Add "nonblock" option for hw layer

Added a new "nonblock" option for hw layer.  This controls the non-blocking
"open" mode as default.

This option is set to TRUE as the default configuration.  If the old behavior
is preferred, set "defaults.pcm.nonblock" to 0 in /etc/asound.conf.

diff --git a/src/conf/alsa.conf b/src/conf/alsa.conf
index 8bb968a..e11ca0b 100644 (file)
--- a/src/conf/alsa.conf
+++ b/src/conf/alsa.conf
@@ -53,6 +53,7 @@ defaults.ctl.card 0
 defaults.pcm.card 0
 defaults.pcm.device 0
 defaults.pcm.subdevice -1
+defaults.pcm.nonblock 1
 defaults.pcm.front.card defaults.pcm.card
 defaults.pcm.front.device defaults.pcm.device
 defaults.pcm.rear.card defaults.pcm.card
@@ -126,10 +127,21 @@ pcm.hw {
                        name defaults.pcm.subdevice
                }
        }               
+       @args.SUBDEV {
+               type integer
+               default {
+                       @func refer
+                       name defaults.pcm.subdevice
+               }
+       }               
        type hw
        card $CARD
        device $DEV
        subdevice $SUBDEV
+       nonblock {
+               @func refer
+               name defaults.pcm.nonblock
+       }
 }
 
 pcm.plughw {

diff --git a/src/pcm/pcm_hw.c b/src/pcm/pcm_hw.c
index 6642688..9cd2e65 100644 (file)
--- a/src/pcm/pcm_hw.c
+++ b/src/pcm/pcm_hw.c
@@ -1231,7 +1231,6 @@ int snd_pcm_hw_open(snd_pcm_t **pcmp, const char *name,
        }
        snd_ctl_close(ctl);
        return snd_pcm_hw_open_fd(pcmp, name, fd, mmap_emulation, sync_ptr_ioctl);
-       
        _err:
        snd_ctl_close(ctl);
        return ret;
@@ -1245,6 +1244,12 @@ This plugin communicates directly with the ALSA kernel driver. It is a raw
 communication without any conversions. The emulation of mmap access can be
 optionally enabled, but expect worse latency in the case.
 
+The nonblock option specifies whether the device is opened in a non-blocking
+manner.  Note that the blocking behavior for read/write access won't be
+changed by this option.  This influences only on the blocking behavior at
+opening the device.  If you would like to keep the compatibility with the
+older ALSA stuff, turn this option off.
+
 \code
 pcm.name {
        type hw                 # Kernel PCM
@@ -1253,6 +1258,7 @@ pcm.name {
        [subdevice INT]         # Subdevice number (default -1: first available)
        [mmap_emulation BOOL]   # Enable mmap emulation for ro/wo devices
        [sync_ptr_ioctl BOOL]   # Use SYNC_PTR ioctl rather than the direct mmap access for control structures
+       [nonblock BOOL]         # Force non-blocking open mode
 }
 \endcode
 
@@ -1285,6 +1291,8 @@ int _snd_pcm_hw_open(snd_pcm_t **pcmp, const char *name,
        long card = -1, device = 0, subdevice = -1;
        const char *str;
        int err, mmap_emulation = 0, sync_ptr_ioctl = 0;
+       int nonblock = 1; /* non-block per default */
+
        snd_config_for_each(i, next, conf) {
                snd_config_t *n = snd_config_iterator_entry(i);
                const char *id;
@@ -1338,6 +1346,13 @@ int _snd_pcm_hw_open(snd_pcm_t **pcmp, const char *name,
                        sync_ptr_ioctl = err;
                        continue;
                }
+               if (strcmp(id, "nonblock") == 0) {
+                       err = snd_config_get_bool(n);
+                       if (err < 0)
+                               continue;
+                       nonblock = err;
+                       continue;
+               }
                SNDERR("Unknown field %s", id);
                return -EINVAL;
        }
@@ -1345,8 +1360,17 @@ int _snd_pcm_hw_open(snd_pcm_t **pcmp, const char *name,
                SNDERR("card is not defined");
                return -EINVAL;
        }
-       return snd_pcm_hw_open(pcmp, name, card, device, subdevice, stream, mode, mmap_emulation, sync_ptr_ioctl);
+       err = snd_pcm_hw_open(pcmp, name, card, device, subdevice, stream,
+                             mode | (nonblock ? SND_PCM_NONBLOCK : 0),
+                             mmap_emulation, sync_ptr_ioctl);
+       if (err < 0)
+               return err;
+       if (nonblock && ! (mode & SND_PCM_NONBLOCK))
+               /* revert to blocking mode for read/write access */
+               snd_pcm_hw_nonblock(*pcmp, 0);
+       return 0;
 }
+
 #ifndef DOC_HIDDEN
 SND_DLSYM_BUILD_VERSION(_snd_pcm_hw_open, SND_PCM_DLSYM_VERSION);
 #endif