49 lines
1.1 KiB
Go
49 lines
1.1 KiB
Go
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build ignore
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package main
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/*
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This program generates table.go. Invoke it as:
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go run gen.go -output table.go
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*/
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import (
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"bytes"
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"flag"
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"fmt"
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"go/format"
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"io/ioutil"
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"log"
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"math"
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)
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// N is the number of entries in the sin look-up table. It must be a power of 2.
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const N = 4096
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var filename = flag.String("output", "table.go", "output file name")
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func main() {
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b := new(bytes.Buffer)
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fmt.Fprintf(b, "// generated by go run gen.go; DO NOT EDIT\n\npackage f32\n\n")
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fmt.Fprintf(b, "const sinTableLen = %d\n\n", N)
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fmt.Fprintf(b, "// sinTable[i] equals sin(i * π / sinTableLen).\n")
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fmt.Fprintf(b, "var sinTable = [sinTableLen]float32{\n")
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for i := 0; i < N; i++ {
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radians := float64(i) * (math.Pi / N)
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fmt.Fprintf(b, "%v,\n", float32(math.Sin(radians)))
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}
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fmt.Fprintf(b, "}\n")
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data, err := format.Source(b.Bytes())
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if err != nil {
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log.Fatal(err)
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}
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if err := ioutil.WriteFile(*filename, data, 0644); err != nil {
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log.Fatal(err)
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}
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}
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