Adding modding folder with a hacked build.

modding/hacked/ss1/serial/rle/Compress.go

@@ -0,0 +1,177 @@
+package rle
+
+import "io"
+
+// Compress compresses the given byte array into the given writer.
+// The optional reference array is used as a delta basis. If provided, bytes will be skipped
+// where the data equals the reference.
+func Compress(writer io.Writer, data []byte, reference []byte) error {
+	end := len(data)
+	refLen := len(reference)
+	ref := func(index int) byte {
+		if index < refLen {
+			return reference[index]
+		}
+		return 0x00
+	}
+
+	countIdenticalBytes := func(from int) int {
+		index := from
+		for (index < end) && (data[index] == ref(index)) {
+			index++
+		}
+		return index - from
+	}
+	countConstantBytes := func(from int, value byte) int {
+		index := from
+		for (index < end) && (data[index] == value) {
+			index++
+		}
+		return index - from
+	}
+
+	{
+		trailingSkip := 0
+
+		for temp := end - 1; (temp >= 0) && (data[temp] == ref(temp)); temp-- {
+			trailingSkip++
+		}
+		end -= trailingSkip % 0x7FFF
+	}
+	start := 0
+	for start < end {
+		identicalByteCount := countIdenticalBytes(start)
+		constByteCount := countConstantBytes(start, data[start])
+
+		switch {
+		case identicalByteCount > 3:
+			err := skipBytes(writer, identicalByteCount)
+			if err != nil {
+				return err
+			}
+			start += identicalByteCount
+		case constByteCount > 3:
+			err := writeConstant(writer, constByteCount, data[start])
+			if err != nil {
+				return err
+			}
+			start += constByteCount
+		default:
+			diffByteCount := 0
+			abort := false
+
+			for (start+diffByteCount) < end && !abort {
+				nextIdenticalByteCount := countIdenticalBytes(start + diffByteCount)
+				nextConstByteCount := countConstantBytes(start+diffByteCount, data[start+diffByteCount])
+
+				if nextIdenticalByteCount < 4 && nextConstByteCount < 4 {
+					if nextIdenticalByteCount > nextConstByteCount {
+						diffByteCount += nextIdenticalByteCount
+					} else {
+						diffByteCount += nextConstByteCount
+					}
+				} else {
+					abort = true
+				}
+			}
+			err := writeRaw(writer, data[start:start+diffByteCount])
+			if err != nil {
+				return err
+			}
+			start += diffByteCount
+		}
+	}
+	return writeExtended(writer, 0x0000)
+}
+
+func writeExtended(writer io.Writer, control uint16, extra ...byte) error {
+	_, err := writer.Write([]byte{0x80, byte(control & 0xFF), byte((control >> 8) & 0xFF)})
+	if err != nil {
+		return err
+	}
+	_, err = writer.Write(extra)
+	return err
+}
+
+func skipBytes(writer io.Writer, size int) error {
+	remain := size
+
+	for remain > 0 {
+		if remain < 0x80 {
+			_, err := writer.Write([]byte{byte(0x80 + remain)})
+			if err != nil {
+				return err
+			}
+			remain = 0
+		} else {
+			lenControl := 0x7FFF
+			if remain < lenControl {
+				lenControl = remain
+			}
+			err := writeExtended(writer, uint16(lenControl))
+			if err != nil {
+				return err
+			}
+			remain -= lenControl
+		}
+	}
+	return nil
+}
+
+func writeConstant(writer io.Writer, size int, value byte) error {
+	start := 0
+
+	for start < size {
+		remain := size - start
+		if remain < 0x100 {
+			_, err := writer.Write([]byte{0x00, byte(remain), value})
+			if err != nil {
+				return err
+			}
+			start = size
+		} else {
+			lenControl := 0x3FFF
+			if remain < lenControl {
+				lenControl = remain
+			}
+			err := writeExtended(writer, 0xC000+uint16(lenControl), value)
+			if err != nil {
+				return err
+			}
+			start += lenControl
+		}
+	}
+	return nil
+}
+
+func writeRaw(writer io.Writer, data []byte) error {
+	end := len(data)
+	start := 0
+
+	for start < end {
+		remain := end - start
+		if remain < 0x80 {
+			_, err := writer.Write([]byte{byte(remain)})
+			if err != nil {
+				return err
+			}
+			_, err = writer.Write(data[start:])
+			if err != nil {
+				return err
+			}
+			start = end
+		} else {
+			lenControl := 0x3FFF
+
+			if remain < lenControl {
+				lenControl = remain
+			}
+			err := writeExtended(writer, 0x8000+uint16(lenControl), data[start:start+lenControl]...)
+			if err != nil {
+				return err
+			}
+			start += lenControl
+		}
+	}
+	return nil
+}