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

     1  dnl  IBM POWER mpn_rshift -- Shift a number right.
     2  
     3  dnl  Copyright 1992, 1994, 1999-2001 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  
    32  dnl  INPUT PARAMETERS
    33  dnl  res_ptr	r3
    34  dnl  s_ptr	r4
    35  dnl  size	r5
    36  dnl  cnt	r6
    37  
    38  include(`../config.m4')
    39  
    40  ASM_START()
    41  PROLOGUE(mpn_rshift)
    42  	sfi	8,6,32
    43  	mtctr	5		C put limb count in CTR loop register
    44  	l	0,0(4)		C read least significant limb
    45  	ai	9,3,-4		C adjust res_ptr since it's offset in the stu:s
    46  	sle	3,0,8		C compute carry limb, and init MQ register
    47  	bdz	Lend2		C if just one limb, skip loop
    48  	lu	0,4(4)		C read 2:nd least significant limb
    49  	sleq	7,0,8		C compute least significant limb of result
    50  	bdz	Lend		C if just two limb, skip loop
    51  Loop:	lu	0,4(4)		C load next higher limb
    52  	stu	7,4(9)		C store previous result during read latency
    53  	sleq	7,0,8		C compute result limb
    54  	bdn	Loop		C loop back until CTR is zero
    55  Lend:	stu	7,4(9)		C store 2:nd most significant limb
    56  Lend2:	sre	7,0,6		C compute most significant limb
    57  	st	7,4(9)		C store it
    58  	br
    59  EPILOGUE(mpn_rshift)