/*                       R E C S I Z E . C
 * BRL-CAD
 *
 * Copyright (c) 1990-2024 United States Government as represented by
 * the U.S. Army Research Laboratory.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * version 2.1 as published by the Free Software Foundation.
 *
 * This program 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 GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this file; see the file named COPYING for more
 * information.
 */
/** @file iges/recsize.c
 *
 * Routine to determine record size of IGES file.
 *
 * According to the spec, the file should be 80 characters per record.
 * The spec does not mention anything about CR or LF at the end of
 * records, so this routine looks for LF's and returns the actual
 * record length.
 *
 * Note: this will work for files with records that are 80 characters
 * long without any CR or LF at end of records, also for files with
 * CR-LF at end of records, and for files with just LF at end of
 * records.  It will not work for files with just CR at end of records
 * (but I haven't seen such an animal yet)
 *
 */

#include "common.h"

#include <errno.h>

#include "./iges_struct.h"
#include "./iges_extern.h"

#define NRECS 20  /* Maximum number of records to sample */
#define NCHAR 256 /* Maximuim number of characters to read in case
		   * there are no LF's
		   */

int
Recsize(void)
{

    int i, j, k = (-1), recl = 0, length[NRECS] = {0}, ch;

    for (j = 0; j < NRECS; j++) {
	i = 1;
	while ((ch = getc(fd)) != '\n' && i < NCHAR && ch != EOF)
	    i++;
	if (i == NCHAR) {
	    recl = 80;
	    break;
	} else if (ch == EOF) {
	    k = j - 1;
	    break;
	} else
	    length[j] = i; /* record this record length */
    }
    if (k == (-1))	/* We didn't encounter an early EOF */
	k = NRECS;

    if (bu_fseek(fd, 0, 0)) {
	/* rewind file */
	bu_log("Cannot rewind file\n");
	perror("Recsize");
	bu_exit(1, NULL);
    }

    if (recl == 0) {
	/* then LF's were found */
	recl = length[1];	/* don't use length[0] */

	/* check for consistent record lengths */
	for (j = 2; j < k; j++) {
	    if (recl != length[j])
		return 0;
	}
    }
    return recl;
}


/*
 * Local Variables:
 * mode: C
 * tab-width: 8
 * indent-tabs-mode: t
 * c-file-style: "stroustrup"
 * End:
 * ex: shiftwidth=4 tabstop=8
 */
