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// file kernel/n/ppc32/cmp.S: comparison of natural integers
/*-----------------------------------------------------------------------+
| Copyright 2005-2006, Michel Quercia (michel.quercia@prepas.org) |
| |
| This file is part of Numerix. Numerix is free software; you can |
| redistribute it and/or modify it under the terms of the GNU Lesser |
| General Public License as published by the Free Software Foundation; |
| either version 2.1 of the License, or (at your option) any later |
| version. |
| |
| The Numerix 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU MP Library; see the file COPYING. If not, |
| write to the Free Software Foundation, Inc., 59 Temple Place - |
| Suite 330, Boston, MA 02111-1307, USA. |
+-----------------------------------------------------------------------+
| |
| Comparaison |
| |
+-----------------------------------------------------------------------*/
; long xn(cmp)(chiffre *a, long la, chiffre *b, long lb)
;
; entre :
; a = naturel de longueur la
; b = naturel de longueur lb
;
; sortie :
; 1 si a > b, 0 si a = b, -1 si a < b
#ifdef assembly_sn_cmp
#undef L
#define L(x) .Lsn_cmp##x
.globl _sn_cmp
_sn_cmp:
; supprime les zros de tte du plus long argument
subf. r2, r6, r4 ; r2 <- la - lb
beq L(compare)
mr r4, r2 ; r4 <- |la-lb|
mr r7, r3 ; r7 <- &a si la > lb, &b sinon
bgt 1f
add r6, r2, r6 ; r6 <- min(la,lb)
mr r7, r5
neg r4, r4
1:
add r8, r4, r6 ; r7 <- &(a_ou_b)[max(la,lb)]
slwi r8, r8, 2
add r7, r7, r8
mtctr r4 ; ctr <- |la-lb|
1:
lwzu r8, -4(r7) ; cherche le dernier chiffre non nul
and. r8, r8, r8
bdnzt eq, 1b
beq L(compare)
srawi r3, r2, 31 ; si trouv, r3 <- sgn(la-lb)
ori r3, r3, 1
blr
; cas la = lb
L(compare):
and. r6, r6, r6 ; si l6 = 0, la comparaison est termine
beq L(equal)
mtctr r6 ; ctr <- la
slwi r6, r6, 2
add r3, r3, r6 ; a += la
add r5, r5, r6
1:
lwzu r7, -4(r3) ; compare a et b chiffre chiffre
lwzu r8, -4(r5)
cmp cr0, r7, r8
bdnzt eq, 1b
beq L(equal)
subfc r8, r8, r7 ; sinon, r3 <- sgn(a-b)
subfe r3, r3, r3
ori r3, r3, 1
blr
L(equal):
li r3, 0
blr
#undef L
#endif /* assembly_sn_cmp */
|
