1 files changed, 89 insertions, 0 deletions
diff --git a/src/math/rand/gen_cooked.go b/src/math/rand/gen_cooked.go
new file mode 100644
index 0000000..782bb66
--- /dev/null
+++ b/src/math/rand/gen_cooked.go
@@ -0,0 +1,89 @@
+// 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.
+
+//go:build ignore
+
+// This program computes the value of rngCooked in rng.go,
+// which is used for seeding all instances of rand.Source.
+// a 64bit and a 63bit version of the array is printed to
+// the standard output.
+
+package main
+
+import "fmt"
+
+const (
+	length = 607
+	tap    = 273
+	mask   = (1 << 63) - 1
+	a      = 48271
+	m      = (1 << 31) - 1
+	q      = 44488
+	r      = 3399
+)
+
+var (
+	rngVec          [length]int64
+	rngTap, rngFeed int
+)
+
+func seedrand(x int32) int32 {
+	hi := x / q
+	lo := x % q
+	x = a*lo - r*hi
+	if x < 0 {
+		x += m
+	}
+	return x
+}
+
+func srand(seed int32) {
+	rngTap = 0
+	rngFeed = length - tap
+	seed %= m
+	if seed < 0 {
+		seed += m
+	} else if seed == 0 {
+		seed = 89482311
+	}
+	x := seed
+	for i := -20; i < length; i++ {
+		x = seedrand(x)
+		if i >= 0 {
+			var u int64
+			u = int64(x) << 20
+			x = seedrand(x)
+			u ^= int64(x) << 10
+			x = seedrand(x)
+			u ^= int64(x)
+			rngVec[i] = u
+		}
+	}
+}
+
+func vrand() int64 {
+	rngTap--
+	if rngTap < 0 {
+		rngTap += length
+	}
+	rngFeed--
+	if rngFeed < 0 {
+		rngFeed += length
+	}
+	x := (rngVec[rngFeed] + rngVec[rngTap])
+	rngVec[rngFeed] = x
+	return x
+}
+
+func main() {
+	srand(1)
+	for i := uint64(0); i < 7.8e12; i++ {
+		vrand()
+	}
+	fmt.Printf("rngVec after 7.8e12 calls to vrand:\n%#v\n", rngVec)
+	for i := range rngVec {
+		rngVec[i] &= mask
+	}
+	fmt.Printf("lower 63bit of rngVec after 7.8e12 calls to vrand:\n%#v\n", rngVec)
+}