github.com/iDigitalFlame/xmt@v0.5.4/util/rand_fast.go (about)

     1  //go:build !stdrand
     2  // +build !stdrand
     3  
     4  // Copyright (C) 2020 - 2023 iDigitalFlame
     5  //
     6  // This program is free software: you can redistribute it and/or modify
     7  // it under the terms of the GNU General Public License as published by
     8  // the Free Software Foundation, either version 3 of the License, or
     9  // any later version.
    10  //
    11  // This program is distributed in the hope that it will be useful,
    12  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    13  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    14  // GNU General Public License for more details.
    15  //
    16  // You should have received a copy of the GNU General Public License
    17  // along with this program.  If not, see <https://www.gnu.org/licenses/>.
    18  //
    19  
    20  package util
    21  
    22  type random struct{}
    23  
    24  func (r random) Int() int {
    25  	return int(abs64(r.Uint64()))
    26  }
    27  func abs32(v uint32) uint32 {
    28  	return v &^ (1 << 31)
    29  }
    30  func abs64(v uint64) uint64 {
    31  	return v &^ (1 << 63)
    32  }
    33  func (random) Int31() int32 {
    34  	return int32(abs32(FastRand()))
    35  }
    36  func (r random) Int63() int64 {
    37  	return int64(abs64(r.Uint64()))
    38  }
    39  func (random) Uint32() uint32 {
    40  	return FastRand()
    41  }
    42  func (random) Uint64() uint64 {
    43  	return uint64(FastRand())<<32 | uint64(FastRand())
    44  }
    45  func (r random) Intn(n int) int {
    46  	return int(abs64(r.Uint64())) % n
    47  }
    48  func (random) Int31n(n int32) int32 {
    49  	return int32(abs32(FastRand())) & n
    50  }
    51  func (r random) Int63n(n int64) int64 {
    52  	return int64(abs64(r.Uint64())) % n
    53  }
    54  func (random) Read(p []byte) (int, error) {
    55  	for i := range p {
    56  		p[i] = byte(FastRandN(256))
    57  	}
    58  	return len(p), nil
    59  }