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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,128 @@ | ||
| package fsrs | ||
|
|
||
| import ( | ||
| "math" | ||
| "strconv" | ||
| "time" | ||
| ) | ||
|
|
||
| type state struct { | ||
| C float64 | ||
| S0 float64 | ||
| S1 float64 | ||
| S2 float64 | ||
| } | ||
|
|
||
| type alea struct { | ||
| c float64 | ||
| s0 float64 | ||
| s1 float64 | ||
| s2 float64 | ||
| } | ||
|
|
||
| func NewAlea(seed interface{}) *alea { | ||
| mash := Mash() | ||
| a := &alea{ | ||
| c: 1, | ||
| s0: mash(" "), | ||
| s1: mash(" "), | ||
| s2: mash(" "), | ||
| } | ||
|
|
||
| if seed == nil { | ||
| seed = time.Now().UnixNano() | ||
| } | ||
|
|
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| seedStr := "" | ||
| switch s := seed.(type) { | ||
| case int: | ||
| seedStr = strconv.Itoa(s) | ||
| case string: | ||
| seedStr = s | ||
| } | ||
|
|
||
| a.s0 -= mash(seedStr) | ||
| if a.s0 < 0 { | ||
| a.s0 += 1 | ||
| } | ||
| a.s1 -= mash(seedStr) | ||
| if a.s1 < 0 { | ||
| a.s1 += 1 | ||
| } | ||
| a.s2 -= mash(seedStr) | ||
| if a.s2 < 0 { | ||
| a.s2 += 1 | ||
| } | ||
|
|
||
| return a | ||
| } | ||
|
|
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| func (a *alea) Next() float64 { | ||
| t := 2091639*a.s0 + a.c*2.3283064365386963e-10 // 2^-32 | ||
| a.s0 = a.s1 | ||
| a.s1 = a.s2 | ||
| a.s2 = t - math.Floor(t) | ||
| a.c = math.Floor(t) | ||
| return a.s2 | ||
| } | ||
|
|
||
| func (a *alea) SetState(state state) { | ||
| a.c = state.C | ||
| a.s0 = state.S0 | ||
| a.s1 = state.S1 | ||
| a.s2 = state.S2 | ||
| } | ||
|
|
||
| func (a *alea) GetState() state { | ||
| return state{ | ||
| C: a.c, | ||
| S0: a.s0, | ||
| S1: a.s1, | ||
| S2: a.s2, | ||
| } | ||
| } | ||
|
|
||
| func Mash() func(string) float64 { | ||
| n := uint32(0xefc8249d) | ||
| return func(data string) float64 { | ||
| for i := 0; i < len(data); i++ { | ||
| n += uint32(data[i]) | ||
| h := 0.02519603282416938 * float64(n) | ||
| n = uint32(h) | ||
| h -= float64(n) | ||
| h *= float64(n) | ||
| n = uint32(h) | ||
| h -= float64(n) | ||
| n += uint32(h * 0x100000000) // 2^32 | ||
| } | ||
| return float64(n) * 2.3283064365386963e-10 // 2^-32 | ||
| } | ||
| } | ||
|
|
||
| type PRNG func() float64 | ||
|
|
||
| func Alea(seed interface{}) PRNG { | ||
| xg := NewAlea(seed) | ||
| prng := func() float64 { | ||
| return xg.Next() | ||
| } | ||
|
|
||
| return prng | ||
| } | ||
|
|
||
| func (prng PRNG) Int32() int32 { | ||
| return int32(prng() * 0x100000000) | ||
| } | ||
|
|
||
| func (prng PRNG) Double() float64 { | ||
| return prng() + float64(uint32(prng()*0x200000))*1.1102230246251565e-16 // 2^-53 | ||
| } | ||
|
|
||
| func (prng PRNG) State(xg *alea) state { | ||
| return xg.GetState() | ||
| } | ||
|
|
||
| func (prng PRNG) ImportState(xg *alea, state state) PRNG { | ||
| xg.SetState(state) | ||
| return prng | ||
| } |
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