/* * Copyright (c) 2020, Arm Limited. All rights reserved. * * SPDX-License-Identifier: BSD-3-Clause */ #include .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