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memcopy.S
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/*
* arch/xtensa/lib/hal/memcopy.S -- Core HAL library functions
* xthal_memcpy and xthal_bcopy
*
* 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 - 2012 Tensilica Inc.
*/
#include <linux/linkage.h>
#include <asm/asmmacro.h>
#include <asm/core.h>
/*
* void *memcpy(void *dst, const void *src, size_t len);
*
* This function is intended to do the same thing as the standard
* library function memcpy() for most cases.
* However, where the source and/or destination references
* an instruction RAM or ROM or a data RAM or ROM, that
* source and/or destination will always be accessed with
* 32-bit load and store instructions (as required for these
* types of devices).
*
* !!!!!!! XTFIXME:
* !!!!!!! Handling of IRAM/IROM has not yet
* !!!!!!! been implemented.
*
* The (general case) algorithm is as follows:
* If destination is unaligned, align it by conditionally
* copying 1 and 2 bytes.
* If source is aligned,
* do 16 bytes with a loop, and then finish up with
* 8, 4, 2, and 1 byte copies conditional on the length;
* else (if source is unaligned),
* do the same, but use SRC to align the source data.
* This code tries to use fall-through branches for the common
* case of aligned source and destination and multiple
* of 4 (or 8) length.
*
* Register use:
* a0/ return address
* a1/ stack pointer
* a2/ return value
* a3/ src
* a4/ length
* a5/ dst
* a6/ tmp
* a7/ tmp
* a8/ tmp
* a9/ tmp
* a10/ tmp
* a11/ tmp
*/
.text
/*
* Byte by byte copy
*/
.align 4
.byte 0 # 1 mod 4 alignment for LOOPNEZ
# (0 mod 4 alignment for LBEG)
.Lbytecopy:
#if XCHAL_HAVE_LOOPS
loopnez a4, .Lbytecopydone
#else /* !XCHAL_HAVE_LOOPS */
beqz a4, .Lbytecopydone
add a7, a3, a4 # a7 = end address for source
#endif /* !XCHAL_HAVE_LOOPS */
.Lnextbyte:
l8ui a6, a3, 0
addi a3, a3, 1
s8i a6, a5, 0
addi a5, a5, 1
#if !XCHAL_HAVE_LOOPS
bne a3, a7, .Lnextbyte # continue loop if $a3:src != $a7:src_end
#endif /* !XCHAL_HAVE_LOOPS */
.Lbytecopydone:
abi_ret_default
/*
* Destination is unaligned
*/
.align 4
.Ldst1mod2: # dst is only byte aligned
_bltui a4, 7, .Lbytecopy # do short copies byte by byte
# copy 1 byte
l8ui a6, a3, 0
addi a3, a3, 1
addi a4, a4, -1
s8i a6, a5, 0
addi a5, a5, 1
_bbci.l a5, 1, .Ldstaligned # if dst is now aligned, then
# return to main algorithm
.Ldst2mod4: # dst 16-bit aligned
# copy 2 bytes
_bltui a4, 6, .Lbytecopy # do short copies byte by byte
l8ui a6, a3, 0
l8ui a7, a3, 1
addi a3, a3, 2
addi a4, a4, -2
s8i a6, a5, 0
s8i a7, a5, 1
addi a5, a5, 2
j .Ldstaligned # dst is now aligned, return to main algorithm
ENTRY(__memcpy)
WEAK(memcpy)
abi_entry_default
# a2/ dst, a3/ src, a4/ len
mov a5, a2 # copy dst so that a2 is return value
.Lcommon:
_bbsi.l a2, 0, .Ldst1mod2 # if dst is 1 mod 2
_bbsi.l a2, 1, .Ldst2mod4 # if dst is 2 mod 4
.Ldstaligned: # return here from .Ldst?mod? once dst is aligned
srli a7, a4, 4 # number of loop iterations with 16B
# per iteration
movi a8, 3 # if source is not aligned,
_bany a3, a8, .Lsrcunaligned # then use shifting copy
/*
* Destination and source are word-aligned, use word copy.
