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kernel/linux-imx6_3.14.28/arch/xtensa/lib/memcopy.S 12.5 KB
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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 <variant/core.h>
  
  	.macro	src_b	r, w0, w1
  #ifdef __XTENSA_EB__
  	src	\r, \w0, \w1
  #else
  	src	\r, \w1, \w0
  #endif
  	.endm
  
  	.macro	ssa8	r
  #ifdef __XTENSA_EB__
  	ssa8b	\r
  #else
  	ssa8l	\r
  #endif
  	.endm
  
  /*
   * 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:
  	retw
  
  /*
   * 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
  
  	.align	4
  	.global	memcpy
  	.type   memcpy,@function
  memcpy:
  
  	entry	sp, 16		# minimal stack frame
  	# 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
  	retw
  .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
  	retw
  .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
  	retw
  .L5:
  	# copy 1 byte
  	l8ui	a6, a3,  0
  	s8i	a6, a5,  0
  	retw
  
  /*
   * 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:	retw
  .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
  	retw
  .L15:
  	# copy 1 byte
  	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:
   * mode:fundamental
   * comment-start: "# "
   * comment-start-skip: "# *"
   * End:
   */