/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2009 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@libsdl.org

*/

#include "SDL_config.h"

/* Allow access to a raw mixing buffer */

#include <sys/types.h>

#include <signal.h>	/* For kill() */

#include "SDL_timer.h"

#include "SDL_audio.h"

#include "../SDL_audiomem.h"

#include "../SDL_audio_c.h"

#include "SDL_alsa_audio.h"

#ifdef SDL_AUDIO_DRIVER_ALSA_DYNAMIC

#include "SDL_name.h"

#include "SDL_loadso.h"

#else

#define SDL_NAME(X)	X

#endif

/* The tag name used by ALSA audio */

#define DRIVER_NAME         "alsa"

/* Audio driver functions */

static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec);

static void ALSA_WaitAudio(_THIS);

static void ALSA_PlayAudio(_THIS);

static Uint8 *ALSA_GetAudioBuf(_THIS);

static void ALSA_CloseAudio(_THIS);

#ifdef SDL_AUDIO_DRIVER_ALSA_DYNAMIC

static const char *alsa_library = SDL_AUDIO_DRIVER_ALSA_DYNAMIC;

static void *alsa_handle = NULL;

static int alsa_loaded = 0;

static int (*SDL_NAME(snd_pcm_open))(snd_pcm_t **pcm, const char *name, snd_pcm_stream_t stream, int mode);

static int (*SDL_NAME(snd_pcm_close))(snd_pcm_t *pcm);

static snd_pcm_sframes_t (*SDL_NAME(snd_pcm_writei))(snd_pcm_t *pcm, const void *buffer, snd_pcm_uframes_t size);

static int (*SDL_NAME(snd_pcm_recover))(snd_pcm_t *pcm, int err, int silent);

static int (*SDL_NAME(snd_pcm_prepare))(snd_pcm_t *pcm);

static int (*SDL_NAME(snd_pcm_drain))(snd_pcm_t *pcm);

static const char *(*SDL_NAME(snd_strerror))(int errnum);

static size_t (*SDL_NAME(snd_pcm_hw_params_sizeof))(void);

static size_t (*SDL_NAME(snd_pcm_sw_params_sizeof))(void);

static void (*SDL_NAME(snd_pcm_hw_params_copy))(snd_pcm_hw_params_t *dst, const snd_pcm_hw_params_t *src);

static int (*SDL_NAME(snd_pcm_hw_params_any))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params);

static int (*SDL_NAME(snd_pcm_hw_params_set_access))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t access);

static int (*SDL_NAME(snd_pcm_hw_params_set_format))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t val);

static int (*SDL_NAME(snd_pcm_hw_params_set_channels))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val);

static int (*SDL_NAME(snd_pcm_hw_params_get_channels))(const snd_pcm_hw_params_t *params, unsigned int *val);

static int (*SDL_NAME(snd_pcm_hw_params_set_rate_near))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir);

static int (*SDL_NAME(snd_pcm_hw_params_set_period_size_near))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val, int *dir);

static int (*SDL_NAME(snd_pcm_hw_params_get_period_size))(const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *frames, int *dir);

static int (*SDL_NAME(snd_pcm_hw_params_set_periods_near))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir);

static int (*SDL_NAME(snd_pcm_hw_params_get_periods))(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir);

static int (*SDL_NAME(snd_pcm_hw_params_set_buffer_size_near))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val);

static int (*SDL_NAME(snd_pcm_hw_params_get_buffer_size))(const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val);

static int (*SDL_NAME(snd_pcm_hw_params))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params);

/*

*/

static int (*SDL_NAME(snd_pcm_sw_params_current))(snd_pcm_t *pcm, snd_pcm_sw_params_t *swparams);

static int (*SDL_NAME(snd_pcm_sw_params_set_start_threshold))(snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_uframes_t val);

static int (*SDL_NAME(snd_pcm_sw_params))(snd_pcm_t *pcm, snd_pcm_sw_params_t *params);

static int (*SDL_NAME(snd_pcm_nonblock))(snd_pcm_t *pcm, int nonblock);

static int (*SDL_NAME(snd_pcm_wait))(snd_pcm_t *pcm, int timeout);

