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#include "libc64/qrand.h"
/**
* The latest generated random number, used to generate the next number in the sequence.
*
* Original name: __qrand_idum
*/
u32 sRandInt = 1;
/**
* Space to store a value to be re-interpreted as a float.
*
* Orignal name: __qrand_itemp
*/
fu gRandFloat;
/**
* Generates the next pseudo-random integer.
*
* Original name: qrand
*/
u32 Rand_Next(void) {
sRandInt = (sRandInt * RAND_MULTIPLIER) + RAND_INCREMENT;
return sRandInt;
}
/**
* Seeds the internal pseudo-random number generator with a provided starting value.
*
* Original name: sqrand
*/
void Rand_Seed(u32 seed) {
sRandInt = seed;
}
/**
* Returns a pseudo-random float between 0.0f and 1.0f from the internal PRNG.
*
* @note Works by generating the next integer, masking it to an IEEE-754 compliant float between 1.0f and 2.0f, and
* subtracting 1.0f.
*
* @remark This is also recommended by Numerical Recipes, pp. 284-5.
*
* Original name: fqrand
*/
f32 Rand_ZeroOne(void) {
sRandInt = (sRandInt * RAND_MULTIPLIER) + RAND_INCREMENT;
gRandFloat.i = ((sRandInt >> 9) | 0x3F800000);
return gRandFloat.f - 1.0f;
}
/**
* Returns a pseudo-random float between -0.5f and 0.5f in the same way as Rand_ZeroOne().
*
* Original name: fqrand2
*/
f32 Rand_Centered(void) {
sRandInt = (sRandInt * RAND_MULTIPLIER) + RAND_INCREMENT;
gRandFloat.i = ((sRandInt >> 9) | 0x3F800000);
return gRandFloat.f - 1.5f;
}
//! All functions below are unused variants of the above four, that use a provided random number variable instead of the
//! internal `sRandInt`
/**
* Seeds a provided pseudo-random number with a provided starting value.
*
* @see Rand_Seed
*
* Original name: sqrand_r
*/
void Rand_Seed_Variable(u32* rndNum, u32 seed) {
*rndNum = seed;
}
/**
* Generates the next pseudo-random number from the provided rndNum.
*
* @see Rand_Next
*
* Original name: qrand_r
*/
u32 Rand_Next_Variable(u32* rndNum) {
u32 t = (*rndNum * RAND_MULTIPLIER) + RAND_INCREMENT;
*rndNum = t;
return t;
}
/**
* Generates the next pseudo-random float between 0.0f and 1.0f from the provided rndNum.
*
* @see Rand_ZeroOne
*
* Original name: fqrand_r
*/
f32 Rand_ZeroOne_Variable(u32* rndNum) {
u32 next = (*rndNum * RAND_MULTIPLIER) + RAND_INCREMENT;
gRandFloat.i = ((*rndNum = next) >> 9) | 0x3F800000;
return gRandFloat.f - 1.0f;
}
/**
* Generates the next pseudo-random float between -0.5f and 0.5f from the provided rndNum.
*
* @see Rand_ZeroOne, Rand_Centered
*
* Original name: fqrand2_r
*/
f32 Rand_Centered_Variable(u32* rndNum) {
u32 next = (*rndNum * RAND_MULTIPLIER) + RAND_INCREMENT;
gRandFloat.i = ((*rndNum = next) >> 9) | 0x3F800000;
return gRandFloat.f - 1.5f;
}
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