
/*! @file dpanel_bmod.c
 * \brief Performs numeric block updates
 *
 * <pre>
 * -- SuperLU routine (version 3.0) --
 * Univ. of California Berkeley, Xerox Palo Alto Research Center,
 * and Lawrence Berkeley National Lab.
 * October 15, 2003
 *
 * Copyright (c) 1994 by Xerox Corporation.  All rights reserved.
 *
 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY
 * EXPRESSED OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
 * 
 * Permission is hereby granted to use or copy this program for any
 * purpose, provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is
 * granted, provided the above notices are retained, and a notice that
 * the code was modified is included with the above copyright notice.
 * </pre>
 */
/*

*/

#include <stdio.h>
#include <stdlib.h>
#include "slu_ddefs.h"

/* 
 * Function prototypes 
 */
void dlsolve(int, int, double *, double *);
void dmatvec(int, int, int, double *, double *, double *);
extern void dcheck_tempv();

/*! \brief
 *
 * <pre>
 * Purpose
 * =======
 *
 *    Performs numeric block updates (sup-panel) in topological order.
 *    It features: col-col, 2cols-col, 3cols-col, and sup-col updates.
 *    Special processing on the supernodal portion of L\U[*,j]
 *
 *    Before entering this routine, the original nonzeros in the panel 
 *    were already copied into the spa[m,w].
 *
 *    Updated/Output parameters-
 *    dense[0:m-1,w]: L[*,j:j+w-1] and U[*,j:j+w-1] are returned 
 *    collectively in the m-by-w vector dense[*]. 
 * </pre>
 */

void
dpanel_bmod (
	    const int  m,          /* in - number of rows in the matrix */
	    const int  w,          /* in */
	    const int  jcol,       /* in */
	    const int  nseg,       /* in */
	    double     *dense,     /* out, of size n by w */
	    double     *tempv,     /* working array */
	    int        *segrep,    /* in */
	    int        *repfnz,    /* in, of size n by w */
	    GlobalLU_t *Glu,       /* modified */
	    SuperLUStat_t *stat    /* output */
	    )
{


#ifdef USE_VENDOR_BLAS
#ifdef _CRAY
    _fcd ftcs1 = _cptofcd("L", strlen("L")),
         ftcs2 = _cptofcd("N", strlen("N")),
         ftcs3 = _cptofcd("U", strlen("U"));
#endif
    int          incx = 1, incy = 1;
    double       alpha, beta;
#endif

    register int k, ksub;
    int          fsupc, nsupc, nsupr, nrow;
    int          krep, krep_ind;
    double       ukj, ukj1, ukj2;
    int          luptr, luptr1, luptr2;
    int          segsze;
    int          block_nrow;  /* no of rows in a block row */
    register int lptr;	      /* Points to the row subscripts of a supernode */
    int          kfnz, irow, no_zeros; 
    register int isub, isub1, i;
    register int jj;	      /* Index through each column in the panel */
    int          *xsup, *supno;
    int          *lsub, *xlsub;
    double       *lusup;
    int          *xlusup;
    int          *repfnz_col; /* repfnz[] for a column in the panel */
    double       *dense_col;  /* dense[] for a column in the panel */
    double       *tempv1;             /* Used in 1-D update */
    double       *TriTmp, *MatvecTmp; /* used in 2-D update */
    double      zero = 0.0;
    double      one = 1.0;
    register int ldaTmp;
    register int r_ind, r_hi;
    static   int first = 1, maxsuper, rowblk, colblk;
    flops_t  *ops = stat->ops;
    
    xsup    = Glu->xsup;
    supno   = Glu->supno;
    lsub    = Glu->lsub;
    xlsub   = Glu->xlsub;
    lusup   = Glu->lusup;
    xlusup  = Glu->xlusup;
    
    if ( first ) {
	maxsuper = SUPERLU_MAX( sp_ienv(3), sp_ienv(7) );
	rowblk   = sp_ienv(4);
	colblk   = sp_ienv(5);
	first = 0;
    }
    ldaTmp = maxsuper + rowblk;

    /* 
     * For each nonz supernode segment of U[*,j] in topological order 
     */
    k = nseg - 1;
    for (ksub = 0; ksub < nseg; ksub++) { /* for each updating supernode */

