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//go:build ignore
package main
import (
"bytes"
"fmt"
"log"
"os"
)
func generateDecodeMap() [256]byte {
const alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
var decodeMap [256]byte
for i := 0; i < len(decodeMap); i++ {
decodeMap[i] = 0xff
}
for i := 0; i < len(alphabet); i++ {
decodeMap[alphabet[i]] = byte(i)
}
// for URL encoding
decodeMap['-'] = decodeMap['+']
decodeMap['_'] = decodeMap['/']
return decodeMap
}
func main() {
f, err := os.OpenFile("decode_map.go", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
if err != nil {
log.Fatal(err)
}
m := generateDecodeMap()
var b bytes.Buffer
fmt.Fprintf(&b, "// Code generated by generate_decode_map.go. DO NOT EDIT.\n\n")
fmt.Fprintf(&b, "package base64dec\n\n")
fmt.Fprintf(&b, "var decodeMap = [256]byte{")
for i, v := range m {
if i%16 == 0 {
fmt.Fprintf(&b, "\n\t")
} else {
fmt.Fprint(&b, " ")
}
fmt.Fprintf(&b, "0x%02x,", v)
}
fmt.Fprintf(&b, "\n}\n")
_, err = f.Write(b.Bytes())
if err != nil {
log.Fatal(err)
}
err = f.Close()
if err != nil {
log.Fatal(err)
}
}
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