Problem

In NXP Semiconductors embedded software, register updates are often done with bit masks. Given a 32-bit unsigned register value, write a function that sets the 5th bit and returns the updated register.

Assume bit positions are 0-indexed from the least significant bit, so the 5th bit means bit index 4.

Formal Specification

• Input: An integer reg representing a 32-bit unsigned register value.
• Output: An integer representing the updated 32-bit value after setting bit 4.
• The operation must preserve all other bits.

Examples

Example 1

• Input: reg = 0
• Output: 16
• Explanation: Bit 4 is set, so 0b0000 becomes 0b10000.

Example 2

• Input: reg = 18
• Output: 18
• Explanation: 18 is 0b10010, and bit 4 is already set, so the value does not change.

Constraints

• 0 <= reg <= 2^32 - 1
• Treat the value as a 32-bit unsigned integer.
• Use a bitwise solution in constant time.

A C macro for this operation would conceptually use reg | (1U << 4). Implement the equivalent logic in Python.