/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013-2020 Damien P. George
 *
 * 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.
 */

#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>

#include "py/reader.h"
#include "py/nativeglue.h"
#include "py/persistentcode.h"
#include "py/bc0.h"
#include "py/objstr.h"
#include "py/mpthread.h"

#if MICROPY_PERSISTENT_CODE_LOAD || MICROPY_PERSISTENT_CODE_SAVE

#include "py/smallint.h"

#define QSTR_LAST_STATIC MP_QSTR_zip

#if MICROPY_DYNAMIC_COMPILER
#define MPY_FEATURE_ARCH_DYNAMIC mp_dynamic_compiler.native_arch
#else
#define MPY_FEATURE_ARCH_DYNAMIC MPY_FEATURE_ARCH
#endif

#if MICROPY_PERSISTENT_CODE_LOAD || (MICROPY_PERSISTENT_CODE_SAVE && !MICROPY_DYNAMIC_COMPILER)
// The bytecode will depend on the number of bits in a small-int, and
// this function computes that (could make it a fixed constant, but it
// would need to be defined in mpconfigport.h).
STATIC int mp_small_int_bits(void) {
 mp_int_t i = MP_SMALL_INT_MAX;
 int n = 1;
 while (i != 0) {
 i >>= 1;
 ++n;
 }
 return n;
}
#endif

#define QSTR_WINDOW_SIZE (32)

typedef struct _qstr_window_t {
 uint16_t idx; // indexes the head of the window
 uint16_t window[QSTR_WINDOW_SIZE];
} qstr_window_t;

// Push a qstr to the head of the window, and the tail qstr is overwritten
STATIC void qstr_window_push(qstr_window_t *qw, qstr qst) {
 qw->idx = (qw->idx + 1) % QSTR_WINDOW_SIZE;
 qw->window[qw->idx] = qst;
}

// Pull an existing qstr from within the window to the head of the window
STATIC qstr qstr_window_pull(qstr_window_t *qw, size_t idx) {
 qstr qst = qw->window[idx];
 if (idx > qw->idx) {
 memmove(&qw->window[idx], &qw->window[idx + 1], (QSTR_WINDOW_SIZE - idx - 1) * sizeof(uint16_t));
 qw->window[QSTR_WINDOW_SIZE - 1] = qw->window[0];
 idx = 0;
 }
 memmove(&qw->window[idx], &qw->window[idx + 1], (qw->idx - idx) * sizeof(uint16_t));
 qw->window[qw->idx] = qst;
 return qst;
}

#if MICROPY_PERSISTENT_CODE_LOAD

// Access a qstr at the given index, relative to the head of the window (0=head)
STATIC qstr qstr_window_access(qstr_window_t *qw, size_t idx) {
 return qstr_window_pull(qw, (qw->idx + QSTR_WINDOW_SIZE - idx) % QSTR_WINDOW_SIZE);
}

#endif

#if MICROPY_PERSISTENT_CODE_SAVE

// Insert a qstr at the head of the window, either by pulling an existing one or pushing a new one
STATIC size_t qstr_window_insert(qstr_window_t *qw, qstr qst) {
 for (size_t idx = 0; idx < QSTR_WINDOW_SIZE; ++idx) {
 if (qw->window[idx] == qst) {
 qstr_window_pull(qw, idx);
 return (qw->idx + QSTR_WINDOW_SIZE - idx) % QSTR_WINDOW_SIZE;
 }
 }
 qstr_window_push(qw, qst);
 return QSTR_WINDOW_SIZE;
}

#endif

typedef struct _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;
 uint code_info_size;
} bytecode_prelude_t;

// ip will point to start of opcodes
// return value will point to simple_name, source_file qstrs
STATIC byte *extract_prelude(const byte **ip, bytecode_prelude_t *prelude) {
 MP_BC_PRELUDE_SIG_DECODE(*ip);
 prelude->n_state = n_state;
 prelude->n_exc_stack = n_exc_stack;
 prelude->scope_flags = scope_flags;
 prelude->n_pos_args = n_pos_args;
 prelude->n_kwonly_args = n_kwonly_args;
 prelude->n_def_pos_args = n_def_pos_args;
 MP_BC_PRELUDE_SIZE_DECODE(*ip);
 byte *ip_info = (byte *)*ip;
 *ip += n_info;
 *ip += n_cell;
 return ip_info;
}

