mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
synced 2024-12-24 19:26:04 +00:00
239 lines
6.3 KiB
ArmAsm
239 lines
6.3 KiB
ArmAsm
/*
|
|
* memcpy - copy memory area
|
|
*
|
|
* Copyright (c) 2012-2020, Arm Limited.
|
|
* SPDX-License-Identifier: MIT
|
|
*/
|
|
|
|
/* Assumptions:
|
|
*
|
|
* ARMv8-a, AArch64, unaligned accesses.
|
|
*
|
|
*/
|
|
|
|
#include "asmdefs.h"
|
|
|
|
#define dstin x0
|
|
#define src x1
|
|
#define count x2
|
|
#define dst x3
|
|
#define srcend x4
|
|
#define dstend x5
|
|
#define A_l x6
|
|
#define A_lw w6
|
|
#define A_h x7
|
|
#define B_l x8
|
|
#define B_lw w8
|
|
#define B_h x9
|
|
#define C_l x10
|
|
#define C_lw w10
|
|
#define C_h x11
|
|
#define D_l x12
|
|
#define D_h x13
|
|
#define E_l x14
|
|
#define E_h x15
|
|
#define F_l x16
|
|
#define F_h x17
|
|
#define G_l count
|
|
#define G_h dst
|
|
#define H_l src
|
|
#define H_h srcend
|
|
#define tmp1 x14
|
|
|
|
/* This implementation handles overlaps and supports both memcpy and memmove
|
|
from a single entry point. It uses unaligned accesses and branchless
|
|
sequences to keep the code small, simple and improve performance.
|
|
|
|
Copies are split into 3 main cases: small copies of up to 32 bytes, medium
|
|
copies of up to 128 bytes, and large copies. The overhead of the overlap
|
|
check is negligible since it is only required for large copies.
|
|
|
|
Large copies use a software pipelined loop processing 64 bytes per iteration.
|
|
The destination pointer is 16-byte aligned to minimize unaligned accesses.
|
|
The loop tail is handled by always copying 64 bytes from the end.
|
|
*/
|
|
|
|
ENTRY (memcpy)
|
|
ENTRY_ALIAS (memmove)
|
|
add srcend, src, count
|
|
add dstend, dstin, count
|
|
cmp count, 128
|
|
b.hi L(copy_long)
|
|
cmp count, 32
|
|
b.hi L(copy32_128)
|
|
|
|
/* Small copies: 0..32 bytes. */
|
|
cmp count, 16
|
|
b.lo L(copy16)
|
|
ldp A_l, A_h, [src]
|
|
ldp D_l, D_h, [srcend, -16]
|
|
stp A_l, A_h, [dstin]
|
|
stp D_l, D_h, [dstend, -16]
|
|
ret
|
|
|
|
/* Copy 8-15 bytes. */
|
|
L(copy16):
|
|
tbz count, 3, L(copy8)
|
|
ldr A_l, [src]
|
|
ldr A_h, [srcend, -8]
|
|
str A_l, [dstin]
|
|
str A_h, [dstend, -8]
|
|
ret
|
|
|
|
.p2align 3
|
|
/* Copy 4-7 bytes. */
|
|
L(copy8):
|
|
tbz count, 2, L(copy4)
|
|
ldr A_lw, [src]
|
|
ldr B_lw, [srcend, -4]
|
|
str A_lw, [dstin]
|
|
str B_lw, [dstend, -4]
|
|
ret
|
|
|
|
/* Copy 0..3 bytes using a branchless sequence. */
|
|
L(copy4):
|
|
cbz count, L(copy0)
|
|
lsr tmp1, count, 1
|
|
ldrb A_lw, [src]
|
|
ldrb C_lw, [srcend, -1]
|
|
ldrb B_lw, [src, tmp1]
|
|
strb A_lw, [dstin]
|
|
strb B_lw, [dstin, tmp1]
|
|
strb C_lw, [dstend, -1]
|
|
L(copy0):
|
|
ret
|
|
|
|
.p2align 4
|
|
/* Medium copies: 33..128 bytes. */
|
|
L(copy32_128):
|
|
ldp A_l, A_h, [src]
|
|
ldp B_l, B_h, [src, 16]
|
|
ldp C_l, C_h, [srcend, -32]
|
|
ldp D_l, D_h, [srcend, -16]
|
|
cmp count, 64
|
|
b.hi L(copy128)
|
|
stp A_l, A_h, [dstin]
|
|
stp B_l, B_h, [dstin, 16]
|
|
stp C_l, C_h, [dstend, -32]
|
|
stp D_l, D_h, [dstend, -16]
|
|
ret
|
|
|
|
.p2align 4
|
|
/* Copy 65..128 bytes. */
|
|
L(copy128):
|
|
ldp E_l, E_h, [src, 32]
|
|
ldp F_l, F_h, [src, 48]
|
|
cmp count, 96
|
|
b.ls L(copy96)
|
|
ldp G_l, G_h, [srcend, -64]
|
|
ldp H_l, H_h, [srcend, -48]
|
|
stp G_l, G_h, [dstend, -64]
|
|
stp H_l, H_h, [dstend, -48]
|
|
L(copy96):
|
|
stp A_l, A_h, [dstin]
|
|
stp B_l, B_h, [dstin, 16]
|
|
stp E_l, E_h, [dstin, 32]
|
|
stp F_l, F_h, [dstin, 48]
|
|
stp C_l, C_h, [dstend, -32]
|
|
stp D_l, D_h, [dstend, -16]
|
|
ret
|
|
|
|
.p2align 4
|
|
/* Copy more than 128 bytes. */
|
|
L(copy_long):
|
|
/* Use backwards copy if there is an overlap. */
|
|
sub tmp1, dstin, src
|
|
cbz tmp1, L(copy0)
|
|
cmp tmp1, count
|
|
b.lo L(copy_long_backwards)
|
|
|
|
/* Copy 16 bytes and then align dst to 16-byte alignment. */
|
|
|
|
ldp D_l, D_h, [src]
|
|
and tmp1, dstin, 15
|
|
bic dst, dstin, 15
|
|
sub src, src, tmp1
|
|
add count, count, tmp1 /* Count is now 16 too large. */
|
|
ldp A_l, A_h, [src, 16]
|
|
stp D_l, D_h, [dstin]
|
|
ldp B_l, B_h, [src, 32]
|
|
ldp C_l, C_h, [src, 48]
|
|
ldp D_l, D_h, [src, 64]!
