AP_HAL_FLYMAPLE: UARTDriver libmaple internal ring buffers enlarge on demand

libraries/AP_HAL_FLYMAPLE/FlymaplePortingNotes.txt

@@ -80,11 +80,11 @@ Pins
 30      Telemetry Rx from radio on Serial3 on connector labelled "GPS". 5V tolerant.
 
 Timers
-SysTick	1000Hz normal timers
-1	RCInput
-2	1000Hz Failsafe timer
-3,4	RCOut
-8	not used by AP
+SysTick			1000Hz normal timers
+1 CH1			RCInput
+2 CH1			1000Hz Failsafe timer
+3 CH1-4, 4 CH1-2	RCOut
+8	   		not used by AP
 
 AP I2CDriver on Flymaple uses the libmaple Wire library, configured to clock
 at about 200kHz. The maximum possible Flymaple could support speed is limited

libraries/AP_HAL_FLYMAPLE/UARTDriver.cpp

@@ -19,6 +19,7 @@
 #include <AP_HAL.h>
 
 #if CONFIG_HAL_BOARD == HAL_BOARD_FLYMAPLE
+#include <stdlib.h>
 
 #include "UARTDriver.h"
 #include "FlymapleWirish.h"
@@ -28,7 +29,9 @@
 using namespace AP_HAL_FLYMAPLE_NS;
 
 FLYMAPLEUARTDriver::FLYMAPLEUARTDriver(HardwareSerial* hws):
-    _hws(hws)
+    _hws(hws),
+    _txBuf(NULL),
+    _txBufSize(63) // libmaple usart default driver buffer of 63
  {}
 
 void FLYMAPLEUARTDriver::begin(uint32_t b) 
@@ -38,7 +41,17 @@ void FLYMAPLEUARTDriver::begin(uint32_t b)
 
 void FLYMAPLEUARTDriver::begin(uint32_t b, uint16_t rxS, uint16_t txS) 
 {
-    begin(b);
+    // Our private buffer can only grow, never shrink
+    if (txS > _txBufSize)
+    {
+	if (_txBuf)
+	    free(_txBuf); // CAUTION: old contents lost
+	_txBuf = (uint8_t*)malloc(txS);
+	_txBufSize = txS;
+    }
+    begin(b); // libmaple internal ring buffer reinititalised to defaults here
+    if (_txBuf)
+	rb_init(_hws->c_dev()->rb, _txBufSize, _txBuf); // Get the ring buffer size we want
 }
 
 void FLYMAPLEUARTDriver::end() 

libraries/AP_HAL_FLYMAPLE/UARTDriver.h

@@ -45,6 +45,8 @@ public:
     size_t write(uint8_t c);
 private:
     HardwareSerial*    _hws;
+    uint8_t*           _txBuf; // If need more than libmaple usart driver buffer of 63
+    uint16_t           _txBufSize; // Allocated space in _txBuf
 };
 
 #endif // __AP_HAL_FLYMAPLE_UARTDRIVER_H__