mirror of
https://github.com/autc04/Retro68.git
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186 lines
2.8 KiB
ArmAsm
186 lines
2.8 KiB
ArmAsm
/*
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* memcmp routine for Z8000
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* Copyright (C) 2004 Christian Groessler <chris@groessler.org>
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*
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* Permission to use, copy, modify, and distribute this file
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* for any purpose is hereby granted without fee, provided that
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* the above copyright notice and this notice appears in all
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* copies.
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*
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* This file is distributed WITHOUT ANY WARRANTY; without even the implied
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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/* int memcmp(const void *b1, const void *b2, size_t length);
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*/
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name "memcmp.S"
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.text
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even
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global _memcmp
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_memcmp:
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#ifdef __Z8001__
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segm
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#ifdef __STD_CALL__
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ldl rr6,rr14(#4)
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ldl rr4,rr14(#8)
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ldl rr2,rr14(#12)
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#endif
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/* rr2 - length (high word ignored)
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* rr4 - b2
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* rr6 - b1
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*/
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clr r1 /* initialize return value */
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testl rr2
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jr z,finish
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bitb rl7,#0 /* odd b1? */
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jr nz,testb2
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bitb rl5,#0 /* odd b2? */
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jr nz,odd_cmp /* b1 even, b2 odd */
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jr t,even_cmp
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testb2:
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bitb rl5,#0
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jr z,odd_cmp /* b2 even, b1 odd */
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cpsib @rr6,@rr4,r3,eq
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jr z,beq /* bytes are the same */
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jr t,byte_diff
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beq: jr ov,finish /* jump if r3 is zero now */
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/* compare words */
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even_cmp:
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ld r2,r3 /* remember length */
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srl r3,#1
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jr z,no_words
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cpsir @rr6,@rr4,r3,ne
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jr nz,no_words
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dec r7,#2
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dec r5,#2 /* point to different bytes */
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ldk r3,#2
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jr t,odd_cmp
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no_words:
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bitb rl2,#0 /* odd length? */
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jr z,finish
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cpsib @rr6,@rr4,r3,eq
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jr z,finish /* last bytes are the same */
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jr t,byte_diff
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/* compare bytes */
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odd_cmp:
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cpsirb @rr6,@rr4,r3,ne
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jr nz,finish
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byte_diff:
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dec r7,#1
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dec r5,#1 /* point to different bytes */
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ldb rl1,@rr6
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clr r0
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ldb rl0,@rr4
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sub r1,r0
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finish: /* set return value */
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#ifdef __STD_CALL__
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ld r7,r1
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#else
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ld r2,r1
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#endif
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#else /* above Z8001, below Z8002 */
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unsegm
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#ifdef __STD_CALL__
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ld r7,r15(#2)
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ld r6,r15(#4)
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ld r5,r15(#6)
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#endif
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/* r5 - length
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* r6 - b2
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* r7 - b1
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*/
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clr r1 /* initialize return value */
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test r5
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jr z,finish
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bitb rl7,#0 /* odd destination address? */
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jr nz,testb2
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bitb rl6,#0 /* odd source address? */
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jr nz,odd_cmp /* b1 even, b2 odd */
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jr t,even_cmp
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testb2:
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bitb rl6,#0
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jr z,odd_cmp /* b2 even, b1 odd */
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cpsib @r7,@r6,r5,eq
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jr z,beq /* bytes are the same */
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jr t,byte_diff
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beq: jr ov,finish /* jump if r3 is zero now */
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/* compare words */
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even_cmp:
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ld r4,r5 /* remember length */
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srl r5,#1
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jr z,no_words
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cpsir @r7,@r6,r5,ne
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jr nz,no_words
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dec r7,#2
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dec r6,#2 /* point to different bytes */
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ldk r5,#2
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jr t,odd_cmp
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no_words:
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bitb rl4,#0 /* odd length? */
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jr z,finish
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cpsib @r7,@r6,r4,eq
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jr z,finish /* last bytes are the same */
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jr t,byte_diff
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/* compare bytes */
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odd_cmp:
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cpsirb @r7,@r6,r5,ne
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jr nz,finish
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byte_diff:
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dec r7,#1
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dec r6,#1 /* point to different bytes */
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ldb rl1,@r7
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clr r0
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ldb rl0,@r6
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sub r1,r0
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finish:
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#ifdef __STD_CALL__
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ld r7,r1
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#else
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ld r2,r1
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#endif
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#endif /* Z8002 */
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ret
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.end
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