/*
 * 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:
//
// func signature : var uint
// contains six values interleaved bit-wise as: xSSSSEAA [xFSSKAED repeated]
// x = extension another byte follows
// S = n_state - 1 number of entries in Python value stack
// E = n_exc_stack number of entries in exception stack
// F = scope_flags four bits of flags, MP_SCOPE_FLAG_xxx
// A = n_pos_args number of arguments this function takes
// K = n_kwonly_args number of keyword-only arguments this function takes
// D = n_def_pos_args number of default positional arguments
//
// prelude size : var uint
// contains two values interleaved bit-wise as: xIIIIIIC repeated
// x = extension another byte follows
// I = n_info number of bytes in source info section
// C = n_cells number of bytes/cells in closure section
//
// source info section:
// simple_name : var qstr
// source_file : var qstr
// <line number info>
//
// closure section:
// local_num0 : byte
// ... : byte
// local_numN : byte N = n_cells-1
//
// <word alignment padding> only needed if bytecode contains pointers
//
// <bytecode>
//
//
// constant table layout:
//
// argname0 : obj (qstr)
// ... : obj (qstr)
// argnameN : obj (qstr) N = num_pos_args + num_kwonly_args
// const0 : obj
// constN : obj

#define MP_BC_PRELUDE_SIG_ENCODE(S, E, scope, out_byte, out_env) \
 do { \
/*// Get values to store in prelude */ \
 size_t F = scope->scope_flags & MP_SCOPE_FLAG_ALL_SIG; \
 size_t A = scope->num_pos_args; \
 size_t K = scope->num_kwonly_args; \
 size_t D = scope->num_def_pos_args; \
 \
/* Adjust S to shrink range, to compress better */ \
 S -= 1; \
 \
/* Encode prelude */ \
/* xSSSSEAA */ \
 uint8_t z = (S & 0xf) << 3 | (E & 1) << 2 | (A & 3); \
 S >>= 4; \
 E >>= 1; \
 A >>= 2; \
 while (S | E | F | A | K | D) { \
 out_byte(out_env, 0x80 | z); \
/* xFSSKAED */ \
 z = (F & 1) << 6 | (S & 3) << 4 | (K & 1) << 3 \
 | (A & 1) << 2 | (E & 1) << 1 | (D & 1); \
 S >>= 2; \
 E >>= 1; \
 F >>= 1; \
 A >>= 1; \
 K >>= 1; \
 D >>= 1; \
 } \
 out_byte(out_env, z); \
 } while (0)

#define MP_BC_PRELUDE_SIG_DECODE_INTO(ip, S, E, F, A, K, D) \
 do { \
 uint8_t z = *(ip)++; \
/* xSSSSEAA */ \
 S = (z >> 3) & 0xf; \
 E = (z >> 2) & 0x1; \
 F = 0; \
 A = z & 0x3; \
 K = 0; \
 D = 0; \
 for (unsigned n = 0; z & 0x80; ++n) { \
 z = *(ip)++; \
/* xFSSKAED */ \
 S |= (z & 0x30) << (2 * n); \
 E |= (z & 0x02) << n; \
 F |= ((z & 0x40) >> 6) << n; \
 A |= (z & 0x4) << n; \
 K |= ((z & 0x08) >> 3) << n; \
 D |= (z & 0x1) << n; \
 } \
 S += 1; \
 } while (0)

#define MP_BC_PRELUDE_SIG_DECODE(ip) \
 size_t n_state, n_exc_stack, scope_flags, n_pos_args, n_kwonly_args, n_def_pos_args; \
 MP_BC_PRELUDE_SIG_DECODE_INTO(ip, n_state, n_exc_stack, scope_flags, n_pos_args, n_kwonly_args, n_def_pos_args)

#define MP_BC_PRELUDE_SIZE_ENCODE(I, C, out_byte, out_env) \
 do { \
/* Encode bit-wise as: xIIIIIIC */ \
 uint8_t z = 0; \
 do { \
 z = (I & 0x3f) << 1 | (C & 1); \
 C >>= 1; \
 I >>= 6; \
 if (C | I) { \
 z |= 0x80; \
 } \
 out_byte(out_env, z); \
 } while (C | I); \
 } while (0)

#define MP_BC_PRELUDE_SIZE_DECODE_INTO(ip, I, C) \
 do { \
 uint8_t z; \
 C = 0; \
 I = 0; \
 for (unsigned n = 0;; ++n) { \
 z = *(ip)++; \
/* xIIIIIIC */ \
 C |= (z & 1) << n; \
 I |= ((z & 0x7e) >> 1) << (6 * n); \
 if (!(z & 0x80)) { \
 break; \
 } \
 } \
 } while (0)

#define MP_BC_PRELUDE_SIZE_DECODE(ip) \
 size_t n_info, n_cell; \
 MP_BC_PRELUDE_SIZE_DECODE_INTO(ip, n_info, n_cell)

// 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 *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