music_modplug.c

/*
  SDL_mixer:  An audio mixer library based on the SDL library
  Copyright (C) 1997-2016 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/

#ifdef MODPLUG_MUSIC

#include "SDL_mixer.h"
#include "dynamic_modplug.h"
#include "music_modplug.h"

static int current_output_channels=0;
static int music_swap8=0;
static int music_swap16=0;
static ModPlug_Settings settings;

int modplug_init(SDL_AudioSpec *spec)
{
    if ( !Mix_Init(MIX_INIT_MODPLUG) ) {
        return -1;
    }

    modplug.ModPlug_GetSettings(&settings);
    settings.mFlags=MODPLUG_ENABLE_OVERSAMPLING;
    current_output_channels=spec->channels;
    settings.mChannels=spec->channels>1?2:1;
    settings.mBits=spec->format&0xFF;

    music_swap8 = 0;
    music_swap16 = 0;

    switch(spec->format)
    {
        case AUDIO_U8:
        case AUDIO_S8: {
            if ( spec->format == AUDIO_S8 ) {
                music_swap8 = 1;
            }
            settings.mBits=8;
        }
        break;

        case AUDIO_S16LSB:
        case AUDIO_S16MSB: {
            /* See if we need to correct MikMod mixing */
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
            if ( spec->format == AUDIO_S16MSB ) {
#else
            if ( spec->format == AUDIO_S16LSB ) {
#endif
                music_swap16 = 1;
            }
            settings.mBits=16;
        }
        break;

        default: {
            Mix_SetError("Unknown hardware audio format");
            return -1;
        }

    }

    settings.mFrequency=spec->freq; /*TODO: limit to 11025, 22050, or 44100 ? */
    settings.mResamplingMode=MODPLUG_RESAMPLE_FIR;
    settings.mReverbDepth=0;
    settings.mReverbDelay=100;
    settings.mBassAmount=0;
    settings.mBassRange=50;
    settings.mSurroundDepth=0;
    settings.mSurroundDelay=10;
    settings.mLoopCount=0;
    modplug.ModPlug_SetSettings(&settings);
    return 0;
}

/* Uninitialize the music players */
void modplug_exit()
{
}

/* Set the volume for a modplug stream */
void modplug_setvolume(modplug_data *music, int volume)
{
    modplug.ModPlug_SetMasterVolume(music->file, volume*4);
}

/* Load a modplug stream from an SDL_RWops object */
modplug_data *modplug_new_RW(SDL_RWops *src, int freesrc)
{
    modplug_data *music = NULL;
    Sint64 offset;
    size_t sz;
    char *buf;

    /* Make sure the modplug library is loaded */
    if ( !Mix_Init(MIX_INIT_MODPLUG) ) {
        return NULL;
    }

    offset = SDL_RWtell(src);
    SDL_RWseek(src, 0, RW_SEEK_END);
    sz = (size_t)(SDL_RWtell(src) - offset);
    SDL_RWseek(src, offset, RW_SEEK_SET);
    buf = (char*)SDL_malloc(sz);
    if (buf) {
        if (SDL_RWread(src, buf, sz, 1) == 1) {
            music = (modplug_data*)SDL_malloc(sizeof(modplug_data));
            if (music) {
                music->playing = 0;
                music->file = modplug.ModPlug_Load(buf, sz);
                if (!music->file) {
                    SDL_free(music);
                    music = NULL;
                }
            } else {
                SDL_OutOfMemory();
            }
        }
        SDL_free(buf);
    } else {
        SDL_OutOfMemory();
    }
    if (music && freesrc) {
        SDL_RWclose(src);
    }
    return music;
}

/* Start playback of a given modplug stream */
void modplug_play(modplug_data *music)
{
    modplug.ModPlug_Seek(music->file,0);
    music->playing=1;
}

/* Return non-zero if a stream is currently playing */
int modplug_playing(modplug_data *music)
{
    return music && music->playing;
}

/* Play some of a stream previously started with modplug_play() */
int modplug_playAudio(modplug_data *music, Uint8 *stream, int len)
{
    if (current_output_channels > 2) {
        int small_len = 2 * len / current_output_channels;
        int i;
        Uint8 *src, *dst;

        i=modplug.ModPlug_Read(music->file, stream, small_len);
        if(i<small_len)
        {
            SDL_memset(stream+i,0,small_len-i);
            music->playing=0;
        }
        /* and extend to len by copying channels */
        src = stream + small_len;
        dst = stream + len;

        switch (settings.mBits) {
            case 8:
                for ( i=small_len/2; i; --i ) {
                    src -= 2;
                    dst -= current_output_channels;
                    dst[0] = src[0];
                    dst[1] = src[1];
                    dst[2] = src[0];
                    dst[3] = src[1];
                    if (current_output_channels == 6) {
                        dst[4] = src[0];
                        dst[5] = src[1];
                    }
                }
                break;
            case 16:
                for ( i=small_len/4; i; --i ) {
                    src -= 4;
                    dst -= 2 * current_output_channels;
                    dst[0] = src[0];
                    dst[1] = src[1];
                    dst[2] = src[2];
                    dst[3] = src[3];
                    dst[4] = src[0];
                    dst[5] = src[1];
                    dst[6] = src[2];
                    dst[7] = src[3];
                    if (current_output_channels == 6) {
                        dst[8] = src[0];
                        dst[9] = src[1];
                        dst[10] = src[2];
                        dst[11] = src[3];
                    }
                }
                break;
        }
    } else {
        int i=modplug.ModPlug_Read(music->file, stream, len);
        if(i<len)
        {
            SDL_memset(stream+i,0,len-i);
            music->playing=0;
        }
    }
    if ( music_swap8 ) {
        Uint8 *dst;
        int i;

        dst = stream;
        for ( i=len; i; --i ) {
            *dst++ ^= 0x80;
        }
    } else
    if ( music_swap16 ) {
        Uint8 *dst, tmp;
        int i;

        dst = stream;
        for ( i=(len/2); i; --i ) {
            tmp = dst[0];
            dst[0] = dst[1];
            dst[1] = tmp;
            dst += 2;
        }
    }
    return 0;
}

/* Stop playback of a stream previously started with modplug_play() */
void modplug_stop(modplug_data *music)
{
    music->playing=0;
}

/* Close the given modplug stream */
void modplug_delete(modplug_data *music)
{
    modplug.ModPlug_Unload(music->file);
    SDL_free(music);
}

/* Jump (seek) to a given position (time is in seconds) */
void modplug_jump_to_time(modplug_data *music, double time)
{
    modplug.ModPlug_Seek(music->file,(int)(time*1000));
}

#endif /* MODPLUG_MUSIC */