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kernel/linux-imx6_3.14.28/arch/sh/lib/memcpy.S 3.56 KB
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  /* $Id: memcpy.S,v 1.3 2001/07/27 11:50:52 gniibe Exp $
   *
   * "memcpy" implementation of SuperH
   *
   * Copyright (C) 1999  Niibe Yutaka
   *
   */
  
  /*
   * void *memcpy(void *dst, const void *src, size_t n);
   * No overlap between the memory of DST and of SRC are assumed.
   */
  
  #include <linux/linkage.h>
  ENTRY(memcpy)
  	tst	r6,r6
  	bt/s	9f		! if n=0, do nothing
  	 mov	r4,r0
  	sub	r4,r5		! From here, r5 has the distance to r0
  	add	r6,r0		! From here, r0 points the end of copying point
  	mov	#12,r1
  	cmp/gt	r6,r1
  	bt/s	7f		! if it's too small, copy a byte at once
  	 add	#-1,r5
  	add	#1,r5
  	!			From here, r6 is free
  	!
  	!      r4   -->  [ ...  ] DST             [ ...  ] SRC
  	!	         [ ...  ]                 [ ...  ]
  	!	           :                        :
  	!      r0   -->  [ ...  ]       r0+r5 --> [ ...  ]
  	!
  	!
  	mov	r5,r1
  	mov	#3,r2
  	and	r2,r1
  	shll2	r1
  	mov	r0,r3		! Save the value on R0 to R3
  	mova	jmptable,r0
  	add	r1,r0
  	mov.l	@r0,r1
  	jmp	@r1
  	 mov	r3,r0		! and back to R0
  	.balign	4
  jmptable:
  	.long	case0
  	.long	case1
  	.long	case2
  	.long	case3
  
  	! copy a byte at once
  7:	mov	r4,r2
  	add	#1,r2
  8:
  	cmp/hi	r2,r0
  	mov.b	@(r0,r5),r1
  	bt/s	8b			! while (r0>r2)
  	 mov.b	r1,@-r0
  9:
  	rts
  	 nop
  
  case0:
  	!
  	!	GHIJ KLMN OPQR -->  GHIJ KLMN OPQR
  	!
  	! First, align to long word boundary
  	mov	r0,r3
  	and	r2,r3
  	tst	r3,r3
  	bt/s	2f
  	 add	#-4,r5
  	add	#3,r5
  1:	dt	r3
  	mov.b	@(r0,r5),r1
  	bf/s	1b
  	 mov.b	r1,@-r0
  	!
  	add	#-3,r5
  2:	! Second, copy a long word at once
  	mov	r4,r2
  	add	#7,r2
  3:	mov.l	@(r0,r5),r1
  	cmp/hi	r2,r0
  	bt/s	3b
  	 mov.l	r1,@-r0
  	!
  	! Third, copy a byte at once, if necessary
  	cmp/eq	r4,r0
  	bt/s	9b
  	 add	#3,r5
  	bra	8b
  	 add	#-6,r2
  
  case1:
  	!
  	!	GHIJ KLMN OPQR -->  ...G HIJK LMNO PQR.
  	!
  	! First, align to long word boundary
  	mov	r0,r3
  	and	r2,r3
  	tst	r3,r3
  	bt/s	2f
  	 add	#-1,r5
  1:	dt	r3
  	mov.b	@(r0,r5),r1
  	bf/s	1b
  	 mov.b	r1,@-r0
  	!
  2:	! Second, read a long word and write a long word at once
  	mov.l	@(r0,r5),r1
  	add	#-4,r5
  	mov	r4,r2
  	add	#7,r2
  	!
  #ifdef __LITTLE_ENDIAN__
  3:	mov	r1,r3		! RQPO
  	shll16	r3
  	shll8	r3		! Oxxx
  	mov.l	@(r0,r5),r1	! NMLK
  	mov	r1,r6
  	shlr8	r6		! xNML
  	or	r6,r3		! ONML
  	cmp/hi	r2,r0
  	bt/s	3b
  	 mov.l	r3,@-r0
  #else
  3:	mov	r1,r3		! OPQR
  	shlr16	r3
  	shlr8	r3		! xxxO
  	mov.l	@(r0,r5),r1	! KLMN
  	mov	r1,r6
  	shll8	r6		! LMNx
  	or	r6,r3		! LMNO
  	cmp/hi	r2,r0
  	bt/s	3b
  	 mov.l	r3,@-r0
  #endif
  	!
  	! Third, copy a byte at once, if necessary
  	cmp/eq	r4,r0
  	bt/s	9b
  	 add	#4,r5
  	bra	8b
  	 add	#-6,r2
  
  case2:
  	!
  	!	GHIJ KLMN OPQR -->  ..GH IJKL MNOP QR..
  	!
  	! First, align to word boundary
  	tst	#1,r0
  	bt/s	2f
  	 add	#-1,r5
  	mov.b	@(r0,r5),r1
  	mov.b	r1,@-r0
  	!
  2:	! Second, read a word and write a word at once
  	add	#-1,r5
  	mov	r4,r2
  	add	#3,r2
  	!
  3:	mov.w	@(r0,r5),r1
  	cmp/hi	r2,r0
  	bt/s	3b
  	 mov.w	r1,@-r0
  	!
  	! Third, copy a byte at once, if necessary
  	cmp/eq	r4,r0
  	bt/s	9b
  	 add	#1,r5
  	mov.b	@(r0,r5),r1
  	rts
  	 mov.b	r1,@-r0
  
  case3:
  	!
  	!	GHIJ KLMN OPQR -->  .GHI JKLM NOPQ R...
  	!
  	! First, align to long word boundary
  	mov	r0,r3
  	and	r2,r3
  	tst	r3,r3
  	bt/s	2f
  	 add	#-1,r5
  1:	dt	r3
  	mov.b	@(r0,r5),r1
  	bf/s	1b
  	 mov.b	r1,@-r0
  	!
  2:	! Second, read a long word and write a long word at once
  	add	#-2,r5
  	mov.l	@(r0,r5),r1
  	add	#-4,r5
  	mov	r4,r2
  	add	#7,r2
  	!
  #ifdef __LITTLE_ENDIAN__
  3:	mov	r1,r3		! RQPO
  	shll8	r3		! QPOx
  	mov.l	@(r0,r5),r1	! NMLK
  	mov	r1,r6
  	shlr16	r6
  	shlr8	r6		! xxxN
  	or	r6,r3		! QPON
  	cmp/hi	r2,r0
  	bt/s	3b
  	 mov.l	r3,@-r0
  #else
  3:	mov	r1,r3		! OPQR
  	shlr8	r3		! xOPQ
  	mov.l	@(r0,r5),r1	! KLMN
  	mov	r1,r6
  	shll16	r6
  	shll8	r6		! Nxxx
  	or	r6,r3		! NOPQ
  	cmp/hi	r2,r0
  	bt/s	3b
  	 mov.l	r3,@-r0
  #endif
  	!
  	! Third, copy a byte at once, if necessary
  	cmp/eq	r4,r0
  	bt/s	9b
  	 add	#6,r5
  	bra	8b
  	 add	#-6,r2