circuitpython/py/modstruct.c

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#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"
#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 uint calcsize_items(const char *fmt) {
// TODO
return strlen(fmt);
}
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;
int sz = mp_binary_get_size(fmt_type, *fmt, &align);
// TODO
assert(sz != -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++) {
mp_obj_t 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++) {
mp_binary_set_val(fmt_type, *fmt++, args[i], &p);
}
return res;
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_pack_obj, 1, -1, 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