/*

  Simple DirectMedia Layer

  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.

*/

#include "../../SDL_internal.h"

#if SDL_AUDIO_DRIVER_ALSA

/* Allow access to a raw mixing buffer */

#include <sys/types.h>

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

#include <errno.h>

#include <string.h>

#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_loadso.h"

#endif

static int (*ALSA_snd_pcm_open)

  (snd_pcm_t **, const char *, snd_pcm_stream_t, int);

static int (*ALSA_snd_pcm_close) (snd_pcm_t * pcm);

static snd_pcm_sframes_t(*ALSA_snd_pcm_writei)

  (snd_pcm_t *, const void *, snd_pcm_uframes_t);

static int (*ALSA_snd_pcm_recover) (snd_pcm_t *, int, int);

static int (*ALSA_snd_pcm_prepare) (snd_pcm_t *);

static int (*ALSA_snd_pcm_drain) (snd_pcm_t *);

static const char *(*ALSA_snd_strerror) (int);

static size_t(*ALSA_snd_pcm_hw_params_sizeof) (void);

static size_t(*ALSA_snd_pcm_sw_params_sizeof) (void);

static void (*ALSA_snd_pcm_hw_params_copy)

  (snd_pcm_hw_params_t *, const snd_pcm_hw_params_t *);

static int (*ALSA_snd_pcm_hw_params_any) (snd_pcm_t *, snd_pcm_hw_params_t *);

static int (*ALSA_snd_pcm_hw_params_set_access)

  (snd_pcm_t *, snd_pcm_hw_params_t *, snd_pcm_access_t);

static int (*ALSA_snd_pcm_hw_params_set_format)

  (snd_pcm_t *, snd_pcm_hw_params_t *, snd_pcm_format_t);

static int (*ALSA_snd_pcm_hw_params_set_channels)

  (snd_pcm_t *, snd_pcm_hw_params_t *, unsigned int);

static int (*ALSA_snd_pcm_hw_params_get_channels)

  (const snd_pcm_hw_params_t *, unsigned int *);

static int (*ALSA_snd_pcm_hw_params_set_rate_near)

  (snd_pcm_t *, snd_pcm_hw_params_t *, unsigned int *, int *);

static int (*ALSA_snd_pcm_hw_params_set_period_size_near)

  (snd_pcm_t *, snd_pcm_hw_params_t *, snd_pcm_uframes_t *, int *);

static int (*ALSA_snd_pcm_hw_params_get_period_size)

  (const snd_pcm_hw_params_t *, snd_pcm_uframes_t *, int *);

static int (*ALSA_snd_pcm_hw_params_set_periods_near)

  (snd_pcm_t *, snd_pcm_hw_params_t *, unsigned int *, int *);

static int (*ALSA_snd_pcm_hw_params_get_periods)

  (const snd_pcm_hw_params_t *, unsigned int *, int *);

static int (*ALSA_snd_pcm_hw_params_set_buffer_size_near)

  (snd_pcm_t *pcm, snd_pcm_hw_params_t *, snd_pcm_uframes_t *);

static int (*ALSA_snd_pcm_hw_params_get_buffer_size)

  (const snd_pcm_hw_params_t *, snd_pcm_uframes_t *);

static int (*ALSA_snd_pcm_hw_params) (snd_pcm_t *, snd_pcm_hw_params_t *);

static int (*ALSA_snd_pcm_sw_params_current) (snd_pcm_t *,

                                              snd_pcm_sw_params_t *);

static int (*ALSA_snd_pcm_sw_params_set_start_threshold)

  (snd_pcm_t *, snd_pcm_sw_params_t *, snd_pcm_uframes_t);

static int (*ALSA_snd_pcm_sw_params) (snd_pcm_t *, snd_pcm_sw_params_t *);

static int (*ALSA_snd_pcm_nonblock) (snd_pcm_t *, int);

static int (*ALSA_snd_pcm_wait)(snd_pcm_t *, int);

static int (*ALSA_snd_pcm_sw_params_set_avail_min)

  (snd_pcm_t *, snd_pcm_sw_params_t *, snd_pcm_uframes_t);

static int (*ALSA_snd_device_name_hint) (int, const char *, void ***);

static char* (*ALSA_snd_device_name_get_hint) (const void *, const char *);

static int (*ALSA_snd_device_name_free_hint) (void **);

#ifdef SDL_AUDIO_DRIVER_ALSA_DYNAMIC

#define snd_pcm_hw_params_sizeof ALSA_snd_pcm_hw_params_sizeof

#define snd_pcm_sw_params_sizeof ALSA_snd_pcm_sw_params_sizeof

static const char *alsa_library = SDL_AUDIO_DRIVER_ALSA_DYNAMIC;

static void *alsa_handle = NULL;

static int

load_alsa_sym(const char *fn, void **addr)

