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

     1  dnl  ARM mpn_rshift.
     2  
     3  dnl  Contributed to the GNU project by Torbjörn Granlund.
     4  
     5  dnl  Copyright 1997, 2000, 2001, 2012 Free Software Foundation, Inc.
     6  
     7  dnl  This file is part of the GNU MP Library.
     8  dnl
     9  dnl  The GNU MP Library is free software; you can redistribute it and/or modify
    10  dnl  it under the terms of either:
    11  dnl
    12  dnl    * the GNU Lesser General Public License as published by the Free
    13  dnl      Software Foundation; either version 3 of the License, or (at your
    14  dnl      option) any later version.
    15  dnl
    16  dnl  or
    17  dnl
    18  dnl    * the GNU General Public License as published by the Free Software
    19  dnl      Foundation; either version 2 of the License, or (at your option) any
    20  dnl      later version.
    21  dnl
    22  dnl  or both in parallel, as here.
    23  dnl
    24  dnl  The GNU MP Library is distributed in the hope that it will be useful, but
    25  dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    26  dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    27  dnl  for more details.
    28  dnl
    29  dnl  You should have received copies of the GNU General Public License and the
    30  dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,
    31  dnl  see https://www.gnu.org/licenses/.
    32  
    33  include(`../config.m4')
    34  
    35  C	     cycles/limb
    36  C StrongARM	 ?
    37  C XScale	 ?
    38  C Cortex-A7	 ?
    39  C Cortex-A8	 ?
    40  C Cortex-A9	 3.5
    41  C Cortex-A15	 ?
    42  
    43  define(`rp',  `r0')
    44  define(`up',  `r1')
    45  define(`n',   `r2')
    46  define(`cnt', `r3')
    47  define(`tnc', `r12')
    48  
    49  ASM_START()
    50  PROLOGUE(mpn_rshift)
    51  	push	{r4, r6, r7, r8}
    52  	ldr	r4, [up]
    53  	rsb	tnc, cnt, #32
    54  
    55  	mov	r7, r4, lsr cnt
    56  	tst	n, #1
    57  	beq	L(evn)			C n even
    58  
    59  L(odd):	subs	n, n, #2
    60  	bcc	L(1)			C n = 1
    61  	ldr	r8, [up, #4]!
    62  	b	L(mid)
    63  
    64  L(evn):	ldr	r6, [up, #4]!
    65  	subs	n, n, #2
    66  	beq	L(end)
    67  
    68  L(top):	ldr	r8, [up, #4]!
    69  	orr	r7, r7, r6, lsl tnc
    70  	str	r7, [rp], #4
    71  	mov	r7, r6, lsr cnt
    72  L(mid):	ldr	r6, [up, #4]!
    73  	orr	r7, r7, r8, lsl tnc
    74  	str	r7, [rp], #4
    75  	mov	r7, r8, lsr cnt
    76  	subs	n, n, #2
    77  	bgt	L(top)
    78  
    79  L(end):	orr	r7, r7, r6, lsl tnc
    80  	str	r7, [rp], #4
    81  	mov	r7, r6, lsr cnt
    82  L(1):	str	r7, [rp]
    83  	mov	r0, r4, lsl tnc
    84  	pop	{r4, r6, r7, r8}
    85  	ret	r14
    86  EPILOGUE()