AP_Winch: fixes from peer review

removed init method
constify now_ms
fixed release_length method comment
fixup sprintf

libraries/AP_Winch/AP_Winch.cpp

@@ -81,22 +81,21 @@ void AP_Winch::init()
     }
 }
 
-// release specified length of cable (in meters) at the specified rate
-// if rate is zero, the RATE_MAX parameter value will be used
+// release specified length of cable (in meters)
 void AP_Winch::release_length(float length)
 {
     if (backend == nullptr) {
         return;
     }
     config.length_desired = backend->get_current_length() + length;
-    config.control_mode = AP_Winch::ControlMode::POSITION;
+    config.control_mode = ControlMode::POSITION;
 }
 
 // deploy line at specified speed in m/s (+ve deploys line, -ve retracts line, 0 stops)
 void AP_Winch::set_desired_rate(float rate)
 {
     config.rate_desired = constrain_float(rate, -get_rate_max(), get_rate_max());
-    config.control_mode = AP_Winch::ControlMode::RATE;
+    config.control_mode = ControlMode::RATE;
 }
 
 // send status to ground station
@@ -117,7 +116,7 @@ bool AP_Winch::pre_arm_check(char *failmsg, uint8_t failmsg_len) const
 
     // fail if unhealthy
     if (!healthy()) {
-        snprintf(failmsg, failmsg_len, "winch unhealthy");
+        hal.util->snprintf(failmsg, failmsg_len, "winch unhealthy");
         return false;
     }
 

libraries/AP_Winch/AP_Winch.h

@@ -47,7 +47,7 @@ public:
     void update();
 
     // relax the winch so it does not attempt to maintain length or rate
-    void relax() { config.control_mode = AP_Winch::ControlMode::RELAXED; }
+    void relax() { config.control_mode = ControlMode::RELAXED; }
 
     // release specified length of cable (in meters)
     void release_length(float length);

libraries/AP_Winch/AP_Winch_Backend.cpp

@@ -2,9 +2,8 @@
 #include <RC_Channel/RC_Channel.h>
 
 // setup rc input and output
-void AP_Winch_Backend::init_input_and_output()
+void AP_Winch_Backend::init()
 {
-
     // set servo output range
     SRV_Channels::set_angle(SRV_Channel::k_winch,  1000);
 
@@ -36,7 +35,7 @@ void AP_Winch_Backend::read_pilot_desired_rate()
         previous_radio_in = rc_input->get_radio_in();
     }
 
-    // check for a significant change in rc input
+    // if significant change in rc input switch to rate mode
     const int16_t radio_in = rc_input->get_radio_in();
     if (config.control_mode != AP_Winch::ControlMode::RATE_FROM_RC) {
         if (abs(radio_in - previous_radio_in) > rc_input->get_dead_zone()) {

libraries/AP_Winch/AP_Winch_Backend.h

@@ -26,7 +26,7 @@ public:
     virtual bool healthy() const = 0;
 
     // initialise the backend
-    virtual void init() = 0;
+    virtual void init();
 
     // update - should be called at at least 10hz
     virtual void update() = 0;
@@ -42,9 +42,6 @@ public:
 
 protected:
 
-    // setup rc input and output
-    void init_input_and_output();
-
     // calculate the pilot desired rate (+ve deploys line, -ve retracts line, 0 stops) from rc input
     // may change the state to RATE and update config.rate_desired
     void read_pilot_desired_rate();

libraries/AP_Winch/AP_Winch_Servo.cpp

@@ -14,12 +14,6 @@ bool AP_Winch_Servo::healthy() const
     return true;
 }
 
-void AP_Winch_Servo::init()
-{
-    // initialise rc input and output
-    init_input_and_output();
-}
-
 void AP_Winch_Servo::update()
 {
     // return immediately if no servo is assigned to control the winch
@@ -37,7 +31,7 @@ void AP_Winch_Servo::update()
 // update pwm outputs to control winch
 void AP_Winch_Servo::control_winch()
 {
-    uint32_t now_ms = AP_HAL::millis();
+    const uint32_t now_ms = AP_HAL::millis();
     float dt = (now_ms - control_update_ms) / 1000.0f;
     if (dt > 1.0f) {
         dt = 0.0f;

libraries/AP_Winch/AP_Winch_Servo.h

@@ -21,15 +21,11 @@
 class AP_Winch_Servo : public AP_Winch_Backend {
 public:
 
-    AP_Winch_Servo(struct AP_Winch::Backend_Config &_config) :
-        AP_Winch_Backend(_config) { }
+    using AP_Winch_Backend::AP_Winch_Backend;
 
     // true if winch is healthy
     bool healthy() const override;
 
-    // initialise the winch
-    void init() override;
-
     // control the winch
     void update() override;