--- /dev/null
+/* -*-c-*-
+ *
+ * $Id: ausys-sdl.c,v 1.1 2002/02/02 19:16:28 mdw Exp $
+ *
+ * Unix-specific (SDL) audio handling
+ *
+ * (c) 2002 Mark Wooding
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of Jog: Programming for a jogging machine.
+ *
+ * Jog 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.
+ *
+ * Jog 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 Jog; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: ausys-sdl.c,v $
+ * Revision 1.1 2002/02/02 19:16:28 mdw
+ * New audio subsystem.
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <sys/types.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <pthread.h>
+
+#include <SDL.h>
+
+#include <mLib/alloc.h>
+#include <mLib/bits.h>
+#include <mLib/sub.h>
+#include <mLib/trace.h>
+
+#include "au.h"
+#include "ausys.h"
+#include "err.h"
+#include "jog.h"
+
+/*----- Data structures ---------------------------------------------------*/
+
+/* --- Queue of samples to play --- */
+
+typedef struct qnode {
+ struct qnode *next; /* Next item in the queue */
+ au_data *a; /* Pointer to sample data */
+} qnode;
+
+/*----- Global variables --------------------------------------------------*/
+
+const char *const ausys_suffix = "wav";
+
+/*----- Static data -------------------------------------------------------*/
+
+static SDL_AudioSpec auspec; /* Driver's selected parameters */
+static qnode *qhead = 0, *qtail = 0; /* Queue of samples to play */
+static qnode *qfree = 0; /* Queue of samples to free */
+
+static pthread_t tid_free; /* The sample-freeing thread */
+static pthread_mutex_t mx_free; /* Mutex for @qfree@ */
+static pthread_cond_t cv_free; /* More sample data to free */
+
+static pthread_mutex_t mx_sub; /* Protects mLib @sub@ functions */
+
+/*----- Thread structure --------------------------------------------------*
+ *
+ * SDL makes a buffer-stuffing thread that @fill@ is run from. This function
+ * reads samples to play from the queue at @qhead@. Hence @qhead@ must be
+ * locked when it's modified, using @SDL_LockAudio@.
+ *
+ * In order to keep latency down when new sample data is wanted, we don't do
+ * potentially tedious things like freeing sample data blocks in the @fill@
+ * thread. Instead, there's a queue of sample blocks which need freeing, and
+ * a separate thread @dofree@ which processes the queue. The queue, @qfree@
+ * is locked by @mx_free@. When new nodes are added to @qfree@, the
+ * condition @cv_free@ is signalled.
+ *
+ * Finally, the mLib `sub' module isn't thread-safe, so it's locked
+ * separately by @mx_sub@.
+ *
+ * There's an ordering on mutexes. If you want more than one mutex at a
+ * time, you must lock the greatest first. The ordering is:
+ *
+ * SDL_Audio > free > sub
+ */
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @fill@ --- *
+ *
+ * Arguments: @void *u@ = user data (ignored)
+ * @octet *q@ = pointer to buffer to fill in
+ * @int qsz@ = size of the buffer
+ *
+ * Returns: ---
+ *
+ * Use: Fills an audio buffer with precomputed stuff.
+ */
+
+static void fill(void *u, octet *q, int qsz)
+{
+ static const octet *p = 0; /* Current place in current sample */
+ static size_t sz = 0; /* How far to go in current sample */
+ qnode *qf = 0, **qft = &qf; /* Samples we've finished with */
+
+ /* --- If @p@ is null we need to get a new sample --- */
+
+ if (!p && qhead) {
+ T( trace(T_AUSYS, "ausys: begin playing `%s'", SYM_NAME(qhead->a->s)); )
+ p = qhead->a->p;
+ sz = qhead->a->sz;
+ }
+
+ /* --- Main queue-filling loop --- */
+
+ while (qsz) {
+ size_t n;
+
+ /* --- If the queue is empty, play silence --- */
+
+ if (!p) {
+ memset(q, auspec.silence, qsz);
+ break;
+ }
+
+ /* --- Fill the buffer with my sample --- */
+exit(0);
+ n = qsz;
+ if (n > sz)
+ n = sz;
+ memcpy(q, p, n);
+ p += n; q += n;
+ sz -= n; qsz -= n;
+
+ /* --- If the sample is used up, throw it away --- */
+
+ if (!sz) {
+ qnode *qq = qhead;
+ qhead = qq->next;
+ if (!qhead)
+ qtail = 0;
+ T( trace(T_AUSYS, "ausys: put `%s' on free list",
+ SYM_NAME(qq->a->s)); )
+ *qft = qq;
+ qft = &qq->next;
+ if (qhead) {
+ T( trace(T_AUSYS, "ausys: begin playing `%s'",
+ SYM_NAME(qhead->a->s)); )
+ p = qhead->a->p;
+ sz = qhead->a->sz;
+ } else {
+ T( trace(T_AUSYS, "ausys: sample queue is empty"); )
+ p = 0;
+ sz = 0;
+ }
+ }
+ }
+
+ /* --- Finally dump freed samples, all in one go --- */
+
+ if (qf) {
+ pthread_mutex_lock(&mx_free);
+ *qft = qfree;
+ qfree = qf;
+ pthread_mutex_unlock(&mx_free);
+ pthread_cond_signal(&cv_free);
+ }
+}
+
+/* --- @dofree@ --- *
+ *
+ * Arguments: @void *u@ = unused pointer
+ *
+ * Returns: An unused pointer.
