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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/riscv/lib/memset.S
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/* SPDX-License-Identifier: GPL-2.0-only */

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/*

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 * Copyright (C) 2013 Regents of the University of California

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 */

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#include <linux/linkage.h>

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#include <asm/asm.h>

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/* void *memset(void *, int, size_t) */

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SYM_FUNC_START(__memset)

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	move t0, a0  /* Preserve return value */

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	/* Defer to byte-oriented fill for small sizes */

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	sltiu a3, a2, 16

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	bnez a3, 4f

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	/*

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	 * Round to nearest XLEN-aligned address

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	 * greater than or equal to start address

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	 */

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	addi a3, t0, SZREG-1

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	andi a3, a3, ~(SZREG-1)

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	beq a3, t0, 2f  /* Skip if already aligned */

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	/* Handle initial misalignment */

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	sub a4, a3, t0

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1:

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	sb a1, 0(t0)

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	addi t0, t0, 1

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	bltu t0, a3, 1b

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	sub a2, a2, a4  /* Update count */

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2: /* Duff's device with 32 XLEN stores per iteration */

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	/* Broadcast value into all bytes */

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	andi a1, a1, 0xff

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	slli a3, a1, 8

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	or a1, a3, a1

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	slli a3, a1, 16

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	or a1, a3, a1

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#ifdef CONFIG_64BIT

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	slli a3, a1, 32

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	or a1, a3, a1

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#endif

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	/* Calculate end address */

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	andi a4, a2, ~(SZREG-1)

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	add a3, t0, a4

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	andi a4, a4, 31*SZREG  /* Calculate remainder */

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	beqz a4, 3f            /* Shortcut if no remainder */

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	neg a4, a4

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	addi a4, a4, 32*SZREG  /* Calculate initial offset */

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	/* Adjust start address with offset */

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	sub t0, t0, a4

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	/* Jump into loop body */

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	/* Assumes 32-bit instruction lengths */

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	la a5, 3f

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#ifdef CONFIG_64BIT

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	srli a4, a4, 1

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#endif

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	add a5, a5, a4

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	jr a5

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3:

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	REG_S a1,        0(t0)

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	REG_S a1,    SZREG(t0)

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	REG_S a1,  2*SZREG(t0)

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	REG_S a1,  3*SZREG(t0)

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	REG_S a1,  4*SZREG(t0)

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	REG_S a1,  5*SZREG(t0)

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	REG_S a1,  6*SZREG(t0)

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	REG_S a1,  7*SZREG(t0)

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	REG_S a1,  8*SZREG(t0)

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	REG_S a1,  9*SZREG(t0)

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	REG_S a1, 10*SZREG(t0)

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	REG_S a1, 11*SZREG(t0)

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	REG_S a1, 12*SZREG(t0)

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	REG_S a1, 13*SZREG(t0)

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	REG_S a1, 14*SZREG(t0)

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	REG_S a1, 15*SZREG(t0)

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	REG_S a1, 16*SZREG(t0)

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	REG_S a1, 17*SZREG(t0)

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	REG_S a1, 18*SZREG(t0)

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	REG_S a1, 19*SZREG(t0)

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	REG_S a1, 20*SZREG(t0)

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	REG_S a1, 21*SZREG(t0)

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	REG_S a1, 22*SZREG(t0)

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	REG_S a1, 23*SZREG(t0)

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	REG_S a1, 24*SZREG(t0)

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	REG_S a1, 25*SZREG(t0)

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	REG_S a1, 26*SZREG(t0)

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	REG_S a1, 27*SZREG(t0)

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	REG_S a1, 28*SZREG(t0)

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	REG_S a1, 29*SZREG(t0)

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	REG_S a1, 30*SZREG(t0)

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	REG_S a1, 31*SZREG(t0)

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	addi t0, t0, 32*SZREG

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	bltu t0, a3, 3b

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	andi a2, a2, SZREG-1  /* Update count */

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4:

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	/* Handle trailing misalignment */

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	beqz a2, 6f

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	add a3, t0, a2

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5:

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	sb a1, 0(t0)

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	addi t0, t0, 1

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	bltu t0, a3, 5b

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6:

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	ret

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SYM_FUNC_END(__memset)

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SYM_FUNC_ALIAS_WEAK(memset, __memset)

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SYM_FUNC_ALIAS(__pi_memset, __memset)

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SYM_FUNC_ALIAS(__pi___memset, __memset)

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