newlib-cygwin/newlib/libc/machine/xscale/memset.c

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#if defined __thumb__
#include "../../string/memset.c"
#else
#include <string.h>
#include "xscale.h"
void *
memset (void *dst, int c, size_t len)
{
int dummy;
asm volatile ("tst %0, #0x3"
#ifndef __OPTIMIZE_SIZE__
"
beq 1f
b 2f
0:
strb %1, [%0], #1
tst %0, #0x3
beq 1f
2:
movs r3, %2
sub %2, %2, #1
bne 0b
# At this point we know that %2 == len == -1 (since the SUB has already taken
# place). If we fall through to the 1: label (as the code used to do), the
# CMP will detect this negative value and branch to the 2: label. This will
# test %2 again, but this time against 0. The test will fail and the loop
# at 2: will go on for (almost) ever. Hence the explicit branch to the end
# of the hand written assembly code.
b 4f
1:
cmp %2, #0x3
bls 2f
and %1, %1, #0xff
orr lr, %1, %1, asl #8
cmp %2, #0xf
orr lr, lr, lr, asl #16
bls 1f
mov r3, lr
mov r4, lr
mov r5, lr
0:
sub %2, %2, #16
stmia %0!, { r3, r4, r5, lr }
cmp %2, #0xf
bhi 0b
1:
cmp %2, #0x7
bls 1f
mov r3, lr
0:
sub %2, %2, #8
stmia %0!, { r3, lr }
cmp %2, #0x7
bhi 0b
1:
cmp %2, #0x3
bls 2f
0:
sub %2, %2, #4
str lr, [%0], #4
cmp %2, #0x3
bhi 0b
"
#endif /* !__OPTIMIZE_SIZE__ */
"
2:
movs r3, %2
sub %2, %2, #1
beq 4f
0:
movs r3, %2
sub %2, %2, #1
strb %1, [%0], #1
bne 0b
4:"
: "=&r" (dummy), "=&r" (c), "=&r" (len)
: "0" (dst), "1" (c), "2" (len)
: "memory", "r3", "r4", "r5", "lr");
return dst;
}
#endif