Initial code commit.

src/bytecode.h

@@ -0,0 +1,70 @@
+#ifndef FUN_BYTECODE_H
+#define FUN_BYTECODE_H
+
+#include <stdint.h>
+#include "value.h"
+
+// VM opcodes
+typedef enum {
+    OP_NOP,
+    OP_LOAD_CONST,     // operand = constant index
+    OP_LOAD_LOCAL,     // operand = local slot index
+    OP_STORE_LOCAL,    // operand = local slot index
+
+    OP_LOAD_GLOBAL,    //
+    OP_STORE_GLOBAL,   //
+
+    OP_ADD,   //
+    OP_SUB,   //
+    OP_MUL,   //
+    OP_DIV,   //
+
+    OP_LT,       // a < b -> push 1/0
+    OP_LTE,      // a <= b -> push 1/0
+    OP_GT,       // a > b -> push 1/0
+    OP_GTE,      // a >= b -> push 1/0
+    OP_EQ,       // a == b -> push 1/0
+    OP_NEQ,      // a != b -> push 1/0
+
+    OP_POP,            // discard top of stack
+    OP_JUMP,           // unconditional jump
+    OP_JUMP_IF_FALSE,  // jump if top of stack is false (0)
+
+    OP_CALL,           // operand = arg count; pops fn + args and enters fn
+    OP_RETURN,         // pop optional return value and return to caller
+
+    OP_PRINT,
+    OP_HALT,
+
+    // add after existing opcodes
+    OP_MOD,          // a % b
+    OP_AND,      // logical AND
+    OP_OR,       // logical OR
+    OP_NOT,      // logical NOT
+
+    OP_DUP,          // duplicate top of stack
+    OP_SWAP,         // swap top two stack values
+} OpCode;
+
+typedef struct {
+    OpCode op;
+    int32_t operand;
+} Instruction;
+
+typedef struct Bytecode {
+    Instruction *instructions;
+    int instr_count;
+
+    Value *constants;
+    int const_count;
+} Bytecode;
+
+// constructors / manipulation
+Bytecode *bytecode_new(void);
+int bytecode_add_constant(Bytecode *bc, Value v); /* stores copy */
+int bytecode_add_instruction(Bytecode *bc, OpCode op, int32_t operand);
+void bytecode_set_operand(Bytecode *bc, int idx, int32_t operand); /* patching */
+void bytecode_free(Bytecode *bc);
+
+#endif
+