From 212dfb23548ed79ba759cbe1d9f1cc189dab9f5a Mon Sep 17 00:00:00 2001
From: "Matthias P. Braendli" <matthias.braendli@mpb.li>
Date: Sun, 8 Jan 2023 16:14:22 +0100
Subject: Rework fl2k buffer size

---
 src/fl2k.rs | 33 ++++++++++++++++++++++++++++-----
 1 file changed, 28 insertions(+), 5 deletions(-)

(limited to 'src/fl2k.rs')

diff --git a/src/fl2k.rs b/src/fl2k.rs
index a17a04d..695d32a 100644
--- a/src/fl2k.rs
+++ b/src/fl2k.rs
@@ -1,5 +1,7 @@
-use std::{ffi::{c_int, c_void}, sync::mpsc};
-use fl2k_ampliphase::{fl2k_dev_t, fl2k_get_device_count, fl2k_open, fl2k_close, fl2k_stop_tx, fl2k_set_sample_rate, fl2k_get_sample_rate, fl2k_start_tx};
+use std::{ffi::{c_int, c_void}, sync::mpsc, mem::swap};
+use fl2k_ampliphase::{fl2k_dev_t, fl2k_get_device_count, fl2k_open, fl2k_close, fl2k_stop_tx, fl2k_set_sample_rate, fl2k_get_sample_rate, fl2k_start_tx, FL2K_BUF_LEN};
+
+const BUF_LEN : usize = FL2K_BUF_LEN as usize;
 
 #[derive(Debug)]
 pub enum FL2KError {
@@ -32,6 +34,9 @@ pub struct FL2K {
     device: *mut fl2k_dev_t,
     callback_ctx: Box<CallbackCtx>,
     tx : mpsc::SyncSender<(Vec<i8>, Vec<i8>)>,
+
+    r_buf : Vec<i8>,
+    g_buf : Vec<i8>
 }
 
 pub struct CallbackCtx {
@@ -88,7 +93,11 @@ impl FL2K {
             abort: false,
         };
         unsafe {
-            let mut fl2k = FL2K { device: std::mem::zeroed(), callback_ctx: Box::new(ctx), tx };
+
+            let r_buf = Vec::with_capacity(2 * BUF_LEN);
+            let g_buf = Vec::with_capacity(2 * BUF_LEN);
+
+            let mut fl2k = FL2K { device: std::mem::zeroed(), callback_ctx: Box::new(ctx), tx, r_buf, g_buf };
             handle_return_value(fl2k_open(&mut fl2k.device, device_index))?;
             Ok(fl2k)
         }
@@ -118,11 +127,25 @@ impl FL2K {
         handle_return_value( unsafe { fl2k_stop_tx(self.device) } )
     }
 
-    pub fn send(&self, r_buf: Vec<i8>, g_buf: Vec<i8>) -> bool {
+    pub fn send(&mut self, mut r_buf: Vec<i8>, mut g_buf: Vec<i8>) -> bool {
         if r_buf.len() != g_buf.len() {
             panic!("r_buf and g_buf must have same length");
         }
-        self.tx.send((r_buf, g_buf)).is_ok()
+
+        self.r_buf.append(&mut r_buf);
+        self.g_buf.append(&mut g_buf);
+
+        if self.r_buf.len() >= BUF_LEN {
+            let mut r = self.r_buf.split_off(BUF_LEN);
+            let mut g = self.g_buf.split_off(BUF_LEN);
+            /* self.r_buf contains head, r contains tail. Swap them, as we want to give the head and keep the tail. */
+            swap(&mut r, &mut self.r_buf);
+            swap(&mut g, &mut self.g_buf);
+            self.tx.send((r, g)).is_ok()
+        }
+        else {
+            true
+        }
     }
 }
 
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