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* Contents: Native C interface to LAPACK utility function
* Author: Intel Corporation
*****************************************************************************/

#include "lapacke_utils.h"

/* Converts input general band matrix from row-major(C) to
 * column-major(Fortran) layout or vice versa.
 */

void LAPACKE_sgb_trans( int matrix_layout, lapack_int m, lapack_int n,
                        lapack_int kl, lapack_int ku,
                        const float *in, lapack_int ldin,
                        float *out, lapack_int ldout )
{
    lapack_int i, j;

    if( in == NULL || out == NULL ) return;

    if( matrix_layout == LAPACK_COL_MAJOR ) {
        for( j = 0; j < MIN( ldout, n ); j++ ) {
            for( i = MAX( ku-j, 0 ); i < MIN3( ldin, m+ku-j, kl+ku+1 );
                 i++ ) {
                out[(size_t)i*ldout+j] = in[i+(size_t)j*ldin];
            }
        }
    } else if ( matrix_layout == LAPACK_ROW_MAJOR ) {
        /* TODO: interchange loops for performance.
         * This is just reference implementation.
         */
        for( j = 0; j < MIN( n, ldin ); j++ ) {
            for( i = MAX( ku-j, 0 ); i < MIN3( ldout, m+ku-j, kl+ku+1 );
                 i++ ) {
                out[i+(size_t)j*ldout] = in[(size_t)i*ldin+j];
            }
        }
    }
}
