byte_checker.c

seed格式数据解压程序,地震分析人员必备

#include <stdio.h>
#include <stdlib.h>
#include <sys/param.h>
#include <strings.h>
#include "constants.h"
#include "globals.h"
#include "output.h"

#define HEADER_SIZE 7

extern char Header_path[];
struct DMC_request *r;

void swap_error_msg();
char *station_word_order();
char *read_station_50_info();
int swap_bytes();
void byte_swap();
 

/* ---------------------------------------------------------------------- */
int bytes_need_swapping(data_header)
struct input_data_logrec *data_header;

{

	if (data_header->hdr.scan.time.year < 1950 ||
		data_header->hdr.scan.time.year > 2010)
		return(TRUE);
	
	return(FALSE);	

}

/* -------------------------------------------------------------------- */

char *read_station_50_info(fptr, buffer)
FILE *fptr;
char buffer[];

{
	int num;
	char wrkstr[20];

	if ((num = fread(buffer, HEADER_SIZE, 1, fptr)) != 1)
        return((char *)NULL);  	/* */

	/* compute block size from header */
	sprintf(wrkstr, "%.4s", buffer + 3);
	num = atoi(wrkstr);

									/* plus one for \n at end */
	if (fread(buffer + HEADER_SIZE, (num - HEADER_SIZE) + 1, 1, fptr) != 1)
		return((char *)NULL);		

	/* make sure is null terminated */
	buffer[num] = 0;

	return(buffer);

}

#define MSB_FIRST 0x76543210                    /* MC680x0 word order */
#define MSB_LAST  0x10325476                    /* VAX, 80x86 word order */
 
/* ------------------------------------------------------------------------ */
int swap_bytes(short_str)
char *short_str;

{
	char tmpchar[4];	/* put here because compiler keeps overwriting 
						 * the func parameter. Seems to only allocate 
						 * one byte on stack for union !
						 */
	union
    {
        unsigned char character[4];
        unsigned long int integer;
    } test4; 	

    /* Construct a 4-byte word of known contents - 0x76543210 */
    test4.character[0] = 0x76;
    test4.character[1] = 0x54;
    test4.character[2] = 0x32;
    test4.character[3] = 0x10;
 
	if (test4.integer == MSB_FIRST)
    {
		if (strcmp(short_str, "10") == 0) 
			return (FALSE);		/* no swapping needed */

		return(TRUE);
	}
	else 
	if (test4.integer == MSB_LAST)
	{
		if (strcmp(short_str, "01") == 0) 
			return (FALSE);		/* no swapping needed */
	
		return (TRUE);
	}
	else
	{
		fprintf (stderr, "ERROR (find_wordorder):  ");
		fprintf (stderr,
					"machine word order, %d, not treated by byte swappers.\n",
					test4.integer);
		fprintf (stderr, "Execution terminating.\n");
		return(FALSE);	/* assume no byte swapping necessary */

	}

}

/* ------------------------------------------------------------------------ */
short swap_2byte(b)
short b;

{
	union
    {
        unsigned char character[2];
        unsigned short int integer;
    } swap2byte;                                /* holds 2-byte word */

    char temp0;

	swap2byte.integer = b;

    temp0 = swap2byte.character[0];
    swap2byte.character[0] = swap2byte.character[1];
    swap2byte.character[1] = temp0;

    return (swap2byte.integer);

}


/* ---------------------------------------------------------------------- */
int swap_4byte(w)
int w;

{
	union
    {
        unsigned char character[4];
        unsigned long int integer;
    } swap4byte;                                /* holds 4-byte word */

    char temp0;
    char temp1;

    swap4byte.integer = w;

    temp0 = swap4byte.character[0];
    temp1 = swap4byte.character[1];
    swap4byte.character[0] = swap4byte.character[3];
    swap4byte.character[1] = swap4byte.character[2];
    swap4byte.character[2] = temp1;
    swap4byte.character[3] = temp0;

    return (swap4byte.integer);

}

/* ---------------------------------------------------------------------- */

void swap_error_msg(msg)
char *msg;

{
	char str[200];

	sprintf(str, "[bytes_need_swapping] %s\n", msg);

	error_handler (WARNING, str);
 
	fprintf(stderr, "Assuming no swapping needed!\n");
 
	perror("pod:bytes_need_swapping");
 
	return;

}

/* ------------------------------------------------------------------------ */