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// This file is part of the CircuitPython project: https://circuitpython.org

//

// SPDX-FileCopyrightText: Copyright (c) 2016 Paul Sokolovsky

// SPDX-FileCopyrightText: Copyright (c) 2017 Scott Shawcroft for Adafruit Industries

// SPDX-FileCopyrightText: Copyright (c) 2017 Michael McWethy

//

// SPDX-License-Identifier: MIT

#include <assert.h>

#include <string.h>

#include "py/runtime.h"

#include "py/binary.h"

#include "py/parsenum.h"

#include "shared-bindings/struct/__init__.h"

static void struct_validate_format(char fmt) {

#if MICROPY_NONSTANDARD_TYPECODES

if (fmt == 'S' || fmt == 'O') {

mp_raise_RuntimeError(MP_ERROR_TEXT("'S' and 'O' are not supported format types"));

}

#endif

}

static char get_fmt_type(const char **fmt) {

char t = **fmt;

switch (t) {

case '!':

t = '>';

break;

case '@':

case '=':

case '<':

case '>':

break;

default:

return '@';

}

// Skip type char

(*fmt)++;

return t;

}

static mp_uint_t get_fmt_num(const char **p) {

const char *num = *p;

uint len = 1;

while (unichar_isdigit(*++num)) {

len++;

}

mp_uint_t val = (mp_uint_t)MP_OBJ_SMALL_INT_VALUE(mp_parse_num_integer(*p, len, 10, NULL));

*p = num;

return val;

}

static mp_uint_t calcsize_items(const char *fmt) {

mp_uint_t cnt = 0;

while (*fmt) {

int num = 1;

if (unichar_isdigit(*fmt)) {

num = get_fmt_num(&fmt);

if (*fmt == 's') {

num = 1;

}

}

// Pad bytes are skipped and don't get included in the item count.

if (*fmt != 'x') {

cnt += num;

}

fmt++;

}

return cnt;

}

mp_uint_t shared_modules_struct_calcsize(mp_obj_t fmt_in) {

const char *fmt = mp_obj_str_get_str(fmt_in);

char fmt_type = get_fmt_type(&fmt);

mp_uint_t size;

for (size = 0; *fmt; fmt++) {

struct_validate_format(*fmt);

mp_uint_t cnt = 1;

if (unichar_isdigit(*fmt)) {

cnt = get_fmt_num(&fmt);

}

if (*fmt == 's') {

size += cnt;

} else {

mp_uint_t align;

size_t sz = mp_binary_get_size(fmt_type, *fmt, &align);

while (cnt--) {

// Apply alignment

size = (size + align - 1) & ~(align - 1);

size += sz;

}

}

}

return size;

}

void shared_modules_struct_pack_into(mp_obj_t fmt_in, byte *p, byte *end_p, size_t n_args, const mp_obj_t *args) {

const char *fmt = mp_obj_str_get_str(fmt_in);

char fmt_type = get_fmt_type(&fmt);

const mp_uint_t total_sz = shared_modules_struct_calcsize(fmt_in);

if (p + total_sz > end_p) {

mp_raise_RuntimeError(MP_ERROR_TEXT("Buffer too small"));

}

size_t i = 0;

byte *p_base = p;

while (*fmt) {

mp_uint_t sz = 1;

struct_validate_format(*fmt);

if (unichar_isdigit(*fmt)) {

sz = get_fmt_num(&fmt);

}

if (*fmt == 's') {

if (i < n_args) {

mp_buffer_info_t bufinfo;

mp_get_buffer_raise(args[i], &bufinfo, MP_BUFFER_READ);

mp_uint_t to_copy = sz;

if (bufinfo.len < to_copy) {

to_copy = bufinfo.len;

}

memcpy(p, bufinfo.buf, to_copy);

memset(p + to_copy, 0, sz - to_copy);

}

i++;

p += sz;

} else {

while (sz--) {

// Pad bytes don't have a corresponding argument.

if (*fmt == 'x') {

mp_binary_set_val(fmt_type, *fmt, MP_OBJ_NEW_SMALL_INT(0), p_base, &p);

} else {

if (i < n_args) {

mp_binary_set_val(fmt_type, *fmt, args[i], p_base, &p);

}

i++;

}

}

}

fmt++;

}

(void)mp_arg_validate_length(n_args, i, MP_QSTR_values);

}

mp_obj_tuple_t *shared_modules_struct_unpack_from(mp_obj_t fmt_in, byte *p, byte *end_p, bool exact_size) {

const char *fmt = mp_obj_str_get_str(fmt_in);

char fmt_type = get_fmt_type(&fmt);

const mp_uint_t num_items = calcsize_items(fmt);

const mp_uint_t total_sz = shared_modules_struct_calcsize(fmt_in);

mp_obj_tuple_t *res = MP_OBJ_TO_PTR(mp_obj_new_tuple(num_items, NULL));

// If exact_size, make sure the buffer is exactly the right size.

// Otherwise just make sure it's big enough.

if (exact_size) {

if (p + total_sz != end_p) {

mp_raise_RuntimeError(MP_ERROR_TEXT("buffer size must match format"));

}

} else {

if (p + total_sz > end_p) {

mp_raise_RuntimeError(MP_ERROR_TEXT("buffer too small"));

}

}

byte *p_base = p;

for (uint i = 0; i < num_items;) {

mp_uint_t sz = 1;

struct_validate_format(*fmt);

if (unichar_isdigit(*fmt)) {

sz = get_fmt_num(&fmt);

}

mp_obj_t item;

if (*fmt == 's') {

item = mp_obj_new_bytes(p, sz);

p += sz;

res->items[i++] = item;

} else {

while (sz--) {

item = mp_binary_get_val(fmt_type, *fmt, p_base, &p);

// Pad bytes are not stored.

if (*fmt != 'x') {

res->items[i++] = item;

}

}

}

fmt++;

}

return res;

}