.

TODO.md

@@ -23,7 +23,7 @@ Decisions:
   - [x] Execution loop (fast)
 - [ ] VM operations
   - [x] Expressions
-  - [ ] Local variables
+  - [x] Local variables
   - [ ] Functions
     - [ ] With parameters
   - [ ] Control flow

lib/tyche.h

@@ -16,7 +16,7 @@ typedef enum {
     T_ERR_TABLE_KEY_NOT_FOUND = -20,
     T_ERR_ASSEMBLER_SYNTAX_ERROR = -30,
     T_ERR_BYTECODE_TOO_SMALL = -40, T_ERR_BYTECODE_INVALID_MAGIC = -41,
-    T_ERR_TYPE_UNEXPECTED = -50, T_ERR_INVALID_OPCODE = -51, T_ERR_EXPR_INCORRECT_TYPES = -52,
+    T_ERR_TYPE_UNEXPECTED = -50, T_ERR_INVALID_OPCODE = -51, T_ERR_EXPR_INCORRECT_TYPES = -52, T_ERR_VALUE_OUT_OF_RANGE = -53,
 } TYC_RESULT;
 
 typedef enum {
@@ -39,6 +39,7 @@ TYC_RESULT tyc_call(TycheVM* t, uint16_t n_pars);
 
 // stack manipulation and query
 size_t     tyc_stack_size(TycheVM* T);
+void       tyc_pushnil(TycheVM* T);
 void       tyc_pushinteger(TycheVM* T, int32_t value);
 TYC_RESULT tyc_type(TycheVM* T, int idx, TYC_TYPE* type);
 TYC_RESULT tyc_tointeger(TycheVM* T, int idx, int32_t* value);

lib/vm.c

@@ -154,6 +154,11 @@ size_t tyc_stack_size(TycheVM* T)
     return stack_len(T->stack);
 }
 
+void tyc_pushnil(TycheVM* T)
+{
+    stack_push(T->stack, create_value_nil());
+}
+
 void tyc_pushinteger(TycheVM* T, int32_t value)
 {
     stack_push(T->stack, create_value_integer(value));
@@ -213,10 +218,49 @@ static TYC_RESULT step(TycheVM* T)
         // stack manipulation
         //
 
+        case TO_PUSHN:
+            tyc_pushnil(T);
+            break;
+
         case TO_PUSHI:
             tyc_pushinteger(T, inst.operand);
             break;
 
+        case TO_PUSHF:
+            if (inst.operand < 0 || inst.operand > code_n_functions(T->code))
+                return T_ERR_VALUE_OUT_OF_RANGE;
+            TRY(stack_push(T->stack, create_value_idx(TT_FUNCTION, inst.operand)))
+            break;
+
+        case TO_POP:
+            TRY(stack_pop(T->stack, NULL))
+            break;
+
+        //
+        // local variables
+        //
+
+        case TO_PUSHV:
+            if (inst.operand <= 0)
+                return T_ERR_VALUE_OUT_OF_RANGE;
+            for (size_t i = 0; i < inst.operand; ++i)
+                tyc_pushnil(T);
+            break;
+
+        case TO_SET:
+            if (inst.operand < 0)
+                return T_ERR_VALUE_OUT_OF_RANGE;
+            TRY(stack_pop(T->stack, &a))
+            TRY(stack_set(T->stack, inst.operand, a))
+            break;
+
+        case TO_DUPV:
+            if (inst.operand < 0)
+                return T_ERR_VALUE_OUT_OF_RANGE;
+            TRY(stack_at(T->stack, inst.operand, &a))
+            stack_push(T->stack, a);
+            break;
+
         //
         // expressions
         //

test/code-tests.lua

@@ -41,5 +41,20 @@ return {
             { parameters = { 20, 3, 'shr' },  name = "Shift right", expected_stack_top = 2},
             { parameters = { 20, 3, 'mod' },  name = "Modulo", expected_stack_top = 2 },
         },
-    }
+    },
+    {
+        name = "VM: local variables",
+        code = [[
+            .func 0
+                pushv 2         ; local a, b
+                pushi 3         ; a = 3
+                set   0
+                pushi 4         ; b = 4
+                set   1
+                dupv  0         ; return a
+                ret
+        ]],
+        expected_stack_size = 1,
+        expected_stack_top = 3,
+    },
 }

test/tests.c

@@ -462,6 +462,6 @@ static void run_assembly_test_template(lua_State* L)
         lua_pop(L, 1);
     }
 
-    lua_pop(L, 2);
+    lua_pop(L, 1);
     free(template);
 }