	/* krep = representative of current k-th supernode
	 * fsupc = first supernodal column
	 * nsupc = no of columns in a supernode
	 * nsupr = no of rows in a supernode
	 */
        krep = segrep[k--];
	fsupc = xsup[supno[krep]];
	nsupc = krep - fsupc + 1;
	nsupr = xlsub[fsupc+1] - xlsub[fsupc];
	nrow = nsupr - nsupc;
	lptr = xlsub[fsupc];
	krep_ind = lptr + nsupc - 1;

	repfnz_col = repfnz;
	dense_col = dense;
	
	if ( nsupc >= colblk && nrow > rowblk ) { /* 2-D block update */

	    TriTmp = tempv;
	
	    /* Sequence through each column in panel -- triangular solves */
	    for (jj = jcol; jj < jcol + w; jj++,
		 repfnz_col += m, dense_col += m, TriTmp += ldaTmp ) {

		kfnz = repfnz_col[krep];
		if ( kfnz == EMPTY ) continue;	/* Skip any zero segment */
	    
		segsze = krep - kfnz + 1;
		luptr = xlusup[fsupc];

		ops[TRSV] += segsze * (segsze - 1);
		ops[GEMV] += 2 * nrow * segsze;
	
		/* Case 1: Update U-segment of size 1 -- col-col update */
		if ( segsze == 1 ) {
		    ukj = dense_col[lsub[krep_ind]];
		    luptr += nsupr*(nsupc-1) + nsupc;

		    for (i = lptr + nsupc; i < xlsub[fsupc+1]; i++) {
			irow = lsub[i];
			dense_col[irow] -= ukj * lusup[luptr];
			++luptr;
		    }

		} else if ( segsze <= 3 ) {
		    ukj = dense_col[lsub[krep_ind]];
		    ukj1 = dense_col[lsub[krep_ind - 1]];
		    luptr += nsupr*(nsupc-1) + nsupc-1;
		    luptr1 = luptr - nsupr;

		    if ( segsze == 2 ) {
			ukj -= ukj1 * lusup[luptr1];
			dense_col[lsub[krep_ind]] = ukj;
			for (i = lptr + nsupc; i < xlsub[fsupc+1]; ++i) {
			    irow = lsub[i];
			    luptr++; luptr1++;
			    dense_col[irow] -= (ukj*lusup[luptr]
						+ ukj1*lusup[luptr1]);
			}
		    } else {
			ukj2 = dense_col[lsub[krep_ind - 2]];
			luptr2 = luptr1 - nsupr;
			ukj1 -= ukj2 * lusup[luptr2-1];
			ukj = ukj - ukj1*lusup[luptr1] - ukj2*lusup[luptr2];
			dense_col[lsub[krep_ind]] = ukj;
			dense_col[lsub[krep_ind-1]] = ukj1;
			for (i = lptr + nsupc; i < xlsub[fsupc+1]; ++i) {
			    irow = lsub[i];
			    luptr++; luptr1++; luptr2++;
			    dense_col[irow] -= ( ukj*lusup[luptr]
                             + ukj1*lusup[luptr1] + ukj2*lusup[luptr2] );
			}
		    }

		} else  {	/* segsze >= 4 */
		    
		    /* Copy U[*,j] segment from dense[*] to TriTmp[*], which
		       holds the result of triangular solves.    */
		    no_zeros = kfnz - fsupc;
		    isub = lptr + no_zeros;
		    for (i = 0; i < segsze; ++i) {
			irow = lsub[isub];
			TriTmp[i] = dense_col[irow]; /* Gather */
			++isub;
		    }
		    
		    /* start effective triangle */
		    luptr += nsupr * no_zeros + no_zeros;

#ifdef USE_VENDOR_BLAS
#ifdef _CRAY
		    STRSV( ftcs1, ftcs2, ftcs3, &segsze, &lusup[luptr], 
			   &nsupr, TriTmp, &incx );
#else
		    dtrsv_( "L", "N", "U", &segsze, &lusup[luptr], 
			   &nsupr, TriTmp, &incx );
#endif
#else		
		    dlsolve ( nsupr, segsze, &lusup[luptr], TriTmp );
#endif
		    

