Merge pull request #36 from saxbophone/josh/35-auto-orient

Add a simple auto-orientation feature to the spiral design.

Author: saxbophone

saxbospiral.png

@@ -24,20 +24,19 @@ change_direction(direction_t current, rotation_t turn) {
  */
 spiral_t
 init_spiral(buffer_t buffer) {
-    // number of lines is number of bits of the data
-    size_t line_count = buffer.size * 8;
+    // number of lines is number of bits of the data, + 1 for the first UP line
+    size_t line_count = (buffer.size * 8) + 1;
     // create spiral_t struct
     spiral_t result = {
         .size = line_count,
         .collides = -1,
         // allocate enough memory for a line_t struct for each bit
         .lines = calloc(sizeof(line_t), line_count),
     };
-    /*
-     * first direction is a one-off, pre-prepare the stored direction for this
-     * if first bit is 0, then first direction is UP, else if 1 then it's RIGHT
-     */
-    direction_t current = ((buffer.bytes[0] & 0b10000000) == 0) ? LEFT : DOWN;
+    // First line is always an UP line - this is for orientation purposes
+    direction_t current = UP;
+    result.lines[0].direction = current;
+    result.lines[0].length = 0;
     /*
      * now, iterate over all the bits in the data and convert to directions
      * that make the spiral pattern, storing these directions in the result lines
@@ -48,7 +47,7 @@ init_spiral(buffer_t buffer) {
             // bit level loop
             uint8_t e = 7 - b; // which power of two to use with bit mask
             uint8_t bit = (buffer.bytes[s] & (1 << e)) >> e; // the currently accessed bit
-            size_t index = (s * 8) + b; // line index
+            size_t index = (s * 8) + b + 1; // line index
             rotation_t rotation; // the rotation we're going to make
             // set rotation direction based on the current bit
             rotation = (bit == 0) ? CLOCKWISE : ANTI_CLOCKWISE;

saxbospiral/initialise.c

@@ -38,22 +38,31 @@ test_init_spiral() {
     buffer.bytes = malloc(buffer.size);
     buffer.bytes = (uint8_t[2]){ 0b01101101, 0b11000111, };
     // build expected output struct
-    spiral_t expected = { .size = 16, };
-    expected.lines = calloc(sizeof(line_t), 16);
-    direction_t directions[16] = {
-        UP, LEFT, DOWN, LEFT, DOWN, RIGHT, DOWN, RIGHT,
-        UP, LEFT, UP, RIGHT, DOWN, RIGHT, UP, LEFT,
+    spiral_t expected = { .size = 17, };
+    expected.lines = calloc(sizeof(line_t), 17);
+    direction_t directions[17] = {
+        UP, RIGHT, UP, LEFT, UP, LEFT, DOWN, LEFT,
+        DOWN, RIGHT, UP, RIGHT, DOWN, LEFT, DOWN, RIGHT, UP
     };
-    for(uint8_t i = 0; i < 16; i++) {
+    for(uint8_t i = 0; i < 17; i++) {
         expected.lines[i].direction = directions[i];
     }
 
     // call init_spiral with buffer and store result
     spiral_t output = init_spiral(buffer);
 
+    if(output.size != expected.size) {
+        result = false;
+    }
     // compare with expected struct
-    for(uint8_t i = 0; i < 16; i++) {
+    for(uint8_t i = 0; i < 17; i++) {
         if(output.lines[i].direction != expected.lines[i].direction) {
+            printf(
+                "%u: %i != %i\n",
+                i,
+                output.lines[i].direction,
+                expected.lines[i].direction
+            );
             result = false;
         }
     }