#endif // MICROPY_PERSISTENT_CODE_LOAD || MICROPY_PERSISTENT_CODE_SAVE

#if MICROPY_PERSISTENT_CODE_LOAD

#include "py/parsenum.h"

STATIC int read_byte(mp_reader_t *reader);
STATIC size_t read_uint(mp_reader_t *reader, byte **out);

#if MICROPY_EMIT_MACHINE_CODE

typedef struct _reloc_info_t {
 mp_reader_t *reader;
 mp_uint_t *const_table;
} reloc_info_t;

#if MICROPY_EMIT_THUMB
STATIC void asm_thumb_rewrite_mov(uint8_t *pc, uint16_t val) {
 // high part
 *(uint16_t *)pc = (*(uint16_t *)pc & 0xfbf0) | (val >> 1 & 0x0400) | (val >> 12);
 // low part
 *(uint16_t *)(pc + 2) = (*(uint16_t *)(pc + 2) & 0x0f00) | (val << 4 & 0x7000) | (val & 0x00ff);

}
#endif

STATIC void arch_link_qstr(uint8_t *pc, bool is_obj, qstr qst) {
 mp_uint_t val = qst;
 if (is_obj) {
 val = (mp_uint_t)MP_OBJ_NEW_QSTR(qst);
 }
 #if MICROPY_EMIT_X86 || MICROPY_EMIT_X64 || MICROPY_EMIT_ARM || MICROPY_EMIT_XTENSA || MICROPY_EMIT_XTENSAWIN
 pc[0] = val & 0xff;
 pc[1] = (val >> 8) & 0xff;
 pc[2] = (val >> 16) & 0xff;
 pc[3] = (val >> 24) & 0xff;
 #elif MICROPY_EMIT_THUMB
 if (is_obj) {
 // qstr object, movw and movt
 asm_thumb_rewrite_mov(pc, val); // movw
 asm_thumb_rewrite_mov(pc + 4, val >> 16); // movt
 } else {
 // qstr number, movw instruction
 asm_thumb_rewrite_mov(pc, val); // movw
 }
 #endif
}

void mp_native_relocate(void *ri_in, uint8_t *text, uintptr_t reloc_text) {
 // Relocate native code
 reloc_info_t *ri = ri_in;
 uint8_t op;
 uintptr_t *addr_to_adjust = NULL;
 while ((op = read_byte(ri->reader)) != 0xff) {
 if (op & 1) {
 // Point to new location to make adjustments
 size_t addr = read_uint(ri->reader, NULL);
 if ((addr & 1) == 0) {
 // Point to somewhere in text
 addr_to_adjust = &((uintptr_t *)text)[addr >> 1];
 } else {
 // Point to somewhere in rodata
 addr_to_adjust = &((uintptr_t *)ri->const_table[1])[addr >> 1];
 }
 }
 op >>= 1;
 uintptr_t dest;
 size_t n = 1;
 if (op <= 5) {
 if (op & 1) {
 // Read in number of adjustments to make
 n = read_uint(ri->reader, NULL);
 }
 op >>= 1;
 if (op == 0) {
 // Destination is text
 dest = reloc_text;
 } else {
 // Destination is rodata (op=1) or bss (op=1 if no rodata, else op=2)
 dest = ri->const_table[op];
 }
 } else if (op == 6) {
 // Destination is mp_fun_table itself
 dest = (uintptr_t)&mp_fun_table;
 } else {
 // Destination is an entry in mp_fun_table
 dest = ((uintptr_t *)&mp_fun_table)[op - 7];
 }
 while (n--) {
 *addr_to_adjust++ += dest;
 }
 }
}

#endif

STATIC int read_byte(mp_reader_t *reader) {
 return reader->readbyte(reader->data);
}

