/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@devolution.com
*/


#include <stdlib.h>
#include <stdio.h>
#include <memory.h>

#include <kernel.h>
#include "swis.h"

#include "SDL_endian.h"
#include "SDL_audio.h"
#include "SDL_audio_c.h"
#include "SDL_audiomem.h"
#include "SDL_sysaudio.h"
#include "SDL_drenderer.h"

#ifndef DISABLE_THREADS
#include <pthread.h>
#endif

#define DigitalRenderer_Activate    0x4F700
#define DigitalRenderer_Deactivate	0x4F701
#define DigitalRenderer_ReadState	0x4F705
#define DigitalRenderer_NewSample	0x4F706
#define DigitalRenderer_NumBuffers	0x4F709
#define DigitalRenderer_StreamSamples  0x4F70A
#define DigitalRenderer_Stream16BitSamples	0x4F70B
#define DigitalRenderer_StreamStatistics	0x4F70C
#define DigitalRenderer_StreamFlags     0x4F70D
#define DigitalRenderer_Activate16		0x4F70F
#define DigitalRenderer_GetFrequency	0x4F710

static int FillBuffer;
extern SDL_AudioDevice *current_audio;

extern int riscos_audiobuffer; /* Override for audio buffer size */

/* Audio driver functions */

static void DRenderer_CloseAudio(_THIS);
static int DRenderer_OpenAudio(_THIS, SDL_AudioSpec *spec);

#ifndef DISABLE_THREADS
static void DRenderer_WaitAudio(_THIS);
static Uint8 *DRenderer_GetAudioBuf(_THIS);
static void DRenderer_PlayAudio(_THIS);
#endif

/* Audio driver bootstrap functions */

/* Define following to dump stats to stdout */
/* #define DUMP_AUDIO */


static int Audio_Available(void)
{
	_kernel_swi_regs regs;
	int available = 0;

	/* Use call to set buffers to also check if Module is loaded */
	regs.r[0] = 0;
	if (_kernel_swi(DigitalRenderer_NumBuffers, &regs, &regs) == 0) available = 1;

    return(available);
}

static void Audio_DeleteDevice(SDL_AudioDevice *device)
{
    free(device->hidden);
    free(device);
}

static SDL_AudioDevice *Audio_CreateDevice(int devindex)
{
    SDL_AudioDevice *this;

    /* Initialize all variables that we clean on shutdown */
    this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
    if ( this ) {
        memset(this, 0, (sizeof *this));
        this->hidden = (struct SDL_PrivateAudioData *)
                malloc((sizeof *this->hidden));
    }
    if ( (this == NULL) || (this->hidden == NULL) ) {
        SDL_OutOfMemory();
        if ( this ) {
            free(this);
        }
        return(0);
    }
    memset(this->hidden, 0, (sizeof *this->hidden));

    /* Set the function pointers */
    this->OpenAudio   = DRenderer_OpenAudio;
    this->CloseAudio  = DRenderer_CloseAudio;
#ifndef DISABLE_THREADS
    this->GetAudioBuf = DRenderer_GetAudioBuf;
    this->PlayAudio   = DRenderer_PlayAudio;
    this->WaitAudio   = DRenderer_WaitAudio;
#endif
    this->free        = Audio_DeleteDevice;

    return this;
}

AudioBootStrap DRENDERER_bootstrap = {
	"drenderer", "RiscOS Digital Renderer Module",
	Audio_Available, Audio_CreateDevice
};

/* Routine called to check and fill audio buffers if necessary */
static Uint8 *buffer = NULL;

#ifdef DISABLE_THREADS

/* Buffer fill routine called during polling */
void DRenderer_FillBuffers()
{
	SDL_AudioDevice *audio = current_audio;

   if ( !audio || ! audio->enabled )
   {
      return;
   }

   if ( ! audio->paused )
   {
	   _kernel_swi_regs regs;
	   /* Check filled buffers count */
	   _kernel_swi(DigitalRenderer_StreamStatistics, &regs, &regs);