*/
# copy 16 bytes per iteration for word-aligned dst and word-aligned src
#if XCHAL_HAVE_LOOPS
loopnez a7, .Loop1done
#else /* !XCHAL_HAVE_LOOPS */
beqz a7, .Loop1done
slli a8, a7, 4
add a8, a8, a3 # a8 = end of last 16B source chunk
#endif /* !XCHAL_HAVE_LOOPS */
.Loop1:
l32i a6, a3, 0
l32i a7, a3, 4
s32i a6, a5, 0
l32i a6, a3, 8
s32i a7, a5, 4
l32i a7, a3, 12
s32i a6, a5, 8
addi a3, a3, 16
s32i a7, a5, 12
addi a5, a5, 16
#if !XCHAL_HAVE_LOOPS
bne a3, a8, .Loop1 # continue loop if a3:src != a8:src_end
#endif /* !XCHAL_HAVE_LOOPS */
.Loop1done:
bbci.l a4, 3, .L2
# copy 8 bytes
l32i a6, a3, 0
l32i a7, a3, 4
addi a3, a3, 8
s32i a6, a5, 0
s32i a7, a5, 4
addi a5, a5, 8
.L2:
bbsi.l a4, 2, .L3
bbsi.l a4, 1, .L4
bbsi.l a4, 0, .L5
abi_ret_default
.L3:
# copy 4 bytes
l32i a6, a3, 0
addi a3, a3, 4
s32i a6, a5, 0
addi a5, a5, 4
bbsi.l a4, 1, .L4
bbsi.l a4, 0, .L5
abi_ret_default
.L4:
# copy 2 bytes
l16ui a6, a3, 0
addi a3, a3, 2
s16i a6, a5, 0
addi a5, a5, 2
bbsi.l a4, 0, .L5
abi_ret_default
.L5:
# copy 1 byte
l8ui a6, a3, 0
s8i a6, a5, 0
abi_ret_default
/*
* Destination is aligned, Source is unaligned
*/
.align 4
.Lsrcunaligned:
_beqz a4, .Ldone # avoid loading anything for zero-length copies
# copy 16 bytes per iteration for word-aligned dst and unaligned src
__ssa8 a3 # set shift amount from byte offset
/* set to 1 when running on ISS (simulator) with the
lint or ferret client, or 0 to save a few cycles */
#define SIM_CHECKS_ALIGNMENT 1
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
and a11, a3, a8 # save unalignment offset for below
sub a3, a3, a11 # align a3
#endif
l32i a6, a3, 0 # load first word
#if XCHAL_HAVE_LOOPS
loopnez a7, .Loop2done
#else /* !XCHAL_HAVE_LOOPS */
beqz a7, .Loop2done
slli a10, a7, 4
add a10, a10, a3 # a10 = end of last 16B source chunk
#endif /* !XCHAL_HAVE_LOOPS */
.Loop2:
l32i a7, a3, 4
l32i a8, a3, 8
__src_b a6, a6, a7
s32i a6, a5, 0
l32i a9, a3, 12
__src_b a7, a7, a8
s32i a7, a5, 4
l32i a6, a3, 16
__src_b a8, a8, a9
s32i a8, a5, 8
addi a3, a3, 16
__src_b a9, a9, a6
s32i a9, a5, 12
addi a5, a5, 16
#if !XCHAL_HAVE_LOOPS
bne a3, a10, .Loop2 # continue loop if a3:src != a10:src_end
#endif /* !XCHAL_HAVE_LOOPS */
.Loop2done:
bbci.l a4, 3, .L12
# copy 8 bytes
l32i a7, a3, 4
l32i a8, a3, 8
__src_b a6, a6, a7
s32i a6, a5, 0
addi a3, a3, 8
__src_b a7, a7, a8
s32i a7, a5, 4
addi a5, a5, 8
mov a6, a8
.L12:
bbci.l a4, 2, .L13
# copy 4 bytes
l32i a7, a3, 4
addi a3, a3, 4
__src_b a6, a6, a7
s32i a6, a5, 0
addi a5, a5, 4
mov a6, a7
.L13:
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
add a3, a3, a11 # readjust a3 with correct misalignment
#endif
bbsi.l a4, 1, .L14
bbsi.l a4, 0, .L15
.Ldone: abi_ret_default
.L14:
# copy 2 bytes
l8ui a6, a3, 0
l8ui a7, a3, 1
addi a3, a3, 2
s8i a6, a5, 0
s8i a7, a5, 1
addi a5, a5, 2
bbsi.l a4, 0, .L15
abi_ret_default
.L15:
# copy 1 byte
l8ui a6, a3, 0
s8i a6, a5, 0
abi_ret_default
ENDPROC(__memcpy)
/*
* void bcopy(const void *src, void *dest, size_t n);
*/
ENTRY(bcopy)
abi_entry_default
# a2=src, a3=dst, a4=len
mov a5, a3
mov a3, a2
mov a2, a5
j .Lmovecommon # go to common code for memmove+bcopy
ENDPROC(bcopy)
/*
* void *memmove(void *dst, const void *src, size_t len);
*
* This function is intended to do the same thing as the standard
* library function memmove() for most cases.