STATIC void read_bytes(mp_reader_t *reader, byte *buf, size_t len) {
 while (len-- > 0) {
 *buf++ = reader->readbyte(reader->data);
 }
}

STATIC size_t read_uint(mp_reader_t *reader, byte **out) {
 size_t unum = 0;
 for (;;) {
 byte b = reader->readbyte(reader->data);
 if (out != NULL) {
 **out = b;
 ++*out;
 }
 unum = (unum << 7) | (b & 0x7f);
 if ((b & 0x80) == 0) {
 break;
 }
 }
 return unum;
}

STATIC qstr load_qstr(mp_reader_t *reader, qstr_window_t *qw) {
 size_t len = read_uint(reader, NULL);
 if (len == 0) {
 // static qstr
 return read_byte(reader);
 }
 if (len & 1) {
 // qstr in window
 return qstr_window_access(qw, len >> 1);
 }
 len >>= 1;
 char *str = m_new(char, len);
 read_bytes(reader, (byte *)str, len);
 qstr qst = qstr_from_strn(str, len);
 m_del(char, str, len);
 qstr_window_push(qw, qst);
 return qst;
}

STATIC mp_obj_t load_obj(mp_reader_t *reader) {
 byte obj_type = read_byte(reader);
 if (obj_type == 'e') {
 return MP_OBJ_FROM_PTR(&mp_const_ellipsis_obj);
 } else {
 size_t len = read_uint(reader, NULL);
 vstr_t vstr;
 vstr_init_len(&vstr, len);
 read_bytes(reader, (byte *)vstr.buf, len);
 if (obj_type == 's' || obj_type == 'b') {
 return mp_obj_new_str_from_vstr(obj_type == 's' ? &mp_type_str : &mp_type_bytes, &vstr);
 } else if (obj_type == 'i') {
 return mp_parse_num_integer(vstr.buf, vstr.len, 10, NULL);
 } else {
 assert(obj_type == 'f' || obj_type == 'c');
 return mp_parse_num_decimal(vstr.buf, vstr.len, obj_type == 'c', false, NULL);
 }
 }
}

STATIC void load_prelude_qstrs(mp_reader_t *reader, qstr_window_t *qw, byte *ip) {
 qstr simple_name = load_qstr(reader, qw);
 ip[0] = simple_name;
 ip[1] = simple_name >> 8;
 qstr source_file = load_qstr(reader, qw);
 ip[2] = source_file;
 ip[3] = source_file >> 8;
}

STATIC void load_prelude(mp_reader_t *reader, qstr_window_t *qw, byte **ip, bytecode_prelude_t *prelude) {
 // Read in the prelude header
 byte *ip_read = *ip;
 read_uint(reader, &ip_read); // read in n_state/etc (is effectively a var-uint)
 read_uint(reader, &ip_read); // read in n_info/n_cell (is effectively a var-uint)

 // Prelude header has been read into *ip, now decode and extract values from it
 extract_prelude((const byte **)ip, prelude);

 // Load qstrs in prelude
 load_prelude_qstrs(reader, qw, ip_read);
 ip_read += 4;

 // Read remaining code info
 read_bytes(reader, ip_read, *ip - ip_read);
}

STATIC void load_bytecode(mp_reader_t *reader, qstr_window_t *qw, byte *ip, byte *ip_top) {
 while (ip < ip_top) {
 *ip = read_byte(reader);
 size_t sz;
 uint f = mp_opcode_format(ip, &sz, false);
 ++ip;
 --sz;
 if (f == MP_BC_FORMAT_QSTR) {
 qstr qst = load_qstr(reader, qw);
 *ip++ = qst;
 *ip++ = qst >> 8;
 sz -= 2;
 } else if (f == MP_BC_FORMAT_VAR_UINT) {
 while ((*ip++ = read_byte(reader)) & 0x80) {
 }
 }
 read_bytes(reader, ip, sz);
 ip += sz;
 }
}

