bytecode2 (#2)

Reviewed-on: #2

src/bytecode/bytecode.hh

@@ -0,0 +1,62 @@
+#ifndef TYCHE_BYTECODE_HH
+#define TYCHE_BYTECODE_HH
+
+#include "bytearray.hh"
+#include "bytecodeprototype.hh"
+
+namespace tyche {
+
+class Bytecode {
+public:
+    explicit Bytecode(ByteArray ba);
+
+    [[nodiscard]] uint32_t n_constants() const;
+    [[nodiscard]] uint32_t n_functions() const;
+
+    [[nodiscard]] int32_t     get_constant_int(uint32_t idx) const;
+    [[nodiscard]] float       get_constant_float(uint32_t idx) const;
+    [[nodiscard]] std::string get_constant_string(uint32_t idx) const;
+
+    struct FunctionDef { uint16_t n_params, locals; };
+    [[nodiscard]] FunctionDef get_function_def(uint32_t function_id) const;
+    [[nodiscard]] uint32_t    get_function_sz(uint32_t function_id) const;
+
+    [[nodiscard]] uint8_t                    get_code_byte(uint32_t function_id, uint32_t idx) const;
+    [[nodiscard]] std::pair<int32_t, size_t> get_code_int(uint32_t function_id, uint32_t idx) const;
+    [[nodiscard]] float                      get_code_float(uint32_t function_id, uint32_t idx) const;
+
+    // TODO - debugging info
+
+    [[nodiscard]] static ByteArray generate(BytecodePrototype const& bp);
+
+private:
+    ByteArray byte_array_;      // the actual data
+
+    static constexpr uint8_t  BYTECODE_VERSION = 1;
+    static constexpr uint32_t MAGIC_NUMBER = 0x74b3c138;
+    static constexpr uint32_t TOC_START = 16,
+                              TOC_N_RECORDS = 8,
+                              TOC_RECORD_SZ = 8,
+                              TOC_SZ = TOC_N_RECORDS * TOC_RECORD_SZ;
+    static constexpr uint32_t CONST_IDX_START = TOC_START + TOC_SZ,
+                              CONST_RECORD_SZ = 4;
+    static constexpr uint32_t FUNCTION_RECORD_SZ = 12;
+
+    enum Sections { SEC_CONST_IDX = 0, SEC_FUNC_IDX = 1, SEC_CONST_DATA = 2, SEC_CODE = 3 };
+
+    // caching for faster reading of data
+    struct Cache {
+        uint32_t constants_idx_addr;
+        uint16_t n_constants;
+        uint32_t constants_start_addr;
+        uint32_t functions_idx_addr;
+        uint32_t n_functions;
+        std::vector<uint32_t> function_addr;
+        std::vector<uint32_t> function_sz;
+    };
+    Cache cache_ {};
+};
+
+}
+
+#endif //TYCHE_BYTECODE_HH