/*
 *** wavout.c
 */

#include "wav.h"

static int file_size;			/* size of file (bytes) */
static int format_size;			/* size of format chunk (bytes) */
static int data_size;			/* size of data chunk (bytes) */
static int nfile, nchunk;
static fpos_t file_pos, format_pos, data_pos;
static int dummy = 0;

void *
revb(seq, n)				/* reverse byte order */
	unsigned char *seq; int n;
{
	int i;
	static unsigned char rev[8];
	for (i=0; i<n; i++) rev[i] = seq[n-i-1];
	return(rev);
}

#define	putbytes(p, sz)	{ fwrite(p, sz, 1, fd); nfile += sz; nchunk += sz; }
/*
#define	putrev(p, sz)	putbytes(revb(p, sz), sz)
*/
#define	putrev(p, sz)	putbytes(p, sz)

void
wavopen(fd, fmt)
	FILE *fd; WAVFMT *fmt;
{
	putbytes("RIFF", 4);
	fgetpos(fd, &file_pos);
	putbytes(&dummy, 4);
	nfile = 0; nchunk = 0;

	putbytes("WAVE", 4);

	/* format chunk */
	putbytes("fmt ", 4);
	fgetpos(fd, &format_pos);
	putbytes(&dummy, 4);
	nchunk = 0;

	putrev(&(fmt->DataID), 2);
	putrev(&(fmt->Channels), 2);
	putrev(&(fmt->SamplingRate), 4);
	putrev(&(fmt->BytesPerSec), 4);
	putrev(&(fmt->BytesPerUnit), 2);
	putrev(&(fmt->BitsPerSample), 2);
	format_size = nchunk;

	/* data chunk header */
	putbytes("data", 4);
	fgetpos(fd, &data_pos);
	putbytes(&dummy, 4);
	nchunk = 0;
}

void
wavclose(fd)
	FILE *fd;
{
	file_size = nfile;
	data_size = nchunk;

	fsetpos(fd, &file_pos);		putrev(&file_size, 4);
	fsetpos(fd, &format_pos);	putrev(&format_size, 4);
	fsetpos(fd, &data_pos);		putrev(&data_size, 4);
	fclose(fd);
}

void
wavdata(fd, data, sz)
	FILE *fd; int data, sz;
{
	if (sz == 1) {
		unsigned char b = data + 128;
		putbytes(&b, 1);
	} else if (sz == 2) {
		short s = data;
		putrev(&s, 2);
	}
}

void
default_format(fmt)
	WAVFMT *fmt;
{
	fmt->DataID = F_PCM;
	fmt->Channels = 1;
	fmt->SamplingRate = 44100;
	fmt->BytesPerSec = 44100*2;
	fmt->BytesPerUnit = 2;
	fmt->BitsPerSample = 16;
}