fileio.c

/*
 * fileio.c
 *
 * HISTORY:
 * quick and dirty hack Linas Vepstas October 1989
 * more hacks ever since -- Linas
 */

#include <endian.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "fileio.h"

extern FILE *Fopen();
extern FILE *Fopenr();

/*-------------------------------------------------------------------*/
// My version of fgets, because fgets is sometimes broken on other machines.
// I don't remember what the problem was.
static char *my_fgets(char *s, int size, FILE *stream)
{
	for (int i=0; i< size; i++)
	{
		int ch =  fgetc(stream);
		s[i] = ch;
		if ('\n' == ch) break;
		if (0 == ch) break;
	}
	return s;
}

/*-------------------------------------------------------------------*/
// Read a *.flo greyscale floating-point pixmap.
// The file format is width, height in ascii, then newline
// then floating point data in machine-native byte order.
// One float per pixel, a total of width*height floats.
float* read_flo_file(const char *fname,
                     unsigned int* data_width, unsigned int* data_height)
{
	/* open input file */
	FILE *fh = Fopenr (fname, ".flo");
	if (NULL == fh) return NULL;

#define CLEN 80
   char str[CLEN];
	my_fgets(str, CLEN, fh);

	sscanf(str, "%d %d", data_width, data_height);
	fprintf(stderr, "Input file %s has width %d height %d \n",
	        fname, *data_width, *data_height);

	size_t datalen = (*data_width) * (*data_height);
	float* data_in = (float *) malloc (datalen * sizeof(float));

	/* read floating point data */
	fread(data_in, sizeof(float), datalen, fh);
	fclose(fh);

	return data_in;
}

/*-------------------------------------------------------------------*/
// Read a *.pfm greyscale floating-point pixmap.
// This reads the PFM file format as described in various places.
float* read_pfm_file(const char *fname,
                     unsigned int* data_width, unsigned int* data_height)
{
	/* open input file */
	FILE *fh = Fopenr (fname, ".pfm");
	if (NULL == fh) return NULL;

#define PFLEN 80
   char str[PFLEN];
	my_fgets(str, PFLEN, fh);

	// Handle only greyscale
	if ('P' != str[0] || 'f' != str[1]) return NULL;

	// Read the dimensions
	my_fgets(str, PFLEN, fh);
	sscanf(str, "%d %d", data_width, data_height);
	fprintf(stderr, "Input file %s has width %d height %d \n",
	        fname, *data_width, *data_height);

	// Read the "scale factor" and ignore it.
	my_fgets(str, PFLEN, fh);
	// double scale = atof(str);

	size_t datalen = (*data_width) * (*data_height);
	float* data_in = (float *) malloc (datalen * sizeof(float));

	/* read floating point data */
	fread(data_in, sizeof(float), datalen, fh);
	fclose(fh);

	return data_in;
}

/*-------------------------------------------------------------------*/
float* read_floats(const char *fname, const char** suff,
                   unsigned int* data_width, unsigned int* data_height)
{
	/* open input file */
	*suff = ".flo";
	float* data_in = read_flo_file(fname, data_width, data_height);
	if (NULL == data_in)
	{
		*suff = ".pfm";
		data_in = read_pfm_file(fname, data_width, data_height);
	}
	if (NULL == data_in)
	{
		*suff = "";
		fprintf (stderr, "Can't open input file %s\n", fname);
		return NULL;
	}
	return data_in;
}

/*-------------------------------------------------------------------*/
// Write a *.flo greyscale floating-point pixmap.
// The file format is width, height in ascii, then newline
// then floating point data in machine-native byte order.
// One float per pixel, a total of width*height floats.
void write_flo_file(const char *fname, float* data,
                    unsigned int data_width, unsigned int data_height)
{
   FILE *fh = Fopen(fname, ".flo");
   if (NULL == fh)
	{
      fprintf (stderr, "Can't open output file %s.flo\n", fname);
		return;
   }

   /* dump the size to output */
   fprintf (fh, "%d %d\n", data_width, data_height);
   fwrite (data, sizeof(float), data_width*data_height, fh);
   fclose (fh);
}

/*-------------------------------------------------------------------*/
// Write a *.pfm greyscale floating-point pixmap.
// The file format is width, height in ascii, then newline
// then floating point data in machine-native byte order.
// One float per pixel, a total of width*height floats.
void write_pfm_file(const char *fname, float* data,
                    unsigned int data_width, unsigned int data_height)
{
	FILE *fh = Fopen(fname, ".pfm");
	if (NULL == fh)
	{
		fprintf (stderr, "Can't open output file %s.pfm\n", fname);
		return;
	}

	/* dump the size to output */
	fprintf (fh, "Pf\n");
	fprintf (fh, "%d %d\n", data_width, data_height);
	double scale = 1.0;
	// if (htonl(47) != 47) scale = -1.0; // Little-endian
	if (htobe16(47) != 47) scale = -1.0; // Little-endian
	fprintf (fh, "%f\n", scale);

	/* And now the data. */
	fwrite (data, sizeof(float), data_width*data_height, fh);
	fclose (fh);
}

/*-------------------------------------------------------------------*/
void write_floats(const char *fname, const char* suff, float* data,
                  unsigned int data_width, unsigned int data_height)
{
	if (0 == strcmp(suff, ".flo"))
		write_flo_file(fname, data, data_width, data_height);

	if (0 == strcmp(suff, ".pfm"))
		write_pfm_file(fname, data, data_width, data_height);
}

/* --------------- END OF FILE ------------------------- */