mirror of https://gitee.com/openkylin/linux.git
121 lines
2.7 KiB
ArmAsm
121 lines
2.7 KiB
ArmAsm
/*
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* Copyright (C) 2013 Regents of the University of California
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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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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ENTRY(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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END(memset)
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