mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-23 12:14:10 +08:00
66a5c40f60
This patch creates wordpart.h and includes it in asm/word-at-a-time.h for all architectures. WORD_AT_A_TIME_CONSTANTS depends on kernel.h because of REPEAT_BYTE. Moving this to another header and including it where necessary allows us to not include the bloated kernel.h. Making this implicit dependency on REPEAT_BYTE explicit allows for later improvements in the lib/string.c inclusion list. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Tanzir Hasan <tanzirh@google.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Link: https://lore.kernel.org/r/20231226-libstringheader-v6-1-80aa08c7652c@google.com Signed-off-by: Kees Cook <keescook@chromium.org>
123 lines
2.8 KiB
C
123 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _ASM_WORD_AT_A_TIME_H
|
|
#define _ASM_WORD_AT_A_TIME_H
|
|
|
|
#include <linux/bitops.h>
|
|
#include <linux/wordpart.h>
|
|
#include <asm/byteorder.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 byte = 0;
|
|
#ifdef CONFIG_64BIT
|
|
if (mask >> 32)
|
|
mask >>= 32;
|
|
else
|
|
byte = 4;
|
|
#endif
|
|
if (mask >> 16)
|
|
mask >>= 16;
|
|
else
|
|
byte += 2;
|
|
return (mask >> 8) ? byte : byte + 1;
|
|
}
|
|
|
|
static inline unsigned long 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;
|
|
}
|
|
|
|
#ifndef zero_bytemask
|
|
#define zero_bytemask(mask) (~1ul << __fls(mask))
|
|
#endif
|
|
|
|
#else
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
struct word_at_a_time {
|
|
const unsigned long one_bits, high_bits;
|
|
};
|
|
|
|
#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
|
|
|
|
#ifdef CONFIG_64BIT
|
|
|
|
/*
|
|
* Jan Achrenius on G+: microoptimized version of
|
|
* the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
|
|
* that works for the bytemasks without having to
|
|
* mask them first.
|
|
*/
|
|
static inline long count_masked_bytes(unsigned long mask)
|
|
{
|
|
return mask*0x0001020304050608ul >> 56;
|
|
}
|
|
|
|
#else /* 32-bit case */
|
|
|
|
/* 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;
|
|
}
|
|
|
|
#endif
|
|
|
|
/* 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;
|
|
}
|
|
|
|
static inline unsigned long create_zero_mask(unsigned long bits)
|
|
{
|
|
bits = (bits - 1) & ~bits;
|
|
return bits >> 7;
|
|
}
|
|
|
|
/* The mask we created is directly usable as a bytemask */
|
|
#define zero_bytemask(mask) (mask)
|
|
|
|
static inline unsigned long find_zero(unsigned long mask)
|
|
{
|
|
return count_masked_bytes(mask);
|
|
}
|
|
|
|
#endif /* __BIG_ENDIAN */
|
|
|
|
#endif /* _ASM_WORD_AT_A_TIME_H */
|