Fix #10; skipping final bit in flip.c

Reading all 31 bits is more efficient, but the scan order from
low-to-high was giving problems in the test suite (since rand() is
not accurate on the LSB portion).  The scan order has thus been
switched from LSB->MSB to MSB->LSB.

Author: fsaad

src/c/flip.c

@@ -11,15 +11,27 @@
 
 #include "flip.h"
 
-static int k = 30;
+static int k = 31;
 static int flip_word = 0;
-static int flip_pos = 0;
+static int flip_pos = 31;
 
 int flip(void){
-    if (flip_pos == 0) {
+    if (flip_pos == k) {
         flip_word = rand();
-        flip_pos = k;
+        flip_pos = 0;
     }
-    --flip_pos;
-    return (flip_word >> flip_pos) & 1;
+    return (flip_word >> flip_pos++) & 1;
 }
+
+// Old implementation scans from lower-to-higher order bits,
+// but rand() has poor quality on lower order bits.
+// int flip(void){
+//     static int k = 31;
+//     static int flip_word = 0;
+//     static int flip_pos = 0;
+//     if (flip_pos == 0) {
+//         flip_word = rand();
+//         flip_pos = k;
+//     }
+//     return (flip_word >> --flip_pos) & 1;
+// }