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.
160 lines
3.8 KiB
160 lines
3.8 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 <variant/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).
|
|
*/
|
|
|
|
/* Load or store instructions that may cause exceptions use the EX macro. */
|
|
|
|
#define EX(insn,reg1,reg2,offset,handler) \
|
|
9: insn reg1, reg2, offset; \
|
|
.section __ex_table, "a"; \
|
|
.word 9b, handler; \
|
|
.previous
|
|
|
|
|
|
.text
|
|
.align 4
|
|
.global memset
|
|
.type memset,@function
|
|
memset:
|
|
entry sp, 16 # minimal stack frame
|
|
# 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
|
|
retw
|
|
|
|
/*
|
|
* 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(s32i, a3, a5, 0, memset_fixup)
|
|
EX(s32i, a3, a5, 4, memset_fixup)
|
|
EX(s32i, a3, a5, 8, memset_fixup)
|
|
EX(s32i, a3, a5, 12, memset_fixup)
|
|
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(s32i, a3, a5, 0, memset_fixup)
|
|
EX(s32i, a3, a5, 4, memset_fixup)
|
|
addi a5, a5, 8
|
|
.L2:
|
|
bbci.l a4, 2, .L3
|
|
# set 4 bytes
|
|
EX(s32i, a3, a5, 0, memset_fixup)
|
|
addi a5, a5, 4
|
|
.L3:
|
|
bbci.l a4, 1, .L4
|
|
# set 2 bytes
|
|
EX(s16i, a3, a5, 0, memset_fixup)
|
|
addi a5, a5, 2
|
|
.L4:
|
|
bbci.l a4, 0, .L5
|
|
# set 1 byte
|
|
EX(s8i, a3, a5, 0, memset_fixup)
|
|
.L5:
|
|
.Lret1:
|
|
retw
|
|
|
|
/*
|
|
* 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(s8i, a3, a5, 0, memset_fixup)
|
|
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(s16i, a3, a5, 0, memset_fixup)
|
|
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(s8i, a3, a5, 0, memset_fixup)
|
|
addi a5, a5, 1
|
|
#if !XCHAL_HAVE_LOOPS
|
|
blt a5, a6, .Lbyteloop
|
|
#endif /* !XCHAL_HAVE_LOOPS */
|
|
.Lbytesetdone:
|
|
retw
|
|
|
|
|
|
.section .fixup, "ax"
|
|
.align 4
|
|
|
|
/* We return zero if a failure occurred. */
|
|
|
|
memset_fixup:
|
|
movi a2, 0
|
|
retw
|
|
|