diff options
| -rw-r--r-- | lib/pure/mersenne.nim | 32 | ||||
| -rw-r--r-- | tests/stdlib/tmersenne.nim | 11 |
2 files changed, 27 insertions, 16 deletions
diff --git a/lib/pure/mersenne.nim b/lib/pure/mersenne.nim index 812893508..6778e2d62 100644 --- a/lib/pure/mersenne.nim +++ b/lib/pure/mersenne.nim @@ -7,12 +7,27 @@ # distribution, for details about the copyright. # +## The [Mersenne Twister](https://en.wikipedia.org/wiki/Mersenne_Twister) +## random number generator. +## +## **Note:** The procs in this module work at compile-time. + +runnableExamples: + var rand = newMersenneTwister(uint32.high) ## must be "var" + doAssert rand.getNum() != rand.getNum() ## pseudorandom number + +## See also +## ======== +## * `random module<random.html>`_ for Nim's standard random number generator + type MersenneTwister* = object + ## The Mersenne Twister. mt: array[0..623, uint32] index: int proc newMersenneTwister*(seed: uint32): MersenneTwister = + ## Creates a new `MersenneTwister` with seed `seed`. result.index = 0 result.mt[0] = seed for i in 1'u32 .. 623'u32: @@ -28,7 +43,7 @@ proc generateNumbers(m: var MersenneTwister) = m.mt[i] = m.mt[i] xor 0x9908b0df'u32 proc getNum*(m: var MersenneTwister): uint32 = - ## Returns the next pseudo random number ranging from 0 to high(uint32) + ## Returns the next pseudorandom `uint32`. if m.index == 0: generateNumbers(m) result = m.mt[m.index] @@ -38,18 +53,3 @@ proc getNum*(m: var MersenneTwister): uint32 = result = result xor ((result shl 7'u32) and 0x9d2c5680'u32) result = result xor ((result shl 15'u32) and 0xefc60000'u32) result = result xor (result shr 18'u32) - - -runnableExamples: - static: - block: - var rando: MersenneTwister = newMersenneTwister(uint32.high) ## Must be "var". - doAssert rando.getNum() != rando.getNum() ## Pseudo random number. Works at compile-time. - - -# Test -when not defined(testing) and isMainModule: - var mt = newMersenneTwister(2525) - - for i in 0..99: - echo mt.getNum diff --git a/tests/stdlib/tmersenne.nim b/tests/stdlib/tmersenne.nim new file mode 100644 index 000000000..2707aa2f2 --- /dev/null +++ b/tests/stdlib/tmersenne.nim @@ -0,0 +1,11 @@ +import std/mersenne + +template main() = + var mt = newMersenneTwister(2525) + + doAssert mt.getNum == 407788156'u32 + doAssert mt.getNum == 1071751096'u32 + doAssert mt.getNum == 3805347140'u32 + +static: main() +main() |