github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpn/arm/v6/submul_1.asm (about)

     1  dnl  ARM mpn_submul_1.
     2  
     3  dnl  Copyright 2012, 2013 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	     cycles/limb
    34  C StrongARM:	 -
    35  C XScale	 -
    36  C Cortex-A7	 ?
    37  C Cortex-A8	 ?
    38  C Cortex-A9	 3.75
    39  C Cortex-A15	 4.0
    40  
    41  C This loop complements U on the fly,
    42  C   U' = B^n - 1 - U
    43  C and then uses that
    44  C   R - U*v = R + U'*v + v - B^n v
    45  
    46  C TODO
    47  C  * Micro-optimise feed-in code.
    48  C  * Optimise for n=1,2 by delaying register saving.
    49  C  * Try using ldm/stm.
    50  
    51  define(`rp',`r0')
    52  define(`up',`r1')
    53  define(`n', `r2')
    54  define(`v0',`r3')
    55  
    56  ASM_START()
    57  PROLOGUE(mpn_submul_1)
    58  	stmfd	sp!, { r4, r5, r6, r7 }
    59  
    60  	ands	r6, n, #3
    61  	mov	r12, v0
    62  	beq	L(fi0)
    63  	cmp	r6, #2
    64  	bcc	L(fi1)
    65  	beq	L(fi2)
    66  
    67  L(fi3):	ldr	r4, [up], #12
    68  	mvn	r4, r4
    69  	ldr	r6, [rp, #0]
    70  	ldr	r5, [up, #-8]
    71  	b	L(lo3)
    72  
    73  L(fi0):	ldr	r5, [up], #16
    74  	mvn	r5, r5
    75  	ldr	r7, [rp], #4
    76  	ldr	r4, [up, #-12]
    77  	b	L(lo0)
    78  
    79  L(fi1):	ldr	r4, [up], #4
    80  	mvn	r4, r4
    81  	ldr	r6, [rp], #8
    82  	subs	n, n, #1
    83  	beq	L(1)
    84  	ldr	r5, [up]
    85  	b	L(lo1)
    86  
    87  L(fi2):	ldr	r5, [up], #8
    88  	mvn	r5, r5
    89  	ldr	r7, [rp], #12
    90  	ldr	r4, [up, #-4]
    91  	b	L(lo2)
    92  
    93  	ALIGN(16)
    94  L(top):	ldr	r6, [rp, #-8]
    95  	ldr	r5, [up]
    96  	str	r7, [rp, #-12]
    97  L(lo1):	umaal	r6, r12, r4, v0
    98  	add	up, up, #16
    99  	mvn	r5, r5
   100  	ldr	r7, [rp, #-4]
   101  	ldr	r4, [up, #-12]
   102  	str	r6, [rp, #-8]
   103  L(lo0):	umaal	r7, r12, r5, v0
   104  	mvn	r4, r4
   105  	ldr	r6, [rp, #0]
   106  	ldr	r5, [up, #-8]
   107  	str	r7, [rp, #-4]
   108  L(lo3):	umaal	r6, r12, r4, v0
   109  	mvn	r5, r5
   110  	ldr	r7, [rp, #4]
   111  	ldr	r4, [up, #-4]
   112  	str	r6, [rp], #16
   113  L(lo2):	umaal	r7, r12, r5, v0
   114  	mvn	r4, r4
   115  	subs	n, n, #4
   116  	bhi	L(top)
   117  
   118  	ldr	r6, [rp, #-8]
   119  	str	r7, [rp, #-12]
   120  L(1):	umaal	r6, r12, r4, v0
   121  	str	r6, [rp, #-8]
   122  	sub	r0, v0, r12
   123  	ldmfd	sp!, { r4, r5, r6, r7 }
   124  	bx	lr
   125  EPILOGUE()