diff --git a/stix/lib/Stix.st b/stix/lib/Stix.st
index 2cb91c5..aa7c0a9 100644
--- a/stix/lib/Stix.st
+++ b/stix/lib/Stix.st
@@ -141,7 +141,6 @@
 
 #class SmallInteger(Number)
 {
-	
 }
 
 #class Boolean(Object)
diff --git a/stix/lib/comp.c b/stix/lib/comp.c
index fc4573e..15bdab4 100644
--- a/stix/lib/comp.c
+++ b/stix/lib/comp.c
@@ -1513,6 +1513,8 @@ static int emit_single_param_instruction (stix_t* stix, int cmd, stix_oow_t para
 
 		case BCODE_JUMP2_FORWARD:
 		case BCODE_JUMP2_BACKWARD:
+		case BCODE_PUSH_INTLIT:
+		case BCODE_PUSH_NEGINTLIT:
 			bc = cmd;
 			goto write_long;
 	}
@@ -1605,10 +1607,16 @@ static int emit_push_smint_literal (stix_t* stix, stix_ooi_t i)
 
 		case 2:
 			return emit_byte_instruction (stix, BCODE_PUSH_TWO);
-
-/* TODO: include some other numbers? like 3 */
 	}
 
+	if (i >= 0 && i <= MAX_CODE_PARAM)
+	{
+		return emit_single_param_instruction(stix, BCODE_PUSH_INTLIT, i);
+	}
+	else if (i < 0 && i >= -(stix_ooi_t)MAX_CODE_PARAM)
+	{
+		return emit_single_param_instruction(stix, BCODE_PUSH_NEGINTLIT, -i);
+	}
 
 	if (add_literal(stix, STIX_OOP_FROM_SMINT(i), &index) <= -1 ||
 	    emit_single_param_instruction(stix, BCODE_PUSH_LITERAL_0, index) <= -1) return -1;
@@ -2161,7 +2169,7 @@ static int compile_method_primitive (stix_t* stix)
 	/* 
 	 * method-primitive := "<"  "primitive:" integer ">"
 	 */
-	int prim_no;
+	stix_ooi_t prim_no;
 	const stix_uch_t* ptr, * end;
 
 	if (!is_token_binsel(stix, VOCA_LT)) 
@@ -2188,14 +2196,14 @@ static int compile_method_primitive (stix_t* stix)
 		return -1;
 	}
 
-/*TODO: more checks the validity of the primitive number. support nubmer with radix and so on support more extensive syntax */
+/*TODO: more checks the validity of the primitive number. support number with radix and so on support more extensive syntax. support primitive name, not number*/
 	ptr = stix->c->tok.name.ptr;
 	end = ptr + stix->c->tok.name.len;
 	prim_no = 0;
 	while (ptr < end && is_digitchar(*ptr)) 
 	{
 		prim_no = prim_no * 10 + (*ptr - '0');
-		if (prim_no > MAX_CODE_PRIMNO)
+		if (!STIX_OOI_IN_PREAMBLE_INDEX_RANGE(prim_no))
 		{
 			set_syntax_error (stix, STIX_SYNERR_PRIMNO, &stix->c->tok.loc, &stix->c->tok.name);
 			return -1;
@@ -3569,7 +3577,7 @@ static int add_compiled_method (stix_t* stix)
 			{
 				preamble_code = STIX_METHOD_PREAMBLE_RETURN_RECEIVER;
 			}
-			else if (stix->c->mth.code.len >= 2 && stix->c->mth.code.ptr[1] == BCODE_RETURN_STACKTOP)
+			else if (stix->c->mth.code.len > 1 && stix->c->mth.code.ptr[1] == BCODE_RETURN_STACKTOP)
 			{
 				switch (stix->c->mth.code.ptr[0])
 				{
@@ -3609,20 +3617,6 @@ static int add_compiled_method (stix_t* stix)
 						preamble_index = 2;
 						break;
 
