Final answer:
To write an LC-3 machine language routine to increment numbers in a range of memory locations, we load the start and end addresses, increment each value, and loop until the range is completed.
Step-by-step explanation:
This LC-3 machine language routine requires iterating over a range of memory addresses defined by the contents of memory locations x3100 and x3101. The process involves loading the start and end addresses, incrementing the value at each memory location, and repeating this until all addresses have been updated. The LC-3 instruction set has the necessary operations to load, store, and increment values:
- Load the start address (A) into a register.
- Load the end address (B) into another register.
- Increment the value at the memory location pointed to by the start address.
- Increment the start address.
- Compare the updated start address with the end address.
- Continue the process until the start address exceeds the end address.
The following is an example of what the routine might look like using generic labels and instructions:
LD R1, A_ADDR ;; Load the start address into R1
LD R2, B_ADDR ;; Load the end address into R2
INCREMENT_LOOP
LD R3, 0(R1) ;; Load the value at the start address
ADD R3, R3, #1 ;; Increment the value
ST R3, 0(R1) ;; Store the incremented value
ADD R1, R1, #1 ;; Increment the start address
NOT R4, R2 ;; Invert end address for comparison
ADD R4, R4, #1 ;; Add 1 to the inverted end address for comparison
ADD R4, R1, R4 ;; Compare start address with end address
BRzp INCREMENT_LOOP ;; Repeat if start address <= end address
A_ADDR .FILL x3100 ;; Address of A
B_ADDR .FILL x3101 ;; Address of B
This routine demonstrates a loop structure that iterates through a given range of addresses, incrementing each stored value by one until the entire range is processed.