From 130f2c3bc86d2acb43ea5219ccc7db959b19d1d4 Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Tue, 21 Feb 2023 20:35:57 +1100
Subject: [PATCH] AP_HAL_ChibiOS: add and use a "bool read(c)" method to AP_HAL

this is much less likely to not work vs the int16_t equivalent
---
 libraries/AP_HAL_ChibiOS/UARTDriver.cpp | 17 +++++++++--------
 libraries/AP_HAL_ChibiOS/UARTDriver.h   |  4 ++--
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/libraries/AP_HAL_ChibiOS/UARTDriver.cpp b/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
index 460b395b60..edbc6d6170 100644
--- a/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
+++ b/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
@@ -736,31 +736,32 @@ ssize_t UARTDriver::read(uint8_t *buffer, uint16_t count)
     return ret;
 }
 
-int16_t UARTDriver::read()
+bool UARTDriver::read(uint8_t &b)
 {
     if (_uart_owner_thd != chThdGetSelfX()) {
-        return -1;
+        return false;
     }
 
-    return UARTDriver::read_locked(0);
+    return UARTDriver::read_locked(0, b);
 }
 
-int16_t UARTDriver::read_locked(uint32_t key)
+bool UARTDriver::read_locked(uint32_t key, uint8_t &b)
 {
     if (lock_read_key != 0 && key != lock_read_key) {
-        return -1;
+        return false;
     }
     if (!_rx_initialised) {
-        return -1;
+        return false;
     }
     uint8_t byte;
     if (!_readbuf.read_byte(&byte)) {
-        return -1;
+        return false;
     }
     if (!_rts_is_active) {
         update_rts_line();
     }
-    return byte;
+    b = byte;
+    return true;
 }
 
 /* write one byte to the port */
diff --git a/libraries/AP_HAL_ChibiOS/UARTDriver.h b/libraries/AP_HAL_ChibiOS/UARTDriver.h
index 2d43dc4136..6a8a67d049 100644
--- a/libraries/AP_HAL_ChibiOS/UARTDriver.h
+++ b/libraries/AP_HAL_ChibiOS/UARTDriver.h
@@ -52,9 +52,9 @@ public:
     uint32_t available_locked(uint32_t key) override;
 
     uint32_t txspace() override;
-    int16_t read() override;
+    bool read(uint8_t &data) override WARN_IF_UNUSED;
     ssize_t read(uint8_t *buffer, uint16_t count) override;
-    int16_t read_locked(uint32_t key) override;
+    bool read_locked(uint32_t key, uint8_t &b) override WARN_IF_UNUSED;
     void _rx_timer_tick(void);
     void _tx_timer_tick(void);