-/*
-					case BCODE_PUSH_LITERAL_0:
-					case BCODE_PUSH_LITERAL_1:
-					case BCODE_PUSH_LITERAL_2:
-					case BCODE_PUSH_LITERAL_3:
-					case BCODE_PUSH_LITERAL_4:
-					case BCODE_PUSH_LITERAL_5:
-					case BCODE_PUSH_LITERAL_6:
-					case BCODE_PUSH_LITERAL_7:
-						 TODO: check the literal frame. if the value in the literal frame is a small integer within the premable index range,
-							 convert ito to PREAMBEL_RETURN_INDEX or NEGINDEX 
-						break;
-*/
-
 					case BCODE_PUSH_INSTVAR_0:
 					case BCODE_PUSH_INSTVAR_1:
 					case BCODE_PUSH_INSTVAR_2:
@@ -3634,29 +3628,39 @@ static int add_compiled_method (stix_t* stix)
 						preamble_code = STIX_METHOD_PREAMBLE_RETURN_INSTVAR;
 						preamble_index = stix->c->mth.code.ptr[0] & 0x7; /* low 3 bits */
 						break;
-
-					
 				}
 			}
-			else if (stix->c->mth.code.ptr[0] == BCODE_PUSH_INSTVAR_X &&
+			else if (stix->c->mth.code.len > STIX_BCODE_LONG_PARAM_SIZE + 1 &&
 			         stix->c->mth.code.ptr[STIX_BCODE_LONG_PARAM_SIZE + 1] == BCODE_RETURN_STACKTOP)
 			{
 				int i;
-
-				STIX_ASSERT (stix->c->mth.code.len >= STIX_BCODE_LONG_PARAM_SIZE + 1);
-
-				preamble_code = STIX_METHOD_PREAMBLE_RETURN_INSTVAR;
-				preamble_index = 0;
-				for (i = 1; i <= STIX_BCODE_LONG_PARAM_SIZE; i++)
+				switch (stix->c->mth.code.ptr[0])
 				{
-					preamble_index = (preamble_index << 8) | stix->c->mth.code.ptr[i];
-					if (!STIX_OOI_IN_PREAMBLE_INDEX_RANGE(preamble_index))
-					{
-						/* the index got out of the range */
-						preamble_code = STIX_METHOD_PREAMBLE_NONE;
+					case BCODE_PUSH_INSTVAR_X:
+						preamble_code = STIX_METHOD_PREAMBLE_RETURN_INSTVAR;
+						goto set_preamble_index;
+
+					case BCODE_PUSH_INTLIT:
+						preamble_code = STIX_METHOD_PREAMBLE_RETURN_INDEX;
+						goto set_preamble_index;
+
+					case BCODE_PUSH_NEGINTLIT:
+						preamble_code = STIX_METHOD_PREAMBLE_RETURN_NEGINDEX;
+						goto set_preamble_index;
+
+					set_preamble_index:
 						preamble_index = 0;
-						break;
-					}
+						for (i = 1; i <= STIX_BCODE_LONG_PARAM_SIZE; i++)
+						{
+							preamble_index = (preamble_index << 8) | stix->c->mth.code.ptr[i];
+						}
+
+						if (!STIX_OOI_IN_PREAMBLE_INDEX_RANGE(preamble_index))
+						{
+							/* the index got out of the range */
+							preamble_code = STIX_METHOD_PREAMBLE_NONE;
+							preamble_index = 0;
+						}
 				}
 			}
 		}
diff --git a/stix/lib/exec.c b/stix/lib/exec.c
index 3a196ad..d9d6181 100644
--- a/stix/lib/exec.c
+++ b/stix/lib/exec.c
@@ -1410,28 +1410,18 @@ printf ("RETURN FALSE AT PREAMBLE\n");
 						ACTIVE_STACK_SETTOP (stix, stix->_false);
 						break;
 
-					case STIX_METHOD_PREAMBLE_RETURN_NEGINDEX:
-printf ("RETURN %d AT PREAMBLE\n", (int)-STIX_METHOD_GET_PREAMBLE_INDEX(preamble));
-						ACTIVE_STACK_POPS (stix, b1);
-						ACTIVE_STACK_SETTOP (stix, STIX_OOP_FROM_SMINT(-STIX_METHOD_GET_PREAMBLE_INDEX(preamble)));
-						break;
-
 					case STIX_METHOD_PREAMBLE_RETURN_INDEX:
 printf ("RETURN %d AT PREAMBLE\n", (int)STIX_METHOD_GET_PREAMBLE_INDEX(preamble));
 						ACTIVE_STACK_POPS (stix, b1);
 						ACTIVE_STACK_SETTOP (stix, STIX_OOP_FROM_SMINT(STIX_METHOD_GET_PREAMBLE_INDEX(preamble)));
 						break;
 
-#if 0
-					case STIX_METHOD_PREAMBLE_RETURN_ZERO:
-					case STIX_METHOD_PREAMBLE_RETURN_ONE:
-					case STIX_METHOD_PREAMBLE_RETURN_TWO:
-printf ("RETURN %d AT PREAMBLE\n", (int)(preamble_code - STIX_METHOD_PREAMBLE_RETURN_NEGONE - 1));
+					case STIX_METHOD_PREAMBLE_RETURN_NEGINDEX:
+printf ("RETURN %d AT PREAMBLE\n", (int)-STIX_METHOD_GET_PREAMBLE_INDEX(preamble));
 						ACTIVE_STACK_POPS (stix, b1);
-						ACTIVE_STACK_SETTOP (stix, STIX_OOP_FROM_SMINT(preamble_code - STIX_METHOD_PREAMBLE_RETURN_NEGONE - 1));
+						ACTIVE_STACK_SETTOP (stix, STIX_OOP_FROM_SMINT(-STIX_METHOD_GET_PREAMBLE_INDEX(preamble)));
 						break;
-#endif
-					
+
 					case STIX_METHOD_PREAMBLE_RETURN_INSTVAR:
 					{
 						stix_oop_oop_t rcv;
@@ -1539,6 +1529,18 @@ printf ("PUSH_TWO\n");
 				ACTIVE_STACK_PUSH (stix, STIX_OOP_FROM_SMINT(2));
 				break;
 
