Compare all percentage fields with compareRealNumbers()

The SPACESHIP_NUMBER() macro does not work well with floating point
values that are possible to be NaNs. Change the compare logic of all
percentage fields of Process entries to use compareRealNumbers().

Signed-off-by: Kang-Che Sung <explorer09@gmail.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/XUtils.c b/XUtils.c
index 9b7735f6..1af0dd4f 100644
--- a/XUtils.c
+++ b/XUtils.c
@@ -12,6 +12,7 @@ in the source distribution for its full text.
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <math.h>
 #include <stdarg.h>
 #include <stdint.h>
 #include <stdlib.h>
@@ -339,6 +340,16 @@ ssize_t full_write(int fd, const void* buf, size_t count) {
    return written;
 }
 
+/* Compares floating point values for ordering data entries. In this function,
+   NaN is considered "less than" any other floating point value (regardless of
+   sign), and two NaNs are considered "equal" regardless of payload. */
+int compareRealNumbers(double a, double b) {
+   int result = isgreater(a, b) - isgreater(b, a);
+   if (result)
+      return result;
+   return !isNaN(a) - !isNaN(b);
+}
+
 /* Computes the sum of all positive floating point values in an array.
    NaN values in the array are skipped. The returned sum will always be
    nonnegative. */