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/* $Id: memscan.S,v 1.4 1996/09/08 02:01:20 davem Exp $
* memscan.S: Optimized memscan for the Sparc.
*
* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
*/
/* In essence, this is just a fancy strlen. */
#define LO_MAGIC 0x01010101
#define HI_MAGIC 0x80808080
.text
.align 4
.globl __memscan_zero, __memscan_generic
.globl memscan
__memscan_zero:
/* %o0 = addr, %o1 = size */
cmp %o1, 0
bne,a 1f
andcc %o0, 3, %g0
retl
nop
1:
be mzero_scan_word
sethi %hi(HI_MAGIC), %g2
ldsb [%o0], %g3
mzero_still_not_word_aligned:
cmp %g3, 0
bne 1f
add %o0, 1, %o0
retl
sub %o0, 1, %o0
1:
subcc %o1, 1, %o1
bne,a 1f
andcc %o0, 3, %g0
retl
nop
1:
bne,a mzero_still_not_word_aligned
ldsb [%o0], %g3
sethi %hi(HI_MAGIC), %g2
mzero_scan_word:
or %g2, %lo(HI_MAGIC), %o3
sethi %hi(LO_MAGIC), %g3
or %g3, %lo(LO_MAGIC), %o2
mzero_next_word:
ld [%o0], %g2
mzero_next_word_preloaded:
sub %g2, %o2, %g2
mzero_next_word_preloaded_next:
andcc %g2, %o3, %g0
bne mzero_byte_zero
add %o0, 4, %o0
mzero_check_out_of_fuel:
subcc %o1, 4, %o1
bg,a 1f
ld [%o0], %g2
retl
nop
1:
b mzero_next_word_preloaded_next
sub %g2, %o2, %g2
/* Check every byte. */
mzero_byte_zero:
ldsb [%o0 - 4], %g2
cmp %g2, 0
bne mzero_byte_one
sub %o0, 4, %g3
retl
mov %g3, %o0
mzero_byte_one:
ldsb [%o0 - 3], %g2
cmp %g2, 0
bne,a mzero_byte_two_and_three
ldsb [%o0 - 2], %g2
retl
sub %o0, 3, %o0
mzero_byte_two_and_three:
cmp %g2, 0
bne,a 1f
ldsb [%o0 - 1], %g2
retl
sub %o0, 2, %o0
1:
cmp %g2, 0
bne,a mzero_next_word_preloaded
ld [%o0], %g2
retl
sub %o0, 1, %o0
mzero_found_it:
retl
sub %o0, 2, %o0
memscan:
__memscan_generic:
/* %o0 = addr, %o1 = c, %o2 = size */
cmp %o2, 0
bne,a 0f
ldub [%o0], %g2
b,a 2f
1:
ldub [%o0], %g2
0:
cmp %g2, %o1
be 2f
addcc %o2, -1, %o2
bne 1b
add %o0, 1, %o0
2:
retl
nop
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