1/* 2 * Copyright (c) 2020, Arm Limited. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7#include <asm_macros.S> 8 9 .global memset 10 11/* ----------------------------------------------------------------------- 12 * void memset(void *dst, int val, size_t count) 13 * 14 * Copy the value of 'val' (converted to an unsigned char) into 15 * each of the first 'count' characters of the object pointed to by 'dst'. 16 * 17 * Returns the value of 'dst'. 18 * ----------------------------------------------------------------------- 19 */ 20func memset 21 cbz w2, exit /* exit if 'count' = 0 */ 22 mov x3, x0 /* keep x0 */ 23 tst x0, #7 24 b.eq aligned /* 8-bytes aligned */ 25 26 /* Unaligned 'dst' */ 27unaligned: 28 strb w1, [x3], #1 29 subs w2, w2, #1 30 b.eq exit /* exit if 0 */ 31 tst x3, #7 32 b.ne unaligned /* continue while unaligned */ 33 34 /* 8-bytes aligned */ 35aligned:cbz x1, x1_zero 36 bfi w1, w1, #8, #8 /* propagate 'val' */ 37 bfi w1, w1, #16, #16 38 bfi x1, x1, #32, #32 39 40x1_zero:ands w4, w2, #~0x3f 41 b.eq less_64 42 43write_64: 44 .rept 4 45 stp x1, x1, [x3], #16 /* write 64 bytes in a loop */ 46 .endr 47 subs w4, w4, #64 48 b.ne write_64 49 ands w2, w2, #0x3f 50 b.eq exit /* exit if 0 */ 51 52less_64:tbz w2, #5, less_32 /* < 32 bytes */ 53 stp x1, x1, [x3], #16 /* write 32 bytes */ 54 stp x1, x1, [x3], #16 55 ands w2, w2, #0x1f 56 b.eq exit 57 58less_32:tbz w2, #4, less_16 /* < 16 bytes */ 59 stp x1, x1, [x3], #16 /* write 16 bytes */ 60 ands w2, w2, #0xf 61 b.eq exit 62 63less_16:tbz w2, #3, less_8 /* < 8 bytes */ 64 str x1, [x3], #8 /* write 8 bytes */ 65 ands w2, w2, #7 66 b.eq exit 67 68less_8: tbz w2, #2, less_4 /* < 4 bytes */ 69 str w1, [x3], #4 /* write 4 bytes */ 70 ands w2, w2, #3 71 b.eq exit 72 73less_4: tbz w2, #1, less_2 /* < 2 bytes */ 74 strh w1, [x3], #2 /* write 2 bytes */ 75 tbz w2, #0, exit 76less_2: strb w1, [x3] /* write 1 byte */ 77exit: ret 78 79endfunc memset 80