|
|
subs count, count, 128 + 16 /* Test and readjust count. */
|
|
b.ls L(copy64_from_end)
|
|
|
|
L(loop64):
|
|
stp A_l, A_h, [dst, 16]
|
|
ldp A_l, A_h, [src, 16]
|
|
stp B_l, B_h, [dst, 32]
|
|
ldp B_l, B_h, [src, 32]
|
|
stp C_l, C_h, [dst, 48]
|
|
ldp C_l, C_h, [src, 48]
|
|
stp D_l, D_h, [dst, 64]!
|
|
ldp D_l, D_h, [src, 64]!
|
|
subs count, count, 64
|
|
b.hi L(loop64)
|
|
|
|
/* Write the last iteration and copy 64 bytes from the end. */
|
|
L(copy64_from_end):
|
|
ldp E_l, E_h, [srcend, -64]
|
|
stp A_l, A_h, [dst, 16]
|
|
ldp A_l, A_h, [srcend, -48]
|
|
stp B_l, B_h, [dst, 32]
|
|
ldp B_l, B_h, [srcend, -32]
|
|
stp C_l, C_h, [dst, 48]
|
|
ldp C_l, C_h, [srcend, -16]
|
|
stp D_l, D_h, [dst, 64]
|
|
stp E_l, E_h, [dstend, -64]
|
|
stp A_l, A_h, [dstend, -48]
|
|
stp B_l, B_h, [dstend, -32]
|
|
stp C_l, C_h, [dstend, -16]
|
|
ret
|
|
|
|
.p2align 4
|
|
|
|
/* Large backwards copy for overlapping copies.
|
|
Copy 16 bytes and then align dst to 16-byte alignment. */
|
|
L(copy_long_backwards):
|
|
ldp D_l, D_h, [srcend, -16]
|
|
and tmp1, dstend, 15
|
|
sub srcend, srcend, tmp1
|
|
sub count, count, tmp1
|
|
ldp A_l, A_h, [srcend, -16]
|
|
stp D_l, D_h, [dstend, -16]
|
|
ldp B_l, B_h, [srcend, -32]
|
|
ldp C_l, C_h, [srcend, -48]
|
|
ldp D_l, D_h, [srcend, -64]!
|
|
sub dstend, dstend, tmp1
|
|
subs count, count, 128
|
|
b.ls L(copy64_from_start)
|
|
|
|
L(loop64_backwards):
|
|
stp A_l, A_h, [dstend, -16]
|
|
ldp A_l, A_h, [srcend, -16]
|
|
stp B_l, B_h, [dstend, -32]
|
|
ldp B_l, B_h, [srcend, -32]
|
|
stp C_l, C_h, [dstend, -48]
|
|
ldp C_l, C_h, [srcend, -48]
|
|
stp D_l, D_h, [dstend, -64]!
|
|
ldp D_l, D_h, [srcend, -64]!
|
|
subs count, count, 64
|
|
b.hi L(loop64_backwards)
|
|
|
|
/* Write the last iteration and copy 64 bytes from the start. */
|
|
L(copy64_from_start):
|
|
ldp G_l, G_h, [src, 48]
|
|
stp A_l, A_h, [dstend, -16]
|
|
ldp A_l, A_h, [src, 32]
|
|
stp B_l, B_h, [dstend, -32]
|
|
ldp B_l, B_h, [src, 16]
|
|
stp C_l, C_h, [dstend, -48]
|
|
ldp C_l, C_h, [src]
|
|
stp D_l, D_h, [dstend, -64]
|
|
stp G_l, G_h, [dstin, 48]
|
|
stp A_l, A_h, [dstin, 32]
|
|
stp B_l, B_h, [dstin, 16]
|
|
stp C_l, C_h, [dstin]
|
|
ret
|
|
|
|
END (memcpy)
|