/*
    Read

        http://z0b.kapsi.fi/snippets.php

    before using this code. Thank you.
*/

// Two helper functions for writing 16- and 32-bit unsigned integers.
// Feel free to replace.
static void write16(const uint16_t v, FILE *f)
{
    fwrite(&v, sizeof(uint16_t), 1, f);
}

static void write32(const uint32_t v, FILE *f)
{
    fwrite(&v, sizeof(uint32_t), 1, f);
}

// this is what you need to call
static void writeWAVHeader(FILE *f,
                           const uint16_t channels, const uint32_t sampleRate,
                           const uint16_t bitsPerSample, const uint32_t size)
{
    if (!f)
        return;

    // Write RIFF chunk start and the file size. Smallest possible
    // header is 44 bytes, excluding the 8 RIFF chunk bytes.
    fputs("RIFF", f);
    write32(size + 44UL - 8UL, f);

    // wave subchunk (strange, it has no size?)
    fputs("WAVE", f);

    // format subchunk
    fputs("fmt ", f);
    write32(16, f);                 // 16 = PCM
    write16(1, f);                  // 1 = PCM, linear quantization
    write16(channels, f);
    write32(sampleRate, f);
    write32(sampleRate * channels * bitsPerSample / 8, f);   // byteRate
    write16(channels * bitsPerSample / 8, f);                // blockAlign
    write16(bitsPerSample, f);

    // data subchunk
    fputs("data", f);
    write32(size, f);
}


// example usage (CD-quality sound):

FILE *wav;
std::vector<int16_t> data;

...

writeWAVHeader(wav, 2, 44100, 16, data.size());
fwrite(&data[0], 2, data.size(), wav);

...