/*
 * matalloc: allocates space for a matrix, returns pointer if successful,
 *  NULL if not.  The matrix elements are initialized to zero bytes.
 */

#include "mex.h"

#include "matalloc.h"

int **matalloc( int rows, int cols)
{
    int **a;		/* result pointer */
    int i;		/* row index */

    if( rows < 1 || cols < 1)
	return 0;

    /*
     * first, get space for rows+1 pointers to int
     */
    if( (a = mxMalloc( (rows+1) * sizeof(int *)) ) == 0)
	return 0;

    /*
     * get space for all of the rows, rows*cols int
     */
    if( (a[0] = a[1] = mxCalloc( rows*cols, sizeof(int)) ) == 0) {
	mxFree(a);
	return 0;
    }

    /*
     * set the pointers a[1]..a[rows-1] to point to their row
     */
    ++a;
    for( i = 1; i < rows; i++)
	a[i] = a[i-1] + cols;

    return a;
}

void matfree( int **a)	/* free space allocated by matalloc */
{
    if( a) {
	mxFree(a[-1]);	/* free the matrix data */
	mxFree(a-1);	/* free the row pointers */
    }
}