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Annotation of OpenXM_contrib/gmp/mpn/m68k/sub_n.S, Revision 1.1.1.1

1.1       maekawa     1: /* mc68020 __mpn_sub_n -- Subtract two limb vectors of the same length > 0 and
                      2:    store difference in a third limb vector.
                      3:
                      4: Copyright (C) 1992, 1994, 1996 Free Software Foundation, Inc.
                      5:
                      6: This file is part of the GNU MP Library.
                      7:
                      8: The GNU MP Library is free software; you can redistribute it and/or modify
                      9: it under the terms of the GNU Library General Public License as published by
                     10: the Free Software Foundation; either version 2 of the License, or (at your
                     11: option) any later version.
                     12:
                     13: The GNU MP Library is distributed in the hope that it will be useful, but
                     14: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     15: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
                     16: License for more details.
                     17:
                     18: You should have received a copy of the GNU Library General Public License
                     19: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
                     20: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     21: MA 02111-1307, USA. */
                     22:
                     23: /*
                     24:   INPUT PARAMETERS
                     25:   res_ptr      (sp + 4)
                     26:   s1_ptr       (sp + 8)
                     27:   s2_ptr       (sp + 16)
                     28:   size         (sp + 12)
                     29: */
                     30:
                     31: #include "sysdep.h"
                     32: #include "asm-syntax.h"
                     33:
                     34:        TEXT
                     35:        ALIGN
                     36:        GLOBL   C_SYMBOL_NAME(__mpn_sub_n)
                     37:
                     38: C_SYMBOL_NAME(__mpn_sub_n:)
                     39: PROLOG(__mpn_sub_n)
                     40: /* Save used registers on the stack.  */
                     41:        movel   R(d2),MEM_PREDEC(sp)
                     42:        movel   R(a2),MEM_PREDEC(sp)
                     43:
                     44: /* Copy the arguments to registers.  Better use movem?  */
                     45:        movel   MEM_DISP(sp,12),R(a2)
                     46:        movel   MEM_DISP(sp,16),R(a0)
                     47:        movel   MEM_DISP(sp,20),R(a1)
                     48:        movel   MEM_DISP(sp,24),R(d2)
                     49:
                     50:        eorw    #1,R(d2)
                     51:        lsrl    #1,R(d2)
                     52:        bcc     L(L1)
                     53:        subql   #1,R(d2)        /* clears cy as side effect */
                     54:
                     55: L(Loop:)
                     56:        movel   MEM_POSTINC(a0),R(d0)
                     57:        movel   MEM_POSTINC(a1),R(d1)
                     58:        subxl   R(d1),R(d0)
                     59:        movel   R(d0),MEM_POSTINC(a2)
                     60: L(L1:) movel   MEM_POSTINC(a0),R(d0)
                     61:        movel   MEM_POSTINC(a1),R(d1)
                     62:        subxl   R(d1),R(d0)
                     63:        movel   R(d0),MEM_POSTINC(a2)
                     64:
                     65:        dbf     R(d2),L(Loop)           /* loop until 16 lsb of %4 == -1 */
                     66:        subxl   R(d0),R(d0)     /* d0 <= -cy; save cy as 0 or -1 in d0 */
                     67:        subl    #0x10000,R(d2)
                     68:        bcs     L(L2)
                     69:        addl    R(d0),R(d0)     /* restore cy */
                     70:        bra     L(Loop)
                     71:
                     72: L(L2:)
                     73:        negl    R(d0)
                     74:
                     75: /* Restore used registers from stack frame.  */
                     76:        movel   MEM_POSTINC(sp),R(a2)
                     77:        movel   MEM_POSTINC(sp),R(d2)
                     78:
                     79:        rts
                     80: EPILOG(__mpn_sub_n)