STATIC mp_raw_code_t *load_raw_code(mp_reader_t *reader, qstr_window_t *qw) {
 // Load function kind and data length
 size_t kind_len = read_uint(reader, NULL);
 int kind = (kind_len & 3) + MP_CODE_BYTECODE;
 size_t fun_data_len = kind_len >> 2;

 #if !MICROPY_EMIT_MACHINE_CODE
 if (kind != MP_CODE_BYTECODE) {
 mp_raise_ValueError(MP_ERROR_TEXT("incompatible .mpy file"));
 }
 #endif

 uint8_t *fun_data = NULL;
 bytecode_prelude_t prelude = {0};
 #if MICROPY_EMIT_MACHINE_CODE
 size_t prelude_offset = 0;
 mp_uint_t type_sig = 0;
 size_t n_qstr_link = 0;
 #endif

 if (kind == MP_CODE_BYTECODE) {
 // Allocate memory for the bytecode
 fun_data = m_new(uint8_t, fun_data_len);

 // Load prelude
 byte *ip = fun_data;
 load_prelude(reader, qw, &ip, &prelude);

 // Load bytecode
 load_bytecode(reader, qw, ip, fun_data + fun_data_len);

 #if MICROPY_EMIT_MACHINE_CODE
 } else {
 // Allocate memory for native data and load it
 size_t fun_alloc;
 MP_PLAT_ALLOC_EXEC(fun_data_len, (void **)&fun_data, &fun_alloc);
 read_bytes(reader, fun_data, fun_data_len);

 if (kind == MP_CODE_NATIVE_PY || kind == MP_CODE_NATIVE_VIPER) {
 // Parse qstr link table and link native code
 n_qstr_link = read_uint(reader, NULL);
 for (size_t i = 0; i < n_qstr_link; ++i) {
 size_t off = read_uint(reader, NULL);
 qstr qst = load_qstr(reader, qw);
 uint8_t *dest = fun_data + (off >> 2);
 if ((off & 3) == 0) {
 // Generic 16-bit link
 dest[0] = qst & 0xff;
 dest[1] = (qst >> 8) & 0xff;
 } else if ((off & 3) == 3) {
 // Generic, aligned qstr-object link
 *(mp_obj_t *)dest = MP_OBJ_NEW_QSTR(qst);
 } else {
 // Architecture-specific link
 arch_link_qstr(dest, (off & 3) == 2, qst);
 }
 }
 }

 if (kind == MP_CODE_NATIVE_PY) {
 // Extract prelude for later use
 prelude_offset = read_uint(reader, NULL);
 const byte *ip = fun_data + prelude_offset;
 byte *ip_info = extract_prelude(&ip, &prelude);
 // Load qstrs in prelude
 load_prelude_qstrs(reader, qw, ip_info);
 } else {
 // Load basic scope info for viper and asm
 prelude.scope_flags = read_uint(reader, NULL);
 prelude.n_pos_args = 0;
 prelude.n_kwonly_args = 0;
 if (kind == MP_CODE_NATIVE_ASM) {
 prelude.n_pos_args = read_uint(reader, NULL);
 type_sig = read_uint(reader, NULL);
 }
 }
 #endif
 }

 size_t n_obj = 0;
 size_t n_raw_code = 0;
 mp_uint_t *const_table = NULL;

 if (kind != MP_CODE_NATIVE_ASM) {
 // Load constant table for bytecode, native and viper

 // Number of entries in constant table
 n_obj = read_uint(reader, NULL);
 n_raw_code = read_uint(reader, NULL);

 // Allocate constant table
 size_t n_alloc = prelude.n_pos_args + prelude.n_kwonly_args + n_obj + n_raw_code;
 #if MICROPY_EMIT_MACHINE_CODE
 if (kind != MP_CODE_BYTECODE) {
 ++n_alloc; // additional entry for mp_fun_table
 if (prelude.scope_flags & MP_SCOPE_FLAG_VIPERRODATA) {
 ++n_alloc; // additional entry for rodata
 }
 if (prelude.scope_flags & MP_SCOPE_FLAG_VIPERBSS) {
 ++n_alloc; // additional entry for BSS
 }
 }
 #endif

 const_table = m_new(mp_uint_t, n_alloc);
 mp_uint_t *ct = const_table;

