/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013, 2014 Damien P. George
 * Copyright (c) 2014 Paul Sokolovsky
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#ifndef MICROPY_INCLUDED_PY_BC_H
#define MICROPY_INCLUDED_PY_BC_H

#include "py/runtime.h"
#include "py/objfun.h"

// bytecode layout:
//
//  n_state         : var uint
//  n_exc_stack     : var uint
//  scope_flags     : byte
//  n_pos_args      : byte          number of arguments this function takes
//  n_kwonly_args   : byte          number of keyword-only arguments this function takes
//  n_def_pos_args  : byte          number of default positional arguments
//
//  code_info_size  : var uint |    code_info_size counts bytes in this chunk
//  simple_name     : var qstr |
//  source_file     : var qstr |
//  <line number info>         |
//  <word alignment padding>   |    only needed if bytecode contains pointers
//
//  local_num0      : byte     |
//  ...             : byte     |
//  local_numN      : byte     |    N = num_cells
//  255             : byte     |    end of list sentinel
//  <bytecode>                 |
//
//
// constant table layout:
//
//  argname0        : obj (qstr)
//  ...             : obj (qstr)
//  argnameN        : obj (qstr)    N = num_pos_args + num_kwonly_args
//  const0          : obj
//  constN          : obj

// Sentinel value for mp_code_state_t.exc_sp_idx
#define MP_CODE_STATE_EXC_SP_IDX_SENTINEL ((uint16_t)-1)

// To convert mp_code_state_t.exc_sp_idx to/from a pointer to mp_exc_stack_t
#define MP_CODE_STATE_EXC_SP_IDX_FROM_PTR(exc_stack, exc_sp) ((exc_sp) + 1 - (exc_stack))
#define MP_CODE_STATE_EXC_SP_IDX_TO_PTR(exc_stack, exc_sp_idx) ((exc_stack) + (exc_sp_idx) - 1)

typedef struct _mp_bytecode_prelude_t {
    uint n_state;
    uint n_exc_stack;
    uint scope_flags;
    uint n_pos_args;
    uint n_kwonly_args;
    uint n_def_pos_args;
    qstr qstr_block_name;
    qstr qstr_source_file;
    const byte *line_info;
    const byte *locals;
    const byte *opcodes;
} mp_bytecode_prelude_t;

// Exception stack entry
typedef struct _mp_exc_stack_t {
    const byte *handler;
    // bit 0 is currently unused
    // bit 1 is whether the opcode was SETUP_WITH or SETUP_FINALLY
    mp_obj_t *val_sp;
    // Saved exception
    mp_obj_base_t *prev_exc;
} mp_exc_stack_t;

typedef struct _mp_code_state_t {
    // The fun_bc entry points to the underlying function object that is being executed.
    // It is needed to access the start of bytecode and the const_table.
    // It is also needed to prevent the GC from reclaiming the bytecode during execution,
    // because the ip pointer below will always point to the interior of the bytecode.
    mp_obj_fun_bc_t *fun_bc;
    const byte *ip;
    mp_obj_t *sp;
    uint16_t n_state;
    uint16_t exc_sp_idx;
    mp_obj_dict_t *old_globals;
    #if MICROPY_STACKLESS
    struct _mp_code_state_t *prev;
    #endif
    #if MICROPY_PY_SYS_SETTRACE
    struct _mp_code_state_t *prev_state;
    struct _mp_obj_frame_t *frame;
    #endif
    // Variable-length
    mp_obj_t state[0];
    // Variable-length, never accessed by name, only as (void*)(state + n_state)
    //mp_exc_stack_t exc_state[0];
} mp_code_state_t;

mp_uint_t mp_decode_uint(const byte **ptr);
mp_uint_t mp_decode_uint_value(const byte *ptr);
const byte *mp_decode_uint_skip(const byte *ptr);

mp_vm_return_kind_t mp_execute_bytecode(mp_code_state_t *code_state, volatile mp_obj_t inject_exc);
mp_code_state_t *mp_obj_fun_bc_prepare_codestate(mp_obj_t func, size_t n_args, size_t n_kw, const mp_obj_t *args);
void mp_setup_code_state(mp_code_state_t *code_state, size_t n_args, size_t n_kw, const mp_obj_t *args);
void mp_bytecode_print(const void *descr, const byte *code, mp_uint_t len, const mp_uint_t *const_table);
void mp_bytecode_print2(const byte *code, size_t len, const mp_uint_t *const_table);
const byte *mp_bytecode_print_str(const byte *ip);
#define mp_bytecode_print_inst(code, const_table) mp_bytecode_print2(code, 1, const_table)

// Helper macros to access pointer with least significant bits holding flags
#define MP_TAGPTR_PTR(x) ((void*)((uintptr_t)(x) & ~((uintptr_t)3)))
#define MP_TAGPTR_TAG0(x) ((uintptr_t)(x) & 1)
#define MP_TAGPTR_TAG1(x) ((uintptr_t)(x) & 2)
#define MP_TAGPTR_MAKE(ptr, tag) ((void*)((uintptr_t)(ptr) | (tag)))

#if MICROPY_PERSISTENT_CODE_LOAD || MICROPY_PERSISTENT_CODE_SAVE

uint mp_opcode_format(const byte *ip, size_t *opcode_size, bool count_var_uint);

#endif

static inline size_t mp_bytecode_get_source_line(const byte *line_info, size_t bc_offset) {
    size_t source_line = 1;
    size_t c;
    while ((c = *line_info)) {
        size_t b, l;
        if ((c & 0x80) == 0) {
            // 0b0LLBBBBB encoding
            b = c & 0x1f;
            l = c >> 5;
            line_info += 1;
        } else {
            // 0b1LLLBBBB 0bLLLLLLLL encoding (l's LSB in second byte)
            b = c & 0xf;
            l = ((c << 4) & 0x700) | line_info[1];
            line_info += 2;
        }
        if (bc_offset >= b) {
            bc_offset -= b;
            source_line += l;
        } else {
            // found source line corresponding to bytecode offset
            break;
        }
    }
    return source_line;
}

#endif // MICROPY_INCLUDED_PY_BC_H