Elf2Mac: support custom entry points

Elf2Mac/Elf2Mac.cc

@@ -95,6 +95,7 @@ int main(int argc, char *argv[])
 	if(boost::algorithm::ends_with(argv[0], "ld"))
 	{
 		string outputFile = "a.out";
+        string entryPoint = "_start";
 		bool elf2mac = false;
 		bool flatoutput = false;
 		bool segments = true;
@@ -116,10 +117,21 @@ int main(int argc, char *argv[])
 			{
 				outputFile = (*p).substr(2);
 			}
-			else if(*p == "-elf2mac")
+			else if(*p == "-elf2mac" || *p == "--elf2mac")
 			{
 				elf2mac = true;
 			}
+            else if(*p == "-e")
+			{
+				++p;
+				if(p == e)
+					errx(EXIT_FAILURE, "-e missing argument");
+				entryPoint = *p;
+			}
+            else if(boost::algorithm::starts_with(*p, "-e"))
+            {
+                entryPoint = (*p).substr(2);
+            }
 			else if(*p == "--mac-flat")
 			{
 				elf2mac = true;
@@ -163,12 +175,11 @@ int main(int argc, char *argv[])
 				ofstream out(tmpfile);
 				if(segments)
 				{
-					segmentMap.CreateLdScript(out, stripMacsbug);
-					segmentMap.CreateLdScript(std::cout, stripMacsbug);
+					segmentMap.CreateLdScript(out, entryPoint, stripMacsbug);
 				}
 				else
 				{
-					CreateFlatLdScript(out, stripMacsbug);
+					CreateFlatLdScript(out, entryPoint, stripMacsbug);
 				}
 			}
 

Elf2Mac/Elf2Mac.h

@@ -21,7 +21,8 @@
 #define ELF2MAC_H
 
 #include <iosfwd>
+#include <string>
 
-void CreateFlatLdScript(std::ostream& out, bool stripMacsbug);
+void CreateFlatLdScript(std::ostream& out, std::string entryPoint, bool stripMacsbug);
 
 #endif // ELF2MAC_H

Elf2Mac/LdScript.cc

@@ -28,7 +28,7 @@
 using std::string;
 
 const char * scriptStart = R"ld(/* ld script for Elf2Mac */
-ENTRY( _start )
+ENTRY( @entryPoint@ )
 SECTIONS
 {
 )ld";
@@ -45,7 +45,7 @@ const char * textSection = R"ld(/* ld script for Elf2Mac */
         SHORT(DEFINED(__break_on_entry) ? 0xA9FF : 0x4e71);
         LONG(0x61000002); /* bsr *+2 */
         SHORT(0x0697); /* addi.l #_, (a7) */
-        LONG(_start - _entry_trampoline - 6);
+        LONG(@entryPoint@ - _entry_trampoline - 6);
 
         PROVIDE(_start = .); /* fallback entry point to a safe spot - needed for libretro bootstrap */
         Retro68InitMultisegApp = .; /* override this for the single-segment case */
@@ -181,16 +181,16 @@ const char * scriptEnd = R"ld(
 )ld";
 
 
-void CreateFlatLdScript(std::ostream& out, bool stripMacsbug)
+void CreateFlatLdScript(std::ostream& out, string entryPoint, bool stripMacsbug)
 {
 	out << "_MULTISEG_APP = 0;\n";
-	out << scriptStart;
+	out << boost::replace_all_copy<string>(scriptStart, "@entryPoint@", entryPoint);
 	if(stripMacsbug)
 	{
 		out << "\t.strippedmacsbugnames 0 (NOLOAD) : { *(.text.*.macsbug) }\n";
 		out << "\t. = 0;\n";
 	}
-	out << textSection << scriptEnd;
+	out << boost::replace_all_copy<string>(textSection, "@entryPoint@", entryPoint) << scriptEnd;
 }
 
 
@@ -211,13 +211,13 @@ void SegmentInfo::WriteFiltersKeep(std::ostream &out, string section)
 	}
 }
 
-void SegmentInfo::CreateLdScript(std::ostream &out)
+void SegmentInfo::CreateLdScript(std::ostream &out, string entryPoint)
 {
 	out << "\t.code" << id << " : {\n";
 	out << "\t\tFILL(0x4E71);\n";
 	if(id == 1)
 	{
-		out << R"ld(
+		out << boost::replace_all_copy<string>(R"ld(
 		_stext = .;
 		FILL(0x4E71);
 		PROVIDE(_rsrc_start = .);
@@ -226,14 +226,14 @@ void SegmentInfo::CreateLdScript(std::ostream &out)
 		SHORT(DEFINED(__break_on_entry) ? 0xA9FF : 0x4e71);
 		LONG(0x61000002);	/* bsr *+2 */
 		SHORT(0x0697); /* addi.l #_, (a7) */
-		LONG(_start - _entry_trampoline - 6);
+		LONG(@entryPoint@ - _entry_trampoline - 6);
 		PROVIDE(_start = .);  /* fallback entry point to a safe spot - needed for libretro bootstrap */
 		SHORT(0x4e75); /* rts */
 
 		FILL(0);
 		*(.relocvars)
 		FILL(0x4E71);
-)ld";
+)ld", "@entryPoint@", entryPoint);
 	}
 	WriteFilters(out, ".text");
 
@@ -284,10 +284,10 @@ void SegmentInfo::CreateLdScript(std::ostream &out)
 
 }
 
-void SegmentMap::CreateLdScript(std::ostream &out, bool stripMacsbug)
+void SegmentMap::CreateLdScript(std::ostream &out, string entryPoint, bool stripMacsbug)
 {
 	out << "_MULTISEG_APP = 1;\n";
-	out << scriptStart;
+	out << boost::replace_all_copy<string>(scriptStart, "@entryPoint@", entryPoint);
 	if(stripMacsbug)
 	{
 		out << "\t.strippedmacsbugnames 0 (NOLOAD) : { *(.text.*.macsbug) }\n";
@@ -295,7 +295,7 @@ void SegmentMap::CreateLdScript(std::ostream &out, bool stripMacsbug)
 	}
 	for(SegmentInfo& seg: segments)
 	{
-		seg.CreateLdScript(out);
+		seg.CreateLdScript(out, entryPoint);
 	}
 
 	out << scriptEnd;

Elf2Mac/SegmentMap.h

@@ -39,7 +39,7 @@ public:
 
 	void WriteFilters(std::ostream& out, std::string section);
 	void WriteFiltersKeep(std::ostream& out, std::string section);
-	void CreateLdScript(std::ostream& out);
+	void CreateLdScript(std::ostream& out, std::string entryPoint);
 };
 
 class SegmentMap
@@ -49,7 +49,7 @@ public:
 	SegmentMap();
 	SegmentMap(std::string filename);
 
-	void CreateLdScript(std::ostream& out, bool stripMacsbug);
+	void CreateLdScript(std::ostream& out, std::string entryPoint, bool stripMacsbug);
 	std::string GetSegmentName(int id);
 };