60 строки
1.6 KiB
C
60 строки
1.6 KiB
C
/*
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* Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
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* University Research and Technology
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* Corporation. All rights reserved.
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* Copyright (c) 2004-2005 The University of Tennessee and The University
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* of Tennessee Research Foundation. All rights
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* reserved.
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* Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
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* University of Stuttgart. All rights reserved.
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* Copyright (c) 2004-2005 The Regents of the University of California.
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* All rights reserved.
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* $COPYRIGHT$
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*
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* Additional copyrights may follow
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*
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* $HEADER$
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*/
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#include "ompi_config.h"
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#include "opal/util/pow2.h"
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/**
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* This routine takes in an interger, and returns the nearest
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* power of 2 integer, same or greater than the input.
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*
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* @param input_integer input value
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*
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* @returnvalue power of 2 integer same or greater than the input
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* parameter.
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*/
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int opal_round_up_to_nearest_pow2(int input_integer)
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{
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int pop_count, highest_used_bit, tmp_input_integer, return_value;
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/* init counters */
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pop_count=0;
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highest_used_bit=-1;
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/* get population count, and highest non-zero bit */
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tmp_input_integer=input_integer;
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while ( tmp_input_integer > 0 ){
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pop_count+=(tmp_input_integer&1);
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highest_used_bit++;
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tmp_input_integer>>=1;
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};
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if( 1 < pop_count ) {
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/* "round" up */
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highest_used_bit++;
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}
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/* generate return value */
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return_value=1<<highest_used_bit;
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return return_value;
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}
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