*SDL project

1 files changed, 51 insertions, 91 deletions

diff --git a/Source/3rdParty/SDL2/src/audio/alsa/SDL_alsa_audio.c b/Source/3rdParty/SDL2/src/audio/alsa/SDL_alsa_audio.c
index 2dba1ff..eff192b 100644
--- a/Source/3rdParty/SDL2/src/audio/alsa/SDL_alsa_audio.c
+++ b/Source/3rdParty/SDL2/src/audio/alsa/SDL_alsa_audio.c
@@ -22,6 +22,10 @@
 
 #if SDL_AUDIO_DRIVER_ALSA
 
+#ifndef SDL_ALSA_NON_BLOCKING
+#define SDL_ALSA_NON_BLOCKING 0
+#endif
+
 /* Allow access to a raw mixing buffer */
 
 #include <sys/types.h>
@@ -90,6 +94,7 @@ static int (*ALSA_snd_pcm_reset)(snd_pcm_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 **);
+static snd_pcm_sframes_t (*ALSA_snd_pcm_avail)(snd_pcm_t *);
 #ifdef SND_CHMAP_API_VERSION
 static snd_pcm_chmap_t* (*ALSA_snd_pcm_get_chmap) (snd_pcm_t *);
 static int (*ALSA_snd_pcm_chmap_print) (const snd_pcm_chmap_t *map, size_t maxlen, char *buf);
@@ -158,6 +163,7 @@ load_alsa_syms(void)
     SDL_ALSA_SYM(snd_device_name_hint);
     SDL_ALSA_SYM(snd_device_name_get_hint);
     SDL_ALSA_SYM(snd_device_name_free_hint);
+    SDL_ALSA_SYM(snd_pcm_avail);
 #ifdef SND_CHMAP_API_VERSION
     SDL_ALSA_SYM(snd_pcm_get_chmap);
     SDL_ALSA_SYM(snd_pcm_chmap_print);
@@ -243,7 +249,24 @@ get_audio_device(void *handle, const int channels)
 static void
 ALSA_WaitDevice(_THIS)
 {
-    /* We're in blocking mode, so there's nothing to do here */
+#if SDL_ALSA_NON_BLOCKING
+    const snd_pcm_sframes_t needed = (snd_pcm_sframes_t) this->spec.samples;
+    while (SDL_AtomicGet(&this->enabled)) {
+        const snd_pcm_sframes_t rc = ALSA_snd_pcm_avail(this->hidden->pcm_handle);
+        if ((rc < 0) && (rc != -EAGAIN)) {
+            /* Hmm, not much we can do - abort */
+            fprintf(stderr, "ALSA snd_pcm_avail failed (unrecoverable): %s\n",
+                        ALSA_snd_strerror(rc));
+            SDL_OpenedAudioDeviceDisconnected(this);
+            return;
+        } else if (rc < needed) {
+            const Uint32 delay = ((needed - (SDL_max(rc, 0))) * 1000) / this->spec.freq;
+            SDL_Delay(SDL_max(delay, 10));
+        } else {
+            break;  /* ready to go! */
+        }
+    }
+#endif
 }
 
 
@@ -422,7 +445,7 @@ static void
 ALSA_CloseDevice(_THIS)
 {
     if (this->hidden->pcm_handle) {
-	/* Wait for the submitted audio to drain
+        /* Wait for the submitted audio to drain
            ALSA_snd_pcm_drop() can hang, so don't use that.
          */
         Uint32 delay = ((this->spec.samples * 1000) / this->spec.freq) * 2;
@@ -435,35 +458,45 @@ ALSA_CloseDevice(_THIS)
 }
 
 static int
-ALSA_finalize_hardware(_THIS, snd_pcm_hw_params_t *hwparams, int override)
+ALSA_set_buffer_size(_THIS, snd_pcm_hw_params_t *params)
 {
     int status;
+    snd_pcm_hw_params_t *hwparams;
     snd_pcm_uframes_t bufsize;
+    snd_pcm_uframes_t persize;
 
-    /* "set" the hardware with the desired parameters */
-    status = ALSA_snd_pcm_hw_params(this->hidden->pcm_handle, hwparams);
+    /* Copy the hardware parameters for this setup */
+    snd_pcm_hw_params_alloca(&hwparams);
+    ALSA_snd_pcm_hw_params_copy(hwparams, params);
+
+    /* Prioritize matching the period size to the requested buffer size */
+    persize = this->spec.samples;
+    status = ALSA_snd_pcm_hw_params_set_period_size_near(
+                this->hidden->pcm_handle, hwparams, &persize, NULL);
     if ( status < 0 ) {
         return(-1);
     }
 
-    /* Get samples for the actual buffer size */
-    status = ALSA_snd_pcm_hw_params_get_buffer_size(hwparams, &bufsize);
+    /* Next try to restrict the parameters to having only two periods */
+    bufsize = this->spec.samples * 2;
+    status = ALSA_snd_pcm_hw_params_set_buffer_size_near(
+                    this->hidden->pcm_handle, hwparams, &bufsize);
     if ( status < 0 ) {
         return(-1);
     }
-    if ( !override && bufsize != this->spec.samples * 2 ) {
+
+    /* "set" the hardware with the desired parameters */
+    status = ALSA_snd_pcm_hw_params(this->hidden->pcm_handle, hwparams);
+    if ( status < 0 ) {
         return(-1);
     }
 
-    /* !!! FIXME: Is this safe to do? */
-    this->spec.samples = bufsize / 2;
+    this->spec.samples = persize;
 
     /* 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,
@@ -475,78 +508,6 @@ ALSA_finalize_hardware(_THIS, snd_pcm_hw_params_t *hwparams, int override)
 }
 
 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;
@@ -692,14 +653,11 @@ ALSA_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
     this->spec.freq = rate;
 
     /* Set the buffer size, in samples */
-    if ( ALSA_set_period_size(this, hwparams, 0) < 0 &&
-         ALSA_set_buffer_size(this, hwparams, 0) < 0 ) {
-        /* Failed to set desired buffer size, do the best you can... */
-        status = ALSA_set_period_size(this, hwparams, 1);
-        if (status < 0) {
-            return SDL_SetError("Couldn't set hardware audio parameters: %s", ALSA_snd_strerror(status));
-        }
+    status = ALSA_set_buffer_size(this, hwparams);
+    if (status < 0) {
+        return SDL_SetError("Couldn't set hardware audio parameters: %s", ALSA_snd_strerror(status));
     }
+
     /* Set the software parameters */
     snd_pcm_sw_params_alloca(&swparams);
     status = ALSA_snd_pcm_sw_params_current(pcm_handle, swparams);
@@ -737,9 +695,11 @@ ALSA_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
         SDL_memset(this->hidden->mixbuf, this->spec.silence, this->hidden->mixlen);
     }
 
+    #if !SDL_ALSA_NON_BLOCKING
     if (!iscapture) {
         ALSA_snd_pcm_nonblock(pcm_handle, 0);
     }
+    #endif
 
     /* We're ready to rock and roll. :-) */
     return 0;