crenshaw: added two assignments (just for testing)

extended emul to properly handle hash collisions in the instruction map

4 files changed, 65 insertions, 22 deletions

diff --git a/crenshaw/README b/crenshaw/README
index 643d4b5..74f0a20 100644
--- a/crenshaw/README
+++ b/crenshaw/README
@@ -26,6 +26,12 @@ TODO: kapstone to actually assemble the code, currently
 we use nasm to produce a binary and we use capstone to decode
 it. What's better?
 
+TODO: architecture-independend 'hlt' instruction to stop
+emulation at the right point?
+
+TODO: we would like to set flavours of the CPU, a real i486
+instruction set or enable/disable certain features like SSE2.
+
 links
 -----
 
@@ -122,3 +128,5 @@ tutor3, getchar/white space handling
 Interestingly he starts with a non-scanner, parser-only approach and
 introduces lexing stuff afterwards.
 
+Checking for LF feels hacky.
+
diff --git a/crenshaw/emul.c b/crenshaw/emul.c
index 2de6aa4..104cac6 100644
--- a/crenshaw/emul.c
+++ b/crenshaw/emul.c
@@ -166,23 +166,35 @@ int main( int argc, char *argv[] )
 	// opcode when reaching a certain EIP address
 	int N = nof_instrs * 2;
 	int p = compute_p( N );
-	N = ( p << N );
-	int *instrs_map = calloc( 1, N );
-AGAIN:
+	N = ( 1 << p );
+	int *instrs_map = calloc( N, sizeof( int ) * 2 );
 	for( int i = 0; i < nof_instrs; i++ ) {
-		int n = mul_hash( instrs[i].address, p );
-		assert( n < N );
-		if( instrs_map[n] != 0 ) {
-			fprintf( stderr, "WARN: hash collision in instruction map, reallocating hash..\n" );
-			assert( N < 31 );
-			N <<= 1;
-			instrs_map = realloc( instrs_map, N );
-			goto AGAIN;
+		int n = mul_hash( instrs[i].address, p ) * 2;
+		assert( n < 2 * N );
+		while( instrs_map[n+1] != 0 ) {
+			n += 2;
+			if( n >= 2 * N ) {
+				n = 0;
+			}
 		}
 		instrs_map[n] = i;
-		printf( "map %08X %d %d\n", instrs[i].address, n, i );
+		instrs_map[n+1] = instrs[i].address;
 	}
-	
+
+	// verify the EIP to instr index map has been constructed correctly
+	for( int i = 0; i < nof_instrs; i++ ) {
+		uint64_t a = instrs[i].address;
+		int n = mul_hash( a, p ) * 2;
+		while( instrs_map[n+1] != a ) {
+			n += 2;
+			if( n >= 2 * N ) {
+				n = 0;
+			}
+		}
+		n = instrs_map[n];
+		assert( n == i );
+	}
+		
 	// write executable code to emulator
 	uerr = uc_mem_write( uc, CODE_START, code, code_size );
 	if( uerr != UC_ERR_OK ) {
@@ -199,15 +211,23 @@ AGAIN:
 	//~ cs_insn *instr = cs_malloc( cs );	
 	bool terminate = false;
 	int iteration = 1;
-	
+
+	printf( "Single step execution:\n" );
 	while( !terminate ) {
 
 		printf( "-- iteration %d\n", iteration );
 		iteration++;
 
-		int n = instrs_map[mul_hash( address, p )];
+		int n = mul_hash( address, p ) * 2;
+		while( instrs_map[n+1] != address ) {
+			n += 2;
+			if( n >= 2 * N ) {
+				n = 0;
+			}
+		}
+		n = instrs_map[n];
 
-		printf( "%04X (%d): ", (unsigned int)address, n );
+		printf( "%04X: ", (unsigned int)address );
 
 		for( int i = 0; i < instrs[n].size; i++ ) {
 			printf( "%02X", instrs[n].bytes[i] );
diff --git a/crenshaw/main.pas b/crenshaw/main.pas
index 339484c..0694ad4 100644
--- a/crenshaw/main.pas
+++ b/crenshaw/main.pas
@@ -2,7 +2,7 @@ program Main;
 
 const
 	TAB = ^I;
-	CR = ^M;
+	LF = ^J;
 
 var Look : char;
 
@@ -101,7 +101,7 @@ begin
 		if symbols[i].name = name then
 			found := true;
 	end;
-	if i = 26 then Abort('Table of variable symbols overflowed');
+	if i = 26 then Abort('Table of symbols overflowed');
 	if not found then begin
 		symbols[nof_symbols].name := name;
 		symbols[nof_symbols].sym_type := sym_type;
@@ -117,10 +117,10 @@ begin
 		Match('(');
 		Match(')');
 		RememberName(name, functionType);
-		EmitLn('call ' + name);
+		EmitLn('call '+name);
 	end else begin
 		RememberName(name, variableType);
-		EmitLn('mov eax, [' + name + ']');
+		EmitLn('mov eax,['+name+']');
 	end;
 end;
 
@@ -201,6 +201,17 @@ begin
 	end;
 end;
 
+procedure Assignment;
+var name : char;
+begin
+	name := GetName;
+	RememberName(name, variableType);
+	Match('=');
+	Expression;
+	EmitLn('lea ebx,['+name+']');
+	EmitLn('mov [ebx],eax');
+end;
+
 procedure Init;
 begin
 	nof_symbols := 0;
@@ -256,6 +267,9 @@ end;
 begin
 	Prologue;
 	Init;
-	Expression;
+	Assignment;
+	Match(LF);
+	Assignment;
+	if Look <> LF then Expected('Newline');
 	Epilogue;
 end.
diff --git a/crenshaw/test.prog b/crenshaw/test.prog
index 880418a..2be58d7 100644
--- a/crenshaw/test.prog
+++ b/crenshaw/test.prog
@@ -1 +1,2 @@
-(4+4)*3/2-3+a-b*f()
+x=(4+4)*3/2-3+a-b*f()
+y=x*2