Add WAV-header to PCM data

pcmwav.h

/* Save 16 bit PCM 44.1kHz stereo data into a WAV-File, so common media
   players will recognize it.
*/

#pragma once

#include <unistd.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <assert.h>
#include <endian.h>

/* important: these values are here for documentation. if they are
   changed, the code must be reviewed */
const int channels = 2;
const int samplerate = 44100;
const int bytespersample = 2;

#define WRITE_OR_DIE(ptr,tp,sz,f) \
  if (fwrite(ptr,tp,sz,f) != sz) return false;

bool dumpwave (bool convert, int nsamples,
	       int16_t* samples, FILE* outfile) {
  int16_t * samples_cur = samples, * samples_end = samples + nsamples;

  if (convert)
    for (; samples_cur < samples_end; ++samples_cur)
      *samples_cur = (int16_t) htole16 ((uint16_t) *samples_cur);

  /* todo: check that writes were successfull */

  size_t out;
  int32_t size;
  int16_t nchan;

  WRITE_OR_DIE("RIFF", sizeof(char), 4, outfile);

  size = (int32_t) htole32 ((uint32_t)(36 + bytespersample
				       * channels * nsamples));
  WRITE_OR_DIE(&size, sizeof(int32_t), 1, outfile);

  WRITE_OR_DIE("WAVEfmt ", sizeof(char), 8, outfile);

  /* chunk size == 16 */
  size = (int32_t) htole32 ((uint32_t) 16);
  WRITE_OR_DIE(&size, sizeof(int32_t), 1, outfile);

  /* format = pcm */
  WRITE_OR_DIE("\1\0", sizeof(char), 2, outfile);

  nchan = (int16_t) htole16 ((uint16_t) channels);
  WRITE_OR_DIE(&nchan, sizeof(int16_t), 1, outfile);
  size = (int32_t) htole32 ((uint32_t) samplerate);
  WRITE_OR_DIE(&size, sizeof(int32_t), 1, outfile);
  size = (int32_t)htole32((uint32_t)(samplerate * channels * bytespersample));
  WRITE_OR_DIE(&size, sizeof(int32_t), 1, outfile);
  nchan = (int16_t) htole16 ((uint16_t) (channels * bytespersample));
  WRITE_OR_DIE(&nchan, sizeof(int16_t), 1, outfile);
  nchan = (int16_t) htole16 ((uint16_t) (8 * bytespersample));
  WRITE_OR_DIE(&nchan, sizeof(int16_t), 1, outfile);
  WRITE_OR_DIE("data", sizeof(char), 4, outfile);
  size = (int32_t) htole32 ((uint32_t) (bytespersample * channels * nsamples));
  WRITE_OR_DIE(&size, sizeof(int32_t), 1, outfile);
  WRITE_OR_DIE(samples, channels * sizeof(int16_t), nsamples, outfile);
  return true;
}