mirror of
https://github.com/emmansun/gmsm.git
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102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
//go:build ignore
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// +build ignore
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package main
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import (
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"bytes"
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"go/format"
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"io"
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"log"
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"os"
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"os/exec"
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)
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// Running this generator requires addchain v0.4.0, which can be installed with
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//
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// go install github.com/mmcloughlin/addchain/cmd/addchain@v0.4.0
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//
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func main() {
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tmplAddchainFile, err := os.CreateTemp("", "addchain-template")
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if err != nil {
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log.Fatal(err)
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}
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defer os.Remove(tmplAddchainFile.Name())
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if _, err := io.WriteString(tmplAddchainFile, tmplAddchain); err != nil {
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log.Fatal(err)
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}
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if err := tmplAddchainFile.Close(); err != nil {
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log.Fatal(err)
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}
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log.Printf("Generating gfp_invert.go...")
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f, err := os.CreateTemp("", "addchain-gfp")
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if err != nil {
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log.Fatal(err)
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}
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defer os.Remove(f.Name())
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cmd := exec.Command("addchain", "search", "0xb640000002a3a6f1d603ab4ff58ec74521f2934b1a7aeedbe56f9b27e351457b")
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cmd.Stderr = os.Stderr
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cmd.Stdout = f
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if err := cmd.Run(); err != nil {
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log.Fatal(err)
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}
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if err := f.Close(); err != nil {
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log.Fatal(err)
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}
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cmd = exec.Command("addchain", "gen", "-tmpl", tmplAddchainFile.Name(), f.Name())
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cmd.Stderr = os.Stderr
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out, err := cmd.Output()
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if err != nil {
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log.Fatal(err)
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}
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out = bytes.Replace(out, []byte("Element"), []byte("gfP"), -1)
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out, err = format.Source(out)
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if err != nil {
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log.Fatal(err)
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}
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if err := os.WriteFile("gfp_invert.go", out, 0644); err != nil {
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log.Fatal(err)
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}
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}
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const tmplAddchain = `// Code generated by {{ .Meta.Name }}. DO NOT EDIT.
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package bn256
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// Invert sets e = 1/x, and returns e.
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//
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// If x == 0, Invert returns e = 0.
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func (e *Element) Invert(x *Element) *Element {
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// Inversion is implemented as exponentiation with exponent p − 2.
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// The sequence of {{ .Ops.Adds }} multiplications and {{ .Ops.Doubles }} squarings is derived from the
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// following addition chain generated with {{ .Meta.Module }} {{ .Meta.ReleaseTag }}.
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//
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{{- range lines (format .Script) }}
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// {{ . }}
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{{- end }}
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//
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var z = new(Element).Set(e)
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{{- range .Program.Temporaries }}
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var {{ . }} = new(Element)
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{{- end }}
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{{ range $i := .Program.Instructions -}}
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{{- with add $i.Op }}
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{{ $i.Output }}.Mul({{ .X }}, {{ .Y }})
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{{- end -}}
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{{- with double $i.Op }}
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{{ $i.Output }}.Square({{ .X }})
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{{- end -}}
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{{- with shift $i.Op -}}
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{{- $first := 0 -}}
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{{- if ne $i.Output.Identifier .X.Identifier }}
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{{ $i.Output }}.Square({{ .X }})
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{{- $first = 1 -}}
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{{- end }}
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for s := {{ $first }}; s < {{ .S }}; s++ {
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{{ $i.Output }}.Square({{ $i.Output }})
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}
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{{- end -}}
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{{- end }}
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return e.Set(z)
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}
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`
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