crenshaw: added brakets

4 files changed, 27 insertions, 18 deletions

diff --git a/crenshaw/README b/crenshaw/README
index 7bad3b5..f95033f 100644
--- a/crenshaw/README
+++ b/crenshaw/README
@@ -1,14 +1,15 @@
-fpc main.pas 
-./main < test.prog > test.asm
-nasm -f elf32 test.asm
-gcc -m32 -march=i486 -ffreestanding -o test test.o
-objcopy -O binary --only-section=.text test test.bin
-ndisasm -b32 test.bin
-./test
+debugging
 
 #gdb ./test
 #(gdb) set disassemble-next-line on 
+#(gdb) display $eax
+#(gdb) display $ebx
 #(gdb) start
 #(gdb) si
 #(gdb) info registers
 
+links
+
+https://en.wikibooks.org/wiki/68000_Assembly
+https://en.wikipedia.org/wiki/X86_instruction_listings
+file:///media/sd/compilertests/doc/Intel 80x86 Assembly Language OpCodes.html#div
diff --git a/crenshaw/build.sh b/crenshaw/build.sh
new file mode 100755
index 0000000..5ef9938
--- /dev/null
+++ b/crenshaw/build.sh
@@ -0,0 +1,7 @@
+fpc main.pas 
+./main < test.prog > test.asm
+nasm -f elf32 test.asm
+gcc -m32 -march=i486 -ffreestanding -o test test.o
+objcopy -O binary --only-section=.text test test.bin
+ndisasm -b32 test.bin
+./test
diff --git a/crenshaw/main.pas b/crenshaw/main.pas
index 12fec6e..04a3624 100644
--- a/crenshaw/main.pas
+++ b/crenshaw/main.pas
@@ -72,10 +72,17 @@ begin;
 	WriteLn(s+':');
 end;
 
+procedure Expression; Forward;
+
 procedure Factor;
 begin
-	EmitLn('mov eax, ' + GetNum);
-	EmitLn('push eax');
+	if Look = '(' then begin
+		Match('(');
+		Expression;
+		Match(')');
+	end
+	else
+		EmitLn('mov eax, ' + GetNum);
 end;
 
 procedure Multiply;
@@ -83,9 +90,7 @@ begin
 	Match('*');
 	Factor;
 	EmitLn('pop ebx');
-	EmitLn('pop eax');
 	EmitLn('mul ebx');
-	EmitLn('push eax');
 end;
 
 procedure Divide;
@@ -93,9 +98,7 @@ begin
 	Match('/');
 	Factor;
 	EmitLn('pop ebx');
-	EmitLn('pop eax');
 	EmitLn('div ebx');
-	EmitLn('push eax');
 end;
 
 procedure Term;
@@ -103,6 +106,7 @@ begin
 	Factor;
 	while Look in ['*', '/'] do
 	begin
+		EmitLn('push eax');
 		case Look of
                         '*': Multiply;
                         '/': Divide;
@@ -116,9 +120,7 @@ begin;
 	Match('+');
 	Term;
 	Emitln('pop ebx');
-	EmitLn('pop eax');
 	EmitLn('add eax, ebx');
-	EmitLn('push eax');
 end;
 
 procedure Subtract;
@@ -126,9 +128,7 @@ begin;
 	Match('-');
 	Term;
 	EmitLn('pop ebx');
-	EmitLn('pop eax');
 	EmitLn('sub eax, ebx');
-	EmitLn('push eax');
 end;
 
 procedure Expression;
@@ -136,6 +136,7 @@ begin
 	Term;
 	while Look in ['+', '-'] do
 	begin
+		EmitLn('push eax');
 		case Look of
 			'+': Add;
 			'-': Subtract;
diff --git a/crenshaw/test.prog b/crenshaw/test.prog
index 95b87fe..a1d75c4 100644
--- a/crenshaw/test.prog
+++ b/crenshaw/test.prog
@@ -1,2 +1,2 @@
-4+4*3/2-3
+(4+4)*3/2-3