 // Load function argument names (initial entries in const_table)
 // (viper has n_pos_args=n_kwonly_args=0 so doesn't load any qstrs here)
 for (size_t i = 0; i < prelude.n_pos_args + prelude.n_kwonly_args; ++i) {
 *ct++ = (mp_uint_t)MP_OBJ_NEW_QSTR(load_qstr(reader, qw));
 }

 #if MICROPY_EMIT_MACHINE_CODE
 if (kind != MP_CODE_BYTECODE) {
 // Populate mp_fun_table entry
 *ct++ = (mp_uint_t)(uintptr_t)&mp_fun_table;

 // Allocate and load rodata if needed
 if (prelude.scope_flags & MP_SCOPE_FLAG_VIPERRODATA) {
 size_t size = read_uint(reader, NULL);
 uint8_t *rodata = m_new(uint8_t, size);
 read_bytes(reader, rodata, size);
 *ct++ = (uintptr_t)rodata;
 }

 // Allocate BSS if needed
 if (prelude.scope_flags & MP_SCOPE_FLAG_VIPERBSS) {
 size_t size = read_uint(reader, NULL);
 uint8_t *bss = m_new0(uint8_t, size);
 *ct++ = (uintptr_t)bss;
 }
 }
 #endif

 // Load constant objects and raw code children
 for (size_t i = 0; i < n_obj; ++i) {
 *ct++ = (mp_uint_t)load_obj(reader);
 }
 for (size_t i = 0; i < n_raw_code; ++i) {
 *ct++ = (mp_uint_t)(uintptr_t)load_raw_code(reader, qw);
 }
 }

 // Create raw_code and return it
 mp_raw_code_t *rc = mp_emit_glue_new_raw_code();
 if (kind == MP_CODE_BYTECODE) {
 // Assign bytecode to raw code object
 mp_emit_glue_assign_bytecode(rc, fun_data,
 #if MICROPY_PERSISTENT_CODE_SAVE || MICROPY_DEBUG_PRINTERS
 fun_data_len,
 #endif
 const_table,
 #if MICROPY_PERSISTENT_CODE_SAVE
 n_obj, n_raw_code,
 #endif
 prelude.scope_flags);

 #if MICROPY_EMIT_MACHINE_CODE
 } else {
 // Relocate and commit code to executable address space
 reloc_info_t ri = {reader, const_table};
 #if defined(MP_PLAT_COMMIT_EXEC)
 void *opt_ri = (prelude.scope_flags & MP_SCOPE_FLAG_VIPERRELOC) ? &ri : NULL;
 fun_data = MP_PLAT_COMMIT_EXEC(fun_data, fun_data_len, opt_ri);
 #else
 if (prelude.scope_flags & MP_SCOPE_FLAG_VIPERRELOC) {
 #if MICROPY_PERSISTENT_CODE_TRACK_RELOC_CODE
 // If native code needs relocations then it's not guaranteed that a pointer to
 // the head of `buf` (containing the machine code) will be retained for the GC
 // to trace. This is because native functions can start inside `buf` and so
 // it's possible that the only GC-reachable pointers are pointers inside `buf`.
 // So put this `buf` on a list of reachable root pointers.
 if (MP_STATE_PORT(track_reloc_code_list) == MP_OBJ_NULL) {
 MP_STATE_PORT(track_reloc_code_list) = mp_obj_new_list(0, NULL);
 }
 mp_obj_list_append(MP_STATE_PORT(track_reloc_code_list), MP_OBJ_FROM_PTR(fun_data));
 #endif
 // Do the relocations.
 mp_native_relocate(&ri, fun_data, (uintptr_t)fun_data);
 }
 #endif

