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/*
 * memmove routine for Z8000
 * Copyright (C) 2004 Christian Groessler <chris@groessler.org>
 *
 * Permission to use, copy, modify, and distribute this file
 * for any purpose is hereby granted without fee, provided that
 * the above copyright notice and this notice appears in all
 * copies.
 *
 * This file is distributed WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 */

/* void *memmove(void *dest, const void *src, size_t length);
 */

        name    "memmove.S"

        .text
        even
global  _memmove

_memmove:

#ifdef __Z8001__
        segm

#ifdef __STD_CALL__
        ldl     rr6,rr14(#4)
        ldl     rr4,rr14(#8)
        ldl     rr2,rr14(#12)
#else
        pushl   @rr14,rr6
#endif

/* rr2  - length        (high word ignored)
 * rr4  - src
 * rr6  - dest
 */

        testl   rr2
        jr      z,finish

/*  check for destructive overlap (src < dest && dest < src + length) */

        cpl     rr6,rr4
        jp      ule,memmove_entry       /* non-destructive, let memcpy do the work */
        ldl     rr0,rr2
        addl    rr0,rr4                 /* rr0 = src + length */
        cpl     rr0,rr6
        jp      ult,memmove_entry       /* non-destructive, let memcpy do the work */

/* set-up pointers to copy backwards, add (length - 1) */
        addl    rr4,rr2                 /* src + length */
        addl    rr6,rr2                 /* dest + length */
        subl    rr4,#1
        subl    rr6,#1

/* check alignment */
        bitb    rl7,#0          /* odd destination address? */
        jr      z,testsrc
        bitb    rl5,#0          /* odd source address? */
        jr      z,odd_copy
        jr      even_copy

testsrc:
        bitb    rl5,#0
        jr      nz,odd_copy     /* src even, dest odd */
        lddb    @rr6,@rr4,r3
        jr      ov,finish       /* jump if r5 is zero now */

/* copy words */
even_copy:
        ld      r2,r3                   /* remember length */
        srl     r3,#1
/*      jr      z,no_words         it cannot be zero here */

        dec     r5,#1
        dec     r7,#1
        lddr    @rr6,@rr4,r3

no_words:
        bitb    rl2,#0          /* odd length? */
        jr      z,finish
        inc     r5,#1
        inc     r7,#1
        lddb    @rr6,@rr4,r2    /* yes, copy last byte */
        jr      finish

/* copy bytes */
odd_copy:
        lddrb   @rr6,@rr4,r3

finish:
#ifdef __STD_CALL__
        ldl     rr6,rr14(#4)
#else
        popl    rr2,@rr14
#endif


#else           /* above Z8001, below Z8002 */


        unsegm

#ifdef __STD_CALL__
        ld      r7,r15(#2)
        ld      r6,r15(#4)
        ld      r5,r15(#6)
#else
        ld      r2,r7           /* buffer pointer return value */
#endif

/* r5  - length
 * r6  - src
 * r7  - dest
 */
        test    r5
        jr      z,finish

/*  check for destructive overlap (src < dest && dest < src + length) */

        cp      r7,r6
        jp      ule,memmove_entry       /* non-destructive, let memcpy do the work */
        ld      r0,r5
        add     r0,r6                   /* r0 = src + length */
        cp      r0,r7
        jp      ult,memmove_entry       /* non-destructive, let memcpy do the work */

/* set-up pointers to copy backwards, add (length - 1) */
        add     r6,r5                   /* src + length */
        add     r7,r5                   /* dest + length */
        dec     r6,#1
        dec     r7,#1

/* check alignment */
        bitb    rl7,#0          /* odd destination address? */
        jr      z,testsrc
        bitb    rl6,#0          /* odd source address? */
        jr      z,odd_copy
        jr      even_copy

testsrc:
        bitb    rl6,#0
        jr      nz,odd_copy     /* src even, dest odd */
        lddb    @r7,@r6,r5
        jr      ov,finish       /* jump if r5 is zero now */

/* copy words */
even_copy:
        ld      r4,r5           /* remember length */
        srl     r5,#1
/*      jr      z,no_words         it cannot be zero here */

        dec     r6,#1
        dec     r7,#1
        lddr    @r7,@r6,r5

no_words:
        bitb    rl4,#0          /* odd length? */
        jr      z,finish
        inc     r6,#1
        inc     r7,#1
        lddb    @r7,@r6,r4      /* yes, copy last byte */
        jr      finish

/* copy bytes */
odd_copy:
        lddrb   @r7,@r6,r5

finish:
#ifdef __STD_CALL__
        ld      r7,r15(#2)
#endif

#endif  /* Z8002 */

        ret
        .end