Change lab01 rotation functions parameter type

[c7stef]

Use unsigned int instead of int for bitwise rotate functions. The reason for this change is that signed integers should generally not be used as bitsets, since some arithmetic operators behave badly in the case of signed integers, as opposed to unsigned (particularly left and right shifts). Here, the problems with int arise in the following ways:

• The proposed solution assigns the unsigned constant 0x80000000, with value 2^31, to a 32-bit signed integer, which can only represent values less than or equal to 2^31 - 1. Assigning this large value to an int has implementation-defined behavior. Legal signed integer values with this particular bit representation (1 followed by 31 zeros) include two's complement -2^31, sign-and-magnitude -0 etc. (depending on the encoding).
• The proposed rotate_left impl shifts signed *number to the left by bits positions, though the C standard document specifies the result of this operation is *number * 2^(bits), and if this value is not representable by int, then the behavior is undefined (this happens whenever a 1 is shifted to or beyond the most significant bit).
• The proposed rotate_right impl similarly shifts signed *number to the right by bits positions, adding the missing piece to the left by way of the | operator. The assumption is that the shift leaves some 0 bits to the left of *number. However, if the most significant bit is 1 (i.e., a negative value), the result of the right shift is implementation-defined. Modern platforms implement arithmetic right shift, which extends the sign of *number by copying the most significant bit, leaving 1 instead of 0 to the left side of *number.

All of these problems can be avoided by using unsigned numbers instead, as they do not exhibit strange behavior with bit operators. Note that using signed integers for the right-hand operands of shift operators is not a problem, hence I left the bits parameter untouched.

[teodutu]

All good. And thanks for the detailed description.

We're now transitioning this content to a more open and granular standard (you can read about it here if you want [1]). In doing so, we're copying the lab content (for now; the lectures will follow) to this repo [2] and translating it into English. We intend to use this new repo starting next semester. So please apply these changes to the rotations exercise in the new repo [3] if you have the time. Remember to respect the contributing guidelines [4] as they're stricter than the ones on this repo.

[1] https://open-education-hub.github.io/methodology/
[2] https://github.com/cs-pub-ro/hardware-software-interface/
[3] https://github.com/cs-pub-ro/hardware-software-interface/tree/main/chapters/intro-computer-architecture/binary-hex/drills/tasks/rotations
[4] https://github.com/cs-pub-ro/hardware-software-interface/blob/main/CONTRIBUTING.md#commits