github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpn/x86/rshift.asm (about)

     1  dnl  x86 mpn_rshift -- mpn right shift.
     2  
     3  dnl  Copyright 1992, 1994, 1996, 1999-2002 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  
    34  C     cycles/limb
    35  C P54	 7.5
    36  C P55	 7.0
    37  C P6	 2.5
    38  C K6	 4.5
    39  C K7	 5.0
    40  C P4	16.5
    41  
    42  
    43  C mp_limb_t mpn_rshift (mp_ptr dst, mp_srcptr src, mp_size_t size,
    44  C                       unsigned shift);
    45  
    46  defframe(PARAM_SHIFT,16)
    47  defframe(PARAM_SIZE, 12)
    48  defframe(PARAM_SRC,  8)
    49  defframe(PARAM_DST,  4)
    50  
    51  	TEXT
    52  	ALIGN(8)
    53  PROLOGUE(mpn_rshift)
    54  
    55  	pushl	%edi
    56  	pushl	%esi
    57  	pushl	%ebx
    58  deflit(`FRAME',12)
    59  
    60  	movl	PARAM_DST,%edi
    61  	movl	PARAM_SRC,%esi
    62  	movl	PARAM_SIZE,%edx
    63  	movl	PARAM_SHIFT,%ecx
    64  
    65  	leal	-4(%edi,%edx,4),%edi
    66  	leal	(%esi,%edx,4),%esi
    67  	negl	%edx
    68  
    69  	movl	(%esi,%edx,4),%ebx	C read least significant limb
    70  	xorl	%eax,%eax
    71  	shrdl(	%cl, %ebx, %eax)	C compute carry limb
    72  	incl	%edx
    73  	jz	L(end)
    74  	pushl	%eax			C push carry limb onto stack
    75  	testb	$1,%dl
    76  	jnz	L(1)			C enter loop in the middle
    77  	movl	%ebx,%eax
    78  
    79  	ALIGN(8)
    80  L(oop):	movl	(%esi,%edx,4),%ebx	C load next higher limb
    81  	shrdl(	%cl, %ebx, %eax)	C compute result limb
    82  	movl	%eax,(%edi,%edx,4)	C store it
    83  	incl	%edx
    84  L(1):	movl	(%esi,%edx,4),%eax
    85  	shrdl(	%cl, %eax, %ebx)
    86  	movl	%ebx,(%edi,%edx,4)
    87  	incl	%edx
    88  	jnz	L(oop)
    89  
    90  	shrl	%cl,%eax		C compute most significant limb
    91  	movl	%eax,(%edi)		C store it
    92  
    93  	popl	%eax			C pop carry limb
    94  
    95  	popl	%ebx
    96  	popl	%esi
    97  	popl	%edi
    98  	ret
    99  
   100  L(end):	shrl	%cl,%ebx		C compute most significant limb
   101  	movl	%ebx,(%edi)		C store it
   102  
   103  	popl	%ebx
   104  	popl	%esi
   105  	popl	%edi
   106  	ret
   107  
   108  EPILOGUE()