mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-24 07:31:32 +00:00
103 lines
1.6 KiB
C
103 lines
1.6 KiB
C
#if defined __thumb__
|
|
|
|
#include "../../string/memchr.c"
|
|
|
|
#else
|
|
|
|
#include <string.h>
|
|
#include "xscale.h"
|
|
|
|
void *
|
|
memchr (const void *start, int c, size_t len)
|
|
{
|
|
const char *str = start;
|
|
|
|
if (len == 0)
|
|
return 0;
|
|
|
|
asm (PRELOADSTR ("%0") : : "r" (start));
|
|
|
|
c &= 0xff;
|
|
|
|
#ifndef __OPTIMIZE_SIZE__
|
|
/* Skip unaligned part. */
|
|
if ((long)str & 3)
|
|
{
|
|
str--;
|
|
do
|
|
{
|
|
if (*++str == c)
|
|
return (void *)str;
|
|
}
|
|
while (((long)str & 3) != 0 && --len > 0);
|
|
}
|
|
|
|
if (len > 3)
|
|
{
|
|
unsigned int c2 = c + (c << 8);
|
|
c2 += c2 << 16;
|
|
|
|
/* Load two constants:
|
|
R7 = 0xfefefeff [ == ~(0x80808080 << 1) ]
|
|
R6 = 0x80808080 */
|
|
|
|
asm (
|
|
"mov r6, #0x80\n\
|
|
add r6, r6, #0x8000\n\
|
|
add r6, r6, r6, lsl #16\n\
|
|
mvn r7, r6, lsl #1\n\
|
|
\n\
|
|
0:\n\
|
|
cmp %1, #0x7\n\
|
|
bls 1f\n\
|
|
\n\
|
|
ldmia %0!, { r3, r9 }\n\
|
|
" PRELOADSTR ("%0") "\n\
|
|
sub %1, %1, #8\n\
|
|
eor r3, r3, %2\n\
|
|
eor r9, r9, %2\n\
|
|
add r2, r3, r7\n\
|
|
add r8, r9, r7\n\
|
|
bic r2, r2, r3\n\
|
|
bic r8, r8, r9\n\
|
|
and r1, r2, r6\n\
|
|
and r9, r8, r6\n\
|
|
orrs r1, r1, r9\n\
|
|
beq 0b\n\
|
|
\n\
|
|
add %1, %1, #8\n\
|
|
sub %0, %0, #8\n\
|
|
1:\n\
|
|
cmp %1, #0x3\n\
|
|
bls 2f\n\
|
|
\n\
|
|
ldr r3, [%0], #4\n\
|
|
" PRELOADSTR ("%0") "\n\
|
|
sub %1, %1, #4\n\
|
|
eor r3, r3, %2\n\
|
|
add r2, r3, r7\n\
|
|
bic r2, r2, r3\n\
|
|
ands r1, r2, r6\n\
|
|
beq 1b\n\
|
|
\n\
|
|
sub %0, %0, #4\n\
|
|
add %1, %1, #4\n\
|
|
2:\n\
|
|
"
|
|
: "=&r" (str), "=&r" (len)
|
|
: "r" (c2), "0" (str), "1" (len)
|
|
: "r1", "r2", "r3", "r6", "r7", "r8", "r9", "cc");
|
|
}
|
|
#endif
|
|
|
|
while (len-- > 0)
|
|
{
|
|
if (*str == c)
|
|
return (void *)str;
|
|
str++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
#endif
|