12.7 and narrowing signed integers

[tjotjos]

I have a question concerning Rule 12.7: Bitwise operators shall not be applied to operands whose underlying type is signed.

I need to transmit a 7-bit signed integer (values are restricted -64 - +63). My current method, shown below, seems to be inconsistent with 12.7.

Code:

int_8 s8a;
uint_8 u8b;
...
u8b = s8a & 0x7F;

Is the following an acceptable solution, or a violation of 10.1? Do I need to use a deviation here for the 7-bit integer?

Code:

int_8 s8a;
uint_8 u8b;
...
u8b = ((uint_8)s8a & 0x7F;

Thank you for your help!