From 988aa992bf5abc42f0d11ba6eec5422078ccb5b7 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_OpticalFlow: 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_OpticalFlow/AP_OpticalFlow_CXOF.cpp | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/libraries/AP_OpticalFlow/AP_OpticalFlow_CXOF.cpp b/libraries/AP_OpticalFlow/AP_OpticalFlow_CXOF.cpp
index ed2a099f46..af3180b95d 100644
--- a/libraries/AP_OpticalFlow/AP_OpticalFlow_CXOF.cpp
+++ b/libraries/AP_OpticalFlow/AP_OpticalFlow_CXOF.cpp
@@ -116,11 +116,10 @@ void AP_OpticalFlow_CXOF::update(void)
     // read any available characters in the serial buffer
     int16_t nbytes = uart->available();
     while (nbytes-- > 0) {
-        int16_t r = uart->read();
-        if (r < 0) {
+        uint8_t c;
+        if (!uart->read(c)) {
             continue;
         }
-        uint8_t c = (uint8_t)r;
         // if buffer is empty and this byte is header, add to buffer
         if (buf_len == 0) {
             if (c == CXOF_HEADER) {