/*
Adapted by Gladiac
For config have a look there
http://icculus.org/lgfaq/#setthatdriver
*/

/*
 * SDL implementation for Quake 3: Arena's GPL source release.
 *
 * This is a replacement of the Linux/OpenSoundSystem code with
 *  an SDL backend, since it allows us to trivially point just about any
 *  existing 2D audio backend known to man on any platform at the code,
 *  plus it benefits from all of SDL's tapdancing to support buggy drivers,
 *  etc, and gets us free ALSA support, too.
 *
 * This is the best idea for a direct modernization of the Linux sound code
 *  in Quake 3. However, it would be nice to replace this with true 3D
 *  positional audio, compliments of OpenAL...
 *
 * Written by Ryan C. Gordon (icculus@icculus.org). Please refer to
 *    http://icculus.org/quake3/ for the latest version of this code.
 *
 *  Patches and comments are welcome at the above address.
 *
 * I cut-and-pasted this from linux_snd.c, and moved it to SDL line-by-line.
 *  There is probably some cruft that could be removed here.
 *
 * You should define USE_SDL=1 and then add this to the makefile.
 *  USE_SDL will disable the Open Sound System target.
 */

/*
Original copyright on Q3A sources:
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Quake III Arena source code.

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

Quake III Arena source code 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with Foobar; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/

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

#include "SDL.h"

#include "../client/client.h"
#include "../client/snd_loc.h"

int snd_inited=0;

cvar_t *s_bits = NULL;
cvar_t *s_channels = NULL;

static qboolean use_custom_memset = qfalse;
// https://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=371 
void Snd_Memset (void* dest, const int val, const size_t count)
{
	int *pDest;
	int i, iterate;

	if (!use_custom_memset)
	{
		memset(dest,val,count);
		return;
	}
	iterate = count / sizeof(int);
	pDest = (int*)dest;
	for(i=0; i<iterate; i++)
	{
		pDest[i] = val;
	}
}

/* The audio callback. All the magic happens here. */
static int dmapos = 0;
static int dmasize = 0;
static void sdl_audio_callback(void *userdata, Uint8 *stream, int len)
{
	int pos = (dmapos * (dma.samplebits/8));
	if (pos >= dmasize)
		dmapos = pos = 0;

	if (!snd_inited)  /* shouldn't happen, but just in case... */
	{
		memset(stream, '\0', len);
		return;
	}
	else
	{
		int tobufend = dmasize - pos;  /* bytes to buffer's end. */
		int len1 = len;
		int len2 = 0;

		if (len1 > tobufend)
		{
			len1 = tobufend;
			len2 = len - len1;
		}
		memcpy(stream, dma.buffer + pos, len1);
		if (len2 <= 0)
			dmapos += (len1 / (dma.samplebits/8));
		else  /* wraparound? */
		{
			memcpy(stream+len1, dma.buffer, len2);
			dmapos = (len2 / (dma.samplebits/8));
		}
	}

	if (dmapos >= dmasize)
		dmapos = 0;
}

static void print_audiospec(const char *str, const SDL_AudioSpec *spec)
{
	Com_Printf("%s:\n", str);

	// I'm sorry this is nasty.
#define PRINT_AUDIO_FMT(x) \
	if (spec->format == x) Com_Printf("Format: %s\n", #x); else
	PRINT_AUDIO_FMT(AUDIO_U8)
		PRINT_AUDIO_FMT(AUDIO_S8)
		PRINT_AUDIO_FMT(AUDIO_U16LSB)
		PRINT_AUDIO_FMT(AUDIO_S16LSB)
		PRINT_AUDIO_FMT(AUDIO_U16MSB)
		PRINT_AUDIO_FMT(AUDIO_S16MSB)
		Com_Printf("Format: UNKNOWN\n");
#undef PRINT_AUDIO_FMT

	Com_Printf("Freq: %d\n", (int) spec->freq);
	Com_Printf("Samples: %d\n", (int) spec->samples);
	Com_Printf("Channels: %d\n", (int) spec->channels);
	Com_Printf("\n");
}

qboolean SNDDMA_Init(void)
{
	char drivername[128];
	SDL_AudioSpec desired;
	SDL_AudioSpec obtained;
	int tmp;

	if (snd_inited)
		return 1;