#define snd_pcm_hw_params_sizeof SDL_NAME(snd_pcm_hw_params_sizeof)

#define snd_pcm_sw_params_sizeof SDL_NAME(snd_pcm_sw_params_sizeof)

/* cast funcs to char* first, to please GCC's strict aliasing rules. */

static struct {

	const char *name;

	void **func;

} alsa_functions[] = {

	{ "snd_pcm_open",	(void**)(char*)&SDL_NAME(snd_pcm_open)		},

	{ "snd_pcm_close",	(void**)(char*)&SDL_NAME(snd_pcm_close)	},

	{ "snd_pcm_writei",	(void**)(char*)&SDL_NAME(snd_pcm_writei)	},

	{ "snd_pcm_recover",	(void**)(char*)&SDL_NAME(snd_pcm_recover)	},

	{ "snd_pcm_prepare",	(void**)(char*)&SDL_NAME(snd_pcm_prepare)	},

	{ "snd_pcm_drain",	(void**)(char*)&SDL_NAME(snd_pcm_drain)	},

	{ "snd_strerror",	(void**)(char*)&SDL_NAME(snd_strerror)		},

	{ "snd_pcm_hw_params_sizeof",		(void**)(char*)&SDL_NAME(snd_pcm_hw_params_sizeof)		},

	{ "snd_pcm_sw_params_sizeof",		(void**)(char*)&SDL_NAME(snd_pcm_sw_params_sizeof)		},

	{ "snd_pcm_hw_params_copy",		(void**)(char*)&SDL_NAME(snd_pcm_hw_params_copy)		},

	{ "snd_pcm_hw_params_any",		(void**)(char*)&SDL_NAME(snd_pcm_hw_params_any)		},

	{ "snd_pcm_hw_params_set_access",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_access)		},

	{ "snd_pcm_hw_params_set_format",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_format)		},

	{ "snd_pcm_hw_params_set_channels",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_channels)	},

	{ "snd_pcm_hw_params_get_channels",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_channels)	},

	{ "snd_pcm_hw_params_set_rate_near",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_rate_near)	},

	{ "snd_pcm_hw_params_set_period_size_near",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_period_size_near)	},

	{ "snd_pcm_hw_params_get_period_size",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_period_size)	},

	{ "snd_pcm_hw_params_set_periods_near",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_periods_near)	},

	{ "snd_pcm_hw_params_get_periods",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_periods)	},

	{ "snd_pcm_hw_params_set_buffer_size_near",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_buffer_size_near) },

	{ "snd_pcm_hw_params_get_buffer_size",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_buffer_size) },

	{ "snd_pcm_hw_params",	(void**)(char*)&SDL_NAME(snd_pcm_hw_params)	},

	{ "snd_pcm_sw_params_current",	(void**)(char*)&SDL_NAME(snd_pcm_sw_params_current)	},

	{ "snd_pcm_sw_params_set_start_threshold",	(void**)(char*)&SDL_NAME(snd_pcm_sw_params_set_start_threshold)	},

	{ "snd_pcm_sw_params",	(void**)(char*)&SDL_NAME(snd_pcm_sw_params)	},

	{ "snd_pcm_nonblock",	(void**)(char*)&SDL_NAME(snd_pcm_nonblock)	},

	{ "snd_pcm_wait",	(void**)(char*)&SDL_NAME(snd_pcm_wait)	},

};

static void UnloadALSALibrary(void) {

	if (alsa_loaded) {

		SDL_UnloadObject(alsa_handle);

		alsa_handle = NULL;

		alsa_loaded = 0;

