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Commit eae8a416 authored by Chris Zankel's avatar Chris Zankel
Browse files

xtensa: fix memmove(), bcopy(), and memcpy(). 



- fix memmove to correctly handle overlapping src and dst;
- fix memcpy loop ending conditions from signed '<=' to '!=';
- modify bcopy to call memmove;

Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: default avatarChris Zankel <chris@zankel.net>
parent c88d8df0

arch/xtensa/lib/memcopy.S

+284 −25
Original line number Diff line number Diff line
@@ -6,7 +6,7 @@ 
 * License.  See the file "COPYING" in the main directory of this archive

 * for more details.

 *

 * Copyright (C) 2002 - 2005 Tensilica Inc.

 * Copyright (C) 2002 - 2012 Tensilica Inc.

 */



#include <variant/core.h>
@@ -27,14 +27,11 @@ 
#endif

	.endm





/*

 * void *memcpy(void *dst, const void *src, size_t len);

 * void *memmove(void *dst, const void *src, size_t len);

 * void *bcopy(const void *src, void *dst, size_t len);

 *

 * This function is intended to do the same thing as the standard

 * library function memcpy() (or bcopy()) for most cases.

 * 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
@@ -45,9 +42,6 @@ 
 * !!!!!!!  Handling of IRAM/IROM has not yet

 * !!!!!!!  been implemented.

 *

 * The bcopy version is provided here to avoid the overhead

 * of an extra call, for callers that require this convention.

 *

 * The (general case) algorithm is as follows:

 *   If destination is unaligned, align it by conditionally

 *     copying 1 and 2 bytes.
@@ -76,17 +70,6 @@ 
 */



	.text

	.align	4

	.global	bcopy

	.type   bcopy,@function

bcopy:

	entry	sp, 16		# minimal stack frame

	# a2=src, a3=dst, a4=len

	mov	a5, a3		# copy dst so that a2 is return value

	mov	a3, a2

	mov	a2, a5

	j	.Lcommon	# go to common code for memcpy+bcopy





/*

 * Byte by byte copy
@@ -107,7 +90,7 @@ bcopy: 
	s8i	a6, a5, 0

	addi	a5, a5, 1

#if !XCHAL_HAVE_LOOPS

	blt	a3, a7, .Lnextbyte

	bne	a3, a7, .Lnextbyte # continue loop if $a3:src != $a7:src_end

#endif /* !XCHAL_HAVE_LOOPS */

.Lbytecopydone:

	retw
@@ -144,9 +127,6 @@ bcopy: 
	.global	memcpy

	.type   memcpy,@function

memcpy:

	.global	memmove

	.type   memmove,@function

memmove:



	entry	sp, 16		# minimal stack frame

	# a2/ dst, a3/ src, a4/ len
@@ -182,7 +162,7 @@ memmove: 
	s32i	a7, a5, 12

	addi	a5, a5, 16

#if !XCHAL_HAVE_LOOPS

	blt	a3, a8, .Loop1

	bne	a3, a8, .Loop1  # continue loop if a3:src != a8:src_end

#endif /* !XCHAL_HAVE_LOOPS */

.Loop1done:

	bbci.l	a4, 3, .L2
@@ -260,7 +240,7 @@ memmove: 
	s32i	a9, a5, 12

	addi	a5, a5, 16

#if !XCHAL_HAVE_LOOPS

	blt	a3, a10, .Loop2

	bne	a3, a10, .Loop2 # continue loop if a3:src != a10:src_end

#endif /* !XCHAL_HAVE_LOOPS */

.Loop2done:

	bbci.l	a4, 3, .L12
@@ -305,6 +285,285 @@ memmove: 
	l8ui	a6, a3,  0

	s8i	a6, a5,  0

	retw





/*

 * void bcopy(const void *src, void *dest, size_t n);

 */

	.align	4

	.global	bcopy

	.type   bcopy,@function

bcopy:

	entry	sp, 16		# minimal stack frame

	# a2=src, a3=dst, a4=len

	mov	a5, a3

	mov	a3, a2

	mov	a2, a5

	j	.Lmovecommon	# go to common code for memmove+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:

	retw



/*

 * 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



	.align	4

	.global	memmove

	.type   memmove,@function

memmove:



	entry	sp, 16		# minimal stack frame

	# 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

	retw

.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

	retw

.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

	retw

.Lback5:

	# copy 1 byte

	addi	a3, a3, -1

	l8ui	a6, a3,  0

	addi	a5, a5, -1

	s8i	a6, a5,  0

	retw



/*

 * 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:

	retw

.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

	retw

.Lback15:

	# copy 1 byte

	addi	a3, a3, -1

	addi	a5, a5, -1

	l8ui	a6, a3,  0

	s8i	a6, a5,  0

	retw





/*

 * Local Variables: