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py: Add ustruct.pack_into and unpack_from

This commit is contained in:
Dave Hylands 2015-12-23 19:11:27 -08:00 committed by Damien George
parent ac16cc9a35
commit a17755ee8b
3 changed files with 118 additions and 19 deletions
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94
py/modstruct.c
View File

@ -132,22 +132,45 @@ STATIC mp_obj_t struct_calcsize(mp_obj_t fmt_in) {
}
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);
STATIC mp_obj_t struct_unpack_from(size_t n_args, const mp_obj_t *args) {
// unpack requires that the buffer be exactly the right size.
// unpack_from requires that the buffer be "big enough".
// Since we implement unpack and unpack_from using the same function
// we relax the "exact" requirement, and only implement "big enough".
const char *fmt = mp_obj_str_get_str(args[0]);
char fmt_type = get_fmt_type(&fmt);
uint size = calcsize_items(fmt);
mp_obj_tuple_t *res = MP_OBJ_TO_PTR(mp_obj_new_tuple(size, NULL));
uint num_items = calcsize_items(fmt);
mp_obj_tuple_t *res = MP_OBJ_TO_PTR(mp_obj_new_tuple(num_items, NULL));
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(data_in, &bufinfo, MP_BUFFER_READ);
mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_READ);
byte *p = bufinfo.buf;
byte *end_p = &p[bufinfo.len];
mp_int_t offset = 0;
for (uint i = 0; i < size;) {
if (n_args > 2) {
// offset arg provided
offset = mp_obj_get_int(args[2]);
if (offset < 0) {
// negative offsets are relative to the end of the buffer
offset = bufinfo.len + offset;
if (offset < 0) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "buffer too small"));
}
}
p += offset;
}
for (uint i = 0; i < num_items;) {
if (*fmt == '\0') {
break;
}
mp_uint_t sz = 1;
if (unichar_isdigit(*fmt)) {
sz = get_fmt_num(&fmt);
}
if (p + sz > end_p) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "buffer too small"));
}
mp_obj_t item;
if (*fmt == 's') {
item = mp_obj_new_bytes(p, sz);
@ -163,23 +186,24 @@ STATIC mp_obj_t struct_unpack(mp_obj_t fmt_in, mp_obj_t data_in) {
}
return MP_OBJ_FROM_PTR(res);
}
MP_DEFINE_CONST_FUN_OBJ_2(struct_unpack_obj, struct_unpack);
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_unpack_from_obj, 2, 3, struct_unpack_from);
STATIC mp_obj_t struct_pack(size_t n_args, const 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]);
STATIC void struct_pack_into_internal(mp_obj_t fmt_in, byte *p, byte* end_p, size_t n_args, const mp_obj_t *args) {
const char *fmt = mp_obj_str_get_str(fmt_in);
char fmt_type = get_fmt_type(&fmt);
mp_int_t size = MP_OBJ_SMALL_INT_VALUE(struct_calcsize(args[0]));
vstr_t vstr;
vstr_init_len(&vstr, size);
byte *p = (byte*)vstr.buf;
memset(p, 0, size);
for (mp_uint_t i = 1; i < n_args;) {
size_t i;
for (i = 0; i < n_args;) {
mp_uint_t sz = 1;
if (*fmt == '\0') {
break;
}
if (unichar_isdigit(*fmt)) {
sz = get_fmt_num(&fmt);
}
if (p + sz > end_p) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "buffer too small"));
}
if (*fmt == 's') {
mp_buffer_info_t bufinfo;
@ -198,16 +222,48 @@ STATIC mp_obj_t struct_pack(size_t n_args, const mp_obj_t *args) {
}
fmt++;
}
}
STATIC mp_obj_t struct_pack(size_t n_args, const mp_obj_t *args) {
// TODO: "The arguments must match the values required by the format exactly."
mp_int_t size = MP_OBJ_SMALL_INT_VALUE(struct_calcsize(args[0]));
vstr_t vstr;
vstr_init_len(&vstr, size);
byte *p = (byte*)vstr.buf;
memset(p, 0, size);
byte *end_p = &p[size];
struct_pack_into_internal(args[0], p, end_p, n_args - 1, &args[1]);
return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_pack_obj, 1, MP_OBJ_FUN_ARGS_MAX, struct_pack);
STATIC mp_obj_t struct_pack_into(size_t n_args, const mp_obj_t *args) {
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_WRITE);
mp_int_t offset = mp_obj_get_int(args[2]);
if (offset < 0) {
// negative offsets are relative to the end of the buffer
offset = (mp_int_t)bufinfo.len + offset;
if (offset < 0) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "buffer too small"));
}
}
byte *p = (byte *)bufinfo.buf;
byte *end_p = &p[bufinfo.len];
p += offset;
struct_pack_into_internal(args[0], p, end_p, n_args - 3, &args[3]);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(struct_pack_into_obj, 3, MP_OBJ_FUN_ARGS_MAX, struct_pack_into);
STATIC const mp_rom_map_elem_t mp_module_struct_globals_table[] = {
{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_ustruct) },
{ MP_ROM_QSTR(MP_QSTR_calcsize), MP_ROM_PTR(&struct_calcsize_obj) },
{ MP_ROM_QSTR(MP_QSTR_pack), MP_ROM_PTR(&struct_pack_obj) },
{ MP_ROM_QSTR(MP_QSTR_unpack), MP_ROM_PTR(&struct_unpack_obj) },
{ MP_ROM_QSTR(MP_QSTR_pack_into), MP_ROM_PTR(&struct_pack_into_obj) },
{ MP_ROM_QSTR(MP_QSTR_unpack), MP_ROM_PTR(&struct_unpack_from_obj) },
{ MP_ROM_QSTR(MP_QSTR_unpack_from), MP_ROM_PTR(&struct_unpack_from_obj) },
};
STATIC MP_DEFINE_CONST_DICT(mp_module_struct_globals, mp_module_struct_globals_table);

2
py/qstrdefs.h
View File

@ -491,7 +491,9 @@ Q(print_exception)
Q(struct)
Q(ustruct)
Q(pack)
Q(pack_into)
Q(unpack)
Q(unpack_from)
Q(calcsize)
#endif

41
tests/basics/struct1.py
View File

@ -66,3 +66,44 @@ except TypeError:
# but later were implemented for all.
print(struct.unpack("<3B2h", b"foo\x12\x34\xff\xff"))
print(struct.pack("<3B", 1, 2, 3))
# pack_into
buf = bytearray(b'>>>123<<<')
struct.pack_into('<bbb', buf, 3, 0x41, 0x42, 0x43)
print(buf)
struct.pack_into('<bbb', buf, -6, 0x44, 0x45, 0x46)
print(buf)
try:
struct.pack_into('<bbb', buf, 7, 0x41, 0x42, 0x43)
except:
print('struct.error')
try:
struct.pack_into('<bbb', buf, -10, 0x41, 0x42, 0x43)
except:
print('struct.error')
# unpack_from
buf = b'0123456789'
print(struct.unpack_from('<b', buf, 4))
print(struct.unpack_from('<b', buf, -4))
try:
print(struct.unpack_from('<b', buf, 10))
except:
print('struct.error')
try:
print(struct.unpack_from('<b', buf, -11))
except:
print('struct.error')
# pack with too many args, not checked by uPy
#try:
# print(struct.pack('ii', 1, 2, 3))
#except:
# print('struct.error')
# pack with too few args, not checked by uPy
#try:
# print(struct.pack('ii', 1))
#except:
# print('struct.error')