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

     1  dnl  ARM/Thumb mpn_sub_n.
     2  
     3  dnl  Copyright 1997, 2000, 2012 Free Software Foundation, Inc.
     4  
     5  dnl  This file is part of the GNU MP Library.
     6  dnl
     7  dnl  The GNU MP Library is free software; you can redistribute it and/or modify
     8  dnl  it under the terms of either:
     9  dnl
    10  dnl    * the GNU Lesser General Public License as published by the Free
    11  dnl      Software Foundation; either version 3 of the License, or (at your
    12  dnl      option) any later version.
    13  dnl
    14  dnl  or
    15  dnl
    16  dnl    * the GNU General Public License as published by the Free Software
    17  dnl      Foundation; either version 2 of the License, or (at your option) any
    18  dnl      later version.
    19  dnl
    20  dnl  or both in parallel, as here.
    21  dnl
    22  dnl  The GNU MP Library is distributed in the hope that it will be useful, but
    23  dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    24  dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    25  dnl  for more details.
    26  dnl
    27  dnl  You should have received copies of the GNU General Public License and the
    28  dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
    29  dnl  see https://www.gnu.org/licenses/.
    30  
    31  include(`../config.m4')
    32  
    33  C INPUT PARAMETERS
    34  define(`rp',	r0)
    35  define(`up',	r1)
    36  define(`vp',	r2)
    37  define(`n',	r3)
    38  
    39  ASM_START()
    40  	.thumb
    41  PROLOGUE(mpn_sub_nc)
    42  	push	{r4, r5, r6}
    43  	ldr	r6, [sp, #12]		C init carry save register
    44  	neg	r6, r6
    45  	b	L(top)
    46  EPILOGUE()
    47  PROLOGUE(mpn_sub_n)
    48  	push	{r4, r5, r6}
    49  	mov	r6, n			C init carry save register
    50  
    51  L(top):	ldmia	up!, {r4}		C load next limb from S1
    52  	cmp	n, r6			C tricky carry restore
    53  	ldmia	vp!, {r5}		C load next limb from S2
    54  	sbc	r4, r5
    55  	stmia	rp!, {r4}		C store result limb to RES
    56  	sbc	r6, r6			C save negated carry
    57  	sub	n, #1
    58  	bne	L(top)
    59  
    60  	neg	r0, r6
    61  	pop	{r4, r5, r6}
    62  	bx	lr
    63  EPILOGUE()