a first tutorial2 expression output

3 files changed, 56 insertions, 1 deletions

diff --git a/crenshaw/README b/crenshaw/README
new file mode 100644
index 0000000..1047944
--- /dev/null
+++ b/crenshaw/README
@@ -0,0 +1,4 @@
+fpc main.pas 
+./main < test.prog > test.asm
+nasm test.asm -f bin -o test.bin
+ndisasm -b32 test.bin
diff --git a/crenshaw/main.pas b/crenshaw/main.pas
index 3adc53b..a5f42ae 100644
--- a/crenshaw/main.pas
+++ b/crenshaw/main.pas
@@ -63,9 +63,58 @@ end;
 
 procedure EmitLn(s : string);
 begin
-	WriteLn;
 	Emit(s);
+	WriteLn;
+end;
+
+
+procedure Term;
+begin
+	EmitLn('mov eax, ' + GetNum);
+end;
+
+procedure Add;
+begin;
+	Match('+');
+	Term;
+	EmitLn('add eax, ebx');
+end;
+
+procedure Subtract;
+begin;
+	Match('-');
+	Term;
+	EmitLn('sub eax, ebx');
+end;
+
+procedure Expression;
+begin
+	Term;
+	EmitLn('mov ebx, eax');
+	case Look of
+		'+': Add;
+		'-': Subtract;
+	else Expected('+/-');
+	end;
+end;
+
+procedure Init;
+begin
+	GetChar;
+end;
+
+procedure Prologue;
+begin
+	EmitLn('[bits 32]');
+end;
+
+procedure Epilogue;
+begin
 end;
 
 begin
+	Prologue;
+	Init;
+	Expression;
+	Epilogue;
 end.
diff --git a/crenshaw/test.prog b/crenshaw/test.prog
new file mode 100644
index 0000000..d6c68c4
--- /dev/null
+++ b/crenshaw/test.prog
@@ -0,0 +1,2 @@
+4+2
+