_zero(unsigned long val, unsigned long *data, const struct word_at_a_time *c)
|
|
{
|
|
unsigned long rhs = val | c->low_bits;
|
|
*data = rhs;
|
|
return (val + c->high_bits) & ~rhs;
|
|
}
|
|
|
|
#else
|
|
|
|
#ifdef CONFIG_64BIT
|
|
|
|
/* unused */
|
|
struct word_at_a_time {
|
|
};
|
|
|
|
#define WORD_AT_A_TIME_CONSTANTS { }
|
|
|
|
/* This will give us 0xff for a NULL char and 0x00 elsewhere */
|
|
static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c)
|
|
{
|
|
unsigned long ret;
|
|
unsigned long zero = 0;
|
|
|
|
asm("cmpb %0,%1,%2" : "=r" (ret) : "r" (a), "r" (zero));
|
|
*bits = ret;
|
|
|
|
return ret;
|
|
}
|
|
|
|
static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)
|
|
{
|
|
return bits;
|
|
}
|
|
|
|
/* Alan Modra's little-endian strlen tail for 64-bit */
|
|
static inline unsigned long create_zero_mask(unsigned long bits)
|
|
{
|
|
unsigned long leading_zero_bits;
|
|
long trailing_zero_bit_mask;
|
|
|
|
asm("addi %1,%2,-1\n\t"
|
|
"andc %1,%1,%2\n\t"
|
|
"popcntd %0,%1"
|
|
: "=r" (leading_zero_bits), "=&r" (trailing_zero_bit_mask)
|
|
: "r" (bits));
|
|
|
|
return leading_zero_bits;
|
|
}
|
|
|
|
static inline unsigned long find_zero(unsigned long mask)
|
|
{
|
|
return mask >> 3;
|
|
}
|
|
|
|
/* This assumes that we never ask for an all 1s bitmask */
|
|
static inline unsigned long zero_bytemask(unsigned long mask)
|
|
{
|
|
return (1UL << mask) - 1;
|
|
}
|
|
|
|
#else /* 32-bit case */
|
|
|
|
struct word_at_a_time {
|
|
const unsigned long one_bits, high_bits;
|
|
};
|
|
|
|
#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
|
|
|
|
/*
|
|
* This is largely generic for little-endian machines, but the
|
|
* optimal byte mask counting is probably going to be something
|
|
* that is architecture-specific. If you have a reliably fast
|
|
* bit count instruction, that might be better than the multiply
|
|
* and shift, for example.
|
|
*/
|
|
|
|
/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
|
|
static inline long count_masked_bytes(long mask)
|
|
{
|
|
/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
|
|
long a = (0x0ff0001+mask) >> 23;
|
|
/* Fix the 1 for 00 case */
|
|
return a & mask;
|
|
}
|
|
|
|
static inline unsigned long create_zero_mask(unsigned long bits)
|
|
{
|
|
bits = (bits - 1) & ~bits;
|
|
return bits >> 7;
|
|
}
|
|
|
|
static inline unsigned long find_zero(unsigned long mask)
|
|
{
|
|
return count_masked_bytes(mask);
|
|
}
|
|
|
|
/* Return nonzero if it has a zero */
|
|
static inline unsigned long has_zero(unsigned long a, unsigned long *bits, const struct word_at_a_time *c)
|
|
{
|
|
unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
|
|
*bits = mask;
|
|
return mask;
|
|
}
|
|
|
|
static inline unsigned long prep_zero_mask(unsigned long a, unsigned long bits, const struct word_at_a_time *c)
|
|
{
|
|
return bits;
|
|
}
|
|
|
|
/* The mask we created is directly usable as a bytemask */
|
|
#define zero_bytemask(mask) (mask)
|
|
|
|
#endif /* CONFIG_64BIT */
|
|
|
|
#endif /* __BIG_ENDIAN__ */
|
|
|
|
/*
|
|
* We use load_unaligned_zero() in a selftest, which builds a userspace
|
|
* program. Some linker scripts seem to discard the .fixup section, so allow
|
|
* the test code to use a different section name.
|
|
*/
|
|
#ifndef FIXUP_SECTION
|
|
#define FIXUP_SECTION ".fixup"
|
|
#endif
|
|
|
|
static inline unsigned long load_unaligned_zeropad(const void *addr)
|
|
{
|
|
unsigned long ret, offset, tmp;
|
|
|
|
asm(
|
|
"1: " PPC_LL "%[ret], 0(%[addr])\n"
|
|
"2:\n"
|
|
".section " FIXUP_SECTION ",\"ax\"\n"
|
|
"3: "
|
|
#ifdef __powerpc64__
|
|
"clrrdi %[tmp], %[addr], 3\n\t"
|
|
"clrlsldi %[offset], %[addr], 61, 3\n\t"
|
|
"ld %[ret], 0(%[tmp])\n\t"
|
|
#ifdef __BIG_ENDIAN__
|
|
"sld %[ret], %[ret], %[offset]\n\t"
|
|
#else
|
|
"srd %[ret], %[ret], %[offset]\n\t"
|
|
#endif
|
|
#else
|
|
"clrrwi %[tmp], %[addr], 2\n\t"
|
|
"clrlslwi %[offset], %[addr], 30, 3\n\t"
|
|
"lwz %[ret], 0(%[tmp])\n\t"
|
|
#ifdef __BIG_ENDIAN__
|
|
"slw %[ret], %[ret], %[offset]\n\t"
|
|
#else
|
|
"srw %[ret], %[ret], %[offset]\n\t"
|
|
#endif
|
|
#endif
|
|
"b 2b\n"
|
|
".previous\n"
|
|
".section __ex_table,\"a\"\n\t"
|
|
PPC_LONG_ALIGN "\n\t"
|
|
PPC_LONG "1b,3b\n"
|
|
".previous"
|
|
: [tmp] "=&b" (tmp), [offset] "=&r" (offset), [ret] "=&r" (ret)
|
|
: [addr] "b" (addr), "m" (*(unsigned long *)addr));
|
|
|
|
return ret;
|
|
}
|
|
|
|
#undef FIXUP_SECTION
|
|
|
|
#endif /* _ASM_WORD_AT_A_TIME_H */
|