Difference between revisions of "Random Numbers"

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m (I supposed we should specify our constants...)
m (Reverted edit of Zc321, changed back to last version by Cyan~Fire)
 
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Latest revision as of 03:53, 30 November 2005

SubSpace uses random numbers primarily in its encryption, generating prizes, and controlling doors.

The following code is used in generating the encrypted keystream, prizes, and doors:

#define MULT_C	0x834E0B5F
#define DIV_C	0x1F31D

DWORD SS_RNG(DWORD seed)
{
	DWORD nseed, temp;

	temp = (MULT_C * (unsigned __int64)seed) >> 32;
	temp = (temp >> 16) + (temp >> 31);	//aka the sign bit

	nseed = (seed % DIV_C) * 16807;
	nseed -= (temp * 2836);
	nseed += 123;

	if (!nseed || nseed > 0x7FFFFFFF)
		nseed += 0x7FFFFFFF;

	return nseed;
}