* However, where the source and/or destination references
* an instruction RAM or ROM or a data RAM or ROM, that
* source and/or destination will always be accessed with
* 32-bit load and store instructions (as required for these
* types of devices).
*
* !!!!!!! XTFIXME:
* !!!!!!! Handling of IRAM/IROM has not yet
* !!!!!!! been implemented.
*
* The (general case) algorithm is as follows:
* If end of source doesn't overlap destination then use memcpy.
* Otherwise do memcpy backwards.
*
* Register use:
* a0/ return address
* a1/ stack pointer
* a2/ return value
* a3/ src
* a4/ length
* a5/ dst
* a6/ tmp
* a7/ tmp
* a8/ tmp
* a9/ tmp
* a10/ tmp
* a11/ tmp
*/
/*
* Byte by byte copy
*/
.align 4
.byte 0 # 1 mod 4 alignment for LOOPNEZ
# (0 mod 4 alignment for LBEG)
.Lbackbytecopy:
#if XCHAL_HAVE_LOOPS
loopnez a4, .Lbackbytecopydone
#else /* !XCHAL_HAVE_LOOPS */
beqz a4, .Lbackbytecopydone
sub a7, a3, a4 # a7 = start address for source
#endif /* !XCHAL_HAVE_LOOPS */
.Lbacknextbyte:
addi a3, a3, -1
l8ui a6, a3, 0
addi a5, a5, -1
s8i a6, a5, 0
#if !XCHAL_HAVE_LOOPS
bne a3, a7, .Lbacknextbyte # continue loop if
# $a3:src != $a7:src_start
#endif /* !XCHAL_HAVE_LOOPS */
.Lbackbytecopydone:
abi_ret_default
/*
* Destination is unaligned
*/
.align 4
.Lbackdst1mod2: # dst is only byte aligned
_bltui a4, 7, .Lbackbytecopy # do short copies byte by byte
# copy 1 byte
addi a3, a3, -1
l8ui a6, a3, 0
addi a5, a5, -1
s8i a6, a5, 0
addi a4, a4, -1
_bbci.l a5, 1, .Lbackdstaligned # if dst is now aligned, then
# return to main algorithm
.Lbackdst2mod4: # dst 16-bit aligned
# copy 2 bytes
_bltui a4, 6, .Lbackbytecopy # do short copies byte by byte
addi a3, a3, -2
l8ui a6, a3, 0
l8ui a7, a3, 1
addi a5, a5, -2
s8i a6, a5, 0
s8i a7, a5, 1
addi a4, a4, -2
j .Lbackdstaligned # dst is now aligned,
# return to main algorithm
ENTRY(__memmove)
WEAK(memmove)
abi_entry_default
# a2/ dst, a3/ src, a4/ len
mov a5, a2 # copy dst so that a2 is return value
.Lmovecommon:
sub a6, a5, a3
bgeu a6, a4, .Lcommon
add a5, a5, a4
add a3, a3, a4
_bbsi.l a5, 0, .Lbackdst1mod2 # if dst is 1 mod 2
_bbsi.l a5, 1, .Lbackdst2mod4 # if dst is 2 mod 4
.Lbackdstaligned: # return here from .Lbackdst?mod? once dst is aligned
srli a7, a4, 4 # number of loop iterations with 16B
# per iteration
movi a8, 3 # if source is not aligned,
_bany a3, a8, .Lbacksrcunaligned # then use shifting copy
/*
* Destination and source are word-aligned, use word copy.
