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[glibc.git] / sysdeps / m88k / sub_n.s
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1 ; mc88100 __mpn_sub -- Subtract two limb vectors of the same length > 0 and
2 ; store difference in a third limb vector.
4 ; Copyright (C) 1992, 1994, 1996 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., 59 Temple Place - Suite 330, Boston,
21 ; MA 02111-1307, USA.
24 ; INPUT PARAMETERS
25 ; res_ptr r2
26 ; s1_ptr r3
27 ; s2_ptr r4
28 ; size r5
30 ; This code has been optimized to run one instruction per clock, avoiding
31 ; load stalls and writeback contention. As a result, the instruction
32 ; order is not always natural.
34 ; The speed is about 4.6 clocks/limb + 18 clocks/limb-vector on an 88100,
35 ; but on the 88110, it seems to run much slower, 6.6 clocks/limb.
37 text
38 align 16
39 global ___mpn_sub_n
40 ___mpn_sub_n:
41 ld r6,r3,0 ; read first limb from s1_ptr
42 extu r10,r5,3
43 ld r7,r4,0 ; read first limb from s2_ptr
45 subu r5,r0,r5
46 mak r5,r5,3<4>
47 bcnd.n eq0,r5,Lzero
48 subu.co r0,r0,r0 ; initialize carry
50 or r12,r0,lo16(Lbase)
51 or.u r12,r12,hi16(Lbase)
52 addu r12,r12,r5 ; r12 is address for entering in loop
54 extu r5,r5,2 ; divide by 4
55 subu r2,r2,r5 ; adjust res_ptr
56 subu r3,r3,r5 ; adjust s1_ptr
57 subu r4,r4,r5 ; adjust s2_ptr
59 or r8,r6,r0
61 jmp.n r12
62 or r9,r7,r0
64 Loop: addu r3,r3,32
65 st r8,r2,28
66 addu r4,r4,32
67 ld r6,r3,0
68 addu r2,r2,32
69 ld r7,r4,0
70 Lzero: subu r10,r10,1 ; subtract 0 + 8r limbs (adj loop cnt)
71 Lbase: ld r8,r3,4
72 subu.cio r6,r6,r7
73 ld r9,r4,4
74 st r6,r2,0
75 ld r6,r3,8 ; subtract 7 + 8r limbs
76 subu.cio r8,r8,r9
77 ld r7,r4,8
78 st r8,r2,4
79 ld r8,r3,12 ; subtract 6 + 8r limbs
80 subu.cio r6,r6,r7
81 ld r9,r4,12
82 st r6,r2,8
83 ld r6,r3,16 ; subtract 5 + 8r limbs
84 subu.cio r8,r8,r9
85 ld r7,r4,16
86 st r8,r2,12
87 ld r8,r3,20 ; subtract 4 + 8r limbs
88 subu.cio r6,r6,r7
89 ld r9,r4,20
90 st r6,r2,16
91 ld r6,r3,24 ; subtract 3 + 8r limbs
92 subu.cio r8,r8,r9
93 ld r7,r4,24
94 st r8,r2,20
95 ld r8,r3,28 ; subtract 2 + 8r limbs
96 subu.cio r6,r6,r7
97 ld r9,r4,28
98 st r6,r2,24
99 bcnd.n ne0,r10,Loop ; subtract 1 + 8r limbs
100 subu.cio r8,r8,r9
102 st r8,r2,28 ; store most significant limb
104 addu.ci r2,r0,r0 ; return carry-out from most sign. limb
105 jmp.n r1
106 xor r2,r2,1