Introduce spaceship comparison for Processes

If currently two unsigned values are compared via `a - b`, in the case b
is actually bigger than a, the result will not be an negative number (as
-1 is expected) but a huge positive number as the subtraction is an
unsigned subtraction.

Avoid over-/underflow affected operations; use comparisons.
Modern compilers will generate sane code, like:
    xor     eax, eax
    cmp     rdi, rsi
    seta    al
    sbb     eax, 0
    ret

1 files changed, 12 insertions, 4 deletions

diff --git a/Macros.h b/Macros.h
index 1064dadb..64aaefa5 100644
--- a/Macros.h
+++ b/Macros.h
@@ -4,19 +4,27 @@
 #include <assert.h> // IWYU pragma: keep
 
 #ifndef MINIMUM
-#define MINIMUM(a, b)         ((a) < (b) ? (a) : (b))
+#define MINIMUM(a, b)             ((a) < (b) ? (a) : (b))
 #endif
 
 #ifndef MAXIMUM
-#define MAXIMUM(a, b)         ((a) > (b) ? (a) : (b))
+#define MAXIMUM(a, b)             ((a) > (b) ? (a) : (b))
 #endif
 
 #ifndef CLAMP
-#define CLAMP(x, low, high)   (assert((low) <= (high)), ((x) > (high)) ? (high) : MAXIMUM(x, low))
+#define CLAMP(x, low, high)       (assert((low) <= (high)), ((x) > (high)) ? (high) : MAXIMUM(x, low))
 #endif
 
 #ifndef ARRAYSIZE
-#define ARRAYSIZE(x)          (sizeof(x) / sizeof((x)[0]))
+#define ARRAYSIZE(x)              (sizeof(x) / sizeof((x)[0]))
+#endif
+
+#ifndef SPACESHIP_NUMBER
+#define SPACESHIP_NUMBER(a, b)    (((a) > (b)) - ((a) < (b)))
+#endif
+
+#ifndef SPACESHIP_NULLSTR
+#define SPACESHIP_NULLSTR(a, b)   strcmp((a) ? (a) : "", (b) ? (b) : "")
 #endif
 
 #ifdef  __GNUC__  // defined by GCC and Clang