Question

我在6502中遇到了另一个问题....

我试图添加两个n字节整数来产生n字节结果。我不完全确定我是否对这个项目能够理解6502芯片，所以对我当前代码的任何反馈都会非常有帮助。

我知道我应该使用INX（递增x寄存器）和DEY（递减y寄存器）但我不确定操作码的位置。

描述：使用绝对索引寻址添加两个n字节整数

Adding two n-byte integers using absolute indexed addressing 
The addends start at memory locations $xxxx, $yyyy, answer is at $zzzz
Byte length of the integers is at $AAAA (¢—>256)

START = $0500
              CLC
              ____
loop          LDA      $0400, x 
              ADC      $0410, x
              STA      $0412, x
             ____
             BNE      loop
             BRK

LDA，ADC和STA在循环之外（第一次在汇编中使用循环）

编辑：

    Variables

A1 = $0600
B1 = $0700
B2 = $0800
Z1 = $0900

    [START] = $0500

            CLC             18  
            LDX             AE  
            LDY     A1      AC
loop:       LDA     B1, x   BD      
            ADC     B2, x   7D  
            STA     Z1, x   9D      
            INX     E8  
            DEY             88  
            BNE    loop     D0

Answer 1

;Adding two n-byte integers using absolute indexed addressing 
;The addends start at memory locations $xxxx, $yyyy, answer is at $zzzz
;Byte length of the integers is at $AAAA (¢—>256)

        CLC
        LDX #0        ; start at the beginning
        LDY $AAAA     ; load length into Y
loop:   LDA $xxxx, X  ; load first operand
        ADC $yyyy, x  ; add second operand
        STA $zzzz, x  ; store result
        INX           ; go on to next byte
        DEY           ; count how many are left
        BNE loop      ; if more, do more

在6502中添加两个n-bytre整数以产生n字节答案？

1 个答案: