src/audio/mme/SDL_mmeaudio.c

/*
    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@libsdl.org
*/
#include "SDL_config.h"

/* Tru64 UNIX MME support */
#include <mme_api.h>

#include "SDL_timer.h"
#include "SDL_audio.h"
#include "../SDL_audio_c.h"
#include "SDL_mmeaudio.h"

static BOOL inUse[NUM_BUFFERS];

/* Audio driver functions */
static int MME_OpenAudio (_THIS, SDL_AudioSpec * spec);
static void MME_WaitAudio (_THIS);
static Uint8 *MME_GetAudioBuf (_THIS);
static void MME_PlayAudio (_THIS);
static void MME_WaitDone (_THIS);
static void MME_CloseAudio (_THIS);

/* Audio driver bootstrap functions */
static int
Audio_Available (void)
{
    return (1);
}

static void
Audio_DeleteDevice (SDL_AudioDevice * device)
{
    if (device) {
        if (device->hidden) {
            SDL_free (device->hidden);
            device->hidden = NULL;
        }
        SDL_free (device);
        device = NULL;
    }
}

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

/* Initialize all variables that we clean on shutdown */
    this = SDL_malloc (sizeof (SDL_AudioDevice));
    if (this) {
        SDL_memset (this, 0, (sizeof *this));
        this->hidden = 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 = MME_OpenAudio;
    this->WaitAudio = MME_WaitAudio;
    this->PlayAudio = MME_PlayAudio;
    this->GetAudioBuf = MME_GetAudioBuf;
    this->WaitDone = MME_WaitDone;
    this->CloseAudio = MME_CloseAudio;
    this->free = Audio_DeleteDevice;

    return this;
}

AudioBootStrap MMEAUDIO_bootstrap = {
    "waveout", "Tru64 MME WaveOut",
    Audio_Available, Audio_CreateDevice
};

static void
SetMMerror (char *function, MMRESULT code)
{
    int len;
    char errbuf[MAXERRORLENGTH];

    SDL_snprintf (errbuf, SDL_arraysize (errbuf), "%s: ", function);
    len = SDL_strlen (errbuf);
    waveOutGetErrorText (code, errbuf + len, MAXERRORLENGTH - len);
    SDL_SetError ("%s", errbuf);
}

static void CALLBACK
MME_CALLBACK (HWAVEOUT hwo,
              UINT uMsg, DWORD dwInstance, LPARAM dwParam1, LPARAM dwParam2)
{
    WAVEHDR *wp = (WAVEHDR *) dwParam1;

    if (uMsg == WOM_DONE)
        inUse[wp->dwUser] = FALSE;
}

static int
MME_OpenAudio (_THIS, SDL_AudioSpec * spec)
{
    MMRESULT result;
    int i;

    mixbuf = NULL;

    /* Set basic WAVE format parameters */
    shm = mmeAllocMem (sizeof (*shm));
    if (shm == NULL) {
        SDL_SetError ("Out of memory: shm");
        return (-1);
    }
    shm->sound = 0;
    shm->wFmt.wf.wFormatTag = WAVE_FORMAT_PCM;

    /* Determine the audio parameters from the AudioSpec */
    switch (spec->format & 0xFF) {
    case 8:
        /* Unsigned 8 bit audio data */
        spec->format = AUDIO_U8;
        shm->wFmt.wBitsPerSample = 8;
        break;
    case 16:
        /* Signed 16 bit audio data */
        spec->format = AUDIO_S16;
        shm->wFmt.wBitsPerSample = 16;
        break;
    default:
        SDL_SetError ("Unsupported audio format");
        return (-1);
    }

    shm->wFmt.wf.nChannels = spec->channels;
    shm->wFmt.wf.nSamplesPerSec = spec->freq;
    shm->wFmt.wf.nBlockAlign =
        shm->wFmt.wf.nChannels * shm->wFmt.wBitsPerSample / 8;
    shm->wFmt.wf.nAvgBytesPerSec =
        shm->wFmt.wf.nSamplesPerSec * shm->wFmt.wf.nBlockAlign;

    /* Check the buffer size -- minimum of 1/4 second (word aligned) */
    if (spec->samples < (spec->freq / 4))
        spec->samples = ((spec->freq / 4) + 3) & ~3;

    /* Update the fragment size as size in bytes */
    SDL_CalculateAudioSpec (spec);

    /* Open the audio device */
    result = waveOutOpen (&(shm->sound),
                          WAVE_MAPPER,
                          &(shm->wFmt.wf),
                          MME_CALLBACK,
                          NULL, (CALLBACK_FUNCTION | WAVE_OPEN_SHAREABLE));
    if (result != MMSYSERR_NOERROR) {
        SetMMerror ("waveOutOpen()", result);
        return (-1);
    }

    /* Create the sound buffers */
    mixbuf = (Uint8 *) mmeAllocBuffer (NUM_BUFFERS * (spec->size));
    if (mixbuf == NULL) {
        SDL_SetError ("Out of memory: mixbuf");
        return (-1);
    }

    for (i = 0; i < NUM_BUFFERS; i++) {
        shm->wHdr[i].lpData = &mixbuf[i * (spec->size)];
        shm->wHdr[i].dwBufferLength = spec->size;
        shm->wHdr[i].dwFlags = 0;
        shm->wHdr[i].dwUser = i;
        shm->wHdr[i].dwLoops = 0;       /* loop control counter */
        shm->wHdr[i].lpNext = NULL;     /* reserved for driver */
        shm->wHdr[i].reserved = 0;
        inUse[i] = FALSE;
    }
    next_buffer = 0;
    return 0;
}

static void
MME_WaitAudio (_THIS)
{
    while (inUse[next_buffer]) {
        mmeWaitForCallbacks ();
        mmeProcessCallbacks ();
    }
}

static Uint8 *
MME_GetAudioBuf (_THIS)
{
    Uint8 *retval;

    inUse[next_buffer] = TRUE;
    retval = (Uint8 *) (shm->wHdr[next_buffer].lpData);
    return retval;
}

static void
MME_PlayAudio (_THIS)
{
    /* Queue it up */
    waveOutWrite (shm->sound, &(shm->wHdr[next_buffer]), sizeof (WAVEHDR));
    next_buffer = (next_buffer + 1) % NUM_BUFFERS;
}

static void
MME_WaitDone (_THIS)
{
    MMRESULT result;
    int i;

    if (shm->sound) {
        for (i = 0; i < NUM_BUFFERS; i++)
            while (inUse[i]) {
                mmeWaitForCallbacks ();
                mmeProcessCallbacks ();
            }
        result = waveOutReset (shm->sound);
        if (result != MMSYSERR_NOERROR)
            SetMMerror ("waveOutReset()", result);
        mmeProcessCallbacks ();
    }
}

static void
MME_CloseAudio (_THIS)
{
    MMRESULT result;

    if (mixbuf) {
        result = mmeFreeBuffer (mixbuf);
        if (result != MMSYSERR_NOERROR)
            SetMMerror ("mmeFreeBuffer", result);
        mixbuf = NULL;
    }

    if (shm) {
        if (shm->sound) {
            result = waveOutClose (shm->sound);
            if (result != MMSYSERR_NOERROR)
                SetMMerror ("waveOutClose()", result);
            mmeProcessCallbacks ();
        }
        result = mmeFreeMem (shm);
        if (result != MMSYSERR_NOERROR)
            SetMMerror ("mmeFreeMem()", result);
        shm = NULL;
    }
}

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