| // 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 "" |
| } |