bucketsort: add comments

c_sequential/bucketsort/bucketsort.c

@@ -2,6 +2,8 @@
 #include <string.h>
 #include "bucketsort.h"
 
+// Printable characters in Ascii (from 34 to 127);
+// actually 127 is also not printable
 #define N_BUCKETS 94
 
 typedef struct {
@@ -42,6 +44,7 @@ long int* bucket_sort(char *a, int length, long int size) {
 
 	// copy the keys to "buckets"
 	for (i = 0; i < size; i++) {
+		// 0x21 = 33d, number of unprintable characters in Ascii
 		b = &buckets[*(a + i * length) - 0x21];
 		b->data[b->total++] = i;
 	}