+ *
+ * Use: Frees unwanted sample queue nodes.
+ */
+
+static void *dofree(void *u)
+{
+ qnode *q, *qq;
+
+ pthread_mutex_lock(&mx_free);
+ for (;;) {
+ T( trace(T_AUSYS, "ausys: dofree sleeping"); )
+ pthread_cond_wait(&cv_free, &mx_free);
+ T( trace(T_AUSYS, "ausys: dofree woken: work to do"); )
+
+ while (qfree) {
+ q = qfree;
+ qfree = 0;
+ pthread_mutex_lock(&mx_sub);
+ while (q) {
+ qq = q->next;
+ T( trace(T_AUSYS, "ausys: freeing `%s'", SYM_NAME(q->a->s)); )
+ au_free_unlocked(q->a);
+ DESTROY(q);
+ q = qq;
+ }
+ pthread_mutex_unlock(&mx_sub);
+ }
+ }
+}
+
+/* --- @ausys_init@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: ---
+ *
+ * Use: Does any initialization required by the system-specific audio
+ * handler.
+ */
+
+void ausys_init(void)
+{
+ SDL_AudioSpec want;
+ pthread_attr_t ta;
+ int e;
+
+ /* --- Crank up the sample-freeing thread --- */
+
+ if ((e = pthread_mutex_init(&mx_free, 0)) != 0 ||
+ (e = pthread_mutex_init(&mx_sub, 0)) != 0 ||
+ (e = pthread_cond_init(&cv_free, 0)) != 0 ||
+ (e = pthread_attr_init(&ta)) != 0 ||
+ (e = pthread_attr_setdetachstate(&ta, PTHREAD_CREATE_DETACHED)) != 0 ||
+ (e = pthread_create(&tid_free, &ta, dofree, 0)) != 0) {
+ err_report(ERR_AUDIO, ERRAU_INIT, e,
+ "couldn't create audio threads: %s", strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+ pthread_attr_destroy(&ta);
+
+ /* --- Crank up the SDL audio subsystem --- */
+
+ if (SDL_Init(SDL_INIT_AUDIO | SDL_INIT_NOPARACHUTE)) {
+ err_report(ERR_AUDIO, ERRAU_INIT, 0,
+ "couldn't initialize SDL audio: %s", SDL_GetError());
+ exit(EXIT_FAILURE);
+ }
+
+ /* --- Open the audio device --- */
+
+ want.freq = 8000;
+ want.format = AUDIO_U8;
+ want.channels = 1;
+ want.samples = 4096;
+ want.callback = fill;
+ want.userdata = 0;
+
+ if (SDL_OpenAudio(&want, &auspec)) {
+ err_report(ERR_AUDIO, ERRAU_INIT, 0,
+ "couldn't open audio device: %s", SDL_GetError());
+ exit(EXIT_FAILURE);
+ }
+
+ /* --- Prepare whatever needs to be done --- */
+
+ SDL_PauseAudio(0);
+
+ T( trace(T_AUSYS, "ausys: initalized ok"); )
+}
+
+/* --- @ausys_shutdown@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: ---
+ *
+ * Use: Does any tidying up required.
+ */
+
+void ausys_shutdown(void)
+{
+ /* --- Busy-wait until sound buffer empties --- */
+
+ while (qhead) {
+ struct timeval tv = { 0, 100000 };
+ select(0, 0, 0, 0, &tv);
+ }
+
+ /* --- Shut stuff down --- */
+
+ pthread_cancel(tid_free);
+ SDL_CloseAudio();
+ SDL_Quit();
+
+ T( trace(T_AUSYS, "ausys: shut down ok"); )
+}
+
+/* --- @ausys_lock@, @ausys_unlock@ --- *
+ *
+ * Arguments: ---
+ *
+ * Returns: ---
+ *
+ * Use: Locks or unlocks the audio subsystem. This protects the
+ * audio queue from becoming corrupted during all the tedious
+ * asynchronous stuff.
