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v/vlib/rand/seed/seed.v

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// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module seed
import time
// nr_next returns a next value based on the previous value `prev`.
[inline]
fn nr_next(prev u32) u32 {
return prev * 1664525 + 1013904223
}
// time_seed_array returns the required number of u32s generated from system time.
pub fn time_seed_array(count int) []u32 {
ctime := time.sys_mono_now()
mut seed := u32(ctime >> 32 ^ (ctime & 0x0000_0000_FFFF_FFFF))
mut seed_data := []u32{cap: count}
for _ in 0 .. count {
seed = nr_next(seed)
seed_data << nr_next(seed)
}
return seed_data
}
// time_seed_32 returns a 32-bit seed generated from system time.
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[manualfree]
pub fn time_seed_32() u32 {
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sa := time_seed_array(1)
res := sa[0]
unsafe { sa.free() }
return res
}
// time_seed_64 returns a 64-bit seed generated from system time.
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[manualfree]
pub fn time_seed_64() u64 {
seed_data := time_seed_array(2)
lower := u64(seed_data[0])
upper := u64(seed_data[1])
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unsafe { seed_data.free() }
res := lower | (upper << 32)
return res
}