Refactor rnd/rndscale/dtrnd to be proper functions

Before this they were macros. Macros are evil.

Author: koraa

inexor/shared/tools.cpp

@@ -5,6 +5,9 @@
 #include <unistd.h>
 #endif
 
+#include <cstdlib>
+#include <limits>
+
 ////////////////////////// strings ////////////////////////////////////////
 
 static string tmpstr[4];
@@ -57,6 +60,20 @@ uint randomMT()
     return y;
 }
 
+int rnd(const int x) {
+    return abs((int)randomMT()) % x;
+}
+
+float rndscale(const double x) {
+    double int_max = std::numeric_limits<int>::max();
+    return abs((int)randomMT()) * x / int_max;
+}
+
+int detrnd(const uint seed, const int x) {
+    return ( (seed*1103515245 + 12345) >>16) %x;
+}
+
+
 ///////////////////////// network ///////////////////////
 
 // all network traffic is in 32bit ints, which are then compressed using the following simple scheme (assumes that most values are small).

inexor/shared/tools.h

@@ -67,12 +67,22 @@ static inline int bitscan(uint mask)
 #endif
 #endif
 
-extern void seedMT(uint seed);
-extern uint randomMT();
-#define rnd(x) ((int)(randomMT()&0x7FFFFFFF)%(x))
-#define rndscale(x) (float((randomMT()&0x7FFFFFFF)*double(x)/double(0x7FFFFFFF)))
-#define detrnd(s, x) ((int)(((((uint)(s))*1103515245+12345)>>16)%(x)))
-
+/// Generate a random integer between 0 and x, excluding x
+///
+/// ```rnd(2) // can producd 0 and 1```
+extern int rnd(const int x);
+
+/// Generate a random float between 0 and x
+///
+/// ```rndscale(1) // min: 0, max: 0.99...```
+extern float rndscale(const double x);
+
+/// Generate a deterministic pseudo-random number
+///
+/// This means, that given the same seed and the same
+/// maximum value (`x`) this function will always return the
+/// same.
+extern int detrnd(const uint seed, const int x);
 
 /// "for"-loop macro definitions
 /// DEPRECATED: Use c++ range based loops instead