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/*
* This routine performs a circular shift of elements in a double vector.
* The signs of shift are defined:
* (-) shift right (or down)
* (+) shift left (or up )
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "f77_name.h"
#include "f_types.h"
#define _DTMP_DIM 256 /* the length of the dTmp buffer */
void
F77_NAME(dvec_cshift,DVEC_CSHIFT)
(double * pdVec, f_int * plLen, f_int * plShift)
{
long lShift2; /* changeable arguments */
/******************************************************************************/
#ifdef _ASSERT
if (0 > *plLen)
{
printf("@DVEC_CSHIFT: Assertion failed.\n");
printf(" *plLen = %li\n",*plLen);
exit(-1);
}
#endif /* _ASSERT */
if (2 > *plLen) return;
if ( 0 == (lShift2 = *plShift % *plLen) ) return;
/******************************************************************************/
/* reduce calls to memmove by shifting the other way fewer times */
if ( labs(2*lShift2) > *plLen )
{
long lTmp = *plLen;
if (0 < lShift2) lTmp = -lTmp;
lShift2 += lTmp;
}
/* Note:
* If memmove fails, the code will abort without warning with
* a bus error. Attempts at checking the value of *memmove on exit
* are meaningless since memmove will not return after failing.
*/
/* shift right/down */
if (0 > lShift2)
{
double *pdVec_save, *pdVec_dest, dTmp[_DTMP_DIM];
long lAwait = -lShift2;
int iNum = (lAwait % _DTMP_DIM);
if (0 < iNum)
{
long lSrcLen = *plLen - iNum;
size_t Bytes = lSrcLen*sizeof(dTmp[1]);
pdVec_save = pdVec + lSrcLen;
pdVec_dest = pdVec + iNum;
{
int i;
for ( i=0; i<iNum; i++) dTmp[i] = *(pdVec_save+i);
memmove( pdVec_dest, pdVec, Bytes);
for ( i=0; i<iNum; i++) *(pdVec+i) = dTmp[i];
lAwait -= iNum;
}
}
iNum = _DTMP_DIM;
if ( 0 < (lAwait /= _DTMP_DIM) )
{
long lSrcLen = *plLen - iNum;
size_t Bytes = lSrcLen*sizeof(dTmp[1]);
pdVec_save = pdVec + lSrcLen;
pdVec_dest = pdVec + iNum;
for ( lAwait=(-lAwait); 0>lAwait; lAwait++)
{
int i;
for ( i=0; i<iNum; i++) dTmp[i] = *(pdVec_save+i);
memmove( pdVec_dest, pdVec, Bytes);
for ( i=0; i<iNum; i++) *(pdVec+i) = dTmp[i];
}
}
}
/* shift left/up */
else
{
double *pdVec_src, *pdVec_restore, dTmp[_DTMP_DIM];
long lAwait = lShift2;
int iNum = (lAwait % _DTMP_DIM);
if (0 < iNum)
{
long lSrcLen = *plLen - iNum;
size_t Bytes = lSrcLen*sizeof(dTmp[1]);
pdVec_src = pdVec + iNum;
pdVec_restore = pdVec + lSrcLen;
{
int i;
for ( i=0; i<iNum; i++) dTmp[i] = *(pdVec+i);
memmove( pdVec, pdVec_src, Bytes);
for ( i=0; i<iNum; i++) *(pdVec_restore+i) = dTmp[i];
lAwait -= iNum;
}
}
iNum = _DTMP_DIM;
if ( 0 < (lAwait /= _DTMP_DIM) )
{
long lSrcLen = *plLen - iNum;
size_t Bytes = lSrcLen*sizeof(dTmp[1]);
pdVec_src = pdVec + iNum;
pdVec_restore = pdVec + lSrcLen;
for ( lAwait=(-lAwait); 0>lAwait; lAwait++)
{
int i;
for ( i=0; i<iNum; i++) dTmp[i] = *(pdVec+i);
memmove( pdVec, pdVec_src, Bytes);
for ( i=0; i<iNum; i++) *(pdVec_restore+i) = dTmp[i];
}
}
}
return;
}
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