1dnl  IBM POWER mpn_sub_n -- Subtract two limb vectors of equal, non-zero
2dnl  length.
3
4dnl  Copyright 1992, 1994-1996, 1999-2001, 2005 Free Software Foundation, Inc.
5
6dnl  This file is part of the GNU MP Library.
7dnl
8dnl  The GNU MP Library is free software; you can redistribute it and/or modify
9dnl  it under the terms of either:
10dnl
11dnl    * the GNU Lesser General Public License as published by the Free
12dnl      Software Foundation; either version 3 of the License, or (at your
13dnl      option) any later version.
14dnl
15dnl  or
16dnl
17dnl    * the GNU General Public License as published by the Free Software
18dnl      Foundation; either version 2 of the License, or (at your option) any
19dnl      later version.
20dnl
21dnl  or both in parallel, as here.
22dnl
23dnl  The GNU MP Library is distributed in the hope that it will be useful, but
24dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
25dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
26dnl  for more details.
27dnl
28dnl  You should have received copies of the GNU General Public License and the
29dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
30dnl  see https://www.gnu.org/licenses/.
31
32
33dnl  INPUT PARAMETERS
34dnl  res_ptr	r3
35dnl  s1_ptr	r4
36dnl  s2_ptr	r5
37dnl  size	r6
38
39include(`../config.m4')
40
41ASM_START()
42PROLOGUE(mpn_sub_n)
43	andil.	10,6,1		C odd or even number of limbs?
44	l	8,0(4)		C load least significant s1 limb
45	l	0,0(5)		C load least significant s2 limb
46	cal	3,-4(3)		C offset res_ptr, it's updated before it's used
47	sri	10,6,1		C count for unrolled loop
48	sf	7,0,8		C subtract least significant limbs, set cy
49	mtctr	10		C copy count into CTR
50	beq	0,Leven		C branch if even # of limbs (# of limbs >= 2)
51
52C We have an odd # of limbs.  Add the first limbs separately.
53	cmpi	1,10,0		C is count for unrolled loop zero?
54	bc	4,6,L1		C bne cr1,L1 (misassembled by gas)
55	st	7,4(3)
56	sfe	3,0,0		C load !cy into ...
57	sfi	3,3,0		C ... return value register
58	br			C return
59
60C We added least significant limbs.  Now reload the next limbs to enter loop.
61L1:	lu	8,4(4)		C load s1 limb and update s1_ptr
62	lu	0,4(5)		C load s2 limb and update s2_ptr
63	stu	7,4(3)
64	sfe	7,0,8		C subtract limbs, set cy
65Leven:	lu	9,4(4)		C load s1 limb and update s1_ptr
66	lu	10,4(5)		C load s2 limb and update s2_ptr
67	bdz	Lend		C If done, skip loop
68
69Loop:	lu	8,4(4)		C load s1 limb and update s1_ptr
70	lu	0,4(5)		C load s2 limb and update s2_ptr
71	sfe	11,10,9		C subtract previous limbs with cy, set cy
72	stu	7,4(3)		C
73	lu	9,4(4)		C load s1 limb and update s1_ptr
74	lu	10,4(5)		C load s2 limb and update s2_ptr
75	sfe	7,0,8		C subtract previous limbs with cy, set cy
76	stu	11,4(3)		C
77	bdn	Loop		C decrement CTR and loop back
78
79Lend:	sfe	11,10,9		C subtract limbs with cy, set cy
80	st	7,4(3)		C
81	st	11,8(3)		C
82	sfe	3,0,0		C load !cy into ...
83	sfi	3,3,0		C ... return value register
84	br
85EPILOGUE(mpn_sub_n)
86