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Annotation of OpenXM_contrib/gmp/mpn/a29k/sub_n.s, Revision 1.1.1.1

1.1       maekawa     1: ; 29000 __mpn_sub -- Subtract two limb vectors of the same length > 0 and
                      2: ; store difference in a third limb vector.
                      3:
                      4: ; Copyright (C) 1992, 1994 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      lr2
                     26: ; s1_ptr       lr3
                     27: ; s2_ptr       lr4
                     28: ; size         lr5
                     29:
                     30: ; We use the loadm/storem instructions and operate on chunks of 8
                     31: ; limbs/per iteration, until less than 8 limbs remain.
                     32:
                     33: ; The 29k has no addition or subtraction instructions that doesn't
                     34: ; affect carry, so we need to save and restore that as soon as we
                     35: ; adjust the pointers.  gr116 is used for this purpose.  Note that
                     36: ; gr116==0 means that carry should be set.
                     37:
                     38:        .sect .lit,lit
                     39:        .text
                     40:        .align  4
                     41:        .global ___mpn_sub_n
                     42:        .word   0x60000
                     43: ___mpn_sub_n:
                     44:        srl     gr117,lr5,3
                     45:        sub     gr118,gr117,1
                     46:        jmpt    gr118,Ltail
                     47:         constn gr116,-1                ; init cy reg
                     48:        sub     gr117,gr117,2           ; count for jmpfdec
                     49:
                     50: ; Main loop working 8 limbs/iteration.
                     51: Loop:  mtsrim  cr,(8-1)
                     52:        loadm   0,0,gr96,lr3
                     53:        add     lr3,lr3,32
                     54:        mtsrim  cr,(8-1)
                     55:        loadm   0,0,gr104,lr4
                     56:        add     lr4,lr4,32
                     57:
                     58:        subr    gr116,gr116,0           ; restore carry
                     59:        subc    gr96,gr96,gr104
                     60:        subc    gr97,gr97,gr105
                     61:        subc    gr98,gr98,gr106
                     62:        subc    gr99,gr99,gr107
                     63:        subc    gr100,gr100,gr108
                     64:        subc    gr101,gr101,gr109
                     65:        subc    gr102,gr102,gr110
                     66:        subc    gr103,gr103,gr111
                     67:        subc    gr116,gr116,gr116       ; gr116 = not(cy)
                     68:
                     69:        mtsrim  cr,(8-1)
                     70:        storem  0,0,gr96,lr2
                     71:        jmpfdec gr117,Loop
                     72:         add    lr2,lr2,32
                     73:
                     74: ; Code for the last up-to-7 limbs.
                     75: ; This code might look very strange, but it's hard to write it
                     76: ; differently without major slowdown.
                     77:
                     78:        and     lr5,lr5,(8-1)
                     79: Ltail: sub     gr118,lr5,1             ; count for CR
                     80:        jmpt    gr118,Lend
                     81:         sub    gr117,lr5,2             ; count for jmpfdec
                     82:
                     83:        mtsr    cr,gr118
                     84:        loadm   0,0,gr96,lr3
                     85:        mtsr    cr,gr118
                     86:        loadm   0,0,gr104,lr4
                     87:
                     88:        subr    gr116,gr116,0           ; restore carry
                     89:
                     90:        jmpfdec gr117,L1
                     91:         subc   gr96,gr96,gr104
                     92:        jmp     Lstore
                     93:         mtsr   cr,gr118
                     94: L1:    jmpfdec gr117,L2
                     95:         subc   gr97,gr97,gr105
                     96:        jmp     Lstore
                     97:         mtsr   cr,gr118
                     98: L2:    jmpfdec gr117,L3
                     99:         subc   gr98,gr98,gr106
                    100:        jmp     Lstore
                    101:         mtsr   cr,gr118
                    102: L3:    jmpfdec gr117,L4
                    103:         subc   gr99,gr99,gr107
                    104:        jmp     Lstore
                    105:         mtsr   cr,gr118
                    106: L4:    jmpfdec gr117,L5
                    107:         subc   gr100,gr100,gr108
                    108:        jmp     Lstore
                    109:         mtsr   cr,gr118
                    110: L5:    jmpfdec gr117,L6
                    111:         subc   gr101,gr101,gr109
                    112:        jmp     Lstore
                    113:         mtsr   cr,gr118
                    114: L6:    subc    gr102,gr102,gr110
                    115:
                    116: Lstore:        storem  0,0,gr96,lr2
                    117:        subc    gr116,gr116,gr116       ; gr116 = not(cy)
                    118:
                    119: Lend:  jmpi    lr0
                    120:         add    gr96,gr116,1