+			case BCODE_PUSH_INTLIT:
+				FETCH_PARAM_CODE_TO (stix, b1);
+				ACTIVE_STACK_PUSH (stix, STIX_OOP_FROM_SMINT(b1));
+printf ("PUSH_INTLIT %d\n", (int)b1);
+				break;
+
+			case BCODE_PUSH_NEGINTLIT:
+				FETCH_PARAM_CODE_TO (stix, b1);
+				ACTIVE_STACK_PUSH (stix, STIX_OOP_FROM_SMINT(-b1));
+printf ("PUSH_NEGINTLIT %d\n", (int)-b1);
+				break;
+
 			/* -------------------------------------------------------- */
 
 			case BCODE_DUP_STACKTOP:
diff --git a/stix/lib/stix-prv.h b/stix/lib/stix-prv.h
index ca9fe70..3038c08 100644
--- a/stix/lib/stix-prv.h
+++ b/stix/lib/stix-prv.h
@@ -30,7 +30,7 @@
 #include "stix.h"
 
 /* you can define this to either 1 or 2 */
-#define STIX_BCODE_LONG_PARAM_SIZE 1
+#define STIX_BCODE_LONG_PARAM_SIZE 2
 
 /* this is useful for debugging. stix_gc() can be called 
  * while stix has not been fully initialized when this is defined*/
@@ -488,16 +488,16 @@ struct stix_compiler_t
 #	define MAX_CODE_NARGS               (0xFFu)
 #	define MAX_CODE_NBLKARGS            (0xFFu)
 #	define MAX_CODE_NBLKTMPRS           (0xFFu)
-#	define MAX_CODE_PRIMNO              (0xFFFFu)
 #	define MAX_CODE_JUMP                (0xFFu)
+#	define MAX_CODE_PARAM               (0xFFu)
 #elif defined(STIX_BCODE_LONG_PARAM_SIZE) && (STIX_BCODE_LONG_PARAM_SIZE == 2)
 #	define MAX_CODE_INDEX               (0xFFFFu)
 #	define MAX_CODE_NTMPRS              (0xFFFFu)
 #	define MAX_CODE_NARGS               (0xFFFFu)
 #	define MAX_CODE_NBLKARGS            (0xFFFFu)
 #	define MAX_CODE_NBLKTMPRS           (0xFFFFu)
-#	define MAX_CODE_PRIMNO              (0xFFFFu)
 #	define MAX_CODE_JUMP                (0xFFFFu)
+#	define MAX_CODE_PARAM               (0xFFFFu)
 #else
 #	error Unsupported STIX_BCODE_LONG_PARAM_SIZE
 #endif
@@ -746,6 +746,7 @@ enum stix_bcode_t
 	BCODE_SEND_MESSAGE_X           = 0xF0, /* 240 */
 	BCODE_SEND_MESSAGE_TO_SUPER_X  = 0xF4, /* 244 */
 
+	/* -------------------------------------- */
 
 	BCODE_JUMP2_FORWARD            = 0xC5, /* 197 */
 	BCODE_JUMP2_BACKWARD           = 0xC9, /* 201 */
@@ -760,6 +761,9 @@ enum stix_bcode_t
 	BCODE_PUSH_ONE                 = 0x89, /* 137 */
 	BCODE_PUSH_TWO                 = 0x8A, /* 138 */
 
+	BCODE_PUSH_INTLIT              = 0xB1, /* 177 */
+	BCODE_PUSH_NEGINTLIT           = 0xB2, /* 178 */
+
 	/* UNUSED 0xE8 - 0xF8 */
 
 	BCODE_DUP_STACKTOP             = 0xF9,
diff --git a/stix/lib/stix.h b/stix/lib/stix.h
index 02c0bdd..5f5fe0c 100644
--- a/stix/lib/stix.h
+++ b/stix/lib/stix.h
@@ -616,9 +616,9 @@ struct stix_method_t
  *  1 - return self
  *  2 - return nil
  *  3 - return true
- *  4 - return false
- *  5 - return -index.
- *  6 - return index.
+ *  4 - return false 
+ *  5 - return index.
+ *  6 - return -index.
  *  7 - return instvar[index]
  *  8 - do primitive[index]
  */
@@ -631,8 +631,8 @@ struct stix_method_t
 #define STIX_METHOD_PREAMBLE_RETURN_NIL      2
 #define STIX_METHOD_PREAMBLE_RETURN_TRUE     3
 #define STIX_METHOD_PREAMBLE_RETURN_FALSE    4
-#define STIX_METHOD_PREAMBLE_RETURN_NEGINDEX 5
-#define STIX_METHOD_PREAMBLE_RETURN_INDEX    6
+#define STIX_METHOD_PREAMBLE_RETURN_INDEX    5
+#define STIX_METHOD_PREAMBLE_RETURN_NEGINDEX 6
 #define STIX_METHOD_PREAMBLE_RETURN_INSTVAR  7
 #define STIX_METHOD_PREAMBLE_PRIMITIVE       8