initial program commit

.gitignore

@@ -23,3 +23,9 @@ go.work.sum
 
 # env file
 .env
+
+# test hex files
+*.hex
+
+# build
+rgb2rgb8

go.mod

@@ -0,0 +1,5 @@
+module github.com/amberisvibin/rgb2rgb8
+
+go 1.23.5
+
+require github.com/wayneashleyberry/truecolor v1.0.1 // indirect

go.sum

@@ -0,0 +1,2 @@
+github.com/wayneashleyberry/truecolor v1.0.1 h1:REnJBycjnvg0AFErbLx2GCmLLar8brlqm62kOKnRsGs=
+github.com/wayneashleyberry/truecolor v1.0.1/go.mod h1:fyL3jRES70g94n+Eu+XLhXYvcseza55ph8zlkmUKW7Q=

rgb2rgb8.go

@@ -0,0 +1,174 @@
+package main
+
+import (
+	"bufio"
+	"encoding/hex"
+	"flag"
+	"fmt"
+	"github.com/wayneashleyberry/truecolor/pkg/color"
+	"math"
+	"os"
+)
+
+var outputFile string
+var verbose bool
+var version bool
+var colors bool
+
+func init() {
+	const (
+		outputDefault  = "out.hex"
+		outputUsage    = "output file"
+		verboseDefault = false
+		verboseUsage   = "verbose output"
+		versionDefault = false
+		versionUsage   = "version info"
+		colorsDefault  = false
+		colorsUsage    = "print colors to terminal (needs 24 bit color support)"
+	)
+	flag.StringVar(&outputFile, "output", outputDefault, outputUsage)
+	flag.StringVar(&outputFile, "o", outputDefault, outputUsage+" (shorthand)")
+	flag.BoolVar(&verbose, "verbose", verboseDefault, verboseUsage)
+	flag.BoolVar(&verbose, "v", verboseDefault, verboseUsage+" (shorthand)")
+	flag.BoolVar(&colors, "colors", colorsDefault, colorsUsage)
+	flag.BoolVar(&colors, "c", colorsDefault, colorsUsage)
+	flag.BoolVar(&version, "version", versionDefault, versionUsage)
+}
+
+func main() {
+	flag.Usage = func() {
+		w := flag.CommandLine.Output()
+		fmt.Fprintf(w, "%s is a utility that converts RGB24 hex palette files to 8bit 3-3-2 RGB.\n", os.Args[0])
+		fmt.Fprintf(w, "Usage:\n")
+		flag.PrintDefaults()
+	}
+
+	flag.Parse()
+
+	if version {
+		fmt.Println("rgb2rgb8 v0.1")
+		fmt.Println("(c) 2025 Amber Zeller")
+		fmt.Println("Distributed under the MIT license")
+		os.Exit(0)
+	}
+
+	if len(flag.Args()) == 0 {
+		fmt.Println("Error: No file specified.")
+		os.Exit(1)
+	}
+
+	var inputFile = flag.Args()[0]
+
+	if verbose {
+		fmt.Println("outputFile:", outputFile)
+		fmt.Println("inputFile:", inputFile)
+	}
+
+	//read input file
+	input, err := os.Open(inputFile)
+	if err != nil {
+		fmt.Println("Error: Cannot read input file", err)
+		os.Exit(2)
+	}
+
+	//create output file
+	output, err := os.OpenFile(outputFile, os.O_WRONLY|os.O_CREATE, 0644)
+	if err != nil {
+		fmt.Println("Error: Cannot create output file.", err)
+		os.Exit(3)
+	}
+
+	defer output.Close()
+
+	//scan through input
+	scanner := bufio.NewScanner(input)
+	var data string
+
+	counter := 1
+	for scanner.Scan() {
+		line := scanner.Text()
+		if verbose {
+			fmt.Println()
+			fmt.Println("Parsing line:", line)
+		}
+		lineHex, err := hex.DecodeString(line)
+		if err != nil || len(lineHex) != 3 {
+			fmt.Println("Error: Failed to parse line as hex.", err)
+		} else {
+			//separate rgb components
+			red := byte(lineHex[0])
+			green := byte(lineHex[1])
+			blue := byte(lineHex[2])
+
+			//and with 11100000
+			red3bitLow := red & 224
+			green3bitLow := green & 224
+			//and with 11000000
+			blue2bitLow := blue & 192
+
+			//and with 11100000 and add 00011111
+			red3bitHigh := (red & 224) + 31
+			green3bitHigh := (green & 224) + 31
+			//and with 11000000 and add 00111111
+			blue2bitHigh := (blue & 192) + 63
+
+			rgb8High := []byte{red3bitHigh, green3bitHigh, blue2bitHigh}
+			rgb8Low := []byte{red3bitLow, green3bitLow, blue2bitLow}
+
+			var redFinal byte
+			var greenFinal byte
+			var blueFinal byte
+
+			if math.Abs(float64(red3bitHigh)-float64(red)) < math.Abs(float64(red3bitLow)-float64(red)) {
+				redFinal = red3bitHigh
+			} else {
+				redFinal = red3bitLow
+			}
+
+			if math.Abs(float64(green3bitHigh)-float64(green)) < math.Abs(float64(green3bitLow)-float64(green)) {
+				greenFinal = green3bitHigh
+			} else {
+				greenFinal = green3bitLow
+			}
+
+			if math.Abs(float64(blue2bitHigh)-float64(blue)) < math.Abs(float64(blue2bitLow)-float64(blue)) {
+				blueFinal = blue2bitHigh
+			} else {
+				blueFinal = blue2bitLow
+			}
+
+			rgb8Final := []byte{redFinal, greenFinal, blueFinal}
+
+			if verbose {
+				fmt.Println("Raw RGB values:", red, green, blue)
+				fmt.Println("High values:", red3bitHigh, green3bitHigh, blue2bitHigh)
+				fmt.Println("Low values:", red3bitLow, green3bitLow, blue2bitLow)
+				fmt.Println("Final values:", redFinal, greenFinal, blueFinal)
+				fmt.Println("Hex high value:", hex.EncodeToString(rgb8High))
+				fmt.Println("Hex high value:", hex.EncodeToString(rgb8Low))
+				fmt.Println("Hex final value:", hex.EncodeToString(rgb8Final))
+			}
+
+			if colors {
+				fmt.Println("Raw  High Low  Final")
+				color.Background(red, green, blue).Print("     ")
+				color.Background(red3bitHigh, green3bitHigh, blue2bitHigh).Print("     ")
+				color.Background(red3bitLow, green3bitLow, blue2bitLow).Print("     ")
+				color.Background(redFinal, greenFinal, blueFinal).Println("     ")
+			}
+
+			data += hex.EncodeToString(rgb8Final) + "\n"
+		}
+		counter++
+	}
+
+	if scanner.Err() != nil {
+		fmt.Println(scanner.Err())
+	}
+
+	_, err = output.WriteString(data)
+	if err != nil {
+		fmt.Println("Error: Failed to write output file.", err)
+		os.Exit(4)
+	}
+}