commit 885d814c70c7186cead9b76b92b199348bec0389
Author: Ignacio Rivero <igna@netpaws.cc>
Date:   Fri Jun 20 08:04:27 2025 -0300

    Initial commit

diff --git a/cat.png b/cat.png
new file mode 100644
index 0000000..5f2440b
Binary files /dev/null and b/cat.png differ
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..44e1e16
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,15 @@
+module catprinter-ble
+
+go 1.22
+
+require (
+	github.com/go-ble/ble v0.0.0-20240122180141-8c5522f54333
+	github.com/disintegration/imaging v1.6.2 // indirect
+	github.com/mattn/go-colorable v0.1.6 // indirect
+	github.com/mattn/go-isatty v0.0.12 // indirect
+	github.com/mgutz/ansi v0.0.0-20170206155736-9520e82c474b // indirect
+	github.com/mgutz/logxi v0.0.0-20161027140823-aebf8a7d67ab // indirect
+	github.com/pkg/errors v0.8.1 // indirect
+	golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8 // indirect
+	golang.org/x/sys v0.0.0-20211204120058-94396e421777 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..3380553
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,43 @@
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/JuulLabs-OSS/cbgo v0.0.1/go.mod h1:L4YtGP+gnyD84w7+jN66ncspFRfOYB5aj9QSXaFHmBA=
+github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/disintegration/imaging v1.6.2 h1:w1LecBlG2Lnp8B3jk5zSuNqd7b4DXhcjwek1ei82L+c=
+github.com/disintegration/imaging v1.6.2/go.mod h1:44/5580QXChDfwIclfc/PCwrr44amcmDAg8hxG0Ewe4=
+github.com/go-ble/ble v0.0.0-20240122180141-8c5522f54333 h1:bQK6D51cNzMSTyAf0HtM30V2IbljHTDam7jru9JNlJA=
+github.com/go-ble/ble v0.0.0-20240122180141-8c5522f54333/go.mod h1:fFJl/jD/uyILGBeD5iQ8tYHrPlJafyqCJzAyTHNJ1Uk=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/mattn/go-colorable v0.1.6 h1:6Su7aK7lXmJ/U79bYtBjLNaha4Fs1Rg9plHpcH+vvnE=
+github.com/mattn/go-colorable v0.1.6/go.mod h1:u6P/XSegPjTcexA+o6vUJrdnUu04hMope9wVRipJSqc=
+github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHXY=
+github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
+github.com/mgutz/ansi v0.0.0-20170206155736-9520e82c474b h1:j7+1HpAFS1zy5+Q4qx1fWh90gTKwiN4QCGoY9TWyyO4=
+github.com/mgutz/ansi v0.0.0-20170206155736-9520e82c474b/go.mod h1:01TrycV0kFyexm33Z7vhZRXopbI8J3TDReVlkTgMUxE=
+github.com/mgutz/logxi v0.0.0-20161027140823-aebf8a7d67ab h1:n8cgpHzJ5+EDyDri2s/GC7a9+qK3/YEGnBsd0uS/8PY=
+github.com/mgutz/logxi v0.0.0-20161027140823-aebf8a7d67ab/go.mod h1:y1pL58r5z2VvAjeG1VLGc8zOQgSOzbKN7kMHPvFXJ+8=
+github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
+github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/raff/goble v0.0.0-20190909174656-72afc67d6a99/go.mod h1:CxaUhijgLFX0AROtH5mluSY71VqpjQBw9JXE2UKZmc4=
+github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
+github.com/sirupsen/logrus v1.5.0/go.mod h1:+F7Ogzej0PZc/94MaYx/nvG9jOFMD2osvC3s+Squfpo=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+github.com/urfave/cli v1.22.2/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
+golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8 h1:hVwzHzIUGRjiF7EcUjqNxk3NCfkPxbDKRdnNE1Rpg0U=
+golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20211204120058-94396e421777 h1:QAkhGVjOxMa+n4mlsAWeAU+BMZmimQAaNiMu+iUi94E=
+golang.org/x/sys v0.0.0-20211204120058-94396e421777/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..c433576
--- /dev/null
+++ b/main.go
@@ -0,0 +1,333 @@
+// catprinter_ble.go
+// A Go reimplementation of the CatPrinterBLE utility
+// using Go's BLE stack and Image processing libraries
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"image/color"
+	"github.com/disintegration/imaging"
+	"log"
+	"os"
+	"os/signal"
+	"time"
+	ble "github.com/go-ble/ble"
+	"github.com/go-ble/ble/linux"
+)
+
+
+var (
+	mainServiceUUID       = ble.MustParse("ae30")
+	printCharacteristic   = ble.MustParse("ae01")
+	notifyCharacteristic  = ble.MustParse("ae02")
+	dataCharacteristic    = ble.MustParse("ae03")
+	targetPrinterName     = "MXW01"
+	scanTimeout           = 10 * time.Second
+	printCommandHeader    = []byte{0x22, 0x21}
+	printCommandFooter    = byte(0xFF)
+)
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func reverseBitsInByte(b byte) byte {
+	b = (b&0xF0)>>4 | (b&0x0F)<<4
+	b = (b&0xCC)>>2 | (b&0x33)<<2
+	b = (b&0xAA)>>1 | (b&0x55)<<1
+	return b
+}
+
