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SPDX is an ISO standard for describing licenses in a computer readable format, which is useful when applying license compliance tools and the like to source code. In addition to ensuring that the Wuffs C distribution is properly annotated to the benefit of projects using Wuffs and SPDX-supporting tools, add it everywhere else where there's a license in this repo for consistency, too.
91 lines
1.8 KiB
Go
91 lines
1.8 KiB
Go
// Copyright 2019 The Wuffs Authors.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//
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// SPDX-License-Identifier: Apache-2.0 OR MIT
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//go:build ignore
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// +build ignore
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package main
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// print-byte-frequencies.go prints the relative frequencies of stdin's bytes.
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//
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// Usage: go run print-byte-frequencies.go < foo.bin
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import (
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"flag"
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"fmt"
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"io"
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"os"
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)
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var (
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showZeroes = flag.Bool("show-zeroes", false, "whether to print zero-frequency bytes")
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)
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func main() {
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if err := main1(); err != nil {
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os.Stderr.WriteString(err.Error() + "\n")
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os.Exit(1)
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}
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}
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func main1() (retErr error) {
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flag.Parse()
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os.Stdout.WriteString("byte count / total = frequency heat\n")
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in := make([]byte, 4096)
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counts := [256]uint64{}
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total := uint64(0)
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for {
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n, err := os.Stdin.Read(in)
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for _, x := range in[:n] {
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counts[x]++
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}
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total += uint64(n)
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if err != nil {
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if err != io.EOF {
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retErr = err
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}
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break
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}
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}
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for c, count := range counts {
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if (count == 0) && !*showZeroes {
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continue
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}
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freq := float64(0)
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if total > 0 {
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freq = float64(count) / float64(total)
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}
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fmt.Printf("0x%02X %c %12d / %12d = %.08f %s\n",
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c, printable(c), count, total, freq, heat(freq))
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}
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return retErr
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}
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func printable(c int) rune {
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if (0x20 <= c) && (c < 0x7F) {
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return rune(c)
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}
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return '.'
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}
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func heat(f float64) string {
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const s = "++++++++"
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i := int(f * 256)
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for n, threshold := len(s), 128; n > 0; n, threshold = n-1, threshold>>1 {
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if i >= threshold {
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return s[:n]
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}
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}
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return ""
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}
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