基于分支循环的LMC程序开发求助：内存地址91-95存1-5

Got it, let's tackle this LMC program requirement. The goal is to store values 1 to 5 into memory addresses 91 to 95 using loops (no hardcoded individual stores)—here's a clean, working approach tailored for the LMC simulator you're using:

Core Approach #

We'll use three key variables to drive the loop:

• A counter to track how many values we've left to store (starts at 5)
• A current value that we increment each iteration (starts at 1)
• A target address that we increment each iteration (starts at 91)

The loop will repeat until the counter hits 0, performing these steps each time:

1. Store the current value at the target address
2. Increment the current value by 1
3. Increment the target address by 1
4. Decrement the counter by 1
5. Check if we need to loop again

Full LMC Code #

LDA COUNT      ; Load loop counter into accumulator
        BRZ END        ; Exit immediately if counter is 0 (safety check)
LOOP    LDA VALUE      ; Load the value we need to store
        STA ADDR       ; Store it at the current target address
        ; Increment the value for next iteration
        LDA VALUE
        ADD ONE
        STA VALUE
        ; Increment the target address for next iteration
        LDA ADDR
        ADD ONE
        STA ADDR
        ; Decrement the loop counter
        LDA COUNT
        SUB ONE
        STA COUNT
        BRZ END        ; If counter is now 0, exit the loop
        BRA LOOP       ; Otherwise, jump back to start of loop
END     HLT            ; Halt the program

; Data section - initialize our variables
COUNT   DATA 5         ; Number of values to store (1-5)
VALUE   DATA 1         ; Starting value to store
ADDR    DATA 91        ; Starting memory address to write to
ONE     DATA 1         ; Constant for increment operations

How It Works (Line-by-Line) #

• Data Section: We define our starting values here. COUNT tells the loop how many times to run, VALUE is the first number we store, ADDR is the first memory location we write to, and ONE is a reusable constant for increments.
• Initial Check: The first LDA COUNT and BRZ END is a safety measure—if someone accidentally sets COUNT to 0, the program exits immediately instead of looping infinitely.
• Loop Body:
  • LDA VALUE + STA ADDR: Writes the current number to the target memory address.
  • The next four lines increment our value by 1 and save it back.
  • The following four lines increment our target address by 1 and save it back.
  • Finally, we decrement the counter. If it hits 0, we jump to END to halt; otherwise, we jump back to LOOP to repeat.

Testing in the Simulator #

After running the program, check memory addresses 91 through 95—you should see:

• Address 91: 1
• Address 92: 2
• Address 93: 3
• Address 94: 4
• Address 95: 5

This avoids hardcoding individual STA 91, STA 92, etc., and uses a finite loop exactly as required.

内容的提问来源于stack exchange，提问作者Sam Hockham