Add audio, fix timing

src/shrooms_vb_core.rs

@@ -1,6 +1,7 @@
-use std::{ffi::c_void, ptr};
+use std::{ffi::c_void, ptr, slice};
 
 use anyhow::{anyhow, Result};
+use num_derive::{FromPrimitive, ToPrimitive};
 
 #[repr(C)]
 struct VB {
@@ -9,6 +10,20 @@ struct VB {
 
 #[allow(non_camel_case_types)]
 type c_int = i32;
+#[allow(non_camel_case_types)]
+type c_uint = u32;
+
+#[repr(u32)]
+#[derive(FromPrimitive, ToPrimitive)]
+enum VBDataType {
+    S8 = 0,
+    U8 = 1,
+    S16 = 2,
+    U16 = 3,
+    S32 = 4,
+    F32 = 5,
+}
+
 type OnFrame = extern "C" fn(sim: *mut VB) -> c_int;
 
 #[link(name = "vb")]
@@ -27,6 +42,13 @@ extern "C" {
         right_stride_x: c_int,
         right_stride_y: c_int,
     );
+    #[link_name = "vbGetSamples"]
+    fn vb_get_samples(
+        sim: *mut VB,
+        typ_: *mut VBDataType,
+        capacity: *mut c_uint,
+        position: *mut c_uint,
+    ) -> *mut c_void;
     #[link_name = "vbGetUserData"]
     fn vb_get_user_data(sim: *mut VB) -> *mut c_void;
     #[link_name = "vbInit"]
@@ -39,6 +61,13 @@ extern "C" {
     fn vb_set_keys(sim: *mut VB, keys: u16) -> u16;
     #[link_name = "vbSetFrameCallback"]
     fn vb_set_frame_callback(sim: *mut VB, on_frame: OnFrame);
+    #[link_name = "vbSetSamples"]
+    fn vb_set_samples(
+        sim: *mut VB,
+        samples: *mut c_void,
+        typ_: VBDataType,
+        capacity: c_uint,
+    ) -> c_int;
     #[link_name = "vbSetUserData"]
     fn vb_set_user_data(sim: *mut VB, tag: *mut c_void);
     #[link_name = "vbSizeOf"]
@@ -53,6 +82,9 @@ extern "C" fn on_frame(sim: *mut VB) -> i32 {
     1
 }
 
+const AUDIO_CAPACITY_SAMPLES: usize = 834 * 4;
+const AUDIO_CAPACITY_FLOATS: usize = AUDIO_CAPACITY_SAMPLES * 2;
+
 struct VBState {
     frame_seen: bool,
 }
@@ -79,6 +111,11 @@ impl CoreVB {
         unsafe { vb_set_user_data(sim, Box::into_raw(Box::new(state)).cast()) };
         unsafe { vb_set_frame_callback(sim, on_frame) };
 
+        // set up audio buffer
+        let audio_buffer = vec![0.0f32; AUDIO_CAPACITY_FLOATS];
+        let samples: *mut c_void = Box::into_raw(audio_buffer.into_boxed_slice()).cast();
+        unsafe { vb_set_samples(sim, samples, VBDataType::F32, AUDIO_CAPACITY_SAMPLES as u32) };
+
         CoreVB { sim }
     }
 
@@ -138,6 +175,25 @@ impl CoreVB {
         true
     }
 
+    pub fn read_samples(&mut self, samples: &mut Vec<f32>) {
+        let mut position = 0;
+        let ptr =
+            unsafe { vb_get_samples(self.sim, ptr::null_mut(), ptr::null_mut(), &mut position) };
+        // SAFETY: position is an offset in a buffer of (f32, f32). so, position * 2 is an offset in a buffer of f32.
+        let read_samples: &mut [f32] =
+            unsafe { slice::from_raw_parts_mut(ptr.cast(), position as usize * 2) };
+        samples.extend_from_slice(read_samples);
+
+        unsafe {
+            vb_set_samples(
+                self.sim,
+                ptr,
+                VBDataType::F32,
+                AUDIO_CAPACITY_SAMPLES as u32,
+            )
+        };
+    }
+
     pub fn set_keys(&mut self, keys: u16) {
         unsafe { vb_set_keys(self.sim, keys) };
     }
@@ -145,6 +201,14 @@ impl CoreVB {
 
 impl Drop for CoreVB {
     fn drop(&mut self) {
+        let ptr =
+            unsafe { vb_get_samples(self.sim, ptr::null_mut(), ptr::null_mut(), ptr::null_mut()) };
+        // SAFETY: the audio buffer originally came from a Vec<u32>
+        let floats: Vec<f32> = unsafe {
+            Vec::from_raw_parts(ptr.cast(), AUDIO_CAPACITY_FLOATS, AUDIO_CAPACITY_FLOATS)
+        };
+        drop(floats);
+
         // SAFETY: the *mut VB owns its userdata.
         // There is no way for the userdata to be null or otherwise invalid.
         let ptr: *mut VBState = unsafe { vb_get_user_data(self.sim).cast() };