 // Assign native code to raw code object
 mp_emit_glue_assign_native(rc, kind,
 fun_data, fun_data_len, const_table,
 #if MICROPY_PERSISTENT_CODE_SAVE
 prelude_offset,
 n_obj, n_raw_code,
 n_qstr_link, NULL,
 #endif
 prelude.n_pos_args, prelude.scope_flags, type_sig);
 #endif
 }
 return rc;
}

mp_raw_code_t *mp_raw_code_load(mp_reader_t *reader) {
 byte header[4];
 read_bytes(reader, header, sizeof(header));
 if (header[0] != 'M'
 || header[1] != MPY_VERSION
 || MPY_FEATURE_DECODE_FLAGS(header[2]) != MPY_FEATURE_FLAGS
 || header[3] > mp_small_int_bits()
 || read_uint(reader, NULL) > QSTR_WINDOW_SIZE) {
 mp_raise_ValueError(MP_ERROR_TEXT("incompatible .mpy file"));
 }
 if (MPY_FEATURE_DECODE_ARCH(header[2]) != MP_NATIVE_ARCH_NONE) {
 byte arch = MPY_FEATURE_DECODE_ARCH(header[2]);
 if (!MPY_FEATURE_ARCH_TEST(arch)) {
 mp_raise_ValueError(MP_ERROR_TEXT("incompatible .mpy arch"));
 }
 }
 qstr_window_t qw;
 qw.idx = 0;
 mp_raw_code_t *rc = load_raw_code(reader, &qw);
 reader->close(reader->data);
 return rc;
}

mp_raw_code_t *mp_raw_code_load_mem(const byte *buf, size_t len) {
 mp_reader_t reader;
 mp_reader_new_mem(&reader, buf, len, 0);
 return mp_raw_code_load(&reader);
}

#if MICROPY_HAS_FILE_READER

mp_raw_code_t *mp_raw_code_load_file(const char *filename) {
 mp_reader_t reader;
 mp_reader_new_file(&reader, filename);
 return mp_raw_code_load(&reader);
}

#endif // MICROPY_HAS_FILE_READER

#endif // MICROPY_PERSISTENT_CODE_LOAD

#if MICROPY_PERSISTENT_CODE_SAVE

#include "py/objstr.h"

STATIC void mp_print_bytes(mp_print_t *print, const byte *data, size_t len) {
 print->print_strn(print->data, (const char *)data, len);
}

#define BYTES_FOR_INT ((BYTES_PER_WORD * 8 + 6) / 7)
STATIC void mp_print_uint(mp_print_t *print, size_t n) {
 byte buf[BYTES_FOR_INT];
 byte *p = buf + sizeof(buf);
 *--p = n & 0x7f;
 n >>= 7;
 for (; n != 0; n >>= 7) {
 *--p = 0x80 | (n & 0x7f);
 }
 print->print_strn(print->data, (char *)p, buf + sizeof(buf) - p);
}

STATIC void save_qstr(mp_print_t *print, qstr_window_t *qw, qstr qst) {
 if (qst <= QSTR_LAST_STATIC) {
 // encode static qstr
 byte buf[2] = {0, qst & 0xff};
 mp_print_bytes(print, buf, 2);
 return;
 }
 size_t idx = qstr_window_insert(qw, qst);
 if (idx < QSTR_WINDOW_SIZE) {
 // qstr found in window, encode index to it
 mp_print_uint(print, idx << 1 | 1);
 return;
 }
 size_t len;
 const byte *str = qstr_data(qst, &len);
 mp_print_uint(print, len << 1);
 mp_print_bytes(print, str, len);
}

STATIC void save_obj(mp_print_t *print, mp_obj_t o) {
 if (mp_obj_is_str_or_bytes(o)) {
 byte obj_type;
 if (mp_obj_is_str(o)) {
 obj_type = 's';
 } else {
 obj_type = 'b';
 }
 size_t len;
 const char *str = mp_obj_str_get_data(o, &len);
 mp_print_bytes(print, &obj_type, 1);
 mp_print_uint(print, len);
 mp_print_bytes(print, (const byte *)str, len);
 } else if (MP_OBJ_TO_PTR(o) == &mp_const_ellipsis_obj) {
 byte obj_type = 'e';
 mp_print_bytes(print, &obj_type, 1);
 } else {
 // we save numbers using a simplistic text representation
 // TODO could be improved
 byte obj_type;
 if (mp_obj_is_type(o, &mp_type_int)) {
 obj_type = 'i';
 #if MICROPY_PY_BUILTINS_COMPLEX
 } else if (mp_obj_is_type(o, &mp_type_complex)) {
 obj_type = 'c';
 #endif
 } else {
 assert(mp_obj_is_float(o));
 obj_type = 'f';
 }
 vstr_t vstr;
 mp_print_t pr;
 vstr_init_print(&vstr, 10, &pr);
 mp_obj_print_helper(&pr, o, PRINT_REPR);
 mp_print_bytes(print, &obj_type, 1);
 mp_print_uint(print, vstr.len);
 mp_print_bytes(print, (const byte *)vstr.buf, vstr.len);
 vstr_clear(&vstr);
 }
}