	}

}

static int LoadALSALibrary(void) {

	int i, retval = -1;

	alsa_handle = SDL_LoadObject(alsa_library);

	if (alsa_handle) {

		alsa_loaded = 1;

		retval = 0;

		for (i = 0; i < SDL_arraysize(alsa_functions); i++) {

			*alsa_functions[i].func = SDL_LoadFunction(alsa_handle,alsa_functions[i].name);

			if (!*alsa_functions[i].func) {

				retval = -1;

				UnloadALSALibrary();

				break;

			}

		}

	}

	return retval;

}

#else

static void UnloadALSALibrary(void) {

	return;

}

static int LoadALSALibrary(void) {

	return 0;

}

#endif /* SDL_AUDIO_DRIVER_ALSA_DYNAMIC */

static const char *get_audio_device(int channels)

{

	const char *device;

	device = SDL_getenv("AUDIODEV");	/* Is there a standard variable name? */

	if ( device == NULL ) {

		switch (channels) {

		case 6:

			device = "plug:surround51";

			break;

		case 4:

			device = "plug:surround40";

			break;

		default:

			device = "default";

			break;

		}

	}

	return device;

}

/* Audio driver bootstrap functions */

static int Audio_Available(void)

{

	int available;

	int status;

	snd_pcm_t *handle;

	available = 0;

	if (LoadALSALibrary() < 0) {

		return available;

	}

	status = SDL_NAME(snd_pcm_open)(&handle, get_audio_device(2), SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);

	if ( status >= 0 ) {

		available = 1;

        	SDL_NAME(snd_pcm_close)(handle);

	}

	UnloadALSALibrary();

	return(available);

}

static void Audio_DeleteDevice(SDL_AudioDevice *device)

{

	SDL_free(device->hidden);

	SDL_free(device);

	UnloadALSALibrary();

}

static SDL_AudioDevice *Audio_CreateDevice(int devindex)

{

	SDL_AudioDevice *this;

	/* Initialize all variables that we clean on shutdown */

	LoadALSALibrary();

	this = (SDL_AudioDevice *)SDL_malloc(sizeof(SDL_AudioDevice));

	if ( this ) {

		SDL_memset(this, 0, (sizeof *this));

		this->hidden = (struct SDL_PrivateAudioData *)

				SDL_malloc((sizeof *this->hidden));

	}

	if ( (this == NULL) || (this->hidden == NULL) ) {

		SDL_OutOfMemory();

		if ( this ) {

			SDL_free(this);

		}

		return(0);

	}

	SDL_memset(this->hidden, 0, (sizeof *this->hidden));

	/* Set the function pointers */

	this->OpenAudio = ALSA_OpenAudio;

	this->WaitAudio = ALSA_WaitAudio;

	this->PlayAudio = ALSA_PlayAudio;

	this->GetAudioBuf = ALSA_GetAudioBuf;

	this->CloseAudio = ALSA_CloseAudio;

	this->free = Audio_DeleteDevice;

	return this;

}

AudioBootStrap ALSA_bootstrap = {

	DRIVER_NAME, "ALSA PCM audio",

	Audio_Available, Audio_CreateDevice

};

/* This function waits until it is possible to write a full sound buffer */

static void ALSA_WaitAudio(_THIS)

{

	/* We're in blocking mode, so there's nothing to do here */

}

/*

 * http://bugzilla.libsdl.org/show_bug.cgi?id=110

 * "For Linux ALSA, this is FL-FR-RL-RR-C-LFE

 *  and for Windows DirectX [and CoreAudio], this is FL-FR-C-LFE-RL-RR"

 */

#define SWIZ6(T) \

    T *ptr = (T *) mixbuf; \

    Uint32 i; \

        T tmp; \

        tmp = ptr[2]; ptr[2] = ptr[4]; ptr[4] = tmp; \

        tmp = ptr[3]; ptr[3] = ptr[5]; ptr[5] = tmp; \

    }

static __inline__ void swizzle_alsa_channels_6_64bit(_THIS) { SWIZ6(Uint64); }

static __inline__ void swizzle_alsa_channels_6_32bit(_THIS) { SWIZ6(Uint32); }

static __inline__ void swizzle_alsa_channels_6_16bit(_THIS) { SWIZ6(Uint16); }

static __inline__ void swizzle_alsa_channels_6_8bit(_THIS) { SWIZ6(Uint8); }

#undef SWIZ6

/*

 * Called right before feeding this->mixbuf to the hardware. Swizzle channels

 *  from Windows/Mac order to the format alsalib will want.

