/* ---------------------------------------------------------------------  
//  Figure 8.4:  Cruise control.                                         
// ---------------------------------------------------------------------  
*/
#include <stdio.h>
#include "throttle.h"

void main( void )                                                              
{ 
    const float eps = 2.5;  /* Fuzz factor for comparison.          */ 
    const float delta = 5.; /* Change amount for throttle setting.  */   

    float throttle;         /* Current throttle setting.            */    
    float target;           /* Desired speed.                       */  
    float speed;            /* Current speed.                       */    
    float dif;              /* Difference between target and actual speeds. */   

    while (! read_on_switch());     /* Leave loop when driver sets speed.   */
    target = read_speed();          /* Initial speed and throttle settings. */
    throttle = read_throttle();                                   

    while (! read_brake()){         /* Leave loop when driver hits brake.   */
        speed = read_speed();
    
        dif = target - speed;       /* Compare current speed to target      */
        if (dif > eps) {
            throttle += delta;
            if (throttle > 90.0) throttle = 90.0;
        }   
        else if (dif < -eps) {
            throttle -= delta;
            if (throttle < 0.0) throttle = 0.0; 
        }
        else puts( "Speed is OK; do nothing." );
        set_throttle( throttle );
    }   
}