find_disc.c

seed格式数据解压程序,地震分析人员必备

/*===========================================================================*/
/* DMC Interim out |             find_disc.c               |   Scan_phase    */
/*===========================================================================*/
/*
	Name:		find_disc.c
	Purpose:	find all time discontinuities within a data file
	Usage:		int find_disc ()
				int	ifd;
				err = find_disc(ifd)
	Input:		int	ifd						open file descriptor
				int precision				time precision
	Output:		int find_disc ()   >=0  number of time segments found
									=-1	error
	Externals:	Debug - setting of environment variable DEBUG (globals.h)
	Messages:	
	Warnings:	
	Errors:		
	Fatals:		
	Called by:	
	Calls to:	cmp_time		compares two times in struct input_time fmt
				add_time		adds e-04 sec to time in struct input_time fmt
				get_scaninfo	get subset of data hdr info and data start/end
	Notes:		Assumes archive data record length = Lrecl
	Problems:	Segment counter (segcnt) does not count skipped segments.
				Assumes all data header records in 680xx-compatible byte order.
	References:	none
	Language:	ANSI standard C, under Sun OS 3.5
	Revisions:	03/22/89  Kevin MacKenzie  original version
*/

                   /*=====================================*/
/*=================|                                       |=================*/
                   /*=====================================*/

#include "output.h"

/* the following definitions provide private storage over multiple entries */
	
int find_disc (ifd, precision)
int						ifd;			/* open file descriptor */
long					precision;		/* time comparison precision, e-04 s */
{
	char				*buf;	/* ptr to input data record buffer */
	int					file_o = 0;		/* file offset pointer */
	int					len;			/* length of buffer returned by read */
	struct	input_scan	rec_scan;		/* data hdr scan info of data record */
	struct	input_time	rec_start;		/* start time of data record */
	struct	input_time	rec_end;		/* end time of data record */
	struct input_time	est_rec_start;	/* estim. start time of next rec */
	struct input_data_logrec *rec;		/* data hdr */
	long				interval;		/* data sample interval,e-04 sec/samp */
	int					i = 1;			/* number of segments */

	buf = (char *)malloc ((unsigned int) Lrecl);
	fprintf (D_OUT,
		"--------------------------------------------------- seg # %d\n",i);

	while ((len = read (ifd, buf, (unsigned int) Lrecl)) > 0)
	{
		rec = (struct input_data_logrec *) buf;
		get_scaninfo (buf, &rec_scan, &rec_start, &rec_end, &interval);
		precision = min (precision, interval / 5);
		if (file_o > 0 && cmp_time (est_rec_start, rec_start, precision) != 0)
		{
			i++;
			fprintf (D_OUT,
		"--------------------------------------------------- seg # %d\n",i);
		}
		fprintf (D_OUT, "number of samples = %8d\n",
			(int)rec->hdr.full.nsamples);
		fprintf (D_OUT, "fracsecs per sample = %6d\n",interval);
		print_time ("data record start=",&rec_start);
		print_time ("data record end=",&rec_end);
		est_rec_start = add_time (rec_end, interval);
		print_time ("estimated start=",&est_rec_start);
		fprintf (D_OUT,"\n");
		file_o += len;		/* increment file offset memory */
	}
	fprintf (D_OUT, "total bytes read = %d\n",file_o);
	return (i);
}