-/* Return the difference from ts0 to ts1 as floating-point seconds. */
-#define TIMESPEC_DIFF(ts0, ts1) (double) (ts1.tv_sec - ts0.tv_sec + \
- (ts1.tv_nsec - ts0.tv_nsec) / 1e9)
+/* Subtract timespec values: Return (a - b) in seconds as a double. */
+#define SUBTRACT_TIMESPEC(a, b) (double) (a.tv_sec - b.tv_sec + \
+ (a.tv_nsec - b.tv_nsec) / 1e9)