 */

static __inline__ void swizzle_alsa_channels(_THIS)

{

    if (this->spec.channels == 6) {

        const Uint16 fmtsize = (this->spec.format & 0xFF); /* bits/channel. */

        if (fmtsize == 16)

            swizzle_alsa_channels_6_16bit(this);

        else if (fmtsize == 8)

            swizzle_alsa_channels_6_8bit(this);

        else if (fmtsize == 32)

            swizzle_alsa_channels_6_32bit(this);

        else if (fmtsize == 64)

            swizzle_alsa_channels_6_64bit(this);

    }

    /* !!! FIXME: update this for 7.1 if needed, later. */

}

static void ALSA_PlayAudio(_THIS)

{

	int status;

	snd_pcm_uframes_t frames_left;

	const Uint8 *sample_buf = (const Uint8 *) mixbuf;

	const int frame_size = (((int) (this->spec.format & 0xFF)) / 8) * this->spec.channels;

	swizzle_alsa_channels(this);

	frames_left = ((snd_pcm_uframes_t) this->spec.samples);

	while ( frames_left > 0 && this->enabled ) {

		/* This works, but needs more testing before going live */

		/*SDL_NAME(snd_pcm_wait)(pcm_handle, -1);*/

		status = SDL_NAME(snd_pcm_writei)(pcm_handle, sample_buf, frames_left);

		if ( status < 0 ) {

			if ( status == -EAGAIN ) {

				/* Apparently snd_pcm_recover() doesn't handle this case - does it assume snd_pcm_wait() above? */

				SDL_Delay(1);

				continue;

			}

			status = SDL_NAME(snd_pcm_recover)(pcm_handle, status, 0);

			if ( status < 0 ) {

				/* Hmm, not much we can do - abort */

				fprintf(stderr, "ALSA write failed (unrecoverable): %s\n", SDL_NAME(snd_strerror)(status));

				this->enabled = 0;

				return;

			}

			continue;

		}

		sample_buf += status * frame_size;

		frames_left -= status;

	}

}

static Uint8 *ALSA_GetAudioBuf(_THIS)

{

	return(mixbuf);

}

static void ALSA_CloseAudio(_THIS)

{

	if ( mixbuf != NULL ) {

		SDL_FreeAudioMem(mixbuf);

		mixbuf = NULL;

	}

	if ( pcm_handle ) {

		SDL_NAME(snd_pcm_drain)(pcm_handle);

		SDL_NAME(snd_pcm_close)(pcm_handle);

		pcm_handle = NULL;

	}

}

static int ALSA_finalize_hardware(_THIS, SDL_AudioSpec *spec, snd_pcm_hw_params_t *hwparams, int override)

{

	int status;

	snd_pcm_uframes_t bufsize;

	/* "set" the hardware with the desired parameters */

	status = SDL_NAME(snd_pcm_hw_params)(pcm_handle, hwparams);

	if ( status < 0 ) {

		return(-1);

	}

	/* Get samples for the actual buffer size */

	status = SDL_NAME(snd_pcm_hw_params_get_buffer_size)(hwparams, &bufsize);

	if ( status < 0 ) {

		return(-1);

	}

	if ( !override && bufsize != spec->samples * 2 ) {

		return(-1);

	}

	/* FIXME: Is this safe to do? */

	spec->samples = bufsize / 2;

