G-Code interpreter

[osresearch]

Should support:

• G0 - Rapid positioning
• G1 - Linear positioning
• M3 - Spindle RPM (clockwise, switch to velocity mode)
• M4 - Spring RPM (anti-clockwise, switch to velocity mode)
• G90 - Set absolute mode
• G91 - Set relative mode
• G92 - Set current position
• M17 - Steppers on
• M18, M0, M112 - Steppers off / e-stop
• M42 - Set I/O pin
• M92 - Set steps/mm
• M114 - Report current position
• M500 - Save eeprom (direction + scale)
• M501 - Restore from eeprom

Reference: https://reprap.org/wiki/G-code

[osresearch]

Currently supported:

static const struct {
        const char * const cmd;
        int (*handler)(const char ** argc, const int count);
        const char * const help;
} gcode_handlers[] = {
        { "G0", gcode_g0, "Move rapid" },
        { "G1", gcode_g0, "Move linear" },
        { "M0", gcode_m0, "Emergency stop" },
        { "M17", gcode_m17, "Motors on" },
        { "M18", gcode_m0, "Motors off" },
        { "M114", gcode_m114, "Report position" },
        { "G92", gcode_g92, "Set position" },
        { "c", gcode_calibrate, "Calibrate encoder" },
        { "?", gcode_help, "Help" },
};