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objint: Implement int.from_bytes() class method and .to_bytes() method.
These two are apprerently the most concise and efficient way to convert int to/from bytes in Python. The alternatives are struct and array modules, but methods using them are more verbose in Python code and less efficient in memory/cycles.
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‎py/objint.c‎

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@@ -261,11 +261,49 @@ mp_obj_t mp_obj_int_binary_op_extra_cases(int op, mp_obj_t lhs_in, mp_obj_t rhs_
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return MP_OBJ_NULL;
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}
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STATIC mp_obj_t int_from_bytes(uint n_args, const mp_obj_t *args) {
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buffer_info_t bufinfo;
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mp_get_buffer_raise(args[0], &bufinfo);
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assert(bufinfo.len >= sizeof(machine_int_t));
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// TODO: Support long ints
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// TODO: Support byteorder param
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// TODO: Support signed param
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return mp_obj_new_int_from_uint(*(machine_uint_t*)bufinfo.buf);
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(int_from_bytes_obj, 1, 3, int_from_bytes);
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STATIC mp_obj_t int_to_bytes(uint n_args, const mp_obj_t *args) {
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machine_int_t val = mp_obj_int_get_checked(args[0]);
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uint len = MP_OBJ_SMALL_INT_VALUE(args[1]);
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byte *data;
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// TODO: Support long ints
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// TODO: Support byteorder param
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// TODO: Support signed param
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mp_obj_t o = mp_obj_str_builder_start(&mp_type_bytes, len, &data);
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memset(data, 0, len);
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memcpy(data, &val, len < sizeof(machine_int_t) ? len : sizeof(machine_int_t));
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return mp_obj_str_builder_end(o);
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}
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STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(int_to_bytes_obj, 2, 4, int_to_bytes);
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STATIC const mp_map_elem_t int_locals_dict_table[] = {
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{ MP_OBJ_NEW_QSTR(MP_QSTR_from_bytes), (mp_obj_t)&int_from_bytes_obj },
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{ MP_OBJ_NEW_QSTR(MP_QSTR_to_bytes), (mp_obj_t)&int_to_bytes_obj },
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};
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STATIC MP_DEFINE_CONST_DICT(int_locals_dict, int_locals_dict_table);
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const mp_obj_type_t mp_type_int = {
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{ &mp_type_type },
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.name = MP_QSTR_int,
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.print = mp_obj_int_print,
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.make_new = mp_obj_int_make_new,
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.unary_op = mp_obj_int_unary_op,
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.binary_op = mp_obj_int_binary_op,
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.locals_dict = (mp_obj_t)&int_locals_dict,
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};

‎py/qstrdefs.h‎

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@@ -96,6 +96,7 @@ Q(eval)
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Q(exec)
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Q(filter)
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Q(float)
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Q(from_bytes)
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Q(getattr)
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Q(globals)
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Q(hash)
@@ -127,6 +128,7 @@ Q(sum)
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Q(super)
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Q(str)
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Q(sys)
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Q(to_bytes)
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Q(tuple)
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Q(type)
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Q(value)

‎tests/basics/int-bytes.py‎

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@@ -0,0 +1,6 @@
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print((10).to_bytes(1, "little"))
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print((111111).to_bytes(4, "little"))
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print((100).to_bytes(10, "little"))
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print(int.from_bytes(b"\x00\x01\0\0\0\0\0\0", "little"))
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print(int.from_bytes(b"\x01\0\0\0\0\0\0\0", "little"))
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print(int.from_bytes(b"\x00\x01\0\0\0\0\0\0", "little"))

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