		} /* else ... */
	    
	    }  /* for jj ... end tri-solves */

	    /* Block row updates; push all the way into dense[*] block */
	    for ( r_ind = 0; r_ind < nrow; r_ind += rowblk ) {
		
		r_hi = SUPERLU_MIN(nrow, r_ind + rowblk);
		block_nrow = SUPERLU_MIN(rowblk, r_hi - r_ind);
		luptr = xlusup[fsupc] + nsupc + r_ind;
		isub1 = lptr + nsupc + r_ind;
		
		repfnz_col = repfnz;
		TriTmp = tempv;
		dense_col = dense;
		
		/* Sequence through each column in panel -- matrix-vector */
		for (jj = jcol; jj < jcol + w; jj++,
		     repfnz_col += m, dense_col += m, TriTmp += ldaTmp) {
		    
		    kfnz = repfnz_col[krep];
		    if ( kfnz == EMPTY ) continue; /* Skip any zero segment */
		    
		    segsze = krep - kfnz + 1;
		    if ( segsze <= 3 ) continue;   /* skip unrolled cases */
		    
		    /* Perform a block update, and scatter the result of
		       matrix-vector to dense[].		 */
		    no_zeros = kfnz - fsupc;
		    luptr1 = luptr + nsupr * no_zeros;
		    MatvecTmp = &TriTmp[maxsuper];
		    
#ifdef USE_VENDOR_BLAS
		    alpha = one; 
                    beta = zero;
#ifdef _CRAY
		    SGEMV(ftcs2, &block_nrow, &segsze, &alpha, &lusup[luptr1], 
			   &nsupr, TriTmp, &incx, &beta, MatvecTmp, &incy);
#else
		    dgemv_("N", &block_nrow, &segsze, &alpha, &lusup[luptr1], 
			   &nsupr, TriTmp, &incx, &beta, MatvecTmp, &incy);
#endif
#else
		    dmatvec(nsupr, block_nrow, segsze, &lusup[luptr1],
			   TriTmp, MatvecTmp);
#endif
		    
		    /* Scatter MatvecTmp[*] into SPA dense[*] temporarily
		     * such that MatvecTmp[*] can be re-used for the
		     * the next blok row update. dense[] will be copied into 
		     * global store after the whole panel has been finished.
		     */
		    isub = isub1;
		    for (i = 0; i < block_nrow; i++) {
			irow = lsub[isub];
			dense_col[irow] -= MatvecTmp[i];
			MatvecTmp[i] = zero;
			++isub;
		    }
		    
		} /* for jj ... */
		
	    } /* for each block row ... */
	    
	    /* Scatter the triangular solves into SPA dense[*] */
	    repfnz_col = repfnz;
	    TriTmp = tempv;
	    dense_col = dense;
	    
	    for (jj = jcol; jj < jcol + w; jj++,
		 repfnz_col += m, dense_col += m, TriTmp += ldaTmp) {
		kfnz = repfnz_col[krep];
		if ( kfnz == EMPTY ) continue; /* Skip any zero segment */
		
		segsze = krep - kfnz + 1;
		if ( segsze <= 3 ) continue; /* skip unrolled cases */
		
		no_zeros = kfnz - fsupc;		
		isub = lptr + no_zeros;
		for (i = 0; i < segsze; i++) {
		    irow = lsub[isub];
		    dense_col[irow] = TriTmp[i];
		    TriTmp[i] = zero;
		    ++isub;
		}
		
	    } /* for jj ... */
	    
	} else { /* 1-D block modification */
	    
	    
	    /* Sequence through each column in the panel */
	    for (jj = jcol; jj < jcol + w; jj++,
		 repfnz_col += m, dense_col += m) {
		
		kfnz = repfnz_col[krep];
		if ( kfnz == EMPTY ) continue;	/* Skip any zero segment */
		
		segsze = krep - kfnz + 1;
		luptr = xlusup[fsupc];

		ops[TRSV] += segsze * (segsze - 1);
		ops[GEMV] += 2 * nrow * segsze;
		
		/* Case 1: Update U-segment of size 1 -- col-col update */
		if ( segsze == 1 ) {
		    ukj = dense_col[lsub[krep_ind]];
		    luptr += nsupr*(nsupc-1) + nsupc;

		    for (i = lptr + nsupc; i < xlsub[fsupc+1]; i++) {
			irow = lsub[i];
			dense_col[irow] -= ukj * lusup[luptr];
			++luptr;
		    }

