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