lovr-ODE/ode/src/fastltsolve.c

/*************************************************************************
 *                                                                       *
 * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith.       *
 * All rights reserved.  Email: [email protected]   Web: www.q12.org          *
 *                                                                       *
 * This library is free software; you can redistribute it and/or         *
 * modify it under the terms of EITHER:                                  *
 *   (1) The GNU Lesser General Public License as published by the Free  *
 *       Software Foundation; either version 2.1 of the License, or (at  *
 *       your option) any later version. The text of the GNU Lesser      *
 *       General Public License is included with this library in the     *
 *       file LICENSE.TXT.                                               *
 *   (2) The BSD-style license that is included with this library in     *
 *       the file LICENSE-BSD.TXT.                                       *
 *                                                                       *
 * This library is distributed in the hope that it will be useful,       *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files    *
 * LICENSE.TXT and LICENSE-BSD.TXT for more details.                     *
 *                                                                       *
 *************************************************************************/

/* generated code, do not edit. */

#include <ode/common.h>
#include "config.h"
#include "matrix.h"

/* solve L^T * x=b, with b containing 1 right hand side.
 * L is an n*n lower triangular matrix with ones on the diagonal.
 * L is stored by rows and its leading dimension is lskip.
 * b is an n*1 matrix that contains the right hand side.
 * b is overwritten with x.
 * this processes blocks of 4.
 */

void _dSolveL1T (const dReal *L, dReal *B, int n, int lskip1)
{  
    /* declare variables - Z matrix, p and q vectors, etc */
    dReal Z11,m11,Z21,m21,Z31,m31,Z41,m41,p1,q1,p2,p3,p4,*ex;
    const dReal *ell;
    int lskip2/*,lskip3*/,i,j;
    /* special handling for L and B because we're solving L1 *transpose* */
    L = L + (n-1)*(lskip1+1);
    B = B + n-1;
    lskip1 = -lskip1;
    /* compute lskip values */
    lskip2 = 2*lskip1;
    /*lskip3 = 3*lskip1;*/
    /* compute all 4 x 1 blocks of X */
    for (i=0; i <= n-4; i+=4) {
        /* compute all 4 x 1 block of X, from rows i..i+4-1 */
        /* set the Z matrix to 0 */
        Z11=0;
        Z21=0;
        Z31=0;
        Z41=0;
        ell = L - i;
        ex = B;
        /* the inner loop that computes outer products and adds them to Z */
        for (j=i-4; j >= 0; j -= 4) {
            /* load p and q values */
            p1=ell[0];
            q1=ex[0];
            p2=ell[-1];
            p3=ell[-2];
            p4=ell[-3];
            /* compute outer product and add it to the Z matrix */
            m11 = p1 * q1;
            m21 = p2 * q1;
            m31 = p3 * q1;
            m41 = p4 * q1;
            ell += lskip1;
            Z11 += m11;
            Z21 += m21;
            Z31 += m31;
            Z41 += m41;
            /* load p and q values */
            p1=ell[0];
            q1=ex[-1];
            p2=ell[-1];
            p3=ell[-2];
            p4=ell[-3];
            /* compute outer product and add it to the Z matrix */
            m11 = p1 * q1;
            m21 = p2 * q1;
            m31 = p3 * q1;
            m41 = p4 * q1;
            ell += lskip1;
            Z11 += m11;
            Z21 += m21;
            Z31 += m31;
            Z41 += m41;
            /* load p and q values */
            p1=ell[0];
            q1=ex[-2];
            p2=ell[-1];
            p3=ell[-2];
            p4=ell[-3];
            /* compute outer product and add it to the Z matrix */
            m11 = p1 * q1;
            m21 = p2 * q1;
            m31 = p3 * q1;
            m41 = p4 * q1;
            ell += lskip1;
            Z11 += m11;
            Z21 += m21;
            Z31 += m31;
            Z41 += m41;
            /* load p and q values */
            p1=ell[0];
            q1=ex[-3];
            p2=ell[-1];
            p3=ell[-2];
            p4=ell[-3];
            /* compute outer product and add it to the Z matrix */
            m11 = p1 * q1;
            m21 = p2 * q1;
            m31 = p3 * q1;
            m41 = p4 * q1;
            ell += lskip1;
            ex -= 4;
            Z11 += m11;
            Z21 += m21;
            Z31 += m31;
            Z41 += m41;
            /* end of inner loop */
        }
        /* compute left-over iterations */
        j += 4;
        for (; j > 0; j--) {
            /* load p and q values */
            p1=ell[0];
            q1=ex[0];
            p2=ell[-1];
            p3=ell[-2];
            p4=ell[-3];
            /* compute outer product and add it to the Z matrix */
            m11 = p1 * q1;
            m21 = p2 * q1;
            m31 = p3 * q1;
            m41 = p4 * q1;
            ell += lskip1;
            ex -= 1;
            Z11 += m11;
            Z21 += m21;
            Z31 += m31;
            Z41 += m41;
        }
        /* finish computing the X(i) block */
        Z11 = ex[0] - Z11;
        ex[0] = Z11;
        p1 = ell[-1];
        Z21 = ex[-1] - Z21 - p1*Z11;
        ex[-1] = Z21;
        p1 = ell[-2];
        p2 = ell[-2+lskip1];
        Z31 = ex[-2] - Z31 - p1*Z11 - p2*Z21;
        ex[-2] = Z31;
        p1 = ell[-3];
        p2 = ell[-3+lskip1];
        p3 = ell[-3+lskip2];
        Z41 = ex[-3] - Z41 - p1*Z11 - p2*Z21 - p3*Z31;
        ex[-3] = Z41;
        /* end of outer loop */
    }
    /* compute rows at end that are not a multiple of block size */
    for (; i < n; i++) {
        /* compute all 1 x 1 block of X, from rows i..i+1-1 */
        /* set the Z matrix to 0 */
        Z11=0;
        ell = L - i;
        ex = B;
        /* the inner loop that computes outer products and adds them to Z */
        for (j=i-4; j >= 0; j -= 4) {
            /* load p and q values */
            p1=ell[0];
            q1=ex[0];
            /* compute outer product and add it to the Z matrix */
            m11 = p1 * q1;
            ell += lskip1;
            Z11 += m11;
            /* load p and q values */
            p1=ell[0];
            q1=ex[-1];
            /* compute outer product and add it to the Z matrix */
            m11 = p1 * q1;
            ell += lskip1;
            Z11 += m11;
            /* load p and q values */
            p1=ell[0];
            q1=ex[-2];
            /* compute outer product and add it to the Z matrix */
            m11 = p1 * q1;
            ell += lskip1;
            Z11 += m11;
            /* load p and q values */
            p1=ell[0];
            q1=ex[-3];
            /* compute outer product and add it to the Z matrix */
            m11 = p1 * q1;
            ell += lskip1;
            ex -= 4;
            Z11 += m11;
            /* end of inner loop */
        }
        /* compute left-over iterations */
        j += 4;
        for (; j > 0; j--) {
            /* load p and q values */
            p1=ell[0];
            q1=ex[0];
            /* compute outer product and add it to the Z matrix */
            m11 = p1 * q1;
            ell += lskip1;
            ex -= 1;
            Z11 += m11;
        }
        /* finish computing the X(i) block */
        Z11 = ex[0] - Z11;
        ex[0] = Z11;
    }
}


#undef dSolveL1T

void dSolveL1T (const dReal *L, dReal *B, int n, int lskip1)
{
    _dSolveL1T (L, B, n, lskip1);
}