add headers

Author: MESYETI

source/app.d

@@ -35,6 +35,7 @@ Flags:
 	-d         - Enables debug symbols (if available)
 	-l LIB     - Links LIB with the linker (if available)
 	-dv VER    - Disables VER
+	-h FILE    - Puts the contents of FILE at the top of the assembly output
 
 Backends:
 	rm86    - Real mode x86 and MS-DOS
@@ -67,6 +68,7 @@ int main(string[] args) {
 	bool            exportSymbols;
 	string[]        link;
 	string[]        disabled;
+	string          header;
 
 	for (size_t i = 1; i < args.length; ++ i) {
 		if (args[i][0] == '-') {
@@ -204,6 +206,21 @@ int main(string[] args) {
 					disabled ~= args[i];
 					break;
 				}
+				case "-h": {
+					++ i;
+					if (i >= args.length) {
+						stderr.writeln("-h expects FILE argument");
+						return 1;
+					}
+
+					if (header != "") {
+						stderr.writeln("Header set multiple times");
+						return 1;
+					}
+
+					header = args[i];
+					break;
+				}
 				default: {
 					stderr.writefln("Unknown flag '%s'", args[i]);
 					return 1;
@@ -220,6 +237,21 @@ int main(string[] args) {
 		}
 	}
 
+	if (header == "") {
+		header = backend.DefaultHeader();
+	}
+	else {
+		try {
+			header = readText(header);
+		}
+		catch (Exception e) {
+			stderr.writefln("%s: %s", header, e.msg);
+			return 1;
+		}
+	}
+
+	backend.output = header ~ '\n';
+
 	if (file == "") {
 		stderr.writeln("No source files");
 		return 1;

source/backends/linux86.d

@@ -168,6 +168,8 @@ class BackendLinux86 : CompilerBackend {
 
 	override long MaxInt() => -1;
 
+	override string DefaultHeader() => "";
+
 	override void BeginMain() {
 		output ~= "__calmain:\n";
 	}

source/backends/rm86.d

@@ -142,6 +142,8 @@ class BackendRM86 : CompilerBackend {
 
 	override long MaxInt() => 0xFFFF;
 
+	override string DefaultHeader() => "";
+
 	override void BeginMain() {
 		output ~= "__calmain:\n";
 	}

source/backends/uxn.d

@@ -114,6 +114,11 @@ class BackendUXN : CompilerBackend {
 
 	override long MaxInt() => 0xFFFF;
 
+	override string DefaultHeader() => "
+		|0 @vsp $2 @arraySrc $2 @arrayDest $2
+		|10 @Console &vector $2 &read $1 &pad $5 &write $1 &error $1
+	";
+
 	override void NewConst(string name, long value, ErrorInfo error = ErrorInfo.init) {
 		consts[name] = Constant(new IntegerNode(error, value));
 	}
@@ -148,7 +153,6 @@ class BackendUXN : CompilerBackend {
 
 	override void Init() {
 		output ~= "|0 @vsp $2 @arraySrc $2 @arrayDest $2\n";
-		output ~= "|00 @System &vector $2 &pad $6 &r $2 &g $2 &b $2\n";
 		output ~= "|10 @Console &vector $2 &read $1 &pad $5 &write $1 &error $1\n";
 		output ~= "|100\n";
 		output ~= "@on-reset\n";

source/backends/y32.d

@@ -117,6 +117,8 @@ class BackendY32 : CompilerBackend {
 
 	override long MaxInt() => 0xFFFFFFFF;
 
+	override string DefaultHeader() => "";
+
 	override void NewConst(string name, long value, ErrorInfo error = ErrorInfo.init) {
 		consts[name] = Constant(new IntegerNode(error, value));
 	}

source/compiler.d

@@ -23,6 +23,7 @@ class CompilerBackend {
 	abstract string[] FinalCommands();
 	abstract long     MaxInt();
 	abstract void     NewConst(string name, long value, ErrorInfo error);
+	abstract string   DefaultHeader();
 
 	abstract void BeginMain();