{

    *addr = SDL_LoadFunction(alsa_handle, fn);

    if (*addr == NULL) {

        /* Don't call SDL_SetError(): SDL_LoadFunction already did. */

        return 0;

    }

    return 1;

}

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

#define SDL_ALSA_SYM(x) \

    if (!load_alsa_sym(#x, (void **) (char *) &ALSA_##x)) return -1

#else

#define SDL_ALSA_SYM(x) ALSA_##x = x

#endif

static int

load_alsa_syms(void)

{

    SDL_ALSA_SYM(snd_pcm_open);

    SDL_ALSA_SYM(snd_pcm_close);

    SDL_ALSA_SYM(snd_pcm_writei);

    SDL_ALSA_SYM(snd_pcm_recover);

    SDL_ALSA_SYM(snd_pcm_prepare);

    SDL_ALSA_SYM(snd_pcm_drain);

    SDL_ALSA_SYM(snd_strerror);

    SDL_ALSA_SYM(snd_pcm_hw_params_sizeof);

    SDL_ALSA_SYM(snd_pcm_sw_params_sizeof);

    SDL_ALSA_SYM(snd_pcm_hw_params_copy);

    SDL_ALSA_SYM(snd_pcm_hw_params_any);

    SDL_ALSA_SYM(snd_pcm_hw_params_set_access);

    SDL_ALSA_SYM(snd_pcm_hw_params_set_format);

    SDL_ALSA_SYM(snd_pcm_hw_params_set_channels);

    SDL_ALSA_SYM(snd_pcm_hw_params_get_channels);

    SDL_ALSA_SYM(snd_pcm_hw_params_set_rate_near);

    SDL_ALSA_SYM(snd_pcm_hw_params_set_period_size_near);

    SDL_ALSA_SYM(snd_pcm_hw_params_get_period_size);

    SDL_ALSA_SYM(snd_pcm_hw_params_set_periods_near);

    SDL_ALSA_SYM(snd_pcm_hw_params_get_periods);

    SDL_ALSA_SYM(snd_pcm_hw_params_set_buffer_size_near);

    SDL_ALSA_SYM(snd_pcm_hw_params_get_buffer_size);

    SDL_ALSA_SYM(snd_pcm_hw_params);

    SDL_ALSA_SYM(snd_pcm_sw_params_current);

    SDL_ALSA_SYM(snd_pcm_sw_params_set_start_threshold);

    SDL_ALSA_SYM(snd_pcm_sw_params);

    SDL_ALSA_SYM(snd_pcm_nonblock);

    SDL_ALSA_SYM(snd_pcm_wait);

    SDL_ALSA_SYM(snd_pcm_sw_params_set_avail_min);

    SDL_ALSA_SYM(snd_device_name_hint);

    SDL_ALSA_SYM(snd_device_name_get_hint);

    SDL_ALSA_SYM(snd_device_name_free_hint);

    return 0;

}

#undef SDL_ALSA_SYM

#ifdef SDL_AUDIO_DRIVER_ALSA_DYNAMIC

static void

UnloadALSALibrary(void)

{

    if (alsa_handle != NULL) {

        SDL_UnloadObject(alsa_handle);

        alsa_handle = NULL;

    }

}

static int

LoadALSALibrary(void)

{

    int retval = 0;

    if (alsa_handle == NULL) {

        alsa_handle = SDL_LoadObject(alsa_library);

        if (alsa_handle == NULL) {

            retval = -1;

            /* Don't call SDL_SetError(): SDL_LoadObject already did. */

        } else {

            retval = load_alsa_syms();

            if (retval < 0) {

                UnloadALSALibrary();

            }

        }

    }

    return retval;

}

#else

static void

UnloadALSALibrary(void)

{

}

static int

LoadALSALibrary(void)

{

    load_alsa_syms();

    return 0;

}

#endif /* SDL_AUDIO_DRIVER_ALSA_DYNAMIC */

static const char *

get_audio_device(void *handle, const int channels)

{

    const char *device;

    if (handle != NULL) {

        return (const char *) handle;

    }

    /* !!! FIXME: we also check "SDL_AUDIO_DEVICE_NAME" at the higher level. */

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

    if (device != NULL) {

        return device;

    }

    if (channels == 6) {

        return "plug:surround51";

    } else if (channels == 4) {

        return "plug:surround40";

    }

    return "default";

}

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

static void

ALSA_WaitDevice(_THIS)

{

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

}

/* !!! FIXME: is there a channel swizzler in alsalib instead? */

/*

 * 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 *) this->hidden->mixbuf; \

    Uint32 i; \

    for (i = 0; i < this->spec.samples; i++, ptr += 6) { \

        T tmp; \

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

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

    }

static SDL_INLINE void

swizzle_alsa_channels_6_64bit(_THIS)

{

    SWIZ6(Uint64);

