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#include "global.h"
// The latest generated random number, used to generate the next number in the sequence.
static u32 sRandInt = 1;
// Space to store a value to be re-interpreted as a float.
static u32 sRandFloat;
/**
* Gets the next integer in the sequence of pseudo-random numbers.
*/
u32 Rand_Next(void) {
return sRandInt = (sRandInt * 1664525) + 1013904223;
}
/**
* Seeds the pseudo-random number generator by providing a starting value.
*/
void Rand_Seed(u32 seed) {
sRandInt = seed;
}
/**
* Returns a pseudo-random floating-point number between 0.0f and 1.0f, by generating
* the next integer and masking it to an IEEE-754 compliant floating-point number
* between 1.0f and 2.0f, returning the result subtract 1.0f.
*/
f32 Rand_ZeroOne(void) {
sRandInt = (sRandInt * 1664525) + 1013904223;
sRandFloat = ((sRandInt >> 9) | 0x3F800000);
return *((f32*)&sRandFloat) - 1.0f;
}
/**
* Returns a pseudo-random floating-point number between -0.5f and 0.5f by the same
* manner in which Rand_ZeroOne generates its result.
*/
f32 Rand_Centered(void) {
sRandInt = (sRandInt * 1664525) + 1013904223;
sRandFloat = ((sRandInt >> 9) | 0x3F800000);
return *((f32*)&sRandFloat) - 1.5f;
}
/**
* Seeds a pseudo-random number at rndNum with a provided seed.
*/
void Rand_Seed_Variable(u32* rndNum, u32 seed) {
*rndNum = seed;
}
/**
* Generates the next pseudo-random integer from the provided rndNum.
*/
u32 Rand_Next_Variable(u32* rndNum) {
return *rndNum = (*rndNum * 1664525) + 1013904223;
}
/**
* Generates the next pseudo-random floating-point number between 0.0f and
* 1.0f from the provided rndNum.
*/
f32 Rand_ZeroOne_Variable(u32* rndNum) {
u32 next = (*rndNum * 1664525) + 1013904223;
// clang-format off
*rndNum = next; sRandFloat = (next >> 9) | 0x3F800000;
// clang-format on
return *((f32*)&sRandFloat) - 1.0f;
}
/**
* Generates the next pseudo-random floating-point number between -0.5f and
* 0.5f from the provided rndNum.
*/
f32 Rand_Centered_Variable(u32* rndNum) {
u32 next = (*rndNum * 1664525) + 1013904223;
// clang-format off
*rndNum = next; sRandFloat = (next >> 9) | 0x3F800000;
// clang-format on
return *((f32*)&sRandFloat) - 1.5f;
}
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