1 files changed, 179 insertions, 0 deletions
diff --git a/libgo/go/rand/rand.go b/libgo/go/rand/rand.go
new file mode 100644
index 000000000..459aed1db
--- /dev/null
+++ b/libgo/go/rand/rand.go
@@ -0,0 +1,179 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package rand implements pseudo-random number generators.
+package rand
+
+import "sync"
+
+// A Source represents a source of uniformly-distributed
+// pseudo-random int64 values in the range [0, 1<<63).
+type Source interface {
+	Int63() int64
+	Seed(seed int64)
+}
+
+// NewSource returns a new pseudo-random Source seeded with the given value.
+func NewSource(seed int64) Source {
+	var rng rngSource
+	rng.Seed(seed)
+	return &rng
+}
+
+// A Rand is a source of random numbers.
+type Rand struct {
+	src Source
+}
+
+// New returns a new Rand that uses random values from src
+// to generate other random values.
+func New(src Source) *Rand { return &Rand{src} }
+
+// Seed uses the provided seed value to initialize the generator to a deterministic state.
+func (r *Rand) Seed(seed int64) { r.src.Seed(seed) }
+
+// Int63 returns a non-negative pseudo-random 63-bit integer as an int64.
+func (r *Rand) Int63() int64 { return r.src.Int63() }
+
+// Uint32 returns a pseudo-random 32-bit value as a uint32.
+func (r *Rand) Uint32() uint32 { return uint32(r.Int63() >> 31) }
+
+// Int31 returns a non-negative pseudo-random 31-bit integer as an int32.
+func (r *Rand) Int31() int32 { return int32(r.Int63() >> 32) }
+
+// Int returns a non-negative pseudo-random int.
+func (r *Rand) Int() int {
+	u := uint(r.Int63())
+	return int(u << 1 >> 1) // clear sign bit if int == int32
+}
+
+// Int63n returns, as an int64, a non-negative pseudo-random number in [0,n).
+func (r *Rand) Int63n(n int64) int64 {
+	if n <= 0 {
+		return 0
+	}
+	max := int64((1 << 63) - 1 - (1<<63)%uint64(n))
+	v := r.Int63()
+	for v > max {
+		v = r.Int63()
+	}
+	return v % n
+}
+
+// Int31n returns, as an int32, a non-negative pseudo-random number in [0,n).
+func (r *Rand) Int31n(n int32) int32 {
+	if n <= 0 {
+		return 0
+	}
+	max := int32((1 << 31) - 1 - (1<<31)%uint32(n))
+	v := r.Int31()
+	for v > max {
+		v = r.Int31()
+	}
+	return v % n
+}
+
+// Intn returns, as an int, a non-negative pseudo-random number in [0,n).
+func (r *Rand) Intn(n int) int {
+	if n <= 1<<31-1 {
+		return int(r.Int31n(int32(n)))
+	}
+	return int(r.Int63n(int64(n)))
+}
+
+// Float64 returns, as a float64, a pseudo-random number in [0.0,1.0).
+func (r *Rand) Float64() float64 { return float64(r.Int63()) / (1 << 63) }
+
+// Float32 returns, as a float32, a pseudo-random number in [0.0,1.0).
+func (r *Rand) Float32() float32 { return float32(r.Float64()) }
+
+// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n).
+func (r *Rand) Perm(n int) []int {
+	m := make([]int, n)
+	for i := 0; i < n; i++ {
+		m[i] = i
+	}
+	for i := 0; i < n; i++ {
+		j := r.Intn(i + 1)
+		m[i], m[j] = m[j], m[i]
+	}
+	return m
+}
+
+/*
+ * Top-level convenience functions
+ */
+
+var globalRand = New(&lockedSource{src: NewSource(1)})
+
+// Seed uses the provided seed value to initialize the generator to a deterministic state.
+func Seed(seed int64) { globalRand.Seed(seed) }
+
+// Int63 returns a non-negative pseudo-random 63-bit integer as an int64.
+func Int63() int64 { return globalRand.Int63() }
+
+// Uint32 returns a pseudo-random 32-bit value as a uint32.
+func Uint32() uint32 { return globalRand.Uint32() }
+
+// Int31 returns a non-negative pseudo-random 31-bit integer as an int32.
+func Int31() int32 { return globalRand.Int31() }
+
+// Int returns a non-negative pseudo-random int.
+func Int() int { return globalRand.Int() }
+
+// Int63n returns, as an int64, a non-negative pseudo-random number in [0,n).
+func Int63n(n int64) int64 { return globalRand.Int63n(n) }
+
+// Int31n returns, as an int32, a non-negative pseudo-random number in [0,n).
+func Int31n(n int32) int32 { return globalRand.Int31n(n) }
+
+// Intn returns, as an int, a non-negative pseudo-random number in [0,n).
+func Intn(n int) int { return globalRand.Intn(n) }
+
+// Float64 returns, as a float64, a pseudo-random number in [0.0,1.0).
+func Float64() float64 { return globalRand.Float64() }
+
+// Float32 returns, as a float32, a pseudo-random number in [0.0,1.0).
+func Float32() float32 { return globalRand.Float32() }
+
+// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n).
+func Perm(n int) []int { return globalRand.Perm(n) }
+
+// NormFloat64 returns a normally distributed float64 in the range
+// [-math.MaxFloat64, +math.MaxFloat64] with
+// standard normal distribution (mean = 0, stddev = 1).
+// To produce a different normal distribution, callers can
+// adjust the output using:
+//
+//  sample = NormFloat64() * desiredStdDev + desiredMean
+//
+func NormFloat64() float64 { return globalRand.NormFloat64() }
+
+// ExpFloat64 returns an exponentially distributed float64 in the range
+// (0, +math.MaxFloat64] with an exponential distribution whose rate parameter
+// (lambda) is 1 and whose mean is 1/lambda (1).
+// To produce a distribution with a different rate parameter,
+// callers can adjust the output using:
+//
+//  sample = ExpFloat64() / desiredRateParameter
+//
+func ExpFloat64() float64 { return globalRand.ExpFloat64() }
+
+type lockedSource struct {
+	lk  sync.Mutex
+	src Source
+}
+
+func (r *lockedSource) Int63() (n int64) {
+	r.lk.Lock()
+	n = r.src.Int63()
+	r.lk.Unlock()
+	return
+}
+
+func (r *lockedSource) Seed(seed int64) {
+	r.lk.Lock()
+	r.src.Seed(seed)
+	r.lk.Unlock()
+}