摩托罗拉68000总成比较号码

Question

我正在编写的程序以一个单数数字、一个空格和一个两位数字的形式输入。该程序将两个数字相加在一起，将数量减少7s直到小于7，并将该数字与一周中的一天相关联。以下是我所拥有的：

start:  initIO                  * Initialize (required for I/O)
    setEVT          * Error handling routines
*   initF           * For floating point macros only       

    linein  buffer          *reads in values
    cvta2   buffer,#1       *provided macro to convert ascii to num, read first digit only
    move.b  D0,D1           *Store value in D1
    cvta2   buffer+2,#2     *read the next two digits after space
    move.b  D0,D2           *store
    add.b   D1,D2           *add them together (I can probably use just one register here)

麻烦就在这里：

for:    cmp.w   week, D2 *<<<<< This is saying invalid syntax, I want to see if the number provided is greater than 7, if not branch out to the next section

/trouble

    ble done
    subq.w  #7,D2        *If num>7, sub 7

done:   

    lineout dmsg

        break                   * Terminate execution
*
*----------------------------------------------------------------------
*       Storage declarations

buffer: dc.b    80
dmsg:   dc.b    'Done',0
week:   dc.b    $7    *If combined value is greater than this, sub 7
*These are the values to check against to get correct reply
sun:    dc.b    $1
mon:    dc.b    $2
tues:   dc.b    $3
weds:   dc.b    $4
thurs:  dc.b    $5
fri:    dc.b    $6
sat:    dc.b    $7
*These are the responses for the output
sunr:   dc.b    'Sunday',0
monr:   dc.b    'Monday',0
tuesr:  dc.b    'Tueday',0
wedsr:  dc.b    'Wednesday',0
thursr: dc.b    'Thursday',0
frir:   dc.b    'Friday',0
satr:   dc.b    'Saturday',0

        end

当我知道如何进行上面的比较时，将会有更多的代码，但是它将是相同的比较，仅使用结果与星期的天数值，以便提供正确的响应。

我尝试过使用cmp的各种形式(cmpa、cmpi.w/l等)，但我似乎找不到一种方法可以比较这两个值。在尝试比较它或类似的东西之前，我是否必须将标记为"week“的值加载到寄存器中？

I/O的例子：

输入：

1 10

输出：

“星期三”

任何洞察力都是值得赞赏的。耽误您时间，实在对不起。

Answer 1

您正在尝试与不支持的寻址模式进行比较(在您的示例中，“week”操作数不是即时值，而是内存地址)。

要将D2与7进行比较，可以使用cmpi (比较立即)：

cmpi.b #7,d2

如果需要操作数作为变量，则必须先将其加载到寄存器中：

lea week,a0
...
cmp.b (a0),d2

还要确保cmp指令中的操作数大小与数据大小相匹配。

Answer 2

编辑(未优化问题的工作代码)：

start:  initIO                  * Initialize (required for I/O)
    setEVT          * Error handling routines
*   initF           * For floating point macros only    

    linein  buffer
    cvta2   buffer,#1   
    move.l  D0,D1
    cvta2   buffer+2,#2
    move.l  D0,D2
    add.l   D1,D2    

    divu.w  #$0007,D2   

    lsr.l   #$08,D2 *Shift remainder
    lsr.l   #$08,D2    

    move.w  sun,A2
    cmp.w   A2,D2
    BNE monday
    lineout sunr
    BEQ end

monday: 
    move.w  mon,A2
    cmp.w   A2,D2
    BNE tuesda
    lineout monr
    BEQ end    

tuesda: 
    move.w  tues,A2
    cmp.w   A2,D2
    BNE wednes
    lineout tuesr
    BEQ end    

wednes: 
    move.w  weds,A2
    cmp.w   A2,D2
    BNE thursd
    lineout wedsr
    BEQ end    

thursd: 
    move.w  thurs,A2
    cmp.w   A2,D2
    BNE friday
    lineout thursr
    BEQ end    

friday: 
    move.w  fri,A2
    cmp.w   A2,D2
    BNE saturd
    lineout frir
    BEQ end    

saturd: 
    lineout satr
    BEQ end    

end:    
        break                   * Terminate execution
*
*----------------------------------------------------------------------
*       Storage declarations

buffer: dc.b    80
wkmsg:  dc.w    'The day of the week is '
week:   equ $7
sun:    dc.w    $1
mon:    dc.w    $2
tues:   dc.w    $3
weds:   dc.w    $4
thurs:  dc.w    $5
fri:    dc.w    $6
sat:    dc.w    $7
sunr:   dc.w    'Sunday',0
monr:   dc.w    'Monday',0
tuesr:  dc.w    'Tueday',0
wedsr:  dc.w    'Wednesday',0
thursr: dc.w    'Thursday',0
frir:   dc.w    'Friday',0
satr:   dc.w    'Saturday',0

        end