github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpn/power/sub_n.asm (about)

     1  dnl  IBM POWER mpn_sub_n -- Subtract two limb vectors of equal, non-zero
     2  dnl  length.
     3  
     4  dnl  Copyright 1992, 1994-1996, 1999-2001, 2005 Free Software Foundation, Inc.
     5  
     6  dnl  This file is part of the GNU MP Library.
     7  dnl
     8  dnl  The GNU MP Library is free software; you can redistribute it and/or modify
     9  dnl  it under the terms of either:
    10  dnl
    11  dnl    * the GNU Lesser General Public License as published by the Free
    12  dnl      Software Foundation; either version 3 of the License, or (at your
    13  dnl      option) any later version.
    14  dnl
    15  dnl  or
    16  dnl
    17  dnl    * the GNU General Public License as published by the Free Software
    18  dnl      Foundation; either version 2 of the License, or (at your option) any
    19  dnl      later version.
    20  dnl
    21  dnl  or both in parallel, as here.
    22  dnl
    23  dnl  The GNU MP Library is distributed in the hope that it will be useful, but
    24  dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    25  dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    26  dnl  for more details.
    27  dnl
    28  dnl  You should have received copies of the GNU General Public License and the
    29  dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
    30  dnl  see https://www.gnu.org/licenses/.
    31  
    32  
    33  dnl  INPUT PARAMETERS
    34  dnl  res_ptr	r3
    35  dnl  s1_ptr	r4
    36  dnl  s2_ptr	r5
    37  dnl  size	r6
    38  
    39  include(`../config.m4')
    40  
    41  ASM_START()
    42  PROLOGUE(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  
    52  C 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  
    60  C We added least significant limbs.  Now reload the next limbs to enter loop.
    61  L1:	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
    65  Leven:	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  
    69  Loop:	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  
    79  Lend:	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
    85  EPILOGUE(mpn_sub_n)