crenshaw: dynamic section of variables

2 files changed, 41 insertions, 4 deletions

diff --git a/crenshaw/main.pas b/crenshaw/main.pas
index 3e9e0a4..55189a7 100644
--- a/crenshaw/main.pas
+++ b/crenshaw/main.pas
@@ -79,14 +79,39 @@ end;
 
 procedure Expression; Forward;
 
+var
+	nof_names : integer;
+	names : array[0..26] of char;
+
+procedure RememberName(name : char);
+var
+	i : integer;
+	found : boolean;
+begin
+	found := false;
+	for i := 0 to nof_names do begin
+		if names[i] = name then
+			found := true;
+	end;
+	if i = 26 then Abort('Table of variable names overflowed');
+	if not found then begin
+		names[nof_names] := name;
+		inc(nof_names);
+	end;
+end;
+
 procedure Factor;
+var name : char;
 begin
 	if Look = '(' then begin
 		Match('(');
 		Expression;
 		Match(')');
-	end
-	else
+	end else if IsAlpha(Look) then begin
+		name := GetName;
+		RememberName(name);
+		EmitLn('mov eax, [' + name + ']');
+	end else
 		EmitLn('mov eax, ' + GetNum);
 end;
 
@@ -126,7 +151,7 @@ begin;
 	Match('+');
 	Term;
 	Emitln('pop ebx');
-	EmitLn('add eax, ebx');
+	EmitLn('add eax,ebx');
 end;
 
 procedure Subtract;
@@ -157,12 +182,14 @@ end;
 
 procedure Init;
 begin
+	nof_names := 0;
 	GetChar;
 end;
 
 procedure Prologue;
 begin
 	WriteLn('[bits 32]');
+	WriteLn('cpu 486');
 	WriteLn('org 0x1000000');
 {	WriteLn('section .text');
 	WriteLn('global main');
@@ -172,9 +199,19 @@ begin
 }
 end;
 
+procedure Variables;
+var i : integer;
+begin
+	for i := 0 to nof_names do begin
+		EmitLabel(names[i]);
+		EmitLn('dw 0');
+	end;
+end;
+
 procedure Epilogue;
 begin
 	EmitLn('hlt');
+	Variables;
 {
 	EmitLn('leave');
 	EmitLn('ret');
diff --git a/crenshaw/test.prog b/crenshaw/test.prog
index c208a59..339791d 100644
--- a/crenshaw/test.prog
+++ b/crenshaw/test.prog
@@ -1 +1 @@
-(4+4)*3/2-3
+(4+4)*3/2-3+a-b