Add ALSA backend

Closes: #63

Cargo.lock

@@ -2,6 +2,7 @@
 name = "librespot"
 version = "0.1.0"
 dependencies = [
+ "alsa 0.0.1 (git+https://github.com/plietar/rust-alsa)",
  "bit-set 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "clippy 0.0.78 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -46,6 +47,14 @@ dependencies = [
  "memchr 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "alsa"
+version = "0.0.1"
+source = "git+https://github.com/plietar/rust-alsa#8c63543fa0ccd971cf15f5675293d19febd6f79e"
+dependencies = [
+ "libc 0.2.13 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "aster"
 version = "0.20.0"

Cargo.toml

@@ -48,6 +48,7 @@ shannon         = { git = "https://github.com/plietar/rust-shannon" }
 vorbis          = "~0.0.14"
 tremor          = { git = "https://github.com/plietar/rust-tremor", optional = true }
 
+alsa            = { git = "https://github.com/plietar/rust-alsa", optional = true }
 portaudio       = { git = "https://github.com/mvdnes/portaudio-rs", optional = true }
 libpulse-sys    = { git = "https://github.com/astro/libpulse-sys", optional = true }
 
@@ -72,6 +73,7 @@ nightly           = ["serde_macros"]
 
 with-tremor       = ["tremor"]
 facebook          = ["hyper/ssl", "openssl"]
+alsa-backend      = ["alsa"]
 portaudio-backend = ["portaudio"]
 pulseaudio-backend= ["libpulse-sys"]
 default           = ["with-syntex", "portaudio-backend"]

README.md

@@ -66,6 +66,7 @@ target/release/librespot [...] --backend portaudio
 ```
 
 The following backends are currently available :
+- ALSA
 - PortAudio 
 - PulseAudio
 

src/audio_backend/alsa.rs

@@ -0,0 +1,38 @@
+use super::{Open, Sink};
+use std::io;
+use alsa::{PCM, Stream, Mode, Format, Access};
+
+pub struct AlsaSink(Option<PCM>, String);
+
+impl Open for AlsaSink {
+   fn open(device: Option<&str>) -> AlsaSink {
+        println!("Using alsa sink");
+
+        let name = device.unwrap_or("default").to_string();
+
+        AlsaSink(None, name)
+    }
+}
+
+impl Sink for AlsaSink {
+    fn start(&mut self) -> io::Result<()> {
+        if self.0.is_some() {
+        } else {
+            self.0 = Some(PCM::open(&*self.1,
+                                    Stream::Playback, Mode::Blocking,
+                                    Format::Signed16, Access::Interleaved,
+                                    2, 44100).ok().unwrap());
+        }
+        Ok(())
+    }
+
+    fn stop(&mut self) -> io::Result<()> {
+        self.0 = None;
+        Ok(())
+    }
+
+    fn write(&mut self, data: &[i16]) -> io::Result<()> {
+        self.0.as_mut().unwrap().write_interleaved(&data).unwrap();
+        Ok(())
+    }
+}

src/audio_backend/mod.rs

@@ -54,6 +54,11 @@ fn mk_sink<S: Sink + Open + 'static>(device: Option<&str>) -> Box<Sink> {
     Box::new(S::open(device))
 }
 
+#[cfg(feature = "alsa-backend")]
+mod alsa;
+#[cfg(feature = "alsa-backend")]
+use self::alsa::AlsaSink;
+
 #[cfg(feature = "portaudio-backend")]
 mod portaudio;
 #[cfg(feature = "portaudio-backend")]
@@ -70,6 +75,8 @@ declare_backends! {
         (&'static str,
          &'static (Fn(Option<&str>) -> Box<Sink> + Sync + Send + 'static))
     ] = &[
+        #[cfg(feature = "alsa-backend")]
+        ("alsa", &mk_sink::<AlsaSink>),
         #[cfg(feature = "portaudio-backend")]
         ("portaudio", &mk_sink::<PortAudioSink>),
         #[cfg(feature = "pulseaudio-backend")]

src/lib.rs

@@ -42,6 +42,9 @@ extern crate tremor as vorbis;
 #[cfg(feature = "openssl")]
 extern crate openssl;
 
+#[cfg(feature = "alsa-backend")]
+extern crate alsa;
+
 #[cfg(feature = "portaudio")]
 extern crate portaudio;