汇编中的递归？佩普/ 8

Question

我试图在汇编中编写一个相当简单的程序，并遇到一些问题。我设法使用while循环编写应用程序，但它在递归时似乎有奇怪的结果。当我为第一个整数输入100而第二个输入10时，它返回正确的答案。但是，如果我选择100和15，我会得到意想不到的结果。

         BR      main
x:       .BLOCK  2
y:       .BLOCK  2 
answer:  .BLOCK  0
;
retVal:  .EQUATE 12
result:  .EQUATE 10
n:       .EQUATE 8
m:       .EQUATE 6
n1:      .EQUATE 2
m1:      .EQUATE 0
myMod:   SUBSP   4,i 
if:      LDA     n,sf
         CPA     m,sf
         BRGE    else,i
         LDA     n,sf
         STA     result,d 
         BR      endIf    
else:    LDA     n,sf
         SUBA    m,sf
         STA     n1,d
         LDA     m,sf
         STA     m1,d
         LDA     n1,i
         STA     -4,s
         LDA     m1,i
         STA     -6,s
         SUBSP   6,i
         CALL    myMod
         ADDSP   6,i
         STA     result,d
endIf:   LDA     result,d
         STA     retVal,s
         RET4
main:    STRO    openMsg,d
         DECI    x,d
         STRO    openMsg,d
         DECI    y,d
         LDA     x,i
         STA     -4,s
         LDA     y,i
         STA     -6,s
         SUBSP   6,i
         CALL    myMod
ra1:     ADDSP   8,i
         DECO    x,d
         STRO    msg1,d
         DECO    y,d
         STRO    msg2,d
         DECO    -2,s
         STOP
openMsg: .ASCII "Enter a positive number: \x00" 
msg1:    .ASCII  " % \x00"
msg2:    .ASCII  " is \x00"  
         .END