/* $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