/* purpose: conversion of binary data with little-endian to ASCII

   Sep. 8, 2006 by Maosheng Zhao */

/* I also accounts for the possible different CPU on different platforms,

   and therefore, it should work on different machines without problem */

#include<stdio.h>

#define COLS 7200

#define ROWS 3600

#define DATA_TYPE unsigned short

/*$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$*/

#define IN_FILE_NAME  "Npp_0.05deg_mean.int16"

#define OUT_FILE_NAME "Npp_0.05deg_mean.ASCII2"

/*$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$*/

int main()

{

    /* definiation of variables will be used */

    FILE *in_f, *out_f;

    static DATA_TYPE data_in[ROWS][COLS];

    int i,j;

    /* the follow definition is for determination the type of CPU */

    int  is_big_endian=0;

    short one=1;

    char *cp;

    /* define a buffer pointer to swap bytes if it is big-endian CPU */

    char temp_char[sizeof(DATA_TYPE)];

    DATA_TYPE *buffer_data; 

    int m;

    /*################################################################*/

    /* main program starts */

    /* open the data file and read all the data */

    in_f = fopen(IN_FILE_NAME,"rb");

    if(in_f == NULL)

    {

	printf("cannot open %s, exit...\n",IN_FILE_NAME);

	exit(0);

    }

    else  /* reading the data */

    {

	/* tell the type of CPU */

	cp = (char*)&one;

	if(*cp == 0)

	   is_big_endian = 1;  /* yes, this is a big-endian CPU */

	else

	   is_big_endian = 0;  /* this is a little-endian CPU */

	if(is_big_endian == 0)

	{

	   printf("This is a little-endian CPU, no need to swap bytes\n");

	   printf("reading data now, please waiting for...\n");

	   fread(data_in,sizeof(DATA_TYPE),COLS*ROWS,in_f);

	}

	else

	{

	   printf("This is a big-endian CPU, which needs to swap bytes\n");

	   printf("reading data now, please waiting for...\n");

	   for(i=0;i<ROWS;i++)

		for(j=0;j<COLS;j++)

		{

	   	   for(m=0;m<sizeof(DATA_TYPE);m++)

			fread(&temp_char[sizeof(DATA_TYPE)-1-m],1,1,in_f);

		   /* swap the byte order */

		   buffer_data = (DATA_TYPE*)temp_char;

		   data_in[i][j] = *buffer_data;

		} /* end of nested loops for i and j */

	}

    }

    /* close the input file */

    fclose(in_f);

    /* write the ASCII to a new file */

    out_f = fopen(OUT_FILE_NAME,"w");

    printf("Please waiting for writing data to %s\n",OUT_FILE_NAME);

    for(i=0;i<ROWS;i++)

	for(j=0;j<COLS;j++)

	    fprintf(out_f,"%6d\n",data_in[i][j]);

    fclose(out_f);

    printf("Finished conversion of binary to ASCII\n");

    return(0);

}