commit f5307e6a755feece4629cc0a899df60a702259dd
Author: mizi <sweetbabyalaska@gmail.com>
Date:   Mon Jan 15 14:39:38 2024 -0900

    [hexxy] init

diff --git a/hexxy.go b/hexxy.go
new file mode 100644
index 0000000..0fab866
--- /dev/null
+++ b/hexxy.go
@@ -0,0 +1,173 @@
+package main
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/jessevdk/go-flags"
+)
+
+var opts struct {
+	NoColor bool `short:"N" long:"no-color" description:"do not print output with color"`
+	Verbose bool `short:"v" long:"verbose" description:"print debugging information and verbose output"`
+}
+
+var Debug = func(string, ...interface{}) {}
+
+type Color struct {
+	disable bool
+	values  [256]string
+}
+
+func (c *Color) Compute() {
+	const WHITEB = "\x1b[1;37m"
+	for i := 0; i < 256; i++ {
+		var fg, bg string
+
+		lowVis := i == 0 || (i >= 16 && i <= 20) || (i >= 232 && i <= 242)
+
+		if lowVis {
+			fg = WHITEB + "\x1b[38;5;" + "255" + "m"
+			bg = "\x1b[48;5;" + strconv.Itoa(int(i)) + "m"
+		} else {
+			fg = "\x1b[38;5;" + strconv.Itoa(int(i)) + "m"
+			bg = ""
+		}
+		c.values[i] = bg + fg
+	}
+}
+
+func (c *Color) Colorize(s string, clr byte) string {
+	const NOCOLOR = "\x1b[0m"
+	return c.values[clr] + s + NOCOLOR
+}
+
+func stdinOpen() bool {
+	stat, _ := os.Stdin.Stat()
+	if stat.Mode()&os.ModeCharDevice == os.ModeCharDevice {
+		return false
+	} else {
+		return true
+	}
+}
+
+func asciiRow(ascii []byte, clr *Color, stdout io.Writer) {
+	var s string
+	for _, b := range ascii {
+		if b >= 33 && b <= 126 {
+			s = clr.Colorize(string(b), b)
+		} else {
+			s = clr.Colorize(".", b)
+		}
+
+		fmt.Fprint(stdout, s)
+	}
+}
+
+func Hexdump(file *os.File, color *Color) error {
+	stdout := bufio.NewWriter(os.Stdout)
+	stderr := os.Stderr
+	ascii := [16]byte{}
+
+	var i uint64 = 0
+	reader := bufio.NewReaderSize(file, 10*1024*1024)
+
+	for {
+		b, err := reader.ReadByte()
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		if err != nil {
+			fmt.Fprintf(stderr, "Failed to read %v: %v\n", file.Name(), err)
+			return err
+		}
+
+		ascii[i%16] = b
+
+		// offset
+		if i%16 == 0 {
+			fmt.Fprintf(stdout, "%08x   ", i)
+		}
+
+		// byte
+		fmt.Fprintf(stdout, color.Colorize("%02x", b)+" ", b)
+
+		// extra space every 4 bytes
+		if (i+1)%4 == 0 {
+			fmt.Fprint(stdout, " ")
+		}
+
+		// print ascii row and newline │ | ┆
+		if (i+1)%16 == 0 {
+			fmt.Fprint(stdout, "│")
+			asciiRow(ascii[:i%16], color, stdout)
+			fmt.Fprintln(stdout, "│")
+			ascii = [16]byte{} // reset
+		}
+
+		i++
+	}
+
+	if i%16 != 0 {
+		left := int(16 - i%16)
+		spaces := 3*left + (left-1)/4 + 1
+		fmt.Fprint(stdout, strings.Repeat(" ", spaces))
+		fmt.Fprint(stdout, "│")
+		asciiRow(ascii[:i%16], color, stdout)
+		fmt.Fprintln(stdout, "│")
+		fmt.Fprintf(stdout, "%08x\n", i)
+	}
+
+	return nil
+}
+
+func Hexxy(args []string) error {
+	color := &Color{}
+
+	if opts.NoColor {
+		color.disable = true
+	}
+
+	if !color.disable {
+		color.Compute()
+	}
+
+	if len(args) < 1 && stdinOpen() {
+		return Hexdump(os.Stdin, color)
+	}
+
+	for _, f := range args {
+		file, err := os.Open(f)
+		if err != nil {
+			return err
+		}
+
+		Hexdump(file, color)
+	}
+
+	return nil
+}
+
+func main() {
+	args, err := flags.Parse(&opts)
+	if flags.WroteHelp(err) {
+		os.Exit(0)
+	}
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if opts.Verbose {
+		Debug = log.Printf
+	}
+
+	if err := Hexxy(args); err != nil {
+		log.Fatal(err)
+	}
+}