/*
*    ___                       ____                  __
*   / _ \___ _    _____ ____  / __/__  __ _____  ___/ /
*  / ___/ _ \ |/|/ / -_) __/ _\ \/ _ \/ // / _ \/ _  /
* /_/   \___/__,__/\__/_/   /___/\___/\_,_/_//_/\_,_/
*
*
*   Original Code by Max Watson
*   Written November 1, 1999
*   To be released under the LGPL
*
*   PowerSound audio mixer function*
*   Mostly taken from the SDL library and its mixer demo
*   borrowed (with additions) by Max Watson <max@blackholesun.com>
*
*   See LICENSE.TXT for more LGPL info
*/

/* This provides the mixing callback for PowerSound */

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include "SDL/SDL_audio.h"
#include "SDL/SDL_mutex.h"
#include "SDL/SDL_timer.h"

#include "powersound.h"

int audio_opened;
SDL_AudioCVT convert;

extern SDL_AudioSpec mixer;
extern SDL_mutex *mixer_lock;
extern PS_Channel channel[PS_MIX_CHANNELS];

extern void PS_ChannelsMix(void *udata, Uint8 *stream, int len);

/* This table is used to add two sound values together and pin
 * the value to avoid overflow.  (used with permission from ARDI)
 * Changed to use 0xFE instead of 0xFF for better sound quality.
 */
static const Uint8 mix8[] =
{
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03,
  0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E,
  0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
  0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24,
  0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
  0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A,
  0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45,
  0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50,
  0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B,
  0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66,
  0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71,
  0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C,
  0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
  0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0x90, 0x91, 0x92,
  0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D,
  0x9E, 0x9F, 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8,
  0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB0, 0xB1, 0xB2, 0xB3,
  0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE,
  0xBF, 0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9,
  0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4,
  0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF,
  0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA,
  0xEB, 0xEC, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5,
  0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE
};

int PS_AudioOpenWithCallback(int frequency, Uint16 format, int channels, int chunksize, void *callback)
{
    int i;
    SDL_AudioSpec desired;

    /* If the mixer is already opened, increment open count */
    if ( audio_opened ) {
        ++audio_opened;
        return(0);
    }

    /* Set the desired format and frequency */
    desired.freq = frequency;
    desired.format = format;
    desired.channels = channels;
    desired.samples = chunksize;
    desired.callback = callback;
    desired.userdata = NULL;

    /* Accept nearly any audio format */
    if ( SDL_OpenAudio(&desired, &mixer) < 0 ) {
        return(-1);
    }

    /* Create the channel lock mutex */
    mixer_lock = SDL_CreateMutex();
    if ( mixer_lock == NULL ) {
        SDL_CloseAudio();
        SDL_SetError("Unable to create mixer lock");
        return(-1);
    }

    /* Clear out the audio channels */
    for ( i=0; i<PS_MIX_CHANNELS; ++i ) {
        channel[i].chunk = NULL;
        channel[i].playing = 0;
        channel[i].looping = 0;
        channel[i].lvol = SDL_MIX_MAXVOLUME;
        channel[i].rvol = SDL_MIX_MAXVOLUME;
    }

    audio_opened = 1;
    SDL_PauseAudio(0);
    return(0);
}

int PS_AudioOpen(int frequency, Uint16 format, int channels, int chunksize)
{
    return PS_AudioOpenWithCallback(frequency, format, channels, chunksize, PS_ChannelsMix);
}

int PS_AudioQuery(int *frequency, Uint16 *format, Uint8 *channels)
{
    if(audio_opened) {
        if(frequency) {
            *frequency = mixer.freq;
        }
        if ( format ) {
            *format = mixer.format;
        }
        if ( channels ) {
            *channels = mixer.channels;
        }
    }
    return(audio_opened);
}

void PS_AudioClose(void)
{
    if ( audio_opened ) {
        if ( audio_opened == 1 ) {
            PS_ChannelHalt(-1);
            SDL_CloseAudio();
            SDL_DestroyMutex(mixer_lock);
        }
        --audio_opened;
    }
}

