mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
153 lines
3.5 KiB
153 lines
3.5 KiB
/* |
|
* arch/xtensa/lib/memset.S |
|
* |
|
* ANSI C standard library function memset |
|
* (Well, almost. .fixup code might return zero.) |
|
* |
|
* This file is subject to the terms and conditions of the GNU General |
|
* Public License. See the file "COPYING" in the main directory of |
|
* this archive for more details. |
|
* |
|
* Copyright (C) 2002 Tensilica Inc. |
|
*/ |
|
|
|
#include <linux/linkage.h> |
|
#include <asm/asmmacro.h> |
|
#include <asm/core.h> |
|
|
|
/* |
|
* void *memset(void *dst, int c, size_t length) |
|
* |
|
* The algorithm is as follows: |
|
* Create a word with c in all byte positions |
|
* If the destination is aligned, |
|
* do 16B chucks with a loop, and then finish up with |
|
* 8B, 4B, 2B, and 1B stores conditional on the length. |
|
* If destination is unaligned, align it by conditionally |
|
* setting 1B and 2B and then go to aligned case. |
|
* This code tries to use fall-through branches for the common |
|
* case of an aligned destination (except for the branches to |
|
* the alignment labels). |
|
*/ |
|
|
|
.text |
|
ENTRY(__memset) |
|
WEAK(memset) |
|
|
|
abi_entry_default |
|
# a2/ dst, a3/ c, a4/ length |
|
extui a3, a3, 0, 8 # mask to just 8 bits |
|
slli a7, a3, 8 # duplicate character in all bytes of word |
|
or a3, a3, a7 # ... |
|
slli a7, a3, 16 # ... |
|
or a3, a3, a7 # ... |
|
mov a5, a2 # copy dst so that a2 is return value |
|
movi a6, 3 # for alignment tests |
|
bany a2, a6, .Ldstunaligned # if dst is unaligned |
|
.L0: # return here from .Ldstunaligned when dst is aligned |
|
srli a7, a4, 4 # number of loop iterations with 16B |
|
# per iteration |
|
bnez a4, .Laligned |
|
abi_ret_default |
|
|
|
/* |
|
* Destination is word-aligned. |
|
*/ |
|
# set 16 bytes per iteration for word-aligned dst |
|
.align 4 # 1 mod 4 alignment for LOOPNEZ |
|
.byte 0 # (0 mod 4 alignment for LBEG) |
|
.Laligned: |
|
#if XCHAL_HAVE_LOOPS |
|
loopnez a7, .Loop1done |
|
#else /* !XCHAL_HAVE_LOOPS */ |
|
beqz a7, .Loop1done |
|
slli a6, a7, 4 |
|
add a6, a6, a5 # a6 = end of last 16B chunk |
|
#endif /* !XCHAL_HAVE_LOOPS */ |
|
.Loop1: |
|
EX(10f) s32i a3, a5, 0 |
|
EX(10f) s32i a3, a5, 4 |
|
EX(10f) s32i a3, a5, 8 |
|
EX(10f) s32i a3, a5, 12 |
|
addi a5, a5, 16 |
|
#if !XCHAL_HAVE_LOOPS |
|
blt a5, a6, .Loop1 |
|
#endif /* !XCHAL_HAVE_LOOPS */ |
|
.Loop1done: |
|
bbci.l a4, 3, .L2 |
|
# set 8 bytes |
|
EX(10f) s32i a3, a5, 0 |
|
EX(10f) s32i a3, a5, 4 |
|
addi a5, a5, 8 |
|
.L2: |
|
bbci.l a4, 2, .L3 |
|
# set 4 bytes |
|
EX(10f) s32i a3, a5, 0 |
|
addi a5, a5, 4 |
|
.L3: |
|
bbci.l a4, 1, .L4 |
|
# set 2 bytes |
|
EX(10f) s16i a3, a5, 0 |
|
addi a5, a5, 2 |
|
.L4: |
|
bbci.l a4, 0, .L5 |
|
# set 1 byte |
|
EX(10f) s8i a3, a5, 0 |
|
.L5: |
|
.Lret1: |
|
abi_ret_default |
|
|
|
/* |
|
* Destination is unaligned |
|
*/ |
|
|
|
.Ldstunaligned: |
|
bltui a4, 8, .Lbyteset # do short copies byte by byte |
|
bbci.l a5, 0, .L20 # branch if dst alignment half-aligned |
|
# dst is only byte aligned |
|
# set 1 byte |
|
EX(10f) s8i a3, a5, 0 |
|
addi a5, a5, 1 |
|
addi a4, a4, -1 |
|
# now retest if dst aligned |
|
bbci.l a5, 1, .L0 # if now aligned, return to main algorithm |
|
.L20: |
|
# dst half-aligned |
|
# set 2 bytes |
|
EX(10f) s16i a3, a5, 0 |
|
addi a5, a5, 2 |
|
addi a4, a4, -2 |
|
j .L0 # dst is now aligned, return to main algorithm |
|
|
|
/* |
|
* Byte by byte set |
|
*/ |
|
.align 4 |
|
.byte 0 # 1 mod 4 alignment for LOOPNEZ |
|
# (0 mod 4 alignment for LBEG) |
|
.Lbyteset: |
|
#if XCHAL_HAVE_LOOPS |
|
loopnez a4, .Lbytesetdone |
|
#else /* !XCHAL_HAVE_LOOPS */ |
|
beqz a4, .Lbytesetdone |
|
add a6, a5, a4 # a6 = ending address |
|
#endif /* !XCHAL_HAVE_LOOPS */ |
|
.Lbyteloop: |
|
EX(10f) s8i a3, a5, 0 |
|
addi a5, a5, 1 |
|
#if !XCHAL_HAVE_LOOPS |
|
blt a5, a6, .Lbyteloop |
|
#endif /* !XCHAL_HAVE_LOOPS */ |
|
.Lbytesetdone: |
|
abi_ret_default |
|
|
|
ENDPROC(__memset) |
|
|
|
.section .fixup, "ax" |
|
.align 4 |
|
|
|
/* We return zero if a failure occurred. */ |
|
|
|
10: |
|
movi a2, 0 |
|
abi_ret_default
|
|
|