amuse/lib/N64MusyXCodec.c

#include "amuse/N64MusyXCodec.h"
#include <stdint.h>
#include <string.h>
#include <stdio.h>

/* Acknowledgements:
 * SubDrag for N64 Sound Tool (http://www.goldeneyevault.com/viewfile.php?id=212)
 * Bobby Smiles for MusyX codec research
 */

static int rdot(unsigned n, const int16_t* x, const int16_t* y)
{
    int accu = 0;

    y += n;

    while (n != 0)
    {
        accu += ((int)*(x++) * (int)*(--y));
        --n;
    }

    return accu;
}

static int16_t adpcm_get_predicted_sample(unsigned char byte, unsigned char mask,
                                          unsigned lshift, unsigned rshift)
{
    int16_t sample = ((int16_t)byte & (int16_t)mask) << lshift;
    sample >>= rshift; /* signed */
    return sample;
}

static void adpcm_get_predicted_frame(int16_t* dst, const unsigned char* src,
                                      const unsigned char* nibbles,
                                      unsigned rshift)
{
    *(dst++) = (src[0] << 8) | src[1];
    *(dst++) = (src[2] << 8) | src[3];

    for (unsigned i=1 ; i<16 ; ++i)
    {
        unsigned char byteData = nibbles[i];

        *(dst++) = adpcm_get_predicted_sample(byteData, 0xf0,  8, rshift);
        *(dst++) = adpcm_get_predicted_sample(byteData, 0x0f, 12, rshift);
    }
}

static unsigned adpcm_decode_upto_8_samples(int16_t* dst, const int16_t* src,
                                            const int16_t* cb_entry,
                                            const int16_t* last_samples,
                                            unsigned size)
{
    if (size == 0)
        return 0;

    const int16_t* book1 = cb_entry;
    const int16_t* book2 = cb_entry + 8;

    int16_t l1 = last_samples[0];
    int16_t l2 = last_samples[1];

    int accu;

    for (unsigned i=0 ; i<size ; ++i)
    {
        accu = (int)src[i] << 11;
        accu += book1[i] * l1 + book2[i] * l2 + rdot(i, book2, src);
        dst[i] = N64MusyXSampClamp(accu >> 11);
    }

    return size;
}

unsigned N64MusyXDecompressFrame(int16_t* out, const uint8_t* in,
                                 const int16_t coefs[8][2][8],
                                 unsigned lastSample)
{
    int16_t frame[32];

    unsigned remSamples = lastSample;
    unsigned samples = 0;
    unsigned procSamples, procRes;

    unsigned char c2 = in[0x8];
    c2 = c2 % 0x80;

    const int16_t* bookPredictors = coefs[(c2 & 0xf0) >> 4][0];
    unsigned int rshift = (c2 & 0x0f);

    adpcm_get_predicted_frame(frame, &in[0x0], &in[0x8], rshift);

    procSamples = (remSamples < 2) ? remSamples : 2;
    memcpy(out, frame, 2 * procSamples);
    samples += procSamples;
    remSamples -= procSamples;
    if (samples == lastSample)
        return samples;

#define adpcm_decode_upto_end_samples(inOffset, outOffset, size) \
    procSamples = (remSamples < size) ? remSamples : size; \
    procRes = adpcm_decode_upto_8_samples(out + inOffset, frame + inOffset, bookPredictors, \
                                          out + outOffset, procSamples); \
    samples += procRes; \
    remSamples -= procRes; \
    if (samples == lastSample) \
        return samples;

    adpcm_decode_upto_end_samples(2, 0, 6);
    adpcm_decode_upto_end_samples(8, 6, 8);
    adpcm_decode_upto_end_samples(16, 14, 8);
    adpcm_decode_upto_end_samples(24, 22, 8);

    out += 32;


    c2 = in[0x18];
    c2 = c2 % 0x80;

    bookPredictors = coefs[(c2 & 0xf0) >> 4][0];
    rshift = (c2 & 0x0f);

    adpcm_get_predicted_frame(frame, &in[0x4], &in[0x18], rshift);

    procSamples = (remSamples < 2) ? remSamples : 2;
    memcpy(out, frame, 2 * procSamples);
    samples += procSamples;
    remSamples -= procSamples;
    if (samples == lastSample)
        return samples;

    adpcm_decode_upto_end_samples(2, 0, 6);
    adpcm_decode_upto_end_samples(8, 6, 8);
    adpcm_decode_upto_end_samples(16, 14, 8);
    adpcm_decode_upto_end_samples(24, 22, 8);

    return samples;
}

unsigned N64MusyXDecompressFrameRanged(int16_t* out, const uint8_t* in,
                                       const int16_t coefs[8][2][8],
                                       unsigned firstSample, unsigned lastSample)
{
    int16_t final[64];
    unsigned procSamples = N64MusyXDecompressFrame(final, in, coefs, firstSample + lastSample);
    unsigned samples = procSamples - firstSample;
    memcpy(out, final + firstSample, samples * 2);
    return samples;
}