STATIC void save_prelude_qstrs(mp_print_t *print, qstr_window_t *qw, const byte *ip) {
 save_qstr(print, qw, ip[0] | (ip[1] << 8)); // simple_name
 save_qstr(print, qw, ip[2] | (ip[3] << 8)); // source_file
}

STATIC void save_bytecode(mp_print_t *print, qstr_window_t *qw, const byte *ip, const byte *ip_top) {
 while (ip < ip_top) {
 size_t sz;
 uint f = mp_opcode_format(ip, &sz, true);
 if (f == MP_BC_FORMAT_QSTR) {
 mp_print_bytes(print, ip, 1);
 qstr qst = ip[1] | (ip[2] << 8);
 save_qstr(print, qw, qst);
 ip += 3;
 sz -= 3;
 }
 mp_print_bytes(print, ip, sz);
 ip += sz;
 }
}

STATIC void save_raw_code(mp_print_t *print, mp_raw_code_t *rc, qstr_window_t *qstr_window) {
 // Save function kind and data length
 mp_print_uint(print, (rc->fun_data_len << 2) | (rc->kind - MP_CODE_BYTECODE));

 bytecode_prelude_t prelude;

 if (rc->kind == MP_CODE_BYTECODE) {
 // Extract prelude
 const byte *ip = rc->fun_data;
 const byte *ip_info = extract_prelude(&ip, &prelude);

 // Save prelude
 mp_print_bytes(print, rc->fun_data, ip_info - (const byte *)rc->fun_data);
 save_prelude_qstrs(print, qstr_window, ip_info);
 ip_info += 4;
 mp_print_bytes(print, ip_info, ip - ip_info);

 // Save bytecode
 const byte *ip_top = (const byte *)rc->fun_data + rc->fun_data_len;
 save_bytecode(print, qstr_window, ip, ip_top);
 #if MICROPY_EMIT_MACHINE_CODE
 } else {
 // Save native code
 mp_print_bytes(print, rc->fun_data, rc->fun_data_len);

 if (rc->kind == MP_CODE_NATIVE_PY || rc->kind == MP_CODE_NATIVE_VIPER) {
 // Save qstr link table for native code
 mp_print_uint(print, rc->n_qstr);
 for (size_t i = 0; i < rc->n_qstr; ++i) {
 mp_print_uint(print, rc->qstr_link[i].off);
 save_qstr(print, qstr_window, rc->qstr_link[i].qst);
 }
 }

 if (rc->kind == MP_CODE_NATIVE_PY) {
 // Save prelude size
 mp_print_uint(print, rc->prelude_offset);

 // Extract prelude and save qstrs in prelude
 const byte *ip = (const byte *)rc->fun_data + rc->prelude_offset;
 const byte *ip_info = extract_prelude(&ip, &prelude);
 save_prelude_qstrs(print, qstr_window, ip_info);
 } else {
 // Save basic scope info for viper and asm
 mp_print_uint(print, rc->scope_flags & MP_SCOPE_FLAG_ALL_SIG);
 prelude.n_pos_args = 0;
 prelude.n_kwonly_args = 0;
 if (rc->kind == MP_CODE_NATIVE_ASM) {
 mp_print_uint(print, rc->n_pos_args);
 mp_print_uint(print, rc->type_sig);
 }
 }
 #endif
 }

 if (rc->kind != MP_CODE_NATIVE_ASM) {
 // Save constant table for bytecode, native and viper

