// Create a length n array to store the state of the generator
int[0..n-1] MT
int index := n+1
const int lower_mask = (1 << r) - 1 // That is, the binary number of
+r 1's
const int upper_mask = lowest w bits of (not lower_mask)
// Initialize the generator from a seed
function seed_mt(int seed) {
index := n
MT[0] := seed
for i from 1 to (n - 1) { // loop over each element
MT[i] := lowest w bits of (f * (MT[i-1] xor (MT[i-1] >> (w-2)
+)) + i)
}
}
// Extract a tempered value based on MT[index]
// calling twist() every n numbers
function extract_number() {
if index >= n {
if index > n {
error "Generator was never seeded"
// Alternatively, seed with constant value; 5489 is used in
+ reference C code[54]
}
twist()
}
int y := MT[index]
y := y xor ((y >> u) and d)
y := y xor ((y << s) and b)
y := y xor ((y << t) and c)
y := y xor (y >> l)
index := index + 1
return lowest w bits of (y)
}
// Generate the next n values from the series x_i
function twist() {
for i from 0 to (n-1) {
int x := (MT[i] and upper_mask)
| (MT[(i+1) mod n] and lower_mask)
int xA := x >> 1
if (x mod 2) != 0 { // lowest bit of x is 1
xA := xA xor a
}
MT[i] := MT[(i + m) mod n] xor xA
}
index := 0
}
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