Add C-project for simulating axis in commandline

before adding the travelMm function the algorithm for moving the
axis between left and right was designed and evaluated via commandline
first.

-> Add this test-code in this commit

testing/cnc-guide/main.c

@@ -0,0 +1,104 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <math.h>
+
+#define MAX 100
+#define MIN 10
+#define TRAVEL MAX-MIN
+
+
+
+//==== VARIABLES ====
+bool direction = true;
+uint16_t posNow = 10;
+
+
+
+//==== FUNCTIONS ====
+
+//print position
+//print line that illustrates the position pos between 0 and MAX 
+//e.g. "|----<=>--------|"
+void printPos(int pos){
+    int width = 50;
+    printf("(%d)|", pos);
+    for (int i = 0; i<(pos) * width/MAX; i++) printf("-");
+    printf("<=>");
+    for (int i = 0; i<(MAX-pos) * width/MAX; i++) printf("-");
+    printf("|\n");
+    return;
+}
+
+
+//move "virtual axis" to absolute coordinate in mm
+void moveToAbs(int d){
+    int posOld = posNow;
+    printf ("moving from %d %s to %d (%s)\n", posNow, direction ? "=>" : "<=", d, direction ? "RIGHT" : "LEFT");
+    posNow = d;
+    //illustrate movement (print position for each coordinate change)
+    for (int i=posOld; i!=posNow; i+=posNow>posOld?1:-1) printPos(i);
+    return;
+}
+
+
+//travel back and forth between MIN and MAX coordinate for a certain distance 
+//negative values are processed reversed
+void travel(int length){
+    int d, remaining;
+    d = abs(length);
+    if(length < 0) direction = !direction; //invert direction in reverse mode
+
+    while (d != 0){
+        //--- currently moving right ---
+        if (direction == true){         //currently moving right
+            remaining = MAX - posNow;   //calc remaining distance fom current position to limit
+            if (d > remaining){         //new distance will exceed limit
+                moveToAbs (MAX);        //move to limit
+                direction = false;      //change current direction for next iteration
+                d = d - remaining;      //decrease target length by already traveled distance
+                printf(" --- changed direction (L) --- \n ");
+            }
+            else {                      //target distance does not reach the limit
+                moveToAbs (posNow + d); //move by (remaining) distance to reach target length
+                d = 0;                  //finished, reset target length (could as well exit loop/break)
+            }
+        }
+
+        //--- currently moving left ---
+        else {
+            remaining = posNow - MIN;
+            if (d > remaining){
+                moveToAbs (MIN);
+                direction = true;
+                d = d - remaining;
+                printf(" --- changed direction (R) --- \n ");
+            }
+            else {
+                moveToAbs (posNow - d); //when moving left the coordinate has to be decreased
+                d = 0;
+            }
+        }
+    }
+
+    if(length < 0) direction = !direction; //undo inversion of direction after reverse mode is finished
+    return;
+}
+
+
+
+//==== MAIN ====
+int main (void)
+{
+    int input;
+    printf("**cable-length-cutter testing cnc-guide**\n");
+    while(1){
+        printf("enter mm to travel:");
+        scanf("%d", &input);
+        travel(input);
+        printf("\n");
+    }
+    return 0;
+}
+

testing/cnc-guide/makefile

@@ -0,0 +1,7 @@
+default: program
+
+program:
+	gcc main.c -o a.out -lm
+
+clean:
+	-rm -f a.out