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/* mc68020 __mpn_sub_n -- Subtract two limb vectors of the same length > 0 and
store difference in a third limb vector.
Copyright (C) 1992, 1994 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with the GNU MP Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
/*
INPUT PARAMETERS
res_ptr (sp + 4)
s1_ptr (sp + 8)
s2_ptr (sp + 16)
size (sp + 12)
*/
#include "asm-syntax.h"
TEXT
ALIGN
GLOBL ___mpn_sub_n
LAB(___mpn_sub_n)
/* Save used registers on the stack. */
INSN2(move,l ,MEM_PREDEC(sp),d2)
INSN2(move,l ,MEM_PREDEC(sp),a2)
/* Copy the arguments to registers. Better use movem? */
INSN2(move,l ,a2,MEM_DISP(sp,12))
INSN2(move,l ,a0,MEM_DISP(sp,16))
INSN2(move,l ,a1,MEM_DISP(sp,20))
INSN2(move,l ,d2,MEM_DISP(sp,24))
INSN2(eor,w ,d2,#1)
INSN2(lsr,l ,d2,#1)
bcc L1
INSN2(subq,l ,d2,#1) /* clears cy as side effect */
LAB(Loop)
INSN2(move,l ,d0,MEM_POSTINC(a0))
INSN2(move,l ,d1,MEM_POSTINC(a1))
INSN2(subx,l ,d0,d1)
INSN2(move,l ,MEM_POSTINC(a2),d0)
LAB(L1) INSN2(move,l ,d0,MEM_POSTINC(a0))
INSN2(move,l ,d1,MEM_POSTINC(a1))
INSN2(subx,l ,d0,d1)
INSN2(move,l ,MEM_POSTINC(a2),d0)
dbf d2,Loop /* loop until 16 lsb of %4 == -1 */
INSN2(subx,l ,d0,d0) /* d0 <= -cy; save cy as 0 or -1 in d0 */
INSN2(sub,l ,d2,#0x10000)
bcs L2
INSN2(add,l ,d0,d0) /* restore cy */
bra Loop
LAB(L2)
INSN1(neg,l ,d0)
/* Restore used registers from stack frame. */
INSN2(move,l ,a2,MEM_POSTINC(sp))
INSN2(move,l ,d2,MEM_POSTINC(sp))
rts
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