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