 // Number of entries in constant table
 mp_print_uint(print, rc->n_obj);
 mp_print_uint(print, rc->n_raw_code);

 const mp_uint_t *const_table = rc->const_table;

 // Save function argument names (initial entries in const_table)
 // (viper has n_pos_args=n_kwonly_args=0 so doesn't save any qstrs here)
 for (size_t i = 0; i < prelude.n_pos_args + prelude.n_kwonly_args; ++i) {
 mp_obj_t o = (mp_obj_t)*const_table++;
 save_qstr(print, qstr_window, MP_OBJ_QSTR_VALUE(o));
 }

 if (rc->kind != MP_CODE_BYTECODE) {
 // Skip saving mp_fun_table entry
 ++const_table;
 }

 // Save constant objects and raw code children
 for (size_t i = 0; i < rc->n_obj; ++i) {
 save_obj(print, (mp_obj_t)*const_table++);
 }
 for (size_t i = 0; i < rc->n_raw_code; ++i) {
 save_raw_code(print, (mp_raw_code_t *)(uintptr_t)*const_table++, qstr_window);
 }
 }
}

STATIC bool mp_raw_code_has_native(mp_raw_code_t *rc) {
 if (rc->kind != MP_CODE_BYTECODE) {
 return true;
 }

 const byte *ip = rc->fun_data;
 bytecode_prelude_t prelude;
 extract_prelude(&ip, &prelude);

 const mp_uint_t *const_table = rc->const_table
 + prelude.n_pos_args + prelude.n_kwonly_args
 + rc->n_obj;

 for (size_t i = 0; i < rc->n_raw_code; ++i) {
 if (mp_raw_code_has_native((mp_raw_code_t *)(uintptr_t)*const_table++)) {
 return true;
 }
 }

 return false;
}

void mp_raw_code_save(mp_raw_code_t *rc, mp_print_t *print) {
 // header contains:
 // byte 'M'
 // byte version
 // byte feature flags
 // byte number of bits in a small int
 // uint size of qstr window
 byte header[4] = {
 'M',
 MPY_VERSION,
 MPY_FEATURE_ENCODE_FLAGS(MPY_FEATURE_FLAGS_DYNAMIC),
 #if MICROPY_DYNAMIC_COMPILER
 mp_dynamic_compiler.small_int_bits,
 #else
 mp_small_int_bits(),
 #endif
 };
 if (mp_raw_code_has_native(rc)) {
 header[2] |= MPY_FEATURE_ENCODE_ARCH(MPY_FEATURE_ARCH_DYNAMIC);
 }
 mp_print_bytes(print, header, sizeof(header));
 mp_print_uint(print, QSTR_WINDOW_SIZE);

 qstr_window_t qw;
 qw.idx = 0;
 memset(qw.window, 0, sizeof(qw.window));
 save_raw_code(print, rc, &qw);
}

// here we define mp_raw_code_save_file depending on the port
// TODO abstract this away properly

#if defined(__i386__) || defined(__x86_64__) || defined(_WIN32) || defined(__unix__)

#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>

STATIC void fd_print_strn(void *env, const char *str, size_t len) {
 int fd = (intptr_t)env;
 MP_THREAD_GIL_EXIT();
 ssize_t ret = write(fd, str, len);
 MP_THREAD_GIL_ENTER();
 (void)ret;
}

void mp_raw_code_save_file(mp_raw_code_t *rc, const char *filename) {
 MP_THREAD_GIL_EXIT();
 int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0644);
 MP_THREAD_GIL_ENTER();
 mp_print_t fd_print = {(void *)(intptr_t)fd, fd_print_strn};
 mp_raw_code_save(rc, &fd_print);
 MP_THREAD_GIL_EXIT();
 close(fd);
 MP_THREAD_GIL_ENTER();
}

#else
#error mp_raw_code_save_file not implemented for this platform
#endif

#endif // MICROPY_PERSISTENT_CODE_SAVE