| /* |
| * memset.c |
| */ |
| |
| #include <string.h> |
| #include <stdint.h> |
| |
| #if defined(__arm__) |
| #include <mcu/cmsis_nvic.h> |
| #endif |
| |
| void *memset(void *dst, int c, size_t n) |
| { |
| char *q = dst; |
| |
| #if defined(__i386__) |
| size_t nl = n >> 2; |
| asm volatile ("cld ; rep ; stosl ; movl %3,%0 ; rep ; stosb" |
| : "+c" (nl), "+D" (q) |
| : "a" ((unsigned char)c * 0x01010101U), "r" (n & 3)); |
| #elif defined(__x86_64__) |
| size_t nq = n >> 3; |
| asm volatile ("cld ; rep ; stosq ; movl %3,%%ecx ; rep ; stosb" |
| :"+c" (nq), "+D" (q) |
| : "a" ((unsigned char)c * 0x0101010101010101U), |
| "r" ((uint32_t) n & 7)); |
| #elif defined(__arm__) |
| asm volatile (".syntax unified \n" |
| /* copy 8-bit value to all 4 bytes in word */ |
| #if __CORTEX_M < 3 |
| /* Cortex-M0 does not support flexible 2nd operand */ |
| " uxtb %[val], %[val] \n" |
| " lsls r4, %[val], #8 \n" |
| " orrs %[val], %[val],r4 \n" |
| " lsls r4, %[val], #16 \n" |
| " orrs %[val], %[val], r4 \n" |
| #else |
| " uxtb %[val], %[val] \n" |
| " orr %[val], %[val], %[val], lsl#8 \n" |
| " orr %[val], %[val], %[val], lsl#16 \n" |
| #endif |
| /* calculate max length of data that are word aligned */ |
| " adds r3, %[buf], %[len] \n" |
| " movs r4, #3 \n" |
| " ands r3, r3, r4 \n" |
| " subs r3, %[len], r3 \n" |
| " bmi 3f \n" |
| " b 2f \n" |
| /* fill non-word aligned bytes at the end of buffer */ |
| "1: subs %[len], #1 \n" |
| " strb %[val], [%[buf], %[len]] \n" |
| "2: cmp %[len], r3 \n" |
| " bne 1b \n" |
| /* fill all word aligned bytes */ |
| " b 2f \n" |
| "1: str %[val], [%[buf], %[len]] \n" |
| "2: subs %[len], #4 \n" |
| " bpl 1b \n" |
| " adds %[len], #4 \n" |
| /* fill remaining non-word aligned bytes */ |
| " b 3f \n" |
| "1: strb %[val], [%[buf], %[len]] \n" |
| "3: subs %[len], #1 \n" |
| " bpl 1b \n" |
| : [buf] "+r" (q), [val] "+r" (c), [len] "+r" (n) |
| : |
| : "r3", "r4", "memory" |
| ); |
| #else |
| while (n--) { |
| *q++ = c; |
| } |
| #endif |
| |
| return dst; |
| } |