#ifdef DUMP_AUDIO
    if (regs.r[0] <= FillBuffer)
    {
       printf("Buffers in use %d\n", regs.r[0]);
    }
#endif

	   while (regs.r[0] <= FillBuffer && !audio->paused)
	   {
	     if ( audio->convert.needed )
		   {
		       int silence;
                       if ( audio->convert.src_format == AUDIO_U8 )
                       {
                       	 silence = 0x80;
                       } else {
                       	 silence = 0;
                       }
                       memset(audio->convert.buf, silence, audio->convert.len);
		       audio->spec.callback(audio->spec.userdata,
				   (Uint8 *)audio->convert.buf,audio->convert.len);
                       SDL_ConvertAudio(&audio->convert);
#if 0
			   if ( audio->convert.len_cvt != audio->spec.size ) {
				   /* Uh oh... probably crashes here; */
			   }
#endif
		       regs.r[0] = (int)audio->convert.buf;
		       regs.r[1] = audio->spec.samples * audio->spec.channels;
		       _kernel_swi(DigitalRenderer_Stream16BitSamples, &regs, &regs);

		   } else
		   {
			/* Fill buffer with silence */
			memset (buffer, 0, audio->spec.size);

			audio->spec.callback(audio->spec.userdata,
				   (Uint8 *)buffer, audio->spec.size);

			regs.r[0] = (int)buffer;
			regs.r[1] = audio->spec.samples * audio->spec.channels;
			 _kernel_swi(DigitalRenderer_Stream16BitSamples, &regs, &regs);
		   }
  		   /* Check if we have enough buffers yet */
   		   _kernel_swi(DigitalRenderer_StreamStatistics, &regs, &regs);
	   }

   }
}

#endif

/* Size of DMA buffer to use */
#define DRENDERER_BUFFER_SIZE 512

/* Number of centiseconds of sound to buffer.
   Hopefully more than the maximum time between calls to the
   FillBuffers routine above (non-threaded) or the PlayAudio
   routine below (threaded).
*/

#define DRENDERER_CSEC_TO_BUFFER 10

static void DeactivateAudio()
{
	_kernel_swi_regs regs;

	/* Close down the digital renderer */
	_kernel_swi(DigitalRenderer_Deactivate, &regs, &regs);

	if (buffer != NULL)
	{
	   free(buffer);
	   buffer = NULL;
	}
}

static int DRenderer_OpenAudio(_THIS, SDL_AudioSpec *spec)
{
	_kernel_swi_regs regs;
	int buffers_per_sample;

#ifdef DUMP_AUDIO
    printf("Request format %d\n", spec->format);
    printf("Request freq   %d\n", spec->freq);
    printf("Samples        %d\n", spec->samples);
    printf("Channels       %d\n", spec->channels);
#endif

	/* Only support signed 16bit format */
	spec->format = AUDIO_S16LSB;

    if (spec->samples < DRENDERER_BUFFER_SIZE) spec->samples = DRENDERER_BUFFER_SIZE;

	buffers_per_sample = spec->samples / DRENDERER_BUFFER_SIZE;

	if ((spec->samples % DRENDERER_BUFFER_SIZE) != 0)
	{
		buffers_per_sample++;
		spec->samples = buffers_per_sample * DRENDERER_BUFFER_SIZE;
	}
	

