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/* memcpy for RISC-V, ignoring buffer alignment
Copyright (C) 2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <sys/asm.h>
/* void *memcpy(void *, const void *, size_t) */
ENTRY (__memcpy_noalignment)
move t6, a0 /* Preserve return value */
/* Bail if 0 */
beqz a2, 7f
/* Jump to byte copy if size < SZREG */
li a4, SZREG
bltu a2, a4, 5f
/* Round down to the nearest "page" size */
andi a4, a2, ~((16*SZREG)-1)
beqz a4, 2f
add a3, a1, a4
/* Copy the first word to get dest word aligned */
andi a5, t6, SZREG-1
beqz a5, 1f
REG_L a6, (a1)
REG_S a6, (t6)
/* Align dst up to a word, move src and size as well. */
addi t6, t6, SZREG-1
andi t6, t6, ~(SZREG-1)
sub a5, t6, a0
add a1, a1, a5
sub a2, a2, a5
/* Recompute page count */
andi a4, a2, ~((16*SZREG)-1)
beqz a4, 2f
1:
/* Copy "pages" (chunks of 16 registers) */
REG_L a4, 0(a1)
REG_L a5, SZREG(a1)
REG_L a6, 2*SZREG(a1)
REG_L a7, 3*SZREG(a1)
REG_L t0, 4*SZREG(a1)
REG_L t1, 5*SZREG(a1)
REG_L t2, 6*SZREG(a1)
REG_L t3, 7*SZREG(a1)
REG_L t4, 8*SZREG(a1)
REG_L t5, 9*SZREG(a1)
REG_S a4, 0(t6)
REG_S a5, SZREG(t6)
REG_S a6, 2*SZREG(t6)
REG_S a7, 3*SZREG(t6)
REG_S t0, 4*SZREG(t6)
REG_S t1, 5*SZREG(t6)
REG_S t2, 6*SZREG(t6)
REG_S t3, 7*SZREG(t6)
REG_S t4, 8*SZREG(t6)
REG_S t5, 9*SZREG(t6)
REG_L a4, 10*SZREG(a1)
REG_L a5, 11*SZREG(a1)
REG_L a6, 12*SZREG(a1)
REG_L a7, 13*SZREG(a1)
REG_L t0, 14*SZREG(a1)
REG_L t1, 15*SZREG(a1)
addi a1, a1, 16*SZREG
REG_S a4, 10*SZREG(t6)
REG_S a5, 11*SZREG(t6)
REG_S a6, 12*SZREG(t6)
REG_S a7, 13*SZREG(t6)
REG_S t0, 14*SZREG(t6)
REG_S t1, 15*SZREG(t6)
addi t6, t6, 16*SZREG
bltu a1, a3, 1b
andi a2, a2, (16*SZREG)-1 /* Update count */
2:
/* Remainder is smaller than a page, compute native word count */
beqz a2, 7f
andi a5, a2, ~(SZREG-1)
andi a2, a2, (SZREG-1)
add a3, a1, a5
/* Jump directly to last word if no words. */
beqz a5, 4f
3:
/* Use single native register copy */
REG_L a4, 0(a1)
addi a1, a1, SZREG
REG_S a4, 0(t6)
addi t6, t6, SZREG
bltu a1, a3, 3b
/* Jump directly out if no more bytes */
beqz a2, 7f
4:
/* Copy the last word unaligned */
add a3, a1, a2
add a4, t6, a2
REG_L a5, -SZREG(a3)
REG_S a5, -SZREG(a4)
ret
5:
/* Copy bytes when the total copy is <SZREG */
add a3, a1, a2
6:
lb a4, 0(a1)
addi a1, a1, 1
sb a4, 0(t6)
addi t6, t6, 1
bltu a1, a3, 6b
7:
ret
END (__memcpy_noalignment)
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