need help debugging assembly code (HCS 12)

Question

need help debugging, when assembly code goes to my subroutine it is printing out the value of register B instead of the value of register A. Any help is much appreciated.

            dc.b    "Type a character"
            dc.b    0    ; using zero terminated strings

         LDS   #ROMStart         ; load stack pointer
         JSR   TermInit         ; needed for Simulator only
LOOP
         LDD   #PROMPT          ; pass the adr of the string
         JSR     printf     ; print the string         
         JSR     getchar     ; call getchar function -result is: character in B
         JSR    putchar
         CMPB           ‘W’     ;COMPARE USER INPUT TO W
         BNE     LOOP       ;
         JSR    WFCN
-------------------------------------------------------------------------------------------------------
  WFCN  PSHA
        LDAA    #$3D
        EORA     #$6F
        JSR     out2hex
        PULA
        RTS```

Answer 1

The names of these C functions have always been misleading. getchar returns an int not char, 16 bits. Similarly, putchar takes a 16 bit int parameter. So it is likely that your specific calling convention uses the double accumulator D (Codewarrior calling convention works like that).

Since D = A + B (and big endian), the results you expect end up in the ls byte, accumulator B.