GIFTranslator: Replace magic constants

Introduce GIFPrivate.h to define these magic constants

Also, make sure that we don't go over LZ_MAX_CODE bits

src/add-ons/translators/gif/GIFLoad.cpp

@@ -26,6 +26,8 @@
 #include <TranslatorFormats.h>
 #include <InterfaceDefs.h>
 
+#include "GIFPrivate.h"
+
 
 extern bool debug;
 
@@ -57,8 +59,8 @@ GIFLoad::GIFLoad(BPositionIO* input, BPositionIO* output)
 		return;
 	}
 
-	while (c != 0x3b) {
+	while (c != TERMINATOR_INTRODUCER) {
-		if (c == 0x2c) {
+		if (c == DESCRIPTOR_INTRODUCER) {
 			if ((!ReadGIFImageHeader()) || (!ReadGIFImageData())) {
 				if (debug) {
 					syslog(LOG_ERR, "GIFLoad::GIFLoad() - "
@@ -75,23 +77,23 @@ GIFLoad::GIFLoad(BPositionIO* input, BPositionIO* output)
 			free(fScanLine);
 			fScanLine = NULL;
 			return;
-		} else if (c == 0x21) {
+		} else if (c == EXTENSION_INTRODUCER) {
 			unsigned char d;
 			if (fInput->Read(&d, 1) < 1) {
 				fatalerror = true;
 				return;
 			}
-			if (d == 0xff) {
+			if (d == LOOP_BLOCK_LABEL) {
 				if (!ReadGIFLoopBlock()) {
 					fatalerror = true;
 					return;
 				}
-			} else if (d == 0xf9) {
+			} else if (d == GRAPHIC_CONTROL_LABEL) {
 				if (!ReadGIFControlBlock()) {
 					fatalerror = true;
 					return;
 				}
-			} else if (d == 0xfe) {
+			} else if (d == COMMENT_EXTENSION_LABEL) {
 				if (!ReadGIFCommentBlock()) {
 					fatalerror = true;
 					return;
@@ -102,7 +104,7 @@ GIFLoad::GIFLoad(BPositionIO* input, BPositionIO* output)
 					return;
 				}
 			}
-		} else if (c != 0x00) {
+		} else if (c != BLOCK_TERMINATOR) {
 			if (!ReadGIFUnknownBlock(c)) {
 				fatalerror = true;
 				return;
@@ -224,10 +226,10 @@ GIFLoad::ReadGIFCommentBlock()
 		if (fInput->Read(comment_data, length) < length)
 			return false;
 
-		comment_data[length] = 0x00;
+		comment_data[length] = BLOCK_TERMINATOR;
 		if (debug)
 			syslog(LOG_INFO, "%s", comment_data);
-	} while (length != 0x00);
+	} while (length != BLOCK_TERMINATOR);
 
 	if (debug)
 		syslog(LOG_INFO, "\n");
@@ -248,7 +250,7 @@ GIFLoad::ReadGIFUnknownBlock(unsigned char c)
 			return false;
 
 		fInput->Seek(length, SEEK_CUR);
-	} while (length != 0x00);
+	} while (length != BLOCK_TERMINATOR);
 
 	return true;
 }
@@ -428,7 +430,7 @@ GIFLoad::ReadGIFImageData()
 		fOldCodeLength = fEntrySize[fNewCode];
 		fNextCode++;
 
