py/modstruct.c

/*
 * This file is part of the Micro Python 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.
 */

#include <assert.h>
#include <string.h>
#include "misc.h"
#include "mpconfig.h"
#include "qstr.h"
#include "obj.h"
#include "builtin.h"
#include "objtuple.h"
#include "objstr.h"
#include "binary.h"
#include "parsenum.h"

#if MICROPY_ENABLE_MOD_STRUCT

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 machine_uint_t get_fmt_num(const char **p) {
    const char *num = *p;
    uint len = 1;
    while (unichar_isdigit(*++num)) {
        len++;
    }
    machine_uint_t val = (machine_uint_t)MP_OBJ_SMALL_INT_VALUE(mp_parse_num_integer(*p, len, 10));
    *p = num;
    return val;
}

STATIC uint calcsize_items(const char *fmt) {
    uint cnt = 0;
    while (*fmt) {
        // TODO supports size spec only for "s"
        if (!unichar_isdigit(*fmt++)) {
            cnt++;
        }
    }
    return cnt;
}

STATIC mp_obj_t struct_calcsize(mp_obj_t fmt_in) {
    const char *fmt = mp_obj_str_get_str(fmt_in);
    char fmt_type = get_fmt_type(&fmt);
    machine_uint_t size;
    for (size = 0; *fmt; fmt++) {
        uint align;
        machine_uint_t cnt = 1;
        if (unichar_isdigit(*fmt)) {
            cnt = get_fmt_num(&fmt);
        }
        if (cnt > 1) {
            // TODO: count spec support only for string len
            assert(*fmt == 's');
        }

        machine_uint_t sz;
        if (*fmt == 's') {
            sz = cnt;
        } else {
            sz = (machine_uint_t)mp_binary_get_size(fmt_type, *fmt, &align);
        }
        // TODO
        assert(sz != (machine_uint_t)-1);
        // Apply alignment
        size = (size + align - 1) & ~(align - 1);
        size += sz;
    }
    return MP_OBJ_NEW_SMALL_INT(size);
}
MP_DEFINE_CONST_FUN_OBJ_1(struct_calcsize_obj, struct_calcsize);

STATIC mp_obj_t struct_unpack(mp_obj_t fmt_in, mp_obj_t data_in) {
    // TODO: "The buffer must contain exactly the amount of data required by the format (len(bytes) must equal calcsize(fmt))."
    const char *fmt = mp_obj_str_get_str(fmt_in);
    char fmt_type = get_fmt_type(&fmt);
    uint size = calcsize_items(fmt);
    mp_obj_tuple_t *res = mp_obj_new_tuple(size, NULL);
    mp_buffer_info_t bufinfo;
    mp_get_buffer_raise(data_in, &bufinfo, MP_BUFFER_READ);
    byte *p = bufinfo.buf;

    for (uint i = 0; i < size; i++) {
        machine_uint_t sz = 1;
        if (unichar_isdigit(*fmt)) {
            sz = get_fmt_num(&fmt);
        }
        if (sz > 1) {
            // TODO: size spec support only for string len
            assert(*fmt == 's');
        }
        mp_obj_t item;
        if (*fmt == 's') {
            item = mp_obj_new_bytes(p, sz);
            p += sz;
            fmt++;
        } else {
            item = mp_binary_get_val(fmt_type, *fmt++, &p);
        }
        res->items[i] = item;
    }
    return res;
}
MP_DEFINE_CONST_FUN_OBJ_2(struct_unpack_obj, struct_unpack);

STATIC mp_obj_t struct_pack(uint n_args, mp_obj_t *args) {
    // TODO: "The arguments must match the values required by the format exactly."
    const char *fmt = mp_obj_str_get_str(args[0]);
    char fmt_type = get_fmt_type(&fmt);
    int size = MP_OBJ_SMALL_INT_VALUE(struct_calcsize(args[0]));
    byte *p;
    mp_obj_t res = mp_obj_str_builder_start(&mp_type_bytes, size, &p);
    memset(p, 0, size);

    for (uint i = 1; i < n_args; i++) {
        machine_uint_t sz = 1;
        if (unichar_isdigit(*fmt)) {
            sz = get_fmt_num(&fmt);
        }
        if (sz > 1) {
            // TODO: size spec support only for string len
            assert(*fmt == 's');
        }

        if (*fmt == 's') {
            mp_buffer_info_t bufinfo;
            mp_get_buffer_raise(args[i], &bufinfo, MP_BUFFER_READ);
            machine_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);
            p += sz;
            fmt++;
        } else {
            mp_binary_set_val(fmt_type, *fmt++, args[i], &p);
        }
    }
    return res;
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_pack_obj, 1, MP_OBJ_FUN_ARGS_MAX, struct_pack);

STATIC const mp_map_elem_t mp_module_struct_globals_table[] = {
    { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_struct) },
    { MP_OBJ_NEW_QSTR(MP_QSTR_calcsize), (mp_obj_t)&struct_calcsize_obj },
    { MP_OBJ_NEW_QSTR(MP_QSTR_pack), (mp_obj_t)&struct_pack_obj },
    { MP_OBJ_NEW_QSTR(MP_QSTR_unpack), (mp_obj_t)&struct_unpack_obj },
};

STATIC const mp_obj_dict_t mp_module_struct_globals = {
    .base = {&mp_type_dict},
    .map = {
        .all_keys_are_qstrs = 1,
        .table_is_fixed_array = 1,
        .used = ARRAY_SIZE(mp_module_struct_globals_table),
        .alloc = ARRAY_SIZE(mp_module_struct_globals_table),
        .table = (mp_map_elem_t*)mp_module_struct_globals_table,
    },
};

const mp_obj_module_t mp_module_struct = {
    .base = { &mp_type_module },
    .name = MP_QSTR_struct,
    .globals = (mp_obj_dict_t*)&mp_module_struct_globals,
};

#endif