mirror of
https://github.com/golang/go
synced 2024-11-19 14:44:40 -07:00
dcc821faf8
This file is not part of the benchmark shootout, and we wrote it, so use the usual copyright header, not a partial version of the shootout license. Fixes #13575. Change-Id: Ib610e2ad82914b4ef096a2424cfffe3383db2d5b Reviewed-on: https://go-review.googlesource.com/17715 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Russ Cox <rsc@golang.org>
74 lines
1.3 KiB
Go
74 lines
1.3 KiB
Go
// 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.
|
|
|
|
// +build ignore
|
|
|
|
package main
|
|
|
|
import (
|
|
big "."
|
|
"fmt"
|
|
"runtime"
|
|
)
|
|
|
|
var (
|
|
tmp1 = big.NewInt(0)
|
|
tmp2 = big.NewInt(0)
|
|
numer = big.NewInt(1)
|
|
accum = big.NewInt(0)
|
|
denom = big.NewInt(1)
|
|
ten = big.NewInt(10)
|
|
)
|
|
|
|
func extractDigit() int64 {
|
|
if big.CmpInt(numer, accum) > 0 {
|
|
return -1
|
|
}
|
|
tmp1.Lsh(numer, 1).Add(tmp1, numer).Add(tmp1, accum)
|
|
big.DivModInt(tmp1, tmp2, tmp1, denom)
|
|
tmp2.Add(tmp2, numer)
|
|
if big.CmpInt(tmp2, denom) >= 0 {
|
|
return -1
|
|
}
|
|
return tmp1.Int64()
|
|
}
|
|
|
|
func nextTerm(k int64) {
|
|
y2 := k*2 + 1
|
|
accum.Add(accum, tmp1.Lsh(numer, 1))
|
|
accum.Mul(accum, tmp1.SetInt64(y2))
|
|
numer.Mul(numer, tmp1.SetInt64(k))
|
|
denom.Mul(denom, tmp1.SetInt64(y2))
|
|
}
|
|
|
|
func eliminateDigit(d int64) {
|
|
accum.Sub(accum, tmp1.Mul(denom, tmp1.SetInt64(d)))
|
|
accum.Mul(accum, ten)
|
|
numer.Mul(numer, ten)
|
|
}
|
|
|
|
func main() {
|
|
i := 0
|
|
k := int64(0)
|
|
for {
|
|
d := int64(-1)
|
|
for d < 0 {
|
|
k++
|
|
nextTerm(k)
|
|
d = extractDigit()
|
|
}
|
|
eliminateDigit(d)
|
|
fmt.Printf("%c", d+'0')
|
|
|
|
if i++; i%50 == 0 {
|
|
fmt.Printf("\n")
|
|
if i >= 1000 {
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
fmt.Printf("\n%d calls; bit sizes: %d %d %d\n", runtime.NumCgoCall(), numer.Len(), accum.Len(), denom.Len())
|
|
}
|