-		if (fNextCode > fMaxCode && fBits != 12) {
+		if (fNextCode > fMaxCode && fBits < LZ_MAX_BITS) {
 			fBits++;
 			fMaxCode = (1 << fBits) - 1;
 		}
@@ -514,6 +516,7 @@ GIFLoad::InitFrame(int size)
 	fEndCode = fClearCode + 1;
 	fNextCode = fClearCode + 2;
 	fMaxCode = (1 << fBits) - 1;
+
 	fPass = 0;
 
 	if (fInterlaced)

src/add-ons/translators/gif/GIFPrivate.h

@@ -0,0 +1,19 @@
+#ifndef GIF_PRIVATE_H
+#define GIF_PRIVATE_H
+
+
+#define BLOCK_TERMINATOR		0x00
+
+#define EXTENSION_INTRODUCER	0x21
+#define DESCRIPTOR_INTRODUCER	0x2c
+#define TERMINATOR_INTRODUCER	0x3b
+
+#define GRAPHIC_CONTROL_LABEL	0xf9
+#define COMMENT_EXTENSION_LABEL	0xfe
+#define LOOP_BLOCK_LABEL		0xff
+
+#define LZ_MAX_CODE				4095
+#define LZ_MAX_BITS				12
+
+
+#endif	// GIF_PRIVATE_H

src/add-ons/translators/gif/GIFSave.cpp

@@ -24,6 +24,8 @@
 #include <stdlib.h>
 #include <syslog.h>
 
+#include "GIFPrivate.h"
+
 
 const int gs_pass_starts_at[] = {0, 4, 2, 1, 0};
 const int gs_increment_pass_by[] = {8, 8, 4, 2, 0};
@@ -173,7 +175,7 @@ GIFSave::GIFSave(BBitmap* bitmap, BPositionIO* output,
 	delete hash;
 
 	// Terminating character
-	char t = 0x3b;
+	char t = TERMINATOR_INTRODUCER;
 	output->Write(&t, 1);
 }
 
@@ -212,7 +214,10 @@ GIFSave::WriteGIFHeader()
 void
 GIFSave::WriteGIFControlBlock()
 {
-	unsigned char b[8] = { 0x21, 0xf9, 0x04, 0, 0, 0, 0, 0x00 };
+	unsigned char b[8] = { 
+		EXTENSION_INTRODUCER, GRAPHIC_CONTROL_LABEL, 0x04, 0x00, 0x00, 0x00,
+		0x00, BLOCK_TERMINATOR
+	};
 	if (palette->UseTransparent()) {
 		b[3] = b[3] | 1;
 		b[6] = palette->TransparentIndex();
@@ -225,7 +230,7 @@ void
 GIFSave::WriteGIFImageHeader()
 {
 	unsigned char header[10];
-	header[0] = 0x2c;
+	header[0] = DESCRIPTOR_INTRODUCER;
 	header[1] = header[2] = 0;
 	header[3] = header[4] = 0;
 
@@ -237,7 +242,7 @@ GIFSave::WriteGIFImageHeader()
 	if (fSettings->SetGetBool(GIF_SETTING_INTERLACED))
 		header[9] = 0x40;
 	else
-		header[9] = 0x00;
+		header[9] = BLOCK_TERMINATOR;
 
 	output->Write(header, 10);
 }
@@ -268,8 +273,8 @@ GIFSave::WriteGIFImageData()
 
 			if (next_code > max_code) {
 				BITS++;
-				if (BITS > 12) {
+				if (BITS > LZ_MAX_BITS) {
-					OutputCode(clear_code, 12);
+					OutputCode(clear_code, LZ_MAX_BITS);
 					BITS = code_size + 1;
 					ResetHashtable();
 					next_code = clear_code + 1;
@@ -285,7 +290,7 @@ GIFSave::WriteGIFImageData()
 	OutputCode(string_code, BITS);
 	OutputCode(end_code, BITS);
 	OutputCode(0, BITS, true);
-	char t = 0x00;
+	char t = BLOCK_TERMINATOR;
 	output->Write(&t, 1);
 	free(code_value);
 	free(prefix_code);
@@ -531,7 +536,7 @@ GIFSave::InitFrame()
 	max_code = (1 << BITS) - 1;
 	string_code = 0;
 	character = 0;
-	table_size = 1 << 12;
+	table_size = 1 << LZ_MAX_BITS;
 
 	bit_count = 0;
 	bit_buffer = 0;