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freebsd
GitHub Repository: freebsd/freebsd-src
 Path: blob/main/lib/libc/riscv/string/memset.S
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/*-

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 * SPDX-License-Identifier: BSD-2-Clause

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 *

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 * Copyright (c) 2024 Strahinja Stanisic <[email protected]>

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 */

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#include <machine/asm.h>

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/*

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 * register a0 - void *dest

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 * register a1 - int c

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 * register a2 - size_t len

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 */

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ENTRY(memset)

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	andi a1, a1, 0xFF

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	sltiu t1, a2, 8

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	mv t0, a0

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	bnez t1, .Lend

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	li t1, 0x0101010101010101

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	mul a1, a1, t1

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	andi t1, a0, 0b111

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	andi t0, a0, ~0b111

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	beqz t1, .Lloop_store_64

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	la t2, .Lduff_start

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	slli t3, t1, 2

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	add t2, t2, t3

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	jr -4(t2)

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.Lduff_start:

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	sb a1, 1(t0)

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	sb a1, 2(t0)

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	sb a1, 3(t0)

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	sb a1, 4(t0)

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	sb a1, 5(t0)

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	sb a1, 6(t0)

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	sb a1, 7(t0)

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	/* a3 = a3 -(8-a) <=> a3 = a3 + (a-8) */

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	addi t1, t1, -8

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	add a2, a2, t1

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	addi t0, t0, 8

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.Lloop_store_64:

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	slti t1, a2, 64

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	bnez t1, .Lstore_rest

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	sd a1, 0(t0)

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	sd a1, 8(t0)

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	sd a1, 16(t0)

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	sd a1, 24(t0)

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	sd a1, 32(t0)

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	sd a1, 40(t0)

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	sd a1, 48(t0)

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	sd a1, 56(t0)

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	addi a2, a2, -64

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	addi t0, t0, 64

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	j .Lloop_store_64

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.Lstore_rest:

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	la t2, .Lduff_rest

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	andi t3, a2, ~0b111

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	srli t4, t3, 1

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	sub t2, t2, t4

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	jr t2

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	sd a1, 56(t0)

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	sd a1, 48(t0)

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	sd a1, 40(t0)

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	sd a1, 32(t0)

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	sd a1, 24(t0)

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	sd a1, 16(t0)

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	sd a1, 8(t0)

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	sd a1, 0(t0)

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.Lduff_rest:

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	add t0, t0, t3

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	sub a2, a2, t3

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.Lend:

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	slli a2, a2, 2

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	la t2, .Lduff_end

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	sub t2, t2, a2

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	jr t2

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	sb a1, 6(t0)

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	sb a1, 5(t0)

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	sb a1, 4(t0)

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	sb a1, 3(t0)

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	sb a1, 2(t0)

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	sb a1, 1(t0)

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	sb a1, (t0)

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.Lduff_end:

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	ret

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END(memset)

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