blob: 152c8a0e7b19f16cb0fac0d4ff0f97e246a0f77b (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
#include "rand.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.
//! This can't be static because it is used in z_kankyo.
u32 gRandFloat;
/**
* Generates the next pseudo-random integer.
*/
u32 Rand_Next(void) {
return sRandInt = (sRandInt * RAND_MULTIPLIER) + RAND_INCREMENT;
}
/**
* Seeds the internal pseudo-random number generator with a provided starting value.
*/
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.
*/
f32 Rand_ZeroOne(void) {
sRandInt = (sRandInt * RAND_MULTIPLIER) + RAND_INCREMENT;
gRandFloat = ((sRandInt >> 9) | 0x3F800000);
return *((f32*)&gRandFloat) - 1.0f;
}
/**
* Returns a pseudo-random float between -0.5f and 0.5f in the same way as Rand_ZeroOne().
*/
f32 Rand_Centered(void) {
sRandInt = (sRandInt * RAND_MULTIPLIER) + RAND_INCREMENT;
gRandFloat = ((sRandInt >> 9) | 0x3F800000);
return *((f32*)&gRandFloat) - 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
*/
void Rand_Seed_Variable(u32* rndNum, u32 seed) {
*rndNum = seed;
}
/**
* Generates the next pseudo-random number from the provided rndNum.
*
* @see Rand_Next
*/
u32 Rand_Next_Variable(u32* rndNum) {
return *rndNum = (*rndNum * RAND_MULTIPLIER) + RAND_INCREMENT;
}
/**
* Generates the next pseudo-random float between 0.0f and 1.0f from the provided rndNum.
*
* @see Rand_ZeroOne
*/
f32 Rand_ZeroOne_Variable(u32* rndNum) {
u32 next = (*rndNum * RAND_MULTIPLIER) + RAND_INCREMENT;
gRandFloat = ((*rndNum = next) >> 9) | 0x3F800000;
return *((f32*)&gRandFloat) - 1.0f;
}
/**
* Generates the next pseudo-random float between -0.5f and 0.5f from the provided rndNum.
*
* @see Rand_ZeroOne, Rand_Centered
*/
f32 Rand_Centered_Variable(u32* rndNum) {
u32 next = (*rndNum * RAND_MULTIPLIER) + RAND_INCREMENT;
gRandFloat = ((*rndNum = next) >> 9) | 0x3F800000;
return *((f32*)&gRandFloat) - 1.5f;
}
|
