77 строки
1.9 KiB
C
77 строки
1.9 KiB
C
/*
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* Copyright (c) 2004-2005 The Trustees of Indiana University.
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* All rights reserved.
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* Copyright (c) 2004-2005 The Trustees of the University of Tennessee.
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* All rights 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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#ifndef OMPI_BIT_OPS_H
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#define OMPI_BIT_OPS_H
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/**
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* Calculates the highest bit in an integer
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*
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* @param value The integer value to examine
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* @param start Position to start looking
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*
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* @returns pos Position of highest-set integer or -1 if none are set.
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*
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* Look at the integer "value" starting at position "start", and move
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* to the right. Return the index of the highest bit that is set to
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* 1.
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*
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* WARNING: *NO* error checking is performed. This is meant to be a
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* fast inline function.
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*/
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static inline int ompi_hibit(int value, int start)
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{
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unsigned int mask;
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--start;
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mask = 1 << start;
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for (; start >= 0; --start, mask >>= 1) {
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if (value & mask) {
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break;
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}
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}
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return start;
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}
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/**
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* Returns the cube dimension of a given value.
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*
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* @param value The integer value to examine
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*
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* @returns cubedim The smallest cube dimension containing that value
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*
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* Look at the integer "value" and calculate the smallest power of two
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* dimension that contains that value.
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*
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* WARNING: *NO* error checking is performed. This is meant to be a
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* fast inline function.
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*/
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static inline int ompi_cube_dim(int value)
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{
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int dim, size;
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for (dim = 0, size = 1; size < value; ++dim, size <<= 1) {
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continue;
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}
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return dim;
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}
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#endif /* OMPI_BIT_OPS_H */
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