/* Tickler Code related to file operations. */

#include <stdio.h>  /* FILE, fopen(), fclose() */
						  /* printf(), fprintf() */
						  /* scanf(), fscanf() */
#include <stdlib.h> /* EXIT_SUCCESS, EXIT_FAILURE, exit() */
#include <limits.h> /* INT_MAX */
#include <math.h>   /* sin() */

#define FALSE (0)
#define TRUE  (!FALSE)

#define READ   (0)
#define WRITE  (1)

#define TEXT   (0)
#define BINARY (1)

#define PI (3.141592654)

#define FREQUENCY (1000.0)
#define SAMPLESperSEC (44200.0)
#define SAMPLES   (1024)

FILE *OpenFile(char *filename, int mode, int type)
{
	char modestr[3];

	switch (mode)
	{
		case READ : modestr[0] = 'r'; break;
		case WRITE: modestr[0] = 'w'; break;
	}

	switch (type)
	{
		case TEXT  : modestr[1] = 't'; break;
		case BINARY: modestr[1] = 'b'; break;
	}

	modestr[2] = '\0';

	return fopen(filename, modestr);
}

int main(void)
{
	FILE *fp;
	char *filename;
	double freq_Hz;
	int v;
	double time, value;
	long int sample;
	long int RiffMarker, DataMarker, EndMarker;
	long int v_long;
	int v_int;

	filename = "sine1000.wav";
	if (NULL == (fp = OpenFile(filename, WRITE, BINARY)))
	{
		printf("Failed to open file <%s>\n");
		exit(EXIT_FAILURE);
	}

	/* RIFF HEADER */
	fwrite("RIFF", 4, 1, fp);
	fwrite("Size", 4, 1, fp); /* Will update with value later */
	RiffMarker = ftell(fp);
	fwrite("WAVE", 4, 1, fp);

	/* FORMAT CHUNK */
	fwrite("fmt ", 4, 1, fp);
	v_long = 16;
	fwrite(&v_long, 4, 1, fp); /* SubChunkSize (16 for PCM) */
	v_int = 1;
	fwrite(&v_int, 2, 1, fp); /* 1 = PMC (no compression) */
	v_int = 1;
	fwrite(&v_int, 2, 1, fp); /* Number of Channels */
	v_long = 44100L;
	fwrite(&v_long, 4, 1, fp); /* Sample Rate */
	v_long = 88200L;
	fwrite(&v_long, 4, 1, fp); /* ByteRate */
	v_int = 2;
	fwrite(&v_int, 2, 1, fp); /* Block Alignment */
	v_int = 16;
	fwrite(&v_int, 2, 1, fp); /* Bits Per Sample */

	/* DATA CHUNK */
	fwrite("data", 4, 1, fp);
	fwrite("Size", 4, 1, fp); /* Will update with value later */
	DataMarker = ftell(fp);

	/* WRITING SINUSOID TO TEXT FILE */
	freq_Hz = FREQUENCY;

	for (sample = 0; sample < SAMPLES; sample++)
	{
		time = (double) sample / SAMPLESperSEC;
		value = sin(2.0*PI*freq_Hz*time);
		v = INT_MAX * value;
		fwrite(&v, 2, 1, fp);
	}
	EndMarker = ftell(fp);

	fseek(fp, RiffMarker-4, SEEK_SET);
	v_long = EndMarker - RiffMarker;
	fwrite(&v_long, 4, 1, fp); /* ByteRate */

	fseek(fp, DataMarker-4, SEEK_SET);
	v_long = EndMarker - DataMarker;
	fwrite(&v_long, 4, 1, fp); /* ByteRate */

	fclose(fp);

	return EXIT_SUCCESS;
}