		} else if ( segsze <= 3 ) {
		    ukj = dense_col[lsub[krep_ind]];
		    luptr += nsupr*(nsupc-1) + nsupc-1;
		    ukj1 = dense_col[lsub[krep_ind - 1]];
		    luptr1 = luptr - nsupr;

		    if ( segsze == 2 ) {
			ukj -= ukj1 * lusup[luptr1];
			dense_col[lsub[krep_ind]] = ukj;
			for (i = lptr + nsupc; i < xlsub[fsupc+1]; ++i) {
			    irow = lsub[i];
			    ++luptr;  ++luptr1;
			    dense_col[irow] -= (ukj*lusup[luptr]
						+ ukj1*lusup[luptr1]);
			}
		    } else {
			ukj2 = dense_col[lsub[krep_ind - 2]];
			luptr2 = luptr1 - nsupr;
			ukj1 -= ukj2 * lusup[luptr2-1];
			ukj = ukj - ukj1*lusup[luptr1] - ukj2*lusup[luptr2];
			dense_col[lsub[krep_ind]] = ukj;
			dense_col[lsub[krep_ind-1]] = ukj1;
			for (i = lptr + nsupc; i < xlsub[fsupc+1]; ++i) {
			    irow = lsub[i];
			    ++luptr; ++luptr1; ++luptr2;
			    dense_col[irow] -= ( ukj*lusup[luptr]
                             + ukj1*lusup[luptr1] + ukj2*lusup[luptr2] );
			}
		    }

		} else  { /* segsze >= 4 */
		    /* 
		     * Perform a triangular solve and block update,
		     * then scatter the result of sup-col update to dense[].
		     */
		    no_zeros = kfnz - fsupc;
		    
		    /* Copy U[*,j] segment from dense[*] to tempv[*]: 
		     *    The result of triangular solve is in tempv[*];
		     *    The result of matrix vector update is in dense_col[*]
		     */
		    isub = lptr + no_zeros;
		    for (i = 0; i < segsze; ++i) {
			irow = lsub[isub];
			tempv[i] = dense_col[irow]; /* Gather */
			++isub;
		    }
		    
		    /* start effective triangle */
		    luptr += nsupr * no_zeros + no_zeros;
		    
#ifdef USE_VENDOR_BLAS
#ifdef _CRAY
		    STRSV( ftcs1, ftcs2, ftcs3, &segsze, &lusup[luptr], 
			   &nsupr, tempv, &incx );
#else
		    dtrsv_( "L", "N", "U", &segsze, &lusup[luptr], 
			   &nsupr, tempv, &incx );
#endif
		    
		    luptr += segsze;	/* Dense matrix-vector */
		    tempv1 = &tempv[segsze];
                    alpha = one;
                    beta = zero;
#ifdef _CRAY
		    SGEMV( ftcs2, &nrow, &segsze, &alpha, &lusup[luptr], 
			   &nsupr, tempv, &incx, &beta, tempv1, &incy );
#else
		    dgemv_( "N", &nrow, &segsze, &alpha, &lusup[luptr], 
			   &nsupr, tempv, &incx, &beta, tempv1, &incy );
#endif
#else
		    dlsolve ( nsupr, segsze, &lusup[luptr], tempv );
		    
		    luptr += segsze;        /* Dense matrix-vector */
		    tempv1 = &tempv[segsze];
		    dmatvec (nsupr, nrow, segsze, &lusup[luptr], tempv, tempv1);
#endif
		    
		    /* Scatter tempv[*] into SPA dense[*] temporarily, such
		     * that tempv[*] can be used for the triangular solve of
		     * the next column of the panel. They will be copied into 
		     * ucol[*] after the whole panel has been finished.
		     */
		    isub = lptr + no_zeros;
		    for (i = 0; i < segsze; i++) {
			irow = lsub[isub];
			dense_col[irow] = tempv[i];
			tempv[i] = zero;
			isub++;
		    }
		    
		    /* Scatter the update from tempv1[*] into SPA dense[*] */
		    /* Start dense rectangular L */
		    for (i = 0; i < nrow; i++) {
			irow = lsub[isub];
			dense_col[irow] -= tempv1[i];
			tempv1[i] = zero;
			++isub;	
		    }
		    
		} /* else segsze>=4 ... */
		
	    } /* for each column in the panel... */
	    
	} /* else 1-D update ... */

    } /* for each updating supernode ... */

}



