github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/tune/alpha.asm (about)

     1  dnl  Alpha time stamp counter access routine.
     2  
     3  dnl  Copyright 2000, 2005 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 void speed_cyclecounter (unsigned int p[2]);
    35  C
    36  
    37  C The rpcc instruction returns a 64-bit value split into two 32-bit fields.
    38  C The lower 32 bits are set by the hardware, and the upper 32 bits are set
    39  C by the operating system.  The real per-process cycle count is the sum of
    40  C these halves.
    41  
    42  C Unfortunately, some operating systems don't get this right.  NetBSD 1.3 is
    43  C known to sometimes put garbage in the upper half.  Whether newer NetBSD
    44  C versions get it right, is unknown to us.
    45  
    46  C rpcc measures cycles elapsed in the user program and hence should be very
    47  C accurate even on a busy system.  Losing cache contents due to task
    48  C switching may have an effect though.
    49  
    50  ASM_START()
    51  PROLOGUE(speed_cyclecounter)
    52  	rpcc	r0
    53  	srl	r0,32,r1
    54  	addq	r1,r0,r0
    55  	stl	r0,0(r16)
    56  	stl	r31,4(r16)		C zero upper return word
    57  	ret	r31,(r26),1
    58  EPILOGUE(speed_cyclecounter)
    59  ASM_END()