File content as of revision 3:7aaf0072cc22:

/**
Programme   "cnc__machine_driver_3"
Author      Jon Freeman

Accepts subset of 'G Code' CNC machine instructions as input from USB serial
Generates 'Step' and 'Direction' signals for X, Y and Z axes, signals suit
standard stepper / servo drive systems.
Also generates similar Step and Dir for spindle
Intended to connect to 25 pin 'D' connector to emulate old PC 'LPT' port
for easy swap with PC/Mach driven CNC systems.
Tested driving Sieg KX3 CNC mill.

Designed to compile and run on:
    Mbed LPC1768
    Freescale KL25Z
    Freescale KL46Z
*/
using namespace std;

typedef float  fl_typ;  //  
const   signed long
                motor_step_per_rev  =   200,    //  KX3 has 200 step per rev steppers
                micro_steps         =   10,      //  Arc Eurotrade choice 2,4,5,8,10,16,20,25,32,40,50,64,100,125,128
                interrupt_period_us =   25, //32, //24.0, //16 is possible with Mbed LPC1768
                interrupt_freq_Hz   =   1000000 / interrupt_period_us,  //  Serious limit when doing all in software, no real limit with FPGA
                spindle_factor      =   interrupt_period_us * 4280, //  Derived empirically
                spindle_max         =   5000;                       //  Stated in KX3 spec

const   fl_typ  ball_screw_pitch_mm =   4.0,    //  KX3 has 4mm pitch ball screws
                pulses_per_mm       =   micro_steps * motor_step_per_rev / ball_screw_pitch_mm,
                n_for_onemmpermin   =   pulses_per_mm * interrupt_period_us * pow(2.0,31) / 60000000.0; //  n pir to produce 1mm/min travel

const   signed long
                max_pulse_freq_Hz   =   interrupt_freq_Hz * 4 / 13, // / 3.25,  //  strictly 2.0, but allow a good margin
                feed_rate_max       =   60 * max_pulse_freq_Hz / pulses_per_mm;   //  units mm per minute
//The output frequency F<sub>out</sub> = 'Kernel Speed (Hz)' * n / (2 to the power of 32)
    
//#define Fourth_Axis
//#define SPI_Enable
#define I2C_Enable
#define ESTOP   0x100   //  bits used in input reading KX3 limit and EStop switches
#define XLIM    1
#define YLIM    2
#define ZLIM    4
#define UNKN    8

const   fl_typ  TWO_PI = 8.0 * atan(1.0);
const   fl_typ  epsilon = 1e-5;
struct  pirbufgrain {
    fl_typ  x,
            y,
            z,
            distance_code,
            f_rate;
    }   ;

struct  singleGparam    {   //  Place to put all we know about 'x' or 'j' etc parameter from G Code line
    fl_typ          flt;
    unsigned long   ul;
    int         i,  c;
    bool            changed;      // Flagged true when new value for this axis found in Gcode line, false otherwise 
}   ;

struct  Gparams {  //  Where possibly messy G code line gets ordered and sorted into
    struct  singleGparam   x, y, z, i, j, r, a, b, c, d;   //  After sorting, know where to find any X, Y etc values !
}   ;