src/audio/dma/SDL_dmaaudio.c
author Ryan C. Gordon <icculus@icculus.org>
Thu, 24 Aug 2006 12:10:46 +0000
changeset 1982 3b4ce57c6215
parent 1895 c121d94672cb
child 2049 5f6550e5184f
child 3795 589bc3d060cd
permissions -rw-r--r--
First shot at new audio data types (int32 and float32). Notable changes: - Converters between types are autogenerated. Instead of making multiple passes over the data with seperate filters for endianess, size, signedness, etc, converting between data types is always one specialized filter. This simplifies SDL_BuildAudioCVT(), which otherwise had a million edge cases with the new types, and makes the actually conversions more CPU cache friendly. Left a stub for adding specific optimized versions of these routines (SSE/MMX/Altivec, assembler, etc) - Autogenerated converters are built by SDL/src/audio/sdlgenaudiocvt.pl. This does not need to be run unless tweaking the code, and thus doesn't need integration into the build system. - Went through all the drivers and tried to weed out all the "Uint16" references that are better specified with the new SDL_AudioFormat typedef. - Cleaned out a bunch of hardcoded bitwise magic numbers and replaced them with new SDL_AUDIO_* macros. - Added initial float32 and int32 support code. Theoretically, existing drivers will push these through converters to get the data they want to feed to the hardware. Still TODO: - Optimize and debug new converters. - Update the CoreAudio backend to accept float32 data directly. - Other backends, too? - SDL_LoadWAV() needs to be updated to support int32 and float32 .wav files (both of which exist and can be generated by 'sox' for testing purposes). - Update the mixer to handle new datatypes. - Optionally update SDL_sound and SDL_mixer, etc.

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 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
    Lesser General Public License for more details.

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

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

/* Allow access to a raw mixing buffer */

#include <stdio.h>
#include <string.h>             /* For strerror() */
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/mman.h>

#if SDL_AUDIO_DRIVER_OSS_SOUNDCARD_H
/* This is installed on some systems */
#include <soundcard.h>
#else
/* This is recommended by OSS */
#include <sys/soundcard.h>
#endif

#ifndef MAP_FAILED
#define MAP_FAILED	((Uint8 *)-1)
#endif

#include "SDL_timer.h"
#include "SDL_audio.h"
#include "../SDL_audio_c.h"
#include "../SDL_audiodev_c.h"
#include "SDL_dmaaudio.h"

/* The tag name used by DMA audio */
#define DMA_DRIVER_NAME         "dma"

/* Open the audio device for playback, and don't block if busy */
#define OPEN_FLAGS	(O_RDWR|O_NONBLOCK)

/* Audio driver functions */
static int DMA_OpenAudio(_THIS, SDL_AudioSpec * spec);
static void DMA_WaitAudio(_THIS);
static void DMA_PlayAudio(_THIS);
static Uint8 *DMA_GetAudioBuf(_THIS);
static void DMA_CloseAudio(_THIS);

/* Audio driver bootstrap functions */

static int
Audio_Available(void)
{
    int available;
    int fd;

    available = 0;

    fd = SDL_OpenAudioPath(NULL, 0, OPEN_FLAGS, 0);
    if (fd >= 0) {
        int caps;
        struct audio_buf_info info;

        if ((ioctl(fd, SNDCTL_DSP_GETCAPS, &caps) == 0) &&
            (caps & DSP_CAP_TRIGGER) && (caps & DSP_CAP_MMAP) &&
            (ioctl(fd, SNDCTL_DSP_GETOSPACE, &info) == 0)) {
            available = 1;
        }
        close(fd);
    }
    return (available);
}

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

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

    /* Initialize all variables that we clean on shutdown */
    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));
    audio_fd = -1;

    /* Set the function pointers */
    this->OpenAudio = DMA_OpenAudio;
    this->WaitAudio = DMA_WaitAudio;
    this->PlayAudio = DMA_PlayAudio;
    this->GetAudioBuf = DMA_GetAudioBuf;
    this->CloseAudio = DMA_CloseAudio;

    this->free = Audio_DeleteDevice;

    return this;
}

AudioBootStrap DMA_bootstrap = {
    DMA_DRIVER_NAME, "OSS /dev/dsp DMA audio",
    Audio_Available, Audio_CreateDevice
};

/* This function waits until it is possible to write a full sound buffer */
static void
DMA_WaitAudio(_THIS)
{
    fd_set fdset;

    /* Check to see if the thread-parent process is still alive */
    {
        static int cnt = 0;
        /* Note that this only works with thread implementations 
           that use a different process id for each thread.
         */
        if (parent && (((++cnt) % 10) == 0)) {  /* Check every 10 loops */
            if (kill(parent, 0) < 0) {
                this->enabled = 0;
            }
        }
    }