	/* Set number of buffers to use - the following should give enough
	   data between calls to the sound polling.
	*/

    if (riscos_audiobuffer == 0)
    {
    	FillBuffer = (int)((double)DRENDERER_CSEC_TO_BUFFER / ((double)DRENDERER_BUFFER_SIZE * 100.0 / (double)spec->freq)) + 1;
    } else FillBuffer = riscos_audiobuffer/DRENDERER_BUFFER_SIZE - buffers_per_sample;

    if (FillBuffer < buffers_per_sample) FillBuffer = buffers_per_sample;
#ifndef DISABLE_THREADS
    if (buffers_per_sample < FillBuffer)
    {
       /* For the threaded version we are only called once per cycle
          so the callback needs to give us the full data we need in
          one go, rather than multiple calls as it the case for the
          non threaded version */
       buffers_per_sample = FillBuffer;
       spec->samples = buffers_per_sample * DRENDERER_BUFFER_SIZE;
    }
#endif
        SDL_CalculateAudioSpec(spec);
	regs.r[0] = FillBuffer + buffers_per_sample;

#ifdef DUMP_AUDIO
    printf("Buffers per sample %d\n", buffers_per_sample);
    printf("Fill buffer        %d\n", FillBuffer);
    printf("Time buffered (ms) %d\n",(int)((1000.0 * regs.r[0] * DRENDERER_BUFFER_SIZE)/(double)spec->freq));
#endif

	if (_kernel_swi(DigitalRenderer_NumBuffers, &regs, &regs) != 0)
    {
       SDL_SetError("Can't set number of streaming sound buffers\n");
       return -1;
    }

	/* Now initialise sound system */
	regs.r[0] = spec->channels;   /* Number of channels */
	regs.r[1] = DRENDERER_BUFFER_SIZE; /* Samples length */
	regs.r[2] = spec->freq; /* frequency */
	regs.r[3] = 1;   /* Restore previous handler on exit */

	if (_kernel_swi(DigitalRenderer_Activate16, &regs, &regs) != 0)
	{
		SDL_SetError("Unable to activate digital renderer in 16 bit mode\n");
		return -1;
	}

	if (_kernel_swi(DigitalRenderer_GetFrequency, &regs, &regs) == 0)
	{
		spec->freq = regs.r[0];
	}

        /* Ensure sound is deactivated if we exit without calling SDL_Quit */
        atexit(DeactivateAudio);

#ifdef DUMP_AUDIO
    printf("Got format %d\n", spec->format);
    printf("Frequency  %d\n", spec->freq);
    printf("Samples    %d\n", spec->samples);
#endif                 

    /* Set to fill buffer with zero if we don't get data to it fast enough */
    regs.r[0] = 1;
    regs.r[1] = ~1;
    _kernel_swi(DigitalRenderer_StreamFlags, &regs, &regs);

	buffer = (Uint8 *)malloc(sizeof(Uint8) * spec->size);
	if (buffer == NULL)
	{
		SDL_OutOfMemory();
		return -1;
	}

#ifdef DISABLE_THREADS
   /* Hopefully returning 2 will show success, but not start up an audio thread */
   return 2;
#else
   /* Success and start audio thread */
   return 0;
#endif
}

static void DRenderer_CloseAudio(_THIS)
{
        DeactivateAudio();
}

#ifndef DISABLE_THREADS

/* Routines for threaded version of audio */

void DRenderer_WaitAudio(_THIS)
{
   _kernel_swi_regs regs;
   int waiting = 1;

   while (waiting)
   {
      /* Check filled buffers count */
      _kernel_swi(DigitalRenderer_StreamStatistics, &regs, &regs);
#if 0
    if (regs.r[0] <= FillBuffer)
    {
       printf("Buffers in use %d\n", regs.r[0]);
    }
#endif
      if (regs.r[0] <= FillBuffer) waiting = 0;
      else pthread_yield();
   }
}

Uint8 *DRenderer_GetAudioBuf(_THIS)
{
    return buffer;
}

void DRenderer_PlayAudio(_THIS)
{
	_kernel_swi_regs regs;

	regs.r[0] = (int)buffer;
	regs.r[1] = current_audio->spec.samples * current_audio->spec.channels;
	_kernel_swi(DigitalRenderer_Stream16BitSamples, &regs, &regs);
}

#endif