NetBSD/sys/lib/libkern/arch/mips/memset.S

50 lines
1.1 KiB
ArmAsm

/* $NetBSD: memset.S,v 1.2 1999/03/15 06:34:10 jonathan Exp $ */
#include <machine/cdefs.h>
#include <mips/asm.h>
#include <machine/endian.h>
.set noreorder
/*
* memset(void *s1, int c, int len)
*/
LEAF(memset)
.set noreorder
blt a2, 12, smallclr # small amount to clear?
move v0, a0 # save s1 for result
sll t1, a1, 8 # compute c << 8 in t1
or t1, t1, a1 # compute c << 8 | c in 11
sll t2, t1, 16 # shift that left 16
or t1, t2, t1 # or together
subu t0, zero, a0 # compute # bytes to word align address
and t0, t0, 3
beq t0, zero, 1f # skip if word aligned
subu a2, a2, t0 # subtract from remaining count
SWHI t1, 0(a0) # store 1, 2, or 3 bytes to align
addu a0, a0, t0
1:
and v1, a2, 3 # compute number of whole words left
subu t0, a2, v1
subu a2, a2, t0
addu t0, t0, a0 # compute ending address
2:
addu a0, a0, 4 # clear words
bne a0, t0, 2b # unrolling loop does not help
sw t1, -4(a0) # since we are limited by memory speed
smallclr:
ble a2, zero, 2f
addu t0, a2, a0 # compute ending address
1:
addu a0, a0, 1 # clear bytes
bne a0, t0, 1b
sb a1, -1(a0)
2:
j ra
nop
.set reorder
END(memset)