    /* See if we need to use timed audio synchronization */
    if (frame_ticks) {
        /* Use timer for general audio synchronization */
        Sint32 ticks;

        ticks = ((Sint32) (next_frame - SDL_GetTicks())) - FUDGE_TICKS;
        if (ticks > 0) {
            SDL_Delay(ticks);
        }
    } else {
        /* Use select() for audio synchronization */
        struct timeval timeout;
        FD_ZERO(&fdset);
        FD_SET(audio_fd, &fdset);
        timeout.tv_sec = 10;
        timeout.tv_usec = 0;
#ifdef DEBUG_AUDIO
        fprintf(stderr, "Waiting for audio to get ready\n");
#endif
        if (select(audio_fd + 1, NULL, &fdset, NULL, &timeout) <= 0) {
            const char *message =
#ifdef AUDIO_OSPACE_HACK
                "Audio timeout - buggy audio driver? (trying ospace)";
#else
                "Audio timeout - buggy audio driver? (disabled)";
#endif
            /* In general we should never print to the screen,
               but in this case we have no other way of letting
               the user know what happened.
             */
            fprintf(stderr, "SDL: %s\n", message);
#ifdef AUDIO_OSPACE_HACK
            /* We may be able to use GET_OSPACE trick */
            frame_ticks = (float) (this->spec->samples * 1000) /
                this->spec->freq;
            next_frame = SDL_GetTicks() + frame_ticks;
#else
            this->enabled = 0;
            /* Don't try to close - may hang */
            audio_fd = -1;
#ifdef DEBUG_AUDIO
            fprintf(stderr, "Done disabling audio\n");
#endif
#endif /* AUDIO_OSPACE_HACK */
        }
#ifdef DEBUG_AUDIO
        fprintf(stderr, "Ready!\n");
#endif
    }
}

static void
DMA_PlayAudio(_THIS)
{
    /* If timer synchronization is enabled, set the next write frame */
    if (frame_ticks) {
        next_frame += frame_ticks;
    }
    return;
}

static Uint8 *
DMA_GetAudioBuf(_THIS)
{
    count_info info;
    int playing;
    int filling;

    /* Get number of blocks, looping if we're not using select() */
    do {
        if (ioctl(audio_fd, SNDCTL_DSP_GETOPTR, &info) < 0) {
            /* Uh oh... */
            this->enabled = 0;
            return (NULL);
        }
    }
    while (frame_ticks && (info.blocks < 1));
#ifdef DEBUG_AUDIO
    if (info.blocks > 1) {
        printf("Warning: audio underflow (%d frags)\n", info.blocks - 1);
    }
#endif
    playing = info.ptr / this->spec.size;
    filling = (playing + 1) % num_buffers;
    return (dma_buf + (filling * this->spec.size));
}

static void
DMA_CloseAudio(_THIS)
{
    if (dma_buf != NULL) {
        munmap(dma_buf, dma_len);
        dma_buf = NULL;
    }
    if (audio_fd >= 0) {
        close(audio_fd);
        audio_fd = -1;
    }
}

static int
DMA_ReopenAudio(_THIS, const char *audiodev, int format, int stereo,
                SDL_AudioSpec * spec)
{
    int frag_spec;
    int value;

    /* Close and then reopen the audio device */
    close(audio_fd);
    audio_fd = open(audiodev, O_RDWR, 0);
    if (audio_fd < 0) {
        SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
        return (-1);
    }

    /* Calculate the final parameters for this audio specification */
    SDL_CalculateAudioSpec(spec);

    /* Determine the power of two of the fragment size */
    for (frag_spec = 0; (0x01 << frag_spec) < spec->size; ++frag_spec);
    if ((0x01 << frag_spec) != spec->size) {
        SDL_SetError("Fragment size must be a power of two");
        return (-1);
    }

    /* Set the audio buffering parameters */
    if (ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag_spec) < 0) {
        SDL_SetError("Couldn't set audio fragment spec");
        return (-1);
    }

    /* Set the audio format */
    value = format;
    if ((ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) || (value != format)) {
        SDL_SetError("Couldn't set audio format");
        return (-1);
    }

    /* Set mono or stereo audio */
    value = (spec->channels > 1);
    if ((ioctl(audio_fd, SNDCTL_DSP_STEREO, &stereo) < 0) ||
        (value != stereo)) {
        SDL_SetError("Couldn't set audio channels");
        return (-1);
    }

    /* Set the DSP frequency */
    value = spec->freq;
    if (ioctl(audio_fd, SNDCTL_DSP_SPEED, &value) < 0) {
        SDL_SetError("Couldn't set audio frequency");
        return (-1);
    }
    spec->freq = value;

