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Fix bug in construction of word-length version of 'c'.

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Preserve input string and return it as per userlevel spec.
This commit is contained in:
jonathan 1999-03-15 06:34:10 +00:00
parent 1990f5b094
commit e22fd3b59d
1 changed files with 14 additions and 8 deletions
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22
sys/lib/libkern/arch/mips/memset.S
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@ -1,4 +1,4 @@
/* $NetBSD: memset.S,v 1.1 1999/01/28 03:08:57 jonathan Exp $ */ /* $NetBSD: memset.S,v 1.2 1999/03/15 06:34:10 jonathan Exp $ */
#include <machine/cdefs.h> #include <machine/cdefs.h>
#include <mips/asm.h> #include <mips/asm.h>
#include <machine/endian.h> #include <machine/endian.h>
@ -10,11 +10,15 @@
* memset(void *s1, int c, int len) * memset(void *s1, int c, int len)
*/ */
LEAF(memset) LEAF(memset)
.set noreorder
blt a2, 12, smallclr # small amount to clear? blt a2, 12, smallclr # small amount to clear?
sll t1, a1, 8 move v0, a0 # save s1 for result
or t1, t1, a1
sll t1, a1, 16 sll t1, a1, 8 # compute c << 8 in t1
or t1, t1, a1 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 subu t0, zero, a0 # compute # bytes to word align address
and t0, t0, 3 and t0, t0, 3
beq t0, zero, 1f # skip if word aligned beq t0, zero, 1f # skip if word aligned
@ -22,14 +26,15 @@ LEAF(memset)
SWHI t1, 0(a0) # store 1, 2, or 3 bytes to align SWHI t1, 0(a0) # store 1, 2, or 3 bytes to align
addu a0, a0, t0 addu a0, a0, t0
1: 1:
and v0, a2, 3 # compute number of words left and v1, a2, 3 # compute number of whole words left
subu t0, a2, v0 subu t0, a2, v1
move a2, v0 subu a2, a2, t0
addu t0, t0, a0 # compute ending address addu t0, t0, a0 # compute ending address
2: 2:
addu a0, a0, 4 # clear words addu a0, a0, 4 # clear words
bne a0, t0, 2b # unrolling loop does not help bne a0, t0, 2b # unrolling loop does not help
sw t1, -4(a0) # since we are limited by memory speed sw t1, -4(a0) # since we are limited by memory speed
smallclr: smallclr:
ble a2, zero, 2f ble a2, zero, 2f
addu t0, a2, a0 # compute ending address addu t0, a2, a0 # compute ending address
@ -40,4 +45,5 @@ smallclr:
2: 2:
j ra j ra
nop nop
.set reorder
END(memset) END(memset)