+func dumpCharacteristics(client ble.Client, svc *ble.Service) {
+	chars, err := client.DiscoverCharacteristics(nil, svc)
+	if err != nil {
+		log.Fatalf("Error discovering characteristics: %v", err)
+	}
+
+	log.Printf("Discovered %d characteristics:", len(chars))
+	for _, c := range chars {
+		props := ""
+		if c.Property&ble.CharRead != 0 {
+			props += "Read "
+		}
+		if c.Property&ble.CharWrite != 0 {
+			props += "Write "
+		}
+		if c.Property&ble.CharWriteNR != 0 {
+			props += "WriteWithoutResponse "
+		}
+		if c.Property&ble.CharNotify != 0 {
+			props += "Notify "
+		}
+		if c.Property&ble.CharIndicate != 0 {
+			props += "Indicate "
+		}
+
+		log.Printf("  UUID: %s, Properties: %s", c.UUID, props)
+	}
+}
+
+func parseNotification(data []byte) {
+	if len(data) < 10 || data[0] != 0x22 || data[1] != 0x21 {
+		fmt.Println("Invalid notification header")
+		return
+	}
+
+	cmd := data[2]
+	switch cmd {
+	case 0xA1: // GetStatus
+		battery := data[9]
+		temp := data[10]
+		statusOk := data[12] == 0
+		statusCode := data[6]
+		errCode := data[13]
+
+		statusMsg := "Unknown"
+		if statusOk {
+			switch statusCode {
+			case 0x0:
+				statusMsg = "Standby"
+			case 0x1:
+				statusMsg = "Printing"
+			case 0x2:
+				statusMsg = "Feeding paper"
+			case 0x3:
+				statusMsg = "Ejecting paper"
+			}
+		} else {
+			switch errCode {
+			case 0x1, 0x9:
+				statusMsg = "No paper"
+			case 0x4:
+				statusMsg = "Overheated"
+			case 0x8:
+				statusMsg = "Low battery"
+			}
+		}
+
+		fmt.Printf("Status: %v (%s), Battery: %d, Temp: %d\n", statusOk, statusMsg, battery, temp)
+	default:
+		fmt.Printf("Unhandled command: 0x%02X\n", cmd)
+	}
+}
+
+const (
+	linePixels   = 384
+	bytesPerLine = linePixels / 8
+)
+
+// Convert image to 1bpp, dithered, and packed bytes
+func loadImageMono(path string) ([]byte, int, error) {
+	img, err := imaging.Open(path, imaging.AutoOrientation(true))
+	if err != nil {
+		return nil, 0, fmt.Errorf("image open error: %v", err)
+	}
+
+	ratio := float64(img.Bounds().Dx()) / float64(img.Bounds().Dy())
+	height := int(float64(linePixels) / ratio)
+	img = imaging.Resize(img, linePixels, height, imaging.Lanczos)
+	img = imaging.Grayscale(img)
+	img = imaging.AdjustContrast(img, 10)
+
+	pixels := make([]byte, (linePixels*height)/8)
+	for y := 0; y < height; y++ {
+		for x := 0; x < linePixels; x++ {
+			gray := color.GrayModel.Convert(img.At(x, y)).(color.Gray)
+			if gray.Y < 127 {
+				idx := (y*linePixels + x) / 8
+				bit := 7 - (x % 8)
+				pixels[idx] |= 1 << bit
+			}
+		}
+	}
+
+	return pixels, height, nil
+}
+
+func sendImageToPrinter(client ble.Client, dataChr, printChr *ble.Characteristic, path string) error {
+	pixels, height, err := loadImageMono(path)
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("Sending image: %dx%d lines\n", linePixels, height)
+
+	cmd := buildCommand(0xA2, []byte{80}) // intensity 80
+	err = client.WriteCharacteristic(printChr, cmd, true)
+	if err != nil {
+		return fmt.Errorf("intensity set failed: %v", err)
+	}
+
+	lines := height
+	param := []byte{
+		byte(lines & 0xFF), byte(lines >> 8),
+		0x30, // reserved
+		0x00, // 1bpp mode
+	}
+	cmd = buildCommand(0xA9, param)
+	err = client.WriteCharacteristic(printChr, cmd, true)
+	if err != nil {
+		return fmt.Errorf("print command failed: %v", err)
+	}
+
+	for y := 0; y < lines; y++ {
+		slice := pixels[y*bytesPerLine : (y+1)*bytesPerLine]
+		reversed := make([]byte, bytesPerLine)
+		for i := 0; i < bytesPerLine; i++ {
+			reversed[i] = reverseBitsInByte(slice[i])
+		}
+	
+		err := client.WriteCharacteristic(dataChr, reversed, true)
+		if err != nil {
+			return fmt.Errorf("line %d write failed: %v", y, err)
+		}
+		time.Sleep(6 * time.Millisecond)
+	}
+
+	cmd = buildCommand(0xAD, []byte{0x00}) // flush
+	err = client.WriteCharacteristic(printChr, cmd, true)
+	if err != nil {
+		return fmt.Errorf("flush failed: %v", err)
+	}
+
+	return nil
+}
+
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Println("Usage: catprinter-ble <image_path>")
+		return
+	}
+	imagePath := os.Args[1]
+
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
+	defer stop()
+
+	d, err := linux.NewDevice()
+	if err != nil {
+		log.Fatalf("Failed to open BLE device: %v", err)
+	}
+	ble.SetDefaultDevice(d)
+
+	log.Println("Scanning for printer...")
