AP_HAL_ChibiOS: only store a single UART frame

ArduPilot · Sep 19, 2023 · 1a8a5f2 · 1a8a5f2
1 parent ca90eb7
commit 1a8a5f2
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Showing 2 changed files with 14 additions and 19 deletions.
diff --git a/libraries/AP_HAL_ChibiOS/UARTDriver.cpp b/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
@@ -489,22 +489,22 @@ void UARTDriver::_begin(uint32_t b, uint16_t rxS, uint16_t txS)
   begin framing. Data from _readbuf is read into _frame_readbuf when an idle ISR is detected.
   _frame_readbuf is sized to be able to accommodate at least frames_in_buffer of size _frame_size
  */
-bool UARTDriver::_begin_framing(uint16_t _frame_size, uint16_t frames_in_buffer)
+bool UARTDriver::_begin_framing(uint16_t _frame_size)
 {
     // disallow framing from a different thread
     if (_uart_owner_thd != chThdGetSelfX()) {
         return false;
     }
 
     _frame_readbuf.clear(); // in case framing was already started
-    _frame_readbuf.set_size((_frame_size + sizeof(uint32_t)) * frames_in_buffer);
+    _frame_readbuf.set_size(_frame_size);
 
     _framing_initialised = true;
 
     return true;
 }
 
-bool UARTDriver::_frames_available()
+bool UARTDriver::_frame_available()
 {
     if (!_framing_initialised) {
         return false;
@@ -520,7 +520,7 @@ bool UARTDriver::_frames_available()
   read bytes (usually the size of the frame) or 0 if no frames are available
   or -1 if an error occurs
  */
-ssize_t UARTDriver::_read_frame(uint8_t *buffer, uint16_t count)
+ssize_t UARTDriver::_read_frame(uint8_t *buffer, uint16_t buf_size)
 {
     if (_uart_owner_thd != chThdGetSelfX()){
         return -1;
@@ -534,18 +534,18 @@ ssize_t UARTDriver::_read_frame(uint8_t *buffer, uint16_t count)
         return -1;
     }
 
-    uint32_t flen;
-    if (_frame_readbuf.read((uint8_t*)&flen, sizeof(uint32_t)) == 0 || flen == 0) {
+    uint32_t flen = _frame_readbuf.available();
+    if (flen == 0) {
         return 0;
     }
 
-    const uint32_t ret = _frame_readbuf.read(buffer, MIN(count, flen));
+    const uint32_t ret = _frame_readbuf.read(buffer, MIN(buf_size, flen));
     if (ret == 0) {
         return 0;
     }
 
-    if (count < flen) {
-        _frame_readbuf.advance(flen - count);
+    if (buf_size < flen) {
+        _frame_readbuf.advance(flen - buf_size);
     }
 
     if (!_rts_is_active) {
@@ -620,15 +620,10 @@ void UARTDriver::transfer_frame()
         return;
     }
 
-    // framing error, restart at the next frame
-    if (fsize > frame_size) {
-        _frame_readbuf.clear();
-        _readbuf.clear();
-        return;
-    }
+    // discard the old frame if necessary
+    _frame_readbuf.clear();
 
     // read the remaining available bytes as a frame
-    _frame_readbuf.write((const uint8_t*)&fsize, sizeof(uint32_t));
     while (fsize > 0) {
         uint32_t avail;
         const uint8_t* buf = _readbuf.readptr(avail);

diff --git a/libraries/AP_HAL_ChibiOS/UARTDriver.h b/libraries/AP_HAL_ChibiOS/UARTDriver.h
@@ -281,9 +281,9 @@ class ChibiOS::UARTDriver : public AP_HAL::UARTDriver {
     bool _discard_input() override;
 
     // frame based operations
-    bool _begin_framing(uint16_t frame_size, uint16_t frames_in_buffer) override;
-    ssize_t _read_frame(uint8_t *buffer, uint16_t count) override;
-    bool _frames_available() override;
+    bool _begin_framing(uint16_t frame_size) override;
+    ssize_t _read_frame(uint8_t *buffer, uint16_t buf_size) override;
+    bool _frame_available() override;
 
 private:
     void transfer_frame();