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[glibc.git] / sysdeps / rs6000 / mul_1.s
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1 # IBM POWER __mpn_mul_1 -- Multiply a limb vector with a limb and store
2 # the result in a second limb vector.
4 # Copyright (C) 1992, 1994 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 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.
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.
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., 675 Mass Ave, Cambridge, MA 02139, USA.
23 # INPUT PARAMETERS
24 # res_ptr r3
25 # s1_ptr r4
26 # size r5
27 # s2_limb r6
29 # The RS/6000 has no unsigned 32x32->64 bit multiplication instruction. To
30 # obtain that operation, we have to use the 32x32->64 signed multiplication
31 # instruction, and add the appropriate compensation to the high limb of the
32 # result. We add the multiplicand if the multiplier has its most significant
33 # bit set, and we add the multiplier if the multiplicand has its most
34 # significant bit set. We need to preserve the carry flag between each
35 # iteration, so we have to compute the compensation carefully (the natural,
36 # srai+and doesn't work). Since the POWER architecture has a branch unit
37 # we can branch in zero cycles, so that's how we perform the additions.
39 .toc
40 .csect .__mpn_mul_1[PR]
41 .align 2
42 .globl __mpn_mul_1
43 .globl .__mpn_mul_1
44 .csect __mpn_mul_1[DS]
45 __mpn_mul_1:
46 .long .__mpn_mul_1[PR], TOC[tc0], 0
47 .csect .__mpn_mul_1[PR]
48 .__mpn_mul_1:
50 cal 3,-4(3)
51 l 0,0(4)
52 cmpi 0,6,0
53 mtctr 5
54 mul 9,0,6
55 srai 7,0,31
56 and 7,7,6
57 mfmq 8
58 ai 0,0,0 # reset carry
59 cax 9,9,7
60 blt Lneg
61 Lpos: bdz Lend
62 Lploop: lu 0,4(4)
63 stu 8,4(3)
64 cmpi 0,0,0
65 mul 10,0,6
66 mfmq 0
67 ae 8,0,9
68 bge Lp0
69 cax 10,10,6 # adjust high limb for negative limb from s1
70 Lp0: bdz Lend0
71 lu 0,4(4)
72 stu 8,4(3)
73 cmpi 0,0,0
74 mul 9,0,6
75 mfmq 0
76 ae 8,0,10
77 bge Lp1
78 cax 9,9,6 # adjust high limb for negative limb from s1
79 Lp1: bdn Lploop
80 b Lend
82 Lneg: cax 9,9,0
83 bdz Lend
84 Lnloop: lu 0,4(4)
85 stu 8,4(3)
86 cmpi 0,0,0
87 mul 10,0,6
88 cax 10,10,0 # adjust high limb for negative s2_limb
89 mfmq 0
90 ae 8,0,9
91 bge Ln0
92 cax 10,10,6 # adjust high limb for negative limb from s1
93 Ln0: bdz Lend0
94 lu 0,4(4)
95 stu 8,4(3)
96 cmpi 0,0,0
97 mul 9,0,6
98 cax 9,9,0 # adjust high limb for negative s2_limb
99 mfmq 0
100 ae 8,0,10
101 bge Ln1
102 cax 9,9,6 # adjust high limb for negative limb from s1
103 Ln1: bdn Lnloop
104 b Lend
106 Lend0: cal 9,0(10)
107 Lend: st 8,4(3)
108 aze 3,9