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py/modstruct: Allow to have "0s" in struct format.

This commit is contained in:
Damien George 2016-05-28 23:27:38 +01:00
parent 282d81a40e
commit 715ee9d925
2 changed files with 37 additions and 15 deletions
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24
py/modstruct.c
View File

@ -103,30 +103,24 @@ STATIC mp_obj_t struct_calcsize(mp_obj_t fmt_in) {
char fmt_type = get_fmt_type(&fmt);
mp_uint_t size;
for (size = 0; *fmt; fmt++) {
mp_uint_t align = 1;
mp_uint_t cnt = 1;
if (unichar_isdigit(*fmt)) {
cnt = get_fmt_num(&fmt);
}
mp_uint_t sz = 0;
if (*fmt == 's') {
sz = cnt;
cnt = 1;
}
while (cnt--) {
// If we already have size for 's' case, don't set it again
if (sz == 0) {
sz = (mp_uint_t)mp_binary_get_size(fmt_type, *fmt, &align);
}
size += cnt;
} else {
mp_uint_t align;
size_t sz = mp_binary_get_size(fmt_type, *fmt, &align);
if (sz == 0) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "unsupported format"));
}
// Apply alignment
size = (size + align - 1) & ~(align - 1);
size += sz;
sz = 0;
while (cnt--) {
// Apply alignment
size = (size + align - 1) & ~(align - 1);
size += sz;
}
}
}
return MP_OBJ_NEW_SMALL_INT(size);

28
tests/basics/struct2.py Normal file
View File

@ -0,0 +1,28 @@
# test ustruct with a count specified before the type
try:
import ustruct as struct
except:
import struct
print(struct.calcsize('0s'))
print(struct.unpack('0s', b''))
print(struct.pack('0s', b'123'))
print(struct.calcsize('2s'))
print(struct.unpack('2s', b'12'))
print(struct.pack('2s', b'123'))
print(struct.calcsize('2H'))
print(struct.unpack('<2H', b'1234'))
print(struct.pack('<2H', 258, 515))
print(struct.calcsize('0s1s0H2H'))
print(struct.unpack('<0s1s0H2H', b'01234'))
print(struct.pack('<0s1s0H2H', b'abc', b'abc', 258, 515))
# check that zero of an unknown type raises an exception
try:
struct.calcsize('0z')
except:
print('Exception')