Centre Blaise Pascal » HPL sur GPU

/* 

 * -- High Performance Computing Linpack Benchmark (HPL)                

 *    HPL - 2.0 - September 10, 2008                          

 *    Antoine P. Petitet                                                

 *    University of Tennessee, Knoxville                                

 *    Innovative Computing Laboratory                                 

 *    (C) Copyright 2000-2008 All Rights Reserved                       

 *                                                                      

 * -- Copyright notice and Licensing terms:                             

 *                                                                      

 * Redistribution  and  use in  source and binary forms, with or without

 * modification, are  permitted provided  that the following  conditions

 * are met:                                                             

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 * notice, this list of conditions and the following disclaimer.        

 *                                                                      

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 * notice, this list of conditions,  and the following disclaimer in the

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 *                                                                      

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 * software must display the following acknowledgement:                 

 * This  product  includes  software  developed  at  the  University  of

 * Tennessee, Knoxville, Innovative Computing Laboratory.             

 *                                                                      

 * 4. The name of the  University,  the name of the  Laboratory,  or the

 * names  of  its  contributors  may  not  be used to endorse or promote

 * products  derived   from   this  software  without  specific  written

 * permission.                                                          

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 * -- Disclaimer:                                                       

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 * THIS  SOFTWARE  IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,  INCLUDING,  BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY

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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 

 * ---------------------------------------------------------------------

 */ 

/*

 * Include files

 */

#include "hpl.h"

#ifdef STDC_HEADERS

void HPL_perm

(

   const int                        N,

   int *                            LINDXA,

   int *                            LINDXAU,

   int *                            IWORK

)

#else

void HPL_perm

( N, LINDXA, LINDXAU, IWORK )

   const int                        N;

   int *                            LINDXA;

   int *                            LINDXAU;

   int *                            IWORK;

#endif

{

/* 

 * Purpose

 * =======

 *

 * HPL_perm combines  two  index  arrays  and generate the corresponding

 * permutation. First, this function computes the inverse of LINDXA, and

 * then combine it with LINDXAU.  Second, in order to be able to perform

 * the permutation in place,  LINDXAU  is overwritten by the sequence of

 * permutation  producing  the  same result.  What we ultimately want to

 * achieve is:  U[LINDXAU[i]] := U[LINDXA[i]] for i in [0..N). After the

 * call to this function,  this in place permutation can be performed by

 * for i in [0..N) swap U[i] with U[LINDXAU[i]].

 *

 * Arguments

 * =========

 *

 * N       (global input)                const int

 *         On entry,  N  specifies the length of the arrays  LINDXA  and

 *         LINDXAU. N should be at least zero.

 *

 * LINDXA  (global input/output)         int *

 *         On entry,  LINDXA  is an array of dimension N  containing the

 *         source indexes. On exit,  LINDXA  contains the combined index

 *         array.

 *

 * LINDXAU (global input/output)         int *

 *         On entry,  LINDXAU is an array of dimension N  containing the

 *         target indexes.  On exit,  LINDXAU  contains  the sequence of

 *         permutation,  that  should be applied  in increasing order to

 *         permute the underlying array U in place.

 *

 * IWORK   (workspace)                   int *

 *         On entry, IWORK is a workarray of dimension N.

 *

 * ---------------------------------------------------------------------

 */ 

/*

 * .. Local Variables ..

 */

   int                        i, j, k, fndd;

/* ..

 * .. Executable Statements ..

 */

/*

 * Inverse LINDXA - combine LINDXA and LINDXAU - Initialize IWORK

 */

   for( i = 0; i < N; i++ ) { IWORK[LINDXA[i]] = i; }

   for( i = 0; i < N; i++ ) { LINDXA[i] = LINDXAU[IWORK[i]]; IWORK[i] = i; }

   for( i = 0; i < N; i++ )

   {

      /* search LINDXA such that    LINDXA[j]  == i */

      j = 0; do { fndd = ( LINDXA[j] == i ); j++; } while( !fndd ); j--;

      /* search IWORK  such that    IWORK[k]   == j */

      k = 0; do { fndd = ( IWORK[k]  == j ); k++; } while( !fndd ); k--;

      /* swap IWORK[i] and IWORK[k]; LINDXAU[i] = k */

      j = IWORK[i]; IWORK[i] = IWORK[k]; IWORK[k] = j;

      LINDXAU[i] = k;

   }

/*

 * End of HPL_perm

 */

}