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// Copyright 2019 The Wuffs Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build ignore
package main
// print-byte-frequencies.go prints the relative frequencies of stdin's bytes.
//
// Usage: go run print-byte-frequencies.go < foo.bin
import (
"flag"
"fmt"
"io"
"os"
)
var (
showZeroes = flag.Bool("show-zeroes", false, "whether to print zero-frequency bytes")
)
func main() {
if err := main1(); err != nil {
os.Stderr.WriteString(err.Error() + "\n")
os.Exit(1)
}
}
func main1() (retErr error) {
flag.Parse()
os.Stdout.WriteString("byte count / total = frequency heat\n")
in := make([]byte, 4096)
counts := [256]uint64{}
total := uint64(0)
for {
n, err := os.Stdin.Read(in)
for _, x := range in[:n] {
counts[x]++
}
total += uint64(n)
if err != nil {
if err != io.EOF {
retErr = err
}
break
}
}
for c, count := range counts {
if (count == 0) && !*showZeroes {
continue
}
freq := float64(0)
if total > 0 {
freq = float64(count) / float64(total)
}
fmt.Printf("0x%02X %c %12d / %12d = %.08f %s\n",
c, printable(c), count, total, freq, heat(freq))
}
return retErr
}
func printable(c int) rune {
if (0x20 <= c) && (c < 0x7F) {
return rune(c)
}
return '.'
}
func heat(f float64) string {
const s = "++++++++"
i := int(f * 256)
for n, threshold := len(s), 128; n > 0; n, threshold = n-1, threshold>>1 {
if i >= threshold {
return s[:n]
}
}
return ""
}