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https://github.com/golang/go
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105 lines
2.9 KiB
Go
105 lines
2.9 KiB
Go
/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of "The Computer Language Benchmarks Game" nor the
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name of "The Computer Language Shootout Benchmarks" nor the names of
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its contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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/* The Computer Language Benchmarks Game
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* http://shootout.alioth.debian.org/
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*
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* contributed by The Go Authors.
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* based on pidigits.c (by Paolo Bonzini & Sean Bartlett,
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* modified by Michael Mellor)
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*/
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package main
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import (
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"fmt"
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big "gmp"
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"runtime"
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)
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var (
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tmp1 = big.NewInt(0)
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tmp2 = big.NewInt(0)
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numer = big.NewInt(1)
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accum = big.NewInt(0)
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denom = big.NewInt(1)
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ten = big.NewInt(10)
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)
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func extractDigit() int64 {
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if big.CmpInt(numer, accum) > 0 {
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return -1
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}
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tmp1.Lsh(numer, 1).Add(tmp1, numer).Add(tmp1, accum)
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big.DivModInt(tmp1, tmp2, tmp1, denom)
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tmp2.Add(tmp2, numer)
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if big.CmpInt(tmp2, denom) >= 0 {
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return -1
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}
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return tmp1.Int64()
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}
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func nextTerm(k int64) {
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y2 := k*2 + 1
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accum.Add(accum, tmp1.Lsh(numer, 1))
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accum.Mul(accum, tmp1.SetInt64(y2))
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numer.Mul(numer, tmp1.SetInt64(k))
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denom.Mul(denom, tmp1.SetInt64(y2))
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}
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func eliminateDigit(d int64) {
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accum.Sub(accum, tmp1.Mul(denom, tmp1.SetInt64(d)))
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accum.Mul(accum, ten)
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numer.Mul(numer, ten)
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}
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func main() {
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i := 0
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k := int64(0)
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for {
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d := int64(-1)
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for d < 0 {
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k++
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nextTerm(k)
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d = extractDigit()
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}
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eliminateDigit(d)
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fmt.Printf("%c", d+'0')
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if i++; i%50 == 0 {
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fmt.Printf("\n")
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if i >= 1000 {
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break
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}
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}
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}
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fmt.Printf("\n%d calls; bit sizes: %d %d %d\n", runtime.Cgocalls(), numer.Len(), accum.Len(), denom.Len())
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}
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