+
+	var adv ble.Advertisement
+	ctxScan, cancel := context.WithTimeout(ctx, 10*time.Second)
+	err = ble.Scan(ctxScan, false, func(a ble.Advertisement) {
+		if a.LocalName() == targetPrinterName {
+			adv = a
+			cancel()
+		}
+	}, nil)
+	if err != nil && err != context.Canceled {
+		log.Fatalf("Scan error: %v", err)
+	}
+	if adv == nil {
+		log.Println("Printer not found.")
+		return
+	}
+
+	log.Println("Connecting...")
+	client, err := ble.Dial(ctx, adv.Addr())
+	if err != nil {
+		log.Fatalf("Connect failed: %v", err)
+	}
+	defer client.CancelConnection()
+
+	mtu, err := client.ExchangeMTU(100)
+	if err != nil {
+		log.Printf("MTU negotiation failed, continuing with default MTU. Reason: %v", err)
+	} else {
+		log.Printf("Negotiated ATT MTU: %d", mtu)
+	}
+
+
+	services, err := client.DiscoverServices([]ble.UUID{mainServiceUUID})
+	if err != nil || len(services) == 0 {
+		log.Fatalf("Service discovery failed: %v", err)
+	}
+	svc := services[0]
+	chars, err := client.DiscoverCharacteristics(nil, svc)
+	if err != nil {
+		log.Fatalf("Char discovery failed: %v", err)
+	}
+
+	var printChr, dataChr *ble.Characteristic
+	for _, c := range chars {
+		switch c.UUID.String() {
+		case printCharacteristic.String():
+			printChr = c
+		case dataCharacteristic.String():
+			dataChr = c
+		}
+	}
+	if printChr == nil || dataChr == nil {
+		log.Fatalf("Required characteristics missing")
+	}
+
+	err = sendImageToPrinter(client, dataChr, printChr, imagePath)
+	if err != nil {
+		log.Fatalf("Failed to print image: %v", err)
+	}
+
+	log.Println("Done!")
+}
+
+func buildCommand(cmdId byte, payload []byte) []byte {
+	cmd := append([]byte{}, printCommandHeader...)
+	cmd = append(cmd, cmdId)
+	cmd = append(cmd, 0x00) // reserved
+	cmd = append(cmd, byte(len(payload)&0xFF), byte(len(payload)>>8))
+	cmd = append(cmd, payload...)
+	cmd = append(cmd, calculateCRC8(payload))
+	cmd = append(cmd, printCommandFooter)
+	return cmd
+}
+
+func calculateCRC8(data []byte) byte {
+	table := [256]byte{
+            0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15,
+            0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d,
+            0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65,
+            0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d,
+            0xe0, 0xe7, 0xee, 0xe9, 0xfc, 0xfb, 0xf2, 0xf5,
+            0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd,
+            0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85,
+            0xa8, 0xaf, 0xa6, 0xa1, 0xb4, 0xb3, 0xba, 0xbd,
+            0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2,
+            0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea,
+            0xb7, 0xb0, 0xb9, 0xbe, 0xab, 0xac, 0xa5, 0xa2,
+            0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a,
+            0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32,
+            0x1f, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0d, 0x0a,
+            0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42,
+            0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a,
+            0x89, 0x8e, 0x87, 0x80, 0x95, 0x92, 0x9b, 0x9c,
+            0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4,
+            0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec,
+            0xc1, 0xc6, 0xcf, 0xc8, 0xdd, 0xda, 0xd3, 0xd4,
+            0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c,
+            0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44,
+            0x19, 0x1e, 0x17, 0x10, 0x05, 0x02, 0x0b, 0x0c,
+            0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34,
+            0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b,
+            0x76, 0x71, 0x78, 0x7f, 0x6a, 0x6d, 0x64, 0x63,
+            0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b,
+            0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13,
+            0xae, 0xa9, 0xa0, 0xa7, 0xb2, 0xb5, 0xbc, 0xbb,
+            0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8d, 0x84, 0x83,
+            0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb,
+            0xe6, 0xe1, 0xe8, 0xef, 0xfa, 0xfd, 0xf4, 0xf3}
+	crc := byte(0)
+	for _, b := range data {
+		crc = table[crc^b]
+	}
+	return crc
+}
+
diff --git a/netpaws_test.png b/netpaws_test.png
new file mode 100644
index 0000000..23943a3
Binary files /dev/null and b/netpaws_test.png differ