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author | metagn <metagngn@gmail.com> | 2022-12-06 11:37:03 +0300 |
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committer | GitHub <noreply@github.com> | 2022-12-06 09:37:03 +0100 |
commit | 739e1badb6e48741e28420739769d3714ac6ceda (patch) | |
tree | 745718d54a61118535ae657ec884dc5bee6d83a6 /lib/deprecated/pure/mersenne.nim | |
parent | 5d469686b05ba0435690fccf6fb6f7d95cf09c73 (diff) | |
download | Nim-739e1badb6e48741e28420739769d3714ac6ceda.tar.gz |
stdlib organization & documentation improvements (#20971)
* stdlib organization & documentation improvements * fix CI * Update doc/lib.md Co-authored-by: Juan Carlos <juancarlospaco@gmail.com> * fix ci, remove jshttpcore, export in jsfetch instead * fix alphabetical order violations * add cmdline, db_odbc Co-authored-by: Juan Carlos <juancarlospaco@gmail.com>
Diffstat (limited to 'lib/deprecated/pure/mersenne.nim')
-rw-r--r-- | lib/deprecated/pure/mersenne.nim | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/lib/deprecated/pure/mersenne.nim b/lib/deprecated/pure/mersenne.nim new file mode 100644 index 000000000..37c5085b1 --- /dev/null +++ b/lib/deprecated/pure/mersenne.nim @@ -0,0 +1,51 @@ +# +# +# Nim's Runtime Library +# (c) Copyright 2015 Nim Contributors +# See the file "copying.txt", included in this +# 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. + +{.deprecated: "use `std/random` instead".} + +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: + result.mt[i] = (0x6c078965'u32 * (result.mt[i-1] xor + (result.mt[i-1] shr 30'u32)) + i) + +proc generateNumbers(m: var MersenneTwister) = + + for i in 0..623: + var y = (m.mt[i] and 0x80000000'u32) + + (m.mt[(i+1) mod 624] and 0x7fffffff'u32) + m.mt[i] = m.mt[(i+397) mod 624] xor uint32(y shr 1'u32) + if (y mod 2'u32) != 0: + m.mt[i] = m.mt[i] xor 0x9908b0df'u32 + +proc getNum*(m: var MersenneTwister): uint32 = + ## Returns the next pseudorandom `uint32`. + if m.index == 0: + generateNumbers(m) + result = m.mt[m.index] + m.index = (m.index + 1) mod m.mt.len + result = result xor (result shr 11'u32) + 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) |