Question

The purpose of the ARM assembly code below is to write the value 1 to bit 2 of Port F without affecting any other port bits. Provide the value of the ORR mask required to make the code below execute as described. Give your answer as a 32-bit hexadecimal number.

Answer 1

The ORR mask required to set bit 2 of Port F to 1 in ARM assembly without changing other bits is 0x00000004. This value in binary corresponds to '0000 0100', which specifically targets bit 2 in a 32-bit register.

Step-by-step explanation:

The student is asking for the value of the ORR mask required to set bit 2 of Port F to 1 in ARM assembly language, without affecting other bits of the port. To set a specific bit to 1, we can use the ORR instruction along with a mask that has a 1 in the position of the bit we want to set. In this case, setting bit 2 would require a mask where bit 2 is set to 1 and all other bits are set to 0. In binary, this is 0000 0100 for the least significant 8 bits, which translates to the corresponding 32-bit hexadecimal value of 0x00000004 when considering a 32-bit ARM processor.

To use this in the ARM assembly code, one would typically load this mask into a register and then use the ORR instruction to OR the mask with the current value of the port, resulting in only bit 2 being set while leaving the other bits unchanged.