*/
# copy 16 bytes per iteration for word-aligned dst and word-aligned src
#if XCHAL_HAVE_LOOPS
loopnez a7, .backLoop1done
#else /* !XCHAL_HAVE_LOOPS */
beqz a7, .backLoop1done
slli a8, a7, 4
sub a8, a3, a8 # a8 = start of first 16B source chunk
#endif /* !XCHAL_HAVE_LOOPS */
.backLoop1:
addi a3, a3, -16
l32i a7, a3, 12
l32i a6, a3, 8
addi a5, a5, -16
s32i a7, a5, 12
l32i a7, a3, 4
s32i a6, a5, 8
l32i a6, a3, 0
s32i a7, a5, 4
s32i a6, a5, 0
#if !XCHAL_HAVE_LOOPS
bne a3, a8, .backLoop1 # continue loop if a3:src != a8:src_start
#endif /* !XCHAL_HAVE_LOOPS */
.backLoop1done:
bbci.l a4, 3, .Lback2
# copy 8 bytes
addi a3, a3, -8
l32i a6, a3, 0
l32i a7, a3, 4
addi a5, a5, -8
s32i a6, a5, 0
s32i a7, a5, 4
.Lback2:
bbsi.l a4, 2, .Lback3
bbsi.l a4, 1, .Lback4
bbsi.l a4, 0, .Lback5
abi_ret_default
.Lback3:
# copy 4 bytes
addi a3, a3, -4
l32i a6, a3, 0
addi a5, a5, -4
s32i a6, a5, 0
bbsi.l a4, 1, .Lback4
bbsi.l a4, 0, .Lback5
abi_ret_default
.Lback4:
# copy 2 bytes
addi a3, a3, -2
l16ui a6, a3, 0
addi a5, a5, -2
s16i a6, a5, 0
bbsi.l a4, 0, .Lback5
abi_ret_default
.Lback5:
# copy 1 byte
addi a3, a3, -1
l8ui a6, a3, 0
addi a5, a5, -1
s8i a6, a5, 0
abi_ret_default
/*
* Destination is aligned, Source is unaligned
*/
.align 4
.Lbacksrcunaligned:
_beqz a4, .Lbackdone # avoid loading anything for zero-length copies
# copy 16 bytes per iteration for word-aligned dst and unaligned src
__ssa8 a3 # set shift amount from byte offset
#define SIM_CHECKS_ALIGNMENT 1 /* set to 1 when running on ISS with
* the lint or ferret client, or 0
* to save a few cycles */
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
and a11, a3, a8 # save unalignment offset for below
sub a3, a3, a11 # align a3
#endif
l32i a6, a3, 0 # load first word
#if XCHAL_HAVE_LOOPS
loopnez a7, .backLoop2done
#else /* !XCHAL_HAVE_LOOPS */
beqz a7, .backLoop2done
slli a10, a7, 4
sub a10, a3, a10 # a10 = start of first 16B source chunk
#endif /* !XCHAL_HAVE_LOOPS */
.backLoop2:
addi a3, a3, -16
l32i a7, a3, 12
l32i a8, a3, 8
addi a5, a5, -16
__src_b a6, a7, a6
s32i a6, a5, 12
l32i a9, a3, 4
__src_b a7, a8, a7
s32i a7, a5, 8
l32i a6, a3, 0
__src_b a8, a9, a8
s32i a8, a5, 4
__src_b a9, a6, a9
s32i a9, a5, 0
#if !XCHAL_HAVE_LOOPS
bne a3, a10, .backLoop2 # continue loop if a3:src != a10:src_start
#endif /* !XCHAL_HAVE_LOOPS */
.backLoop2done:
bbci.l a4, 3, .Lback12
# copy 8 bytes
addi a3, a3, -8
l32i a7, a3, 4
l32i a8, a3, 0
addi a5, a5, -8
__src_b a6, a7, a6
s32i a6, a5, 4
__src_b a7, a8, a7
s32i a7, a5, 0
mov a6, a8
.Lback12:
bbci.l a4, 2, .Lback13
# copy 4 bytes
addi a3, a3, -4
l32i a7, a3, 0
addi a5, a5, -4
__src_b a6, a7, a6
s32i a6, a5, 0
mov a6, a7
.Lback13:
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
add a3, a3, a11 # readjust a3 with correct misalignment
#endif
bbsi.l a4, 1, .Lback14
bbsi.l a4, 0, .Lback15
.Lbackdone:
abi_ret_default
.Lback14:
# copy 2 bytes
addi a3, a3, -2
l8ui a6, a3, 0
l8ui a7, a3, 1
addi a5, a5, -2
s8i a6, a5, 0
s8i a7, a5, 1
bbsi.l a4, 0, .Lback15
abi_ret_default
.Lback15:
# copy 1 byte
addi a3, a3, -1
addi a5, a5, -1
l8ui a6, a3, 0
s8i a6, a5, 0
abi_ret_default
ENDPROC(__memmove)