+ */
+
+void ausys_lock(void)
+{
+ pthread_mutex_lock(&mx_free);
+ pthread_mutex_lock(&mx_sub);
+ T( trace(T_AUSYS, "ausys: acquired lock"); )
+}
+
+void ausys_unlock(void)
+{
+ pthread_mutex_unlock(&mx_sub);
+ pthread_mutex_unlock(&mx_free);
+ T( trace(T_AUSYS, "ausys: released lock"); )
+}
+
+/* --- @ausys_decode@ --- *
+ *
+ * Arguments: @au_sample *s@ = pointer to sample block
+ * @const void *p@ = pointer to sample file contents
+ * @size_t sz@ = size of sample file contents
+ *
+ * Returns: Pointer to a sample data structure.
+ *
+ * Use: Decodes a WAV file into something the system-specific layer
+ * actually wants to deal with.
+ */
+
+au_data *ausys_decode(au_sample *s, const void *p, size_t sz)
+{
+ au_data *a;
+ SDL_AudioCVT cvt;
+ SDL_AudioSpec spec;
+ SDL_RWops *rw;
+ Uint8 *buf;
+ Uint32 len;
+ void *q;
+
+ /* --- Firstly, extract the audio data from the WAV file --- */
+
+ rw = SDL_RWFromMem((void *)p, sz);
+ if (!SDL_LoadWAV_RW(rw, 1, &spec, &buf, &len)) {
+ err_report(ERR_AUDIO, ERRAU_OPEN, 0,
+ "can't read WAV file for `%s': %s",
+ SYM_NAME(s), SDL_GetError());
+ goto fail_0;
+ }
+
+ /* --- Now convert that to the driver's expected format --- */
+
+ if (SDL_BuildAudioCVT(&cvt, spec.format, spec.channels, spec.freq,
+ auspec.format, auspec.channels, auspec.freq) == -1) {
+ err_report(ERR_AUDIO, ERRAU_OPEN, 0,
+ "can't build conversion structure for `%s': %s",
+ SYM_NAME(s), SDL_GetError());
+ goto fail_1;
+ }
+
+ cvt.buf = xmalloc(len * cvt.len_mult);
+ cvt.len = len;
+ memcpy(cvt.buf, buf, len);
+ SDL_FreeWAV(buf);
+
+ if (SDL_ConvertAudio(&cvt)) {
+ err_report(ERR_AUDIO, ERRAU_OPEN, 0,
+ "can't convert `%s': %s", SYM_NAME(s), SDL_GetError());
+ goto fail_2;
+ }
+
+ /* --- Now fiddle with buffers --- */
+
+ sz = len * cvt.len_ratio;
+ if (cvt.len_ratio >= 1)
+ q = cvt.buf;
+ else {
+ q = xmalloc(sz);
+ memcpy(q, cvt.buf, sz);
+ xfree(cvt.buf);
+ }
+
+ /* --- Construct a new node --- */
+
+ pthread_mutex_lock(&mx_sub);
+ a = CREATE(au_data);
+ pthread_mutex_unlock(&mx_sub);
+ a->p = q;
+ a->sz = sz;
+
+ T( trace(T_AUSYS, "ausys: decoded `%s' ok", SYM_NAME(s)); )
+ return (a);
+
+ /* --- Tidy up after errors --- */
+
+fail_2:
+ xfree(cvt.buf);
+ goto fail_0;
+fail_1:
+ SDL_FreeWAV(buf);
+fail_0:
+ return (0);
+}
+
+/* --- @ausys_queue@ --- *
+ *
+ * Arguments: @au_data *a@ = an audio thingy to play
+ *
+ * Returns: ---
+ *
+ * Use: Queues an audio sample to be played. The sample should be
+ * freed (with @au_free@) when it's no longer wanted.
+ */
+
+void ausys_queue(au_data *a)
+{
+ qnode *q;
+
+ pthread_mutex_lock(&mx_sub);
+ q = CREATE(qnode);
+ pthread_mutex_unlock(&mx_sub);
+ q->next = 0;
+ q->a = a;
+ SDL_LockAudio();
+ if (qtail)
+ qtail->next = q;
+ else
+ qhead = q;
+ qtail = q;
+ SDL_UnlockAudio();
+ T( trace(T_AUSYS, "ausys: queuing `%s'", SYM_NAME(a->s)); )
+}
+
+/* --- @ausys_free@ --- *
+ *
+ * Arguments: @au_data *a@ = an audio thingy to free
+ *
+ * Returns: ---
+ *
+ * Use: Frees a decoded audio sample.
+ */
+
+void ausys_free(au_data *a)
+{
+ xfree(a->p);
+ DESTROY(a);
+ T( trace(T_AUSYS, "ausys: freeing data for `%s' ok", SYM_NAME(a->s)); )
+}
+
+/*----- That's all, folks -------------------------------------------------*/
~mdw / jog / blobdiff