1 ; 29000 __gmpn_sub -- Subtract two limb vectors of the same length > 0 and
2 ; store difference in a third limb vector.
4 ; Copyright (C) 1992, 1994, 2000 Free Software Foundation, Inc.
6 ; This file is part of the GNU MP Library.
8 ; The GNU MP Library is free software; you can redistribute it and/or modify
9 ; it under the terms of the GNU Lesser General Public License as published by
10 ; the Free Software Foundation; either version 2.1 of the License, or (at your
11 ; option) any later version.
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 Lesser General Public
16 ; License for more details.
18 ; You should have received a copy of the GNU Lesser 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,
30 ; We use the loadm/storem instructions and operate on chunks of 8
31 ; limbs/per iteration, until less than 8 limbs remain.
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.
47 constn gr116,-1 ; init cy reg
48 sub gr117,gr117,2 ; count for jmpfdec
50 ; Main loop working 8 limbs/iteration.
58 subr gr116,gr116,0 ; restore carry
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)
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.
79 Ltail: sub gr118,lr5,1 ; count for CR
81 sub gr117,lr5,2 ; count for jmpfdec
88 subr gr116,gr116,0 ; restore carry
107 subc gr100,gr100,gr108
111 subc gr101,gr101,gr109
114 L6: subc gr102,gr102,gr110
116 Lstore: storem 0,0,gr96,lr2
117 subc gr116,gr116,gr116 ; gr116 = not(cy)