(svn r11940) -Codechange: Store short filename once per open file instead of once per sprite cache entry. Not all file types need this, but most of the time no sprite cache entry needed it either.
/* $Id$ */
/** @file random_func.hpp */
#ifndef RANDOM_FUNC_HPP
#define RANDOM_FUNC_HPP
#if defined(__APPLE__)
/* Apple already has Random declared */
#define Random OTTD_Random
#endif /* __APPLE__ */
/**************
* Warning: DO NOT enable this unless you understand what it does
*
* If enabled, in a network game all randoms will be dumped to the
* stdout if the first client joins (or if you are a client). This
* is to help finding desync problems.
*
* Warning: DO NOT enable this unless you understand what it does
**************/
//#define RANDOM_DEBUG
// Enable this to produce higher quality random numbers.
// Doesn't work with network yet.
// #define MERSENNE_TWISTER
void SetRandomSeed(uint32 seed);
#ifdef RANDOM_DEBUG
#define Random() DoRandom(__LINE__, __FILE__)
uint32 DoRandom(int line, const char *file);
#define RandomRange(max) DoRandomRange(max, __LINE__, __FILE__)
uint DoRandomRange(uint max, int line, const char *file);
#else
uint32 Random();
uint RandomRange(uint max);
#endif
uint32 InteractiveRandom(); // Used for random sequences that are not the same on the other end of the multiplayer link
uint InteractiveRandomRange(uint max);
/**
* Checks if a given randomize-number is below a given probability.
*
* This function is used to check if the given probability by the fraction of (a/b)
* is greater than low 16 bits of the given randomize-number v.
*
* Do not use this function twice on the same random 16 bits as it will yield
* the same result. One can use a random number for two calls to Chance16I,
* where one call sends the low 16 bits and the other the high 16 bits.
*
* @param a The numerator of the fraction
* @param b The denominator of the fraction, must of course not be null
* @param r The given randomize-number
* @return True if v is less or equals (a/b)
*/
static inline bool Chance16I(const uint a, const uint b, const uint32 r)
{
assert(b != 0);
return (uint16)r < (uint16)((a << 16) / b);
}
/**
* Flips a coin with a given probability.
*
* This macro can be used to get true or false randomized according to a
* given probability. The parameter a and b create a percent value with
* (a/b). The macro returns true in (a/b) percent.
*
* @see Chance16I()
* @param a The numerator of the fraction
* @param b The denominator of the fraction
* @return True in (a/b) percent
*/
static inline bool Chance16(const uint a, const uint b)
{
return Chance16I(a, b, Random());
}
/**
* Flips a coin with a given probability and saves the randomize-number in a variable.
*
* This function uses the same parameters as Chance16. The third parameter
* must be a variable the randomize-number from Random() is saved in.
*
* The low 16 bits of r will already be used and can therefor not be passed to
* Chance16I. One can only send the high 16 bits to Chance16I.
*
* @see Chance16I()
* @param a The numerator of the fraction
* @param b The denominator of the fraction
* @param r The variable to save the randomize-number from Random()
* @return True in (a/b) percent
*/
static inline bool Chance16R(const uint a, const uint b, uint32 &r)
{
r = Random();
return Chance16I(a, b, r);
}
extern uint32 _random_seeds[2][2];
#endif /* RANDOM_FUNC_HPP */