	Com_Printf("SDL Audio driver initializing...\n");

	if (!s_bits) {
		s_bits = Cvar_Get("s_bits", "16", CVAR_ARCHIVE);
		s_channels = Cvar_Get("s_channels", "2", CVAR_ARCHIVE);
	}

	if (!SDL_WasInit(SDL_INIT_AUDIO))
	{
		Com_Printf("Calling SDL_Init(SDL_INIT_AUDIO)...\n");
		if (SDL_Init(SDL_INIT_AUDIO) == -1)
		{
			Com_Printf("SDL_Init(SDL_INIT_AUDIO) failed: %s\n", SDL_GetError());
			return qfalse;
		}
		Com_Printf("SDL_Init(SDL_INIT_AUDIO) passed.\n");
	}

	if (SDL_AudioDriverName(drivername, sizeof (drivername)) == NULL)
		Q_strncpyz(drivername, "(UNKNOWN)", sizeof(drivername));
	Com_Printf("SDL audio driver is \"%s\"\n", drivername);

	memset(&desired, '\0', sizeof (desired));
	memset(&obtained, '\0', sizeof (obtained));

	if (s_khz->integer == 44)
		desired.freq = 44100;
	else if (s_khz->integer == 22)
		desired.freq = 22050;
	else
		desired.freq = 11025;

	desired.format = ((s_bits->integer != 16) ? AUDIO_U8 : AUDIO_S16SYS);

	// I dunno if this is the best idea, but I'll give it a try...
	//  should probably check a cvar for this...
	// just pick a sane default.
	if (desired.freq <= 11025)
		desired.samples = 256;
	else if (desired.freq <= 22050)
		desired.samples = 512;
	else if (desired.freq <= 44100)
		desired.samples = 1024;
	else
		desired.samples = 2048;  // (*shrug*)

	desired.channels = s_channels->integer;
	desired.callback = sdl_audio_callback;

	if (SDL_OpenAudio(&desired, &obtained) == -1)
	{
		Com_Printf("SDL_OpenAudio() failed: %s\n", SDL_GetError());
		SDL_QuitSubSystem(SDL_INIT_AUDIO);
		return qfalse;
	}

	print_audiospec("Format we requested from SDL audio device", &desired);
	print_audiospec("Format we actually got", &obtained);

	// dma.samples needs to be big, or id's mixer will just refuse to
	//  work at all; we need to keep it significantly bigger than the
	//  amount of SDL callback samples, and just copy a little each time
	//  the callback runs.
	// 32768 is what the OSS driver filled in here on my system. I don't
	//  know if it's a good value overall, but at least we know it's
	//  reasonable...this is why I let the user override.
	tmp = (obtained.samples * obtained.channels) * 4;

	if (tmp & (tmp - 1))  // not a power of two? Seems to confuse something.
	{
		int val = 1;
		while (val < tmp)
			val <<= 1;

		val >>= 1;
		Com_Printf("WARNING: sdlmixsamps wasn't a power of two (%d), so we made it one (%d).\n", tmp, val);
		tmp = val;
	}

	dmapos = 0;
	dma.samplebits = obtained.format & 0xFF;  // first byte of format is bits.
	dma.channels = obtained.channels;
	dma.samples = tmp;
	dma.submission_chunk = 1;
	dma.speed = obtained.freq;
	dmasize = (dma.samples * (dma.samplebits/8));
	dma.buffer = calloc(1, dmasize);

	Com_Printf("Starting SDL audio callback...\n");
	SDL_PauseAudio(0);  // start callback.

	Com_Printf("SDL audio initialized.\n");
	snd_inited = 1;
	return qtrue;
}

int SNDDMA_GetDMAPos(void)
{
	return dmapos;
}

void SNDDMA_Shutdown(void)
{
	Com_Printf("Closing SDL audio device...\n");

	SDL_PauseAudio(1);
	SDL_CloseAudio();
	SDL_QuitSubSystem(SDL_INIT_AUDIO);

	free(dma.buffer);
	dma.buffer = NULL;
	dmapos = dmasize = 0;
	snd_inited = 0;

	Com_Printf("SDL audio device shut down.\n");
}

/*
==============
SNDDMA_Submit

Send sound to device if buffer isn't really the dma buffer
===============
*/
void SNDDMA_Submit(void)
{
	SDL_UnlockAudio();
}

void SNDDMA_BeginPainting (void)
{
	SDL_LockAudio();
}
