mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
synced 2024-12-12 16:01:15 +01:00
134 lines
3.1 KiB
ArmAsm
134 lines
3.1 KiB
ArmAsm
/* memcmp - compare memory
|
|
*
|
|
* Copyright (c) 2013, Arm Limited.
|
|
* SPDX-License-Identifier: MIT
|
|
*/
|
|
|
|
/* Assumptions:
|
|
*
|
|
* ARMv8-a, AArch64, unaligned accesses.
|
|
*/
|
|
|
|
#include "asmdefs.h"
|
|
|
|
/* Parameters and result. */
|
|
#define src1 x0
|
|
#define src2 x1
|
|
#define limit x2
|
|
#define result w0
|
|
|
|
/* Internal variables. */
|
|
#define data1 x3
|
|
#define data1w w3
|
|
#define data1h x4
|
|
#define data2 x5
|
|
#define data2w w5
|
|
#define data2h x6
|
|
#define tmp1 x7
|
|
#define tmp2 x8
|
|
|
|
ENTRY (memcmp)
|
|
subs limit, limit, 8
|
|
b.lo L(less8)
|
|
|
|
ldr data1, [src1], 8
|
|
ldr data2, [src2], 8
|
|
cmp data1, data2
|
|
b.ne L(return)
|
|
|
|
subs limit, limit, 8
|
|
b.gt L(more16)
|
|
|
|
ldr data1, [src1, limit]
|
|
ldr data2, [src2, limit]
|
|
b L(return)
|
|
|
|
L(more16):
|
|
ldr data1, [src1], 8
|
|
ldr data2, [src2], 8
|
|
cmp data1, data2
|
|
bne L(return)
|
|
|
|
/* Jump directly to comparing the last 16 bytes for 32 byte (or less)
|
|
strings. */
|
|
subs limit, limit, 16
|
|
b.ls L(last_bytes)
|
|
|
|
/* We overlap loads between 0-32 bytes at either side of SRC1 when we
|
|
try to align, so limit it only to strings larger than 128 bytes. */
|
|
cmp limit, 96
|
|
b.ls L(loop16)
|
|
|
|
/* Align src1 and adjust src2 with bytes not yet done. */
|
|
and tmp1, src1, 15
|
|
add limit, limit, tmp1
|
|
sub src1, src1, tmp1
|
|
sub src2, src2, tmp1
|
|
|
|
/* Loop performing 16 bytes per iteration using aligned src1.
|
|
Limit is pre-decremented by 16 and must be larger than zero.
|
|
Exit if <= 16 bytes left to do or if the data is not equal. */
|
|
.p2align 4
|
|
L(loop16):
|
|
ldp data1, data1h, [src1], 16
|
|
ldp data2, data2h, [src2], 16
|
|
subs limit, limit, 16
|
|
ccmp data1, data2, 0, hi
|
|
ccmp data1h, data2h, 0, eq
|
|
b.eq L(loop16)
|
|
|
|
cmp data1, data2
|
|
bne L(return)
|
|
mov data1, data1h
|
|
mov data2, data2h
|
|
cmp data1, data2
|
|
bne L(return)
|
|
|
|
/* Compare last 1-16 bytes using unaligned access. */
|
|
L(last_bytes):
|
|
add src1, src1, limit
|
|
add src2, src2, limit
|
|
ldp data1, data1h, [src1]
|
|
ldp data2, data2h, [src2]
|
|
cmp data1, data2
|
|
bne L(return)
|
|
mov data1, data1h
|
|
mov data2, data2h
|
|
cmp data1, data2
|
|
|
|
/* Compare data bytes and set return value to 0, -1 or 1. */
|
|
L(return):
|
|
#ifndef __AARCH64EB__
|
|
rev data1, data1
|
|
rev data2, data2
|
|
#endif
|
|
cmp data1, data2
|
|
L(ret_eq):
|
|
cset result, ne
|
|
cneg result, result, lo
|
|
ret
|
|
|
|
.p2align 4
|
|
/* Compare up to 8 bytes. Limit is [-8..-1]. */
|
|
L(less8):
|
|
adds limit, limit, 4
|
|
b.lo L(less4)
|
|
ldr data1w, [src1], 4
|
|
ldr data2w, [src2], 4
|
|
cmp data1w, data2w
|
|
b.ne L(return)
|
|
sub limit, limit, 4
|
|
L(less4):
|
|
adds limit, limit, 4
|
|
beq L(ret_eq)
|
|
L(byte_loop):
|
|
ldrb data1w, [src1], 1
|
|
ldrb data2w, [src2], 1
|
|
subs limit, limit, 1
|
|
ccmp data1w, data2w, 0, ne /* NZCV = 0b0000. */
|
|
b.eq L(byte_loop)
|
|
sub result, data1w, data2w
|
|
ret
|
|
|
|
END (memcmp)
|