}

static SDL_INLINE void

swizzle_alsa_channels_6_32bit(_THIS)

{

    SWIZ6(Uint32);

}

static SDL_INLINE void

swizzle_alsa_channels_6_16bit(_THIS)

{

    SWIZ6(Uint16);

}

static SDL_INLINE void

swizzle_alsa_channels_6_8bit(_THIS)

{

    SWIZ6(Uint8);

}

#undef SWIZ6

/*

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

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

 */

static SDL_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_PlayDevice(_THIS)

{

    int status;

    const Uint8 *sample_buf = (const Uint8 *) this->hidden->mixbuf;

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

                                this->spec.channels;

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

    swizzle_alsa_channels(this);

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

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

        /* ALSA_snd_pcm_wait(this->hidden->pcm_handle, -1); */

        status = ALSA_snd_pcm_writei(this->hidden->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 = ALSA_snd_pcm_recover(this->hidden->pcm_handle, status, 0);

            if (status < 0) {

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

                fprintf(stderr, "ALSA write failed (unrecoverable): %s\n",

                        ALSA_snd_strerror(status));

                SDL_OpenedAudioDeviceDisconnected(this);

                return;

            }

            continue;

        }

        sample_buf += status * frame_size;

        frames_left -= status;

    }

}

static Uint8 *

ALSA_GetDeviceBuf(_THIS)

{

    return (this->hidden->mixbuf);

}

static void

ALSA_CloseDevice(_THIS)

{

    if (this->hidden != NULL) {

        SDL_FreeAudioMem(this->hidden->mixbuf);

        this->hidden->mixbuf = NULL;

        if (this->hidden->pcm_handle) {

            ALSA_snd_pcm_drain(this->hidden->pcm_handle);

            ALSA_snd_pcm_close(this->hidden->pcm_handle);

            this->hidden->pcm_handle = NULL;

        }

        SDL_free(this->hidden);

        this->hidden = NULL;

    }

}

static int

ALSA_finalize_hardware(_THIS, snd_pcm_hw_params_t *hwparams, int override)

{

    int status;

    snd_pcm_uframes_t bufsize;

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

    status = ALSA_snd_pcm_hw_params(this->hidden->pcm_handle, hwparams);

    if ( status < 0 ) {

        return(-1);

    }

    /* Get samples for the actual buffer size */

    status = ALSA_snd_pcm_hw_params_get_buffer_size(hwparams, &bufsize);

    if ( status < 0 ) {

        return(-1);

    }

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

        return(-1);

    }

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

    this->spec.samples = bufsize / 2;

    /* This is useful for debugging */

    if ( SDL_getenv("SDL_AUDIO_ALSA_DEBUG") ) {

        snd_pcm_uframes_t persize = 0;

        unsigned int periods = 0;

        ALSA_snd_pcm_hw_params_get_period_size(hwparams, &persize, NULL);

        ALSA_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, 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);

    ALSA_snd_pcm_hw_params_copy(hwparams, params);

    if ( !override ) {

        env = SDL_getenv("SDL_AUDIO_ALSA_SET_PERIOD_SIZE");

        if ( env ) {

            override = SDL_atoi(env);

            if ( override == 0 ) {

                return(-1);

            }

        }

    }

    frames = this->spec.samples;

    status = ALSA_snd_pcm_hw_params_set_period_size_near(

                this->hidden->pcm_handle, hwparams, &frames, NULL);

    if ( status < 0 ) {

        return(-1);

    }

    periods = 2;

    status = ALSA_snd_pcm_hw_params_set_periods_near(

                this->hidden->pcm_handle, hwparams, &periods, NULL);

    if ( status < 0 ) {

        return(-1);

    }

    return ALSA_finalize_hardware(this, hwparams, override);

}

static int

ALSA_set_buffer_size(_THIS, 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);

    ALSA_snd_pcm_hw_params_copy(hwparams, params);

    if ( !override ) {

        env = SDL_getenv("SDL_AUDIO_ALSA_SET_BUFFER_SIZE");

        if ( env ) {

            override = SDL_atoi(env);

            if ( override == 0 ) {

                return(-1);

            }

        }

    }

    frames = this->spec.samples * 2;

    status = ALSA_snd_pcm_hw_params_set_buffer_size_near(

                    this->hidden->pcm_handle, hwparams, &frames);

    if ( status < 0 ) {

        return(-1);

    }

    return ALSA_finalize_hardware(this, hwparams, override);

}

static int

ALSA_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)

{

    int status = 0;

    snd_pcm_t *pcm_handle = NULL;

    snd_pcm_hw_params_t *hwparams = NULL;

    snd_pcm_sw_params_t *swparams = NULL;

    snd_pcm_format_t format = 0;

    SDL_AudioFormat test_format = 0;

    unsigned int rate = 0;

    unsigned int channels = 0;