32bit support

[seerickcode]

Trying to use this in a Raspberry PI 3 with a stock raspbian 32bit kernel/os.

consts::PCM_BUFFER_SIZE is set as a u64

This is causing issues with calls to quad_alsa_sys::snd_pcm_hw_params_set_buffer_size because it's also platform dependent, and will be built to expect an u32 or u64.

error[E0308]: mismatched types
  --> src/alsa_snd.rs:43:70
   |
43 |     if sys::snd_pcm_hw_params_set_buffer_size(pcm_handle, hw_params, consts::PCM_BUFFER_SIZE) < 0 {
   |                                                                      ^^^^^^^^^^^^^^^^^^^^^^^ expected `u32`, found `u64`
   |
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
   |
43 |     if sys::snd_pcm_hw_params_set_buffer_size(pcm_handle, hw_params, consts::PCM_BUFFER_SIZE.try_into().unwrap()) < 0 {
   |                                                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Also since quad_alsa_sys::snd_pcm_writei will return the frames written as a u32, this line fails:

error[E0308]: mismatched types
   --> src/alsa_snd.rs:128:29
    |
128 |         if frames_writen == -libc::EPIPE as i64 {
    |                             ^^^^^^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert `frames_writen` from `i32` to `i64`, matching the type of `-libc::EPIPE as i64`
    |
128 |         if i64::from(frames_writen) == -libc::EPIPE as i64 {
    |            ^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to previous error

This later I can certainly do the i64 up convert as suggested, but for the first issue, with the snd_pcm_hw_params_set_buffer_size what is the best way to handle this?

I am still pretty new to rust. I make it a usize, but quad_alsa_sys is making this a u32 or u64 at compile time probably from the underlying C library. Is this something to be fixed in that library (quad_alsa_sys) to change the function to use usize?

If I force the const to u32 of course everything works fine, but that's now hard coding it to only work on 32bit systems.

[seerickcode]

I think I figured it out digging into quad_alsa_sys..

diff --git a/src/alsa_snd.rs b/src/alsa_snd.rs
index 61c5c9f..9807ea6 100644
--- a/src/alsa_snd.rs
+++ b/src/alsa_snd.rs
@@ -10,7 +10,7 @@ mod consts {
     pub const DEVICE: &'static str = "default\0";
     pub const RATE: u32 = 44100;
     pub const CHANNELS: u32 = 2;
-    pub const PCM_BUFFER_SIZE: u64 = 4096;
+    pub const PCM_BUFFER_SIZE: ::std::os::raw::c_ulong = 4096;
 }
 
 unsafe fn setup_pcm_device() -> *mut sys::snd_pcm_t {
@@ -125,7 +125,7 @@ unsafe fn audio_thread(mut mixer: crate::mixer::Mixer) {
             buffer.as_ptr() as *const _,
             frames_to_deliver as _,
         );
-        if frames_writen == -libc::EPIPE as i64 {
+        if frames_writen == -libc::EPIPE as ::std::os::raw::c_long {
             println!("Underrun occured: -EPIPE, attempting recover");
 
             sys::snd_pcm_recover(pcm_handle, frames_writen as _, 0);

And now everything is happy

[not-fl3]

Solved with #29