	/* This is useful for debugging */

	if ( getenv("SDL_AUDIO_ALSA_DEBUG") ) {

		snd_pcm_uframes_t persize = 0;

		unsigned int periods = 0;

		SDL_NAME(snd_pcm_hw_params_get_period_size)(hwparams, &persize, NULL);

		SDL_NAME(snd_pcm_hw_params_get_periods)(hwparams, &periods, NULL);

		fprintf(stderr, "ALSA: period size = %ld, periods = %u, buffer size = %lu\n", persize, periods, bufsize);

	}

	return(0);

}

static int ALSA_set_period_size(_THIS, SDL_AudioSpec *spec, snd_pcm_hw_params_t *params, int override)

{

	const char *env;

	int status;

	snd_pcm_hw_params_t *hwparams;

	snd_pcm_uframes_t frames;

	unsigned int periods;

	/* Copy the hardware parameters for this setup */

	snd_pcm_hw_params_alloca(&hwparams);

	SDL_NAME(snd_pcm_hw_params_copy)(hwparams, params);

	if ( !override ) {

		env = getenv("SDL_AUDIO_ALSA_SET_PERIOD_SIZE");

		if ( env ) {

			override = SDL_atoi(env);

			if ( override == 0 ) {

				return(-1);

			}

		}

	}

	frames = spec->samples;

	status = SDL_NAME(snd_pcm_hw_params_set_period_size_near)(pcm_handle, hwparams, &frames, NULL);

	if ( status < 0 ) {

		return(-1);

	}

	periods = 2;

	status = SDL_NAME(snd_pcm_hw_params_set_periods_near)(pcm_handle, hwparams, &periods, NULL);

	if ( status < 0 ) {

		return(-1);

	}

	return ALSA_finalize_hardware(this, spec, hwparams, override);

}

static int ALSA_set_buffer_size(_THIS, SDL_AudioSpec *spec, snd_pcm_hw_params_t *params, int override)

{

	const char *env;

	int status;

	snd_pcm_hw_params_t *hwparams;

	snd_pcm_uframes_t frames;

	/* Copy the hardware parameters for this setup */

	snd_pcm_hw_params_alloca(&hwparams);

	SDL_NAME(snd_pcm_hw_params_copy)(hwparams, params);

	if ( !override ) {

		env = getenv("SDL_AUDIO_ALSA_SET_BUFFER_SIZE");

		if ( env ) {

			override = SDL_atoi(env);

			if ( override == 0 ) {

				return(-1);

			}

		}

	}

	frames = spec->samples * 2;

	status = SDL_NAME(snd_pcm_hw_params_set_buffer_size_near)(pcm_handle, hwparams, &frames);

	if ( status < 0 ) {

		return(-1);

	}

	return ALSA_finalize_hardware(this, spec, hwparams, override);

}

static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec)

{

	int                  status;

	snd_pcm_hw_params_t *hwparams;

	snd_pcm_sw_params_t *swparams;

	snd_pcm_format_t     format;

	unsigned int         rate;

	unsigned int 	     channels;

	Uint16               test_format;

	/* Open the audio device */

	/* Name of device should depend on # channels in spec */

	status = SDL_NAME(snd_pcm_open)(&pcm_handle, get_audio_device(spec->channels), SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);

	if ( status < 0 ) {

		SDL_SetError("Couldn't open audio device: %s", SDL_NAME(snd_strerror)(status));

		return(-1);

	}

	/* Figure out what the hardware is capable of */

	snd_pcm_hw_params_alloca(&hwparams);

	status = SDL_NAME(snd_pcm_hw_params_any)(pcm_handle, hwparams);

	if ( status < 0 ) {

		SDL_SetError("Couldn't get hardware config: %s", SDL_NAME(snd_strerror)(status));

		ALSA_CloseAudio(this);

		return(-1);

	}

	/* SDL only uses interleaved sample output */

	status = SDL_NAME(snd_pcm_hw_params_set_access)(pcm_handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED);