279 lines
9.3 KiB
C
279 lines
9.3 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2013, 2014 Damien P. George
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* Copyright (c) 2014 Paul Sokolovsky
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <assert.h>
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#include <string.h>
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#include "py/runtime.h"
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#include "py/builtin.h"
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#include "py/objtuple.h"
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#include "py/binary.h"
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#include "py/parsenum.h"
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#if MICROPY_PY_STRUCT
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/*
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This module implements most of character typecodes from CPython, with
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some extensions:
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O - (Pointer to) an arbitrary Python object. This is useful for callback
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data, etc. Note that you must keep reference to passed object in
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your Python application, otherwise it may be garbage-collected,
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and then when you get back this value from callback it may be
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invalid (and lead to crash).
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S - Pointer to a string (returned as a Python string). Note the
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difference from "Ns", - the latter says "in this place of structure
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is character data of up to N bytes length", while "S" means
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"in this place of a structure is a pointer to zero-terminated
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character data".
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*/
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STATIC char get_fmt_type(const char **fmt) {
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char t = **fmt;
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switch (t) {
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case '!':
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t = '>';
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break;
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case '@':
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case '=':
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case '<':
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case '>':
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break;
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default:
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return '@';
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}
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// Skip type char
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(*fmt)++;
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return t;
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}
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STATIC mp_uint_t get_fmt_num(const char **p) {
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const char *num = *p;
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uint len = 1;
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while (unichar_isdigit(*++num)) {
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len++;
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}
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mp_uint_t val = (mp_uint_t)MP_OBJ_SMALL_INT_VALUE(mp_parse_num_integer(*p, len, 10, NULL));
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*p = num;
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return val;
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}
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STATIC size_t calc_size_items(const char *fmt, size_t *total_sz) {
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char fmt_type = get_fmt_type(&fmt);
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size_t total_cnt = 0;
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size_t size;
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for (size = 0; *fmt; fmt++) {
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mp_uint_t cnt = 1;
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if (unichar_isdigit(*fmt)) {
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cnt = get_fmt_num(&fmt);
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}
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if (*fmt == 'x') {
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size += cnt;
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} else if (*fmt == 's') {
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total_cnt += 1;
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size += cnt;
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} else {
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total_cnt += cnt;
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size_t align;
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size_t sz = mp_binary_get_size(fmt_type, *fmt, &align);
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while (cnt--) {
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// Apply alignment
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size = (size + align - 1) & ~(align - 1);
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size += sz;
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}
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}
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}
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*total_sz = size;
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return total_cnt;
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}
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STATIC mp_obj_t struct_calcsize(mp_obj_t fmt_in) {
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const char *fmt = mp_obj_str_get_str(fmt_in);
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size_t size;
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calc_size_items(fmt, &size);
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return MP_OBJ_NEW_SMALL_INT(size);
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}
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MP_DEFINE_CONST_FUN_OBJ_1(struct_calcsize_obj, struct_calcsize);
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STATIC mp_obj_t struct_unpack_from(size_t n_args, const mp_obj_t *args) {
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// unpack requires that the buffer be exactly the right size.
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// unpack_from requires that the buffer be "big enough".
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// Since we implement unpack and unpack_from using the same function
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// we relax the "exact" requirement, and only implement "big enough".
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const char *fmt = mp_obj_str_get_str(args[0]);
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size_t total_sz;
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size_t num_items = calc_size_items(fmt, &total_sz);
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char fmt_type = get_fmt_type(&fmt);
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mp_obj_tuple_t *res = MP_OBJ_TO_PTR(mp_obj_new_tuple(num_items, NULL));
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mp_buffer_info_t bufinfo;
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mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_READ);
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byte *p = bufinfo.buf;
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byte *end_p = &p[bufinfo.len];
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mp_int_t offset = 0;
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if (n_args > 2) {
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// offset arg provided
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offset = mp_obj_get_int(args[2]);
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if (offset < 0) {
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// negative offsets are relative to the end of the buffer
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offset = bufinfo.len + offset;
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if (offset < 0) {
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mp_raise_ValueError(MP_ERROR_TEXT("buffer too small"));
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}
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}
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p += offset;
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}
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byte *p_base = p;
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// Check that the input buffer is big enough to unpack all the values
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if (p + total_sz > end_p) {
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mp_raise_ValueError(MP_ERROR_TEXT("buffer too small"));
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}
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for (size_t i = 0; i < num_items;) {
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mp_uint_t cnt = 1;
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if (unichar_isdigit(*fmt)) {
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cnt = get_fmt_num(&fmt);
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}
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mp_obj_t item;
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if (*fmt == 'x') {
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p += cnt;
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} else if (*fmt == 's') {
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item = mp_obj_new_bytes(p, cnt);
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p += cnt;
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res->items[i++] = item;
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} else {
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while (cnt--) {
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item = mp_binary_get_val(fmt_type, *fmt, p_base, &p);
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res->items[i++] = item;
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}
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}
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fmt++;
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}
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return MP_OBJ_FROM_PTR(res);
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}
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MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_unpack_from_obj, 2, 3, struct_unpack_from);
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// This function assumes there is enough room in p to store all the values
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STATIC void struct_pack_into_internal(mp_obj_t fmt_in, byte *p, size_t n_args, const mp_obj_t *args) {
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const char *fmt = mp_obj_str_get_str(fmt_in);
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char fmt_type = get_fmt_type(&fmt);
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byte *p_base = p;
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size_t i;
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for (i = 0; i < n_args;) {
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mp_uint_t cnt = 1;
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if (*fmt == '\0') {
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// more arguments given than used by format string; CPython raises struct.error here
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break;
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}
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if (unichar_isdigit(*fmt)) {
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cnt = get_fmt_num(&fmt);
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}
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if (*fmt == 'x') {
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memset(p, 0, cnt);
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p += cnt;
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} else if (*fmt == 's') {
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mp_buffer_info_t bufinfo;
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mp_get_buffer_raise(args[i++], &bufinfo, MP_BUFFER_READ);
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mp_uint_t to_copy = cnt;
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if (bufinfo.len < to_copy) {
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to_copy = bufinfo.len;
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}
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memcpy(p, bufinfo.buf, to_copy);
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memset(p + to_copy, 0, cnt - to_copy);
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p += cnt;
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} else {
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// If we run out of args then we just finish; CPython would raise struct.error
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while (cnt-- && i < n_args) {
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mp_binary_set_val(fmt_type, *fmt, args[i++], p_base, &p);
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}
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}
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fmt++;
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}
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}
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STATIC mp_obj_t struct_pack(size_t n_args, const mp_obj_t *args) {
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// TODO: "The arguments must match the values required by the format exactly."
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mp_int_t size = MP_OBJ_SMALL_INT_VALUE(struct_calcsize(args[0]));
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vstr_t vstr;
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vstr_init_len(&vstr, size);
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byte *p = (byte *)vstr.buf;
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memset(p, 0, size);
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struct_pack_into_internal(args[0], p, n_args - 1, &args[1]);
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return mp_obj_new_bytes_from_vstr(&vstr);
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}
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MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_pack_obj, 1, MP_OBJ_FUN_ARGS_MAX, struct_pack);
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STATIC mp_obj_t struct_pack_into(size_t n_args, const mp_obj_t *args) {
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mp_buffer_info_t bufinfo;
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mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_WRITE);
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mp_int_t offset = mp_obj_get_int(args[2]);
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if (offset < 0) {
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// negative offsets are relative to the end of the buffer
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offset = (mp_int_t)bufinfo.len + offset;
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if (offset < 0) {
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mp_raise_ValueError(MP_ERROR_TEXT("buffer too small"));
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}
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}
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byte *p = (byte *)bufinfo.buf;
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byte *end_p = &p[bufinfo.len];
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p += offset;
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// Check that the output buffer is big enough to hold all the values
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mp_int_t sz = MP_OBJ_SMALL_INT_VALUE(struct_calcsize(args[0]));
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if (p + sz > end_p) {
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mp_raise_ValueError(MP_ERROR_TEXT("buffer too small"));
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}
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struct_pack_into_internal(args[0], p, n_args - 3, &args[3]);
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return mp_const_none;
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}
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MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_pack_into_obj, 3, MP_OBJ_FUN_ARGS_MAX, struct_pack_into);
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STATIC const mp_rom_map_elem_t mp_module_struct_globals_table[] = {
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{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_struct) },
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{ MP_ROM_QSTR(MP_QSTR_calcsize), MP_ROM_PTR(&struct_calcsize_obj) },
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{ MP_ROM_QSTR(MP_QSTR_pack), MP_ROM_PTR(&struct_pack_obj) },
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{ MP_ROM_QSTR(MP_QSTR_pack_into), MP_ROM_PTR(&struct_pack_into_obj) },
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{ MP_ROM_QSTR(MP_QSTR_unpack), MP_ROM_PTR(&struct_unpack_from_obj) },
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{ MP_ROM_QSTR(MP_QSTR_unpack_from), MP_ROM_PTR(&struct_unpack_from_obj) },
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};
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STATIC MP_DEFINE_CONST_DICT(mp_module_struct_globals, mp_module_struct_globals_table);
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const mp_obj_module_t mp_module_struct = {
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.base = { &mp_type_module },
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.globals = (mp_obj_dict_t *)&mp_module_struct_globals,
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};
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MP_REGISTER_EXTENSIBLE_MODULE(MP_QSTR_struct, mp_module_struct);
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#endif
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