mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-24 03:53:31 +00:00
3c60e59a4f
Add src and dst address checking, if they are the same address, just return and don't copy data anymore. Signed-off-by: Rick Chen <rick@andestech.com> Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
161 lines
3.3 KiB
ArmAsm
161 lines
3.3 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/*
|
|
* Copyright (C) 2013 Regents of the University of California
|
|
*/
|
|
|
|
#include <linux/linkage.h>
|
|
#include <asm/asm.h>
|
|
|
|
/* void *memcpy(void *, const void *, size_t) */
|
|
ENTRY(__memcpy)
|
|
WEAK(memcpy)
|
|
beq a0, a1, .copy_end
|
|
/* Save for return value */
|
|
mv t6, a0
|
|
|
|
/*
|
|
* Register allocation for code below:
|
|
* a0 - start of uncopied dst
|
|
* a1 - start of uncopied src
|
|
* t0 - end of uncopied dst
|
|
*/
|
|
add t0, a0, a2
|
|
|
|
/*
|
|
* Use bytewise copy if too small.
|
|
*
|
|
* This threshold must be at least 2*SZREG to ensure at least one
|
|
* wordwise copy is performed. It is chosen to be 16 because it will
|
|
* save at least 7 iterations of bytewise copy, which pays off the
|
|
* fixed overhead.
|
|
*/
|
|
li a3, 16
|
|
bltu a2, a3, .Lbyte_copy_tail
|
|
|
|
/*
|
|
* Bytewise copy first to align a0 to word boundary.
|
|
*/
|
|
addi a2, a0, SZREG-1
|
|
andi a2, a2, ~(SZREG-1)
|
|
beq a0, a2, 2f
|
|
1:
|
|
lb a5, 0(a1)
|
|
addi a1, a1, 1
|
|
sb a5, 0(a0)
|
|
addi a0, a0, 1
|
|
bne a0, a2, 1b
|
|
2:
|
|
|
|
/*
|
|
* Now a0 is word-aligned. If a1 is also word aligned, we could perform
|
|
* aligned word-wise copy. Otherwise we need to perform misaligned
|
|
* word-wise copy.
|
|
*/
|
|
andi a3, a1, SZREG-1
|
|
bnez a3, .Lmisaligned_word_copy
|
|
|
|
/* Unrolled wordwise copy */
|
|
addi t0, t0, -(16*SZREG-1)
|
|
bgeu a0, t0, 2f
|
|
1:
|
|
REG_L a2, 0(a1)
|
|
REG_L a3, SZREG(a1)
|
|
REG_L a4, 2*SZREG(a1)
|
|
REG_L a5, 3*SZREG(a1)
|
|
REG_L a6, 4*SZREG(a1)
|
|
REG_L a7, 5*SZREG(a1)
|
|
REG_L t1, 6*SZREG(a1)
|
|
REG_L t2, 7*SZREG(a1)
|
|
REG_L t3, 8*SZREG(a1)
|
|
REG_L t4, 9*SZREG(a1)
|
|
REG_L t5, 10*SZREG(a1)
|
|
REG_S a2, 0(a0)
|
|
REG_S a3, SZREG(a0)
|
|
REG_S a4, 2*SZREG(a0)
|
|
REG_S a5, 3*SZREG(a0)
|
|
REG_S a6, 4*SZREG(a0)
|
|
REG_S a7, 5*SZREG(a0)
|
|
REG_S t1, 6*SZREG(a0)
|
|
REG_S t2, 7*SZREG(a0)
|
|
REG_S t3, 8*SZREG(a0)
|
|
REG_S t4, 9*SZREG(a0)
|
|
REG_S t5, 10*SZREG(a0)
|
|
REG_L a2, 11*SZREG(a1)
|
|
REG_L a3, 12*SZREG(a1)
|
|
REG_L a4, 13*SZREG(a1)
|
|
REG_L a5, 14*SZREG(a1)
|
|
REG_L a6, 15*SZREG(a1)
|
|
addi a1, a1, 16*SZREG
|
|
REG_S a2, 11*SZREG(a0)
|
|
REG_S a3, 12*SZREG(a0)
|
|
REG_S a4, 13*SZREG(a0)
|
|
REG_S a5, 14*SZREG(a0)
|
|
REG_S a6, 15*SZREG(a0)
|
|
addi a0, a0, 16*SZREG
|
|
bltu a0, t0, 1b
|
|
2:
|
|
/* Post-loop increment by 16*SZREG-1 and pre-loop decrement by SZREG-1 */
|
|
addi t0, t0, 15*SZREG
|
|
|
|
/* Wordwise copy */
|
|
bgeu a0, t0, 2f
|
|
1:
|
|
REG_L a5, 0(a1)
|
|
addi a1, a1, SZREG
|
|
REG_S a5, 0(a0)
|
|
addi a0, a0, SZREG
|
|
bltu a0, t0, 1b
|
|
2:
|
|
addi t0, t0, SZREG-1
|
|
|
|
.Lbyte_copy_tail:
|
|
/*
|
|
* Bytewise copy anything left.
|
|
*/
|
|
beq a0, t0, 2f
|
|
1:
|
|
lb a5, 0(a1)
|
|
addi a1, a1, 1
|
|
sb a5, 0(a0)
|
|
addi a0, a0, 1
|
|
bne a0, t0, 1b
|
|
2:
|
|
|
|
mv a0, t6
|
|
.copy_end:
|
|
ret
|
|
|
|
.Lmisaligned_word_copy:
|
|
/*
|
|
* Misaligned word-wise copy.
|
|
* For misaligned copy we still perform word-wise copy, but we need to
|
|
* use the value fetched from the previous iteration and do some shifts.
|
|
* This is safe because we wouldn't access more words than necessary.
|
|
*/
|
|
|
|
/* Calculate shifts */
|
|
slli t3, a3, 3
|
|
sub t4, x0, t3 /* negate is okay as shift will only look at LSBs */
|
|
|
|
/* Load the initial value and align a1 */
|
|
andi a1, a1, ~(SZREG-1)
|
|
REG_L a5, 0(a1)
|
|
|
|
addi t0, t0, -(SZREG-1)
|
|
/* At least one iteration will be executed here, no check */
|
|
1:
|
|
srl a4, a5, t3
|
|
REG_L a5, SZREG(a1)
|
|
addi a1, a1, SZREG
|
|
sll a2, a5, t4
|
|
or a2, a2, a4
|
|
REG_S a2, 0(a0)
|
|
addi a0, a0, SZREG
|
|
bltu a0, t0, 1b
|
|
|
|
/* Update pointers to correct value */
|
|
addi t0, t0, SZREG-1
|
|
add a1, a1, a3
|
|
|
|
j .Lbyte_copy_tail
|
|
END(__memcpy)
|