| /* |
| * Copyright (c) 2020, Arm Limited. All rights reserved. |
| * |
| * SPDX-License-Identifier: BSD-3-Clause |
| */ |
| |
| #include <asm_macros.S> |
| |
| .syntax unified |
| .global memset |
| |
| /* ----------------------------------------------------------------------- |
| * void memset(void *dst, int val, size_t count) |
| * |
| * Copy the value of 'val' (converted to an unsigned char) into |
| * each of the first 'count' characters of the object pointed to by 'dst'. |
| * |
| * Returns the value of 'dst'. |
| * ----------------------------------------------------------------------- |
| */ |
| func memset |
| cmp r2, #0 |
| bxeq lr /* return if 'count' = 0 */ |
| mov r12, r0 /* keep r0 */ |
| tst r0, #3 |
| beq aligned /* 4-bytes aligned */ |
| |
| /* Unaligned 'dst' */ |
| unaligned: |
| strb r1, [r12], #1 |
| subs r2, r2, #1 |
| bxeq lr /* return if 0 */ |
| tst r12, #3 |
| bne unaligned /* continue while unaligned */ |
| |
| /* 4-bytes aligned */ |
| aligned:bfi r1, r1, #8, #8 /* propagate 'val' */ |
| bfi r1, r1, #16, #16 |
| |
| mov r3, r1 |
| |
| cmp r2, #16 |
| blo less_16 |
| |
| push {r4, lr} |
| mov r4, r1 |
| mov lr, r1 |
| |
| cmp r2, #32 |
| blo less_32 |
| |
| write_32: |
| stmia r12!, {r1, r3, r4, lr} /* write 32 bytes in a loop */ |
| stmia r12!, {r1, r3, r4, lr} |
| subs r2, r2, #32 |
| popeq {r4, pc} /* return if 0 */ |
| cmp r2, #32 |
| bhs write_32 |
| |
| less_32:cmp r2, #16 |
| stmiahs r12!, {r1, r3, r4, lr} /* write 16 bytes */ |
| popeq {r4, pc} /* return if 16 */ |
| pop {r4, lr} |
| |
| less_16:lsls r2, r2, #29 /* C = r2[3]; N = r2[2]; Z = r2[2:0] */ |
| stmiacs r12!, {r1, r3} /* write 8 bytes */ |
| bxeq lr /* return if 8 */ |
| strmi r1, [r12], #4 /* write 4 bytes */ |
| lsls r2, r2, #1 /* N = r2[1]; Z = r2[0] */ |
| strhmi r1, [r12], #2 /* write 2 bytes */ |
| strbne r1, [r12] /* write 1 byte */ |
| bx lr |
| |
| endfunc memset |