py: Start implementing "struct" module.
Only calcsize() and unpack() functions provided so far, for little-endian
byte order. Format strings don't support repition spec (like "2b3i").
Unfortunately, dealing with all the various binary type sizes and alignments
will lead to quite a bloated "binary" helper functions - if optimizing for
speed. Need to think if using dynamic parametrized algos makes more sense.
diff --git a/py/modstruct.c b/py/modstruct.c
new file mode 100644
index 0000000..b5110df
--- /dev/null
+++ b/py/modstruct.c
@@ -0,0 +1,94 @@
+#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 "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);
+ assert(fmt_type == '<'); (void)fmt_type;
+ uint size;
+ for (size = 0; *fmt; fmt++) {
+ int sz = mp_binary_get_size(*fmt);
+ // TODO
+ assert(sz != -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);
+ assert(fmt_type == '<'); (void)fmt_type;
+ uint size = calcsize_items(fmt);
+ mp_obj_tuple_t *res = mp_obj_new_tuple(size, NULL);
+ buffer_info_t bufinfo;
+ mp_get_buffer_raise(data_in, &bufinfo);
+ byte *p = bufinfo.buf;
+
+ for (uint i = 0; i < size; i++) {
+ mp_obj_t item = mp_binary_get_val_unaligned_le(*fmt++, &p);
+ res->items[i] = item;
+ }
+ return res;
+}
+MP_DEFINE_CONST_FUN_OBJ_2(struct_unpack_obj, struct_unpack);
+
+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_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 = sizeof(mp_module_struct_globals_table) / sizeof(mp_map_elem_t),
+ .alloc = sizeof(mp_module_struct_globals_table) / sizeof(mp_map_elem_t),
+ .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