/* The volume ranges from 0 - 128 */
#define ADJUST_VOLUME(s, v)	(s = (s*v)/SDL_MIX_MAXVOLUME)
#define ADJUST_VOLUME_U8(s, v)	(s = (((s-128)*v)/SDL_MIX_MAXVOLUME)+128)

void PS_AudioMix (Uint8 *dst, Uint8 *src, Uint32 len, int lvol, int rvol)
{
    Uint16 format;
    int sv_chan=1;

    if ( lvol == 0 && rvol == 0) {
        return;
    }

    /* Mix the user-level audio format */
    format = mixer.format;
    switch (format) {

    case AUDIO_U8: {
        int dst_sample;

        while ( len-- ) {
            dst_sample = mix8[*dst+*src];

            //Only mix if correct channel and vol !0
            if(sv_chan && lvol)
                ADJUST_VOLUME(dst_sample, lvol);
            else if(!sv_chan &&rvol)
                ADJUST_VOLUME(dst_sample, rvol);

            *dst = dst_sample;
            ++dst;
            ++src;
            sv_chan = !sv_chan;
        }
    }
    break;

    case AUDIO_S8: {
        Sint8 *dst8, *src8;
        int dst_sample;
        const int max_audioval = ((1<<(8-1))-1);
        const int min_audioval = -(1<<(8-1));

        src8 = (Sint8 *)src;
        dst8 = (Sint8 *)dst;
        while ( len-- ) {
            dst_sample = *src8 + *dst8;

            //Only mix if correct channel and vol !0
            if(sv_chan && lvol)
                ADJUST_VOLUME(dst_sample, lvol);
            else if(!sv_chan && rvol)
                ADJUST_VOLUME(dst_sample, rvol);

            if ( dst_sample > max_audioval ) {
                *dst8 = max_audioval;
            } else
                if ( dst_sample < min_audioval ) {
                    *dst8 = min_audioval;
                } else {
                    *dst8 = dst_sample;
                }
            ++dst8;
            ++src8;
            sv_chan = !sv_chan;
        }
    }
    break;

    case AUDIO_S16LSB: {
        Sint16 src1, src2;
        int dst_sample;
        const int max_audioval = ((1<<(16-1))-1);
        const int min_audioval = -(1<<(16-1));

        len /= 2;
        while ( len-- ) {
            src1 = ((src[1])<<8|src[0]);
            src2 = ((dst[1])<<8|dst[0]);
            src += 2;
            dst_sample = src1+src2;

            //Only mix if correct channel and vol !0
            if(sv_chan && lvol)
                ADJUST_VOLUME(dst_sample, lvol);
            else if(!sv_chan &&rvol)
                ADJUST_VOLUME(dst_sample, rvol);
            if ( dst_sample > max_audioval ) {
                dst_sample = max_audioval;
            } else
                if ( dst_sample < min_audioval ) {
                    dst_sample = min_audioval;
                }

            dst[0] = dst_sample&0xFF;
            dst_sample >>= 8;
            dst[1] = dst_sample&0xFF;
            dst += 2;
            sv_chan = !sv_chan;
        }
    }
    break;

    case AUDIO_S16MSB: {
        Sint16 src1, src2;
        int dst_sample;
        const int max_audioval = ((1<<(16-1))-1);
        const int min_audioval = -(1<<(16-1));

        len /= 2;
        while ( len-- ) {
            src1 = ((src[0])<<8|src[1]);
            src2 = ((dst[0])<<8|dst[1]);
            src += 2;
            dst_sample = src1+src2;

            //Only mix if correct channel and vol !0
            if(sv_chan && lvol)
                ADJUST_VOLUME(dst_sample, lvol);
            else if(rvol)
                ADJUST_VOLUME(dst_sample, rvol);

            if ( dst_sample > max_audioval ) {
                dst_sample = max_audioval;
            } else
                if ( dst_sample < min_audioval ) {
                    dst_sample = min_audioval;
                }
            dst[1] = dst_sample&0xFF;
            dst_sample >>= 8;
            dst[0] = dst_sample&0xFF;
            dst += 2;
            sv_chan = !sv_chan;
        }
    }
    break;

    default: /* If this happens... FIXME! */
        SDL_SetError("PS_AudioMix(): unknown audio format");
        return;
    }
}


void PS_AudioLock()
{
   SDL_LockAudio();
}



void PS_AudioUnlock()
{
   SDL_UnlockAudio();

   return;
}



void PS_AudioPause(int onoff)
{
   SDL_PauseAudio(onoff);

   return;
}