AP_HAL_Linux: SPIUARTDriver: add some cosmetic changes

Mainly changes to follow the coding style and reduce the complexity a
little bit.

libraries/AP_HAL_Linux/SPIUARTDriver.cpp

@@ -1,18 +1,16 @@
 #include "SPIUARTDriver.h"
 
+#include <assert.h>
 #include <stdlib.h>
 #include <cstdio>
 
 #include <AP_HAL/AP_HAL.h>
 #include <AP_HAL/utility/RingBuffer.h>
 
-extern const AP_HAL::HAL& hal;
+extern const AP_HAL::HAL &hal;
 
-#define SPIUART_DEBUG 0
+#ifdef SPIUART_DEBUG
-
+#include <stdio.h>
-#include <cassert>
-
-#if SPIUART_DEBUG
 #define debug(fmt, args ...)  do {hal.console->printf("[SPIUARTDriver]: %s:%d: " fmt "\n", __FUNCTION__, __LINE__, ## args); } while(0)
 #define error(fmt, args ...)  do {fprintf(stderr,"%s:%d: " fmt "\n", __FUNCTION__, __LINE__, ## args); } while(0)
 #else
@@ -22,49 +20,34 @@ extern const AP_HAL::HAL& hal;
 
 using namespace Linux;
 
-SPIUARTDriver::SPIUARTDriver() :
+SPIUARTDriver::SPIUARTDriver()
-    UARTDriver(false),
+    : UARTDriver(false)
-    _dev(nullptr),
-    _last_update_timestamp(0),
-    _buffer(NULL),
-    _external(false)
 {
-    _readbuf = NULL;
-    _writebuf = NULL;
-}
-
-bool SPIUARTDriver::sem_take_nonblocking()
-{
-    return _dev->get_semaphore()->take_nonblocking();
-}
-
-void SPIUARTDriver::sem_give()
-{
-    _dev->get_semaphore()->give();
 }
 
 void SPIUARTDriver::begin(uint32_t b, uint16_t rxS, uint16_t txS)
 {
     if (device_path != NULL) {
-        UARTDriver::begin(b,rxS,txS);
+        UARTDriver::begin(b, rxS, txS);
-        if ( is_initialized()) {
+        if (is_initialized()) {
             _external = true;
             return;
         }
     }
 
+    if (!is_initialized()) {
+        _dev = hal.spi->get_device("ublox");
+        if (!_dev) {
+            return;
+        }
+    }
+
     if (rxS < 1024) {
         rxS = 2048;
     }
     if (txS < 1024) {
         txS = 2048;
     }
-    if (!is_initialized()) {
-        _dev = hal.spi->get_device("ublox");
-        if (!_dev) {
-            return;
-        }
-    }
 
     /*
      allocate the read buffer
@@ -101,8 +84,6 @@ void SPIUARTDriver::begin(uint32_t b, uint16_t rxS, uint16_t txS)
         }
     }
 
-   _dev = hal.spi->get_device("ublox");
-
     switch (b) {
     case 4000000U:
         if (is_initialized()) {
@@ -133,13 +114,13 @@ int SPIUARTDriver::_write_fd(const uint8_t *buf, uint16_t size)
         return UARTDriver::_write_fd(buf,size);
     }
 
-    if (!sem_take_nonblocking()) {
+    if (!_dev->get_semaphore()->take_nonblocking()) {
         return 0;
     }
 
     _dev->transfer_fullduplex(buf, _buffer, size);
 
-    sem_give();
+    _dev->get_semaphore()->give();
 
     BUF_ADVANCEHEAD(_writebuf, size);
 
@@ -186,9 +167,7 @@ int SPIUARTDriver::_write_fd(const uint8_t *buf, uint16_t size)
         BUF_ADVANCETAIL(_readbuf, n);
     }
 
-
     return ret;
-
 }
 
 static uint8_t ff_stub[300] = {0xff};
@@ -199,23 +178,21 @@ int SPIUARTDriver::_read_fd(uint8_t *buf, uint16_t n)
         return UARTDriver::_read_fd(buf, n);
     }
 
-    if (!sem_take_nonblocking()) {
-        return 0;
-    }
-
     /* Make SPI transactions shorter. It can save SPI bus from keeping too
      * long. It's essential for NavIO as MPU9250 is on the same bus and
      * doesn't like to be waiting. Making transactions more frequent but shorter
      * is a win.
      */
-
     if (n > 100) {
         n = 100;
     }
 
-    _dev->transfer_fullduplex(ff_stub, buf, n);
+    if (!_dev->get_semaphore()->take_nonblocking()) {
+        return 0;
+    }
 
-    sem_give();
+    _dev->transfer_fullduplex(ff_stub, buf, n);
+    _dev->get_semaphore()->give();
 
     BUF_ADVANCETAIL(_readbuf, n);
 
@@ -228,6 +205,7 @@ void SPIUARTDriver::_timer_tick(void)
         UARTDriver::_timer_tick();
         return;
     }
+
     /* lower the update rate */
     if (AP_HAL::micros() - _last_update_timestamp < 10000) {
         return;

libraries/AP_HAL_Linux/SPIUARTDriver.h

@@ -15,14 +15,11 @@ protected:
     int _write_fd(const uint8_t *buf, uint16_t n);
     int _read_fd(uint8_t *buf, uint16_t n);
 
-private:
-    bool sem_take_nonblocking();
-    void sem_give();
-
     AP_HAL::OwnPtr<AP_HAL::SPIDevice> _dev;
 
+    uint8_t *_buffer;
+
     uint32_t _last_update_timestamp;
 
-    uint8_t *_buffer;
     bool _external;
 };