mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-26 06:04:14 +08:00
11ec50caed
Whilst architectures may be able to do better than this (which they can, by simply defining their own macro), this is a generic stab at a zero_bytemask implementation for the asm-generic, big-endian word-at-a-time implementation. On arm64, a clz instruction is used to implement the fls efficiently. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
61 lines
1.4 KiB
C
61 lines
1.4 KiB
C
#ifndef _ASM_WORD_AT_A_TIME_H
|
|
#define _ASM_WORD_AT_A_TIME_H
|
|
|
|
/*
|
|
* This says "generic", but it's actually big-endian only.
|
|
* Little-endian can use more efficient versions of these
|
|
* interfaces, see for example
|
|
* arch/x86/include/asm/word-at-a-time.h
|
|
* for those.
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
|
|
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 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;
|
|
}
|
|
|
|
#ifndef zero_bytemask
|
|
#ifdef CONFIG_64BIT
|
|
#define zero_bytemask(mask) (~0ul << fls64(mask))
|
|
#else
|
|
#define zero_bytemask(mask) (~0ul << fls(mask))
|
|
#endif /* CONFIG_64BIT */
|
|
#endif /* zero_bytemask */
|
|
|
|
#endif /* _ASM_WORD_AT_A_TIME_H */
|