    /* We successfully re-opened the audio */
    return (0);
}

static int
DMA_OpenAudio(_THIS, SDL_AudioSpec * spec)
{
    char audiodev[1024];
    int format;
    int stereo;
    int value;
    SDL_AudioFormat test_format;
    struct audio_buf_info info;

    /* Reset the timer synchronization flag */
    frame_ticks = 0.0;

    /* Open the audio device */
    audio_fd = SDL_OpenAudioPath(audiodev, sizeof(audiodev), OPEN_FLAGS, 0);
    if (audio_fd < 0) {
        SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
        return (-1);
    }
    dma_buf = NULL;
    ioctl(audio_fd, SNDCTL_DSP_RESET, 0);

    /* Get a list of supported hardware formats */
    if (ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &value) < 0) {
        SDL_SetError("Couldn't get audio format list");
        return (-1);
    }

    /* Try for a closest match on audio format */
    format = 0;
    for (test_format = SDL_FirstAudioFormat(spec->format);
         !format && test_format;) {
#ifdef DEBUG_AUDIO
        fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
#endif
        switch (test_format) {
        case AUDIO_U8:
            if (value & AFMT_U8) {
                format = AFMT_U8;
            }
            break;
        case AUDIO_S8:
            if (value & AFMT_S8) {
                format = AFMT_S8;
            }
            break;
        case AUDIO_S16LSB:
            if (value & AFMT_S16_LE) {
                format = AFMT_S16_LE;
            }
            break;
        case AUDIO_S16MSB:
            if (value & AFMT_S16_BE) {
                format = AFMT_S16_BE;
            }
            break;
        case AUDIO_U16LSB:
            if (value & AFMT_U16_LE) {
                format = AFMT_U16_LE;
            }
            break;
        case AUDIO_U16MSB:
            if (value & AFMT_U16_BE) {
                format = AFMT_U16_BE;
            }
            break;
        default:
            format = 0;
            break;
        }
        if (!format) {
            test_format = SDL_NextAudioFormat();
        }
    }
    if (format == 0) {
        SDL_SetError("Couldn't find any hardware audio formats");
        return (-1);
    }
    spec->format = test_format;

    /* Set the audio format */
    value = format;
    if ((ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) || (value != format)) {
        SDL_SetError("Couldn't set audio format");
        return (-1);
    }

    /* Set mono or stereo audio (currently only two channels supported) */
    stereo = (spec->channels > 1);
    ioctl(audio_fd, SNDCTL_DSP_STEREO, &stereo);
    if (stereo) {
        spec->channels = 2;
    } else {
        spec->channels = 1;
    }

    /* Because some drivers don't allow setting the buffer size
       after setting the format, we must re-open the audio device
       once we know what format and channels are supported
     */
    if (DMA_ReopenAudio(this, audiodev, format, stereo, spec) < 0) {
        /* Error is set by DMA_ReopenAudio() */
        return (-1);
    }

    /* Memory map the audio buffer */
    if (ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &info) < 0) {
        SDL_SetError("Couldn't get OSPACE parameters");
        return (-1);
    }
    spec->size = info.fragsize;
    spec->samples = spec->size / ((spec->format & 0xFF) / 8);
    spec->samples /= spec->channels;
    num_buffers = info.fragstotal;
    dma_len = num_buffers * spec->size;
    dma_buf = (Uint8 *) mmap(NULL, dma_len, PROT_WRITE, MAP_SHARED,
                             audio_fd, 0);
    if (dma_buf == MAP_FAILED) {
        SDL_SetError("DMA memory map failed");
        dma_buf = NULL;
        return (-1);
    }
    SDL_memset(dma_buf, spec->silence, dma_len);

    /* Check to see if we need to use select() workaround */
    {
        char *workaround;
        workaround = SDL_getenv("SDL_DSP_NOSELECT");
        if (workaround) {
            frame_ticks = (float) (spec->samples * 1000) / spec->freq;
            next_frame = SDL_GetTicks() + frame_ticks;
        }
    }

    /* Trigger audio playback */
    value = 0;
    ioctl(audio_fd, SNDCTL_DSP_SETTRIGGER, &value);
    value = PCM_ENABLE_OUTPUT;
    if (ioctl(audio_fd, SNDCTL_DSP_SETTRIGGER, &value) < 0) {
        SDL_SetError("Couldn't trigger audio output");
        return (-1);
    }

    /* Get the parent process id (we're the parent of the audio thread) */
    parent = getpid();

    /* We're ready to rock and roll. :-) */
    return (0);
}

/* vi: set ts=4 sw=4 expandtab: */