File comment and license.

apgbpal.go

@@ -1,9 +1,32 @@
 package main
 
+// Binary apgbpal creates a 56-byte file named "test.pal" in the current working
+// directory. I hope it might be an Analogue Pocket GB Palette file, but I don't
+// know that for sure yet.
+
+// apgbpal is licensed under 0BSD.
+//
+// Zero-Clause BSD
+// =============
+//
+// Permission to use, copy, modify, and/or distribute this software for
+// any purpose with or without fee is hereby granted.
+//
+// THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL
+// WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
+// OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE
+// FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+// DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
+// AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
+// OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+
 import (
 	"fmt"
-	"strings"
 	"log"
+	"os"
+	"strconv"
+	"strings"
 )
 
 type RGBA struct {
@@ -14,11 +37,11 @@ type RGBA struct {
 }
 
 func (c RGBA) Bytes() [4]byte {
-	return [4]byte {c.R, c.G, cB, c.A}
+	return [4]byte{c.R, c.G, c.B, c.A}
 }
 
 func HexByteAt(str string, index int) (byte, error) {
-	if len(string) < index + 2 {
+	if len(str) < index+2 {
 		return 0, fmt.Errorf("no hex byte at %d in too short string %q", index, str)
 	}
 	big, err := strconv.ParseUint(str[index:index+1], 16, 8)
@@ -28,7 +51,7 @@ func HexByteAt(str string, index int) (byte, error) {
 	return byte(big), nil
 }
 
-func MustParseRGBA(str string) RGBA {
+func ParseRGBA(str string) (RGBA, error) {
 	s := strings.TrimSpace(str)
 	s = strings.ToLower(s)
 	s, _ = strings.CutPrefix(s, "#")
@@ -40,20 +63,22 @@ func MustParseRGBA(str string) RGBA {
 		var err error
 		ret.A, err = HexByteAt(s, 6)
 		if err != nil {
-			log.Fatalf("can't parse alpha channel: %v", err)
+			return RGBA{}, fmt.Errorf("can't parse alpha channel: %v", err)
 		}
 	default:
-		log.Fatalf("%q is not an RGBA value: wrong length after trimming", str)
+		return RGBA{}, fmt.Errorf("%q is not an RGBA value: wrong length after trimming", str)
 	}
-	if ret.R, err := HexByteAt(s, 0); err != nil {
-		log.Fatalf("can't parse red channel: %v", err)
+	var err error
+	if ret.R, err = HexByteAt(s, 0); err != nil {
+		return RGBA{}, fmt.Errorf("can't parse red channel: %v", err)
 	}
-	if ret.G, err := HexByteAt(s, 2); err != nil {
-		log.Fatalf("can't parse green channel: %v", err)
+	if ret.G, err = HexByteAt(s, 2); err != nil {
+		return RGBA{}, fmt.Errorf("can't parse green channel: %v", err)
 	}
-	if ret.B, err := HexByteAt(s, 4); err != nil {
-		log.Fatalf("can't parse blue channel: %v", err)
+	if ret.B, err = HexByteAt(s, 4); err != nil {
+		return RGBA{}, fmt.Errorf("can't parse blue channel: %v", err)
 	}
+	return ret, nil
 }
 
 type BGPal [4]RGBA
@@ -66,7 +91,7 @@ func (b BGPal) Bytes() [20]byte {
 	for c := 0; c < 4; c++ {
 		bb := b[c].Bytes()
 		for i := 0; i < 4; i++ {
-			ret[3+i+4*c]=bb[i]
+			ret[3+i+4*c] = bb[i]
 		}
 	}
 	ret[19] = '\n'
@@ -79,7 +104,8 @@ func MustParseBGPal(strs []string) BGPal {
 	}
 	var ret BGPal
 	for i := 0; i < 4; i++ {
-		ret[i], err := MustParseRGBA(strs[i])
+		var err error
+		ret[i], err = ParseRGBA(strs[i])
 		if err != nil {
 			log.Fatalf("MustParseBGPal can't parse at %d: %v", i, err)
 		}
@@ -99,20 +125,25 @@ func (o OBJPal) Bytes(indexchar byte) [18]byte {
 	for c := 0; c < 3; c++ {
 		oo := o[c].Bytes()
 		for i := 0; i < 4; i++ {
-			ret[5+i+4*c]=oo[i]
+			ret[5+i+4*c] = oo[i]
 		}
 	}
 	ret[17] = '\n'
 	return ret
 }
 
-func MustParseOBJPal {
+func MustParseOBJPal(strs []string) OBJPal {
+	if len(strs) == 4 {
+		log.Println("Discarding index 0 of OBJ pal")
+		strs = strs[1:]
+	}
 	if len(strs) != 3 {
-	log.Fatalf("MustParseObjPal requires length 3, got %d", len(strs))
+		log.Fatalf("MustParseObjPal requires length 3, got %d", len(strs))
 	}
 	var ret OBJPal
 	for i := 0; i < 3; i++ {
-		ret[i], err := MustParseRGBA(strs[i])
+		var err error
+		ret[i], err = ParseRGBA(strs[i])
 		if err != nil {
 			log.Fatalf("MustParseOBJPal can't parse at %d: %v", i, err)
 		}
@@ -121,7 +152,7 @@ func MustParseOBJPal {
 }
 
 type APGBPal struct {
-	BG BGPal
+	BG   BGPal
 	OBJ0 OBJPal
 	OBJ1 OBJPal
 }
@@ -140,3 +171,27 @@ func (a APGBPal) Bytes() [56]byte {
 	return ret
 }
 
+func main() {
+	f, err := os.OpenFile(
+		"test.pal",
+		os.O_WRONLY|os.O_CREATE|os.O_EXCL,
+		0644)
+	if err != nil {
+		log.Fatalf("can't create test.pal: %v", err)
+	}
+	aUpPal := APGBPal{
+		BG:   MustParseBGPal([]string{"ffffff", "ff8484", "943a3a", "000000"}),
+		OBJ0: MustParseOBJPal([]string{"7bff31", "008400", "000000"}),
+		OBJ1: MustParseOBJPal([]string{"63a5ff", "0000ff", "000000"}),
+	}
+	palb := aUpPal.Bytes()
+	n, err := f.Write(palb[:])
+	if err != nil {
+		log.Fatalf("can't save test.pal: %v", err)
+	}
+	if n != 56 {
+		log.Fatalf("unexpected write length: %d", n)
+	}
+	f.Close()
+	os.Exit(0)
+}