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py/objint: from_bytes(): Implement "byteorder" param and arbitrary precision.

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If result guaranteedly fits in a small int, it is handled in objint.c.
Otherwise, it is delegated to mp_obj_int_from_bytes_impl(), which should
be implemented by individual objint_*.c, similar to
mp_obj_int_to_bytes_impl().
This commit is contained in:
Paul Sokolovsky 2017-01-21 20:14:18 +03:00
parent 1b42f5251f
commit bec7bfb29d
3 changed files with 26 additions and 12 deletions
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31
py/objint.c
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@ -374,26 +374,33 @@ mp_obj_t mp_obj_int_binary_op_extra_cases(mp_uint_t op, mp_obj_t lhs_in, mp_obj_
// this is a classmethod
STATIC mp_obj_t int_from_bytes(size_t n_args, const mp_obj_t *args) {
// TODO: Support long ints
// TODO: Support byteorder param
// TODO: Support signed param (assumes signed=False at the moment)
(void)n_args;
if (args[2] != MP_OBJ_NEW_QSTR(MP_QSTR_little)) {
mp_not_implemented("");
}
// get the buffer info
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_READ);
// convert the bytes to an integer
mp_uint_t value = 0;
for (const byte* buf = (const byte*)bufinfo.buf + bufinfo.len - 1; buf >= (byte*)bufinfo.buf; buf--) {
value = (value << 8) | *buf;
}
#if MICROPY_LONGINT_IMPL != MICROPY_LONGINT_IMPL_NONE
// If result guaranteedly fits in small int, use that
if (!MP_SMALL_INT_FITS(1 << (bufinfo.len * 8 - 1))) {
return mp_obj_int_from_bytes_impl(args[2] != MP_OBJ_NEW_QSTR(MP_QSTR_little), bufinfo.len, bufinfo.buf);
} else
#endif
{
const byte* buf = (const byte*)bufinfo.buf;
int delta = 1;
if (args[2] == MP_OBJ_NEW_QSTR(MP_QSTR_little)) {
buf += bufinfo.len - 1;
delta = -1;
}
return mp_obj_new_int_from_uint(value);
mp_uint_t value = 0;
for (; bufinfo.len--; buf += delta) {
value = (value << 8) | *buf;
}
return mp_obj_new_int_from_uint(value);
}
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(int_from_bytes_fun_obj, 3, 4, int_from_bytes);

1
py/objint.h
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@ -59,6 +59,7 @@ char *mp_obj_int_formatted(char **buf, size_t *buf_size, size_t *fmt_size, mp_co
char *mp_obj_int_formatted_impl(char **buf, size_t *buf_size, size_t *fmt_size, mp_const_obj_t self_in,
int base, const char *prefix, char base_char, char comma);
mp_int_t mp_obj_int_hash(mp_obj_t self_in);
mp_obj_t mp_obj_int_from_bytes_impl(bool big_endian, size_t len, const byte *buf);
void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, size_t len, byte *buf);
int mp_obj_int_sign(mp_obj_t self_in);
mp_obj_t mp_obj_int_abs(mp_obj_t self_in);

6
py/objint_mpz.c
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@ -107,6 +107,12 @@ char *mp_obj_int_formatted_impl(char **buf, size_t *buf_size, size_t *fmt_size,
return str;
}
mp_obj_t mp_obj_int_from_bytes_impl(bool big_endian, size_t len, const byte *buf) {
mp_obj_int_t *o = mp_obj_int_new_mpz();
mpz_set_from_bytes(&o->mpz, big_endian, len, buf);
return MP_OBJ_FROM_PTR(o);
}
void mp_obj_int_to_bytes_impl(mp_obj_t self_in, bool big_endian, size_t len, byte *buf) {
assert(MP_OBJ_IS_TYPE(self_in, &mp_type_int));
mp_obj_int_t *self = MP_OBJ_TO_PTR(self_in);