Re: A82: ASM code problem

[Prev][Next][Index][Thread]

Re: A82: ASM code problem

In a message dated 97-07-07 22:26:05 EDT, you write:

<< At 07:54 PM 7/7/97 -0400, you wrote:
 >>   call (FINAL_ADDR)
 >
 >Well... CALL (FINAL_ADDR) should mean call the address that's stored at
 'FINAL_ADDR', but that's not an instruction in Z80 assembly language, so
 I'm assuming it's supposed to be CALL_(FINAL_ADDR), which is the
 Zshell/Ash/Oshell-82 defines for calling even though the program will be at
 another place.

 No, I meant call (FINAL_ADDR).  The call opcode does exist (see the Z80
 Instruction Set Summary).  The source I sent to this list is only a small
 portion of the ROM_CALL routine that I will be using in ASH <-> OShell.  I
 sent the source because I wanted to see if there was any errors in my
 knowledge of Z80 ASM.  I have narrowed my problem down to just a line or
 two of code.  The following code does NOT work:

 #include "ti-82.h"
 FINAL_ADDR = $8C2B         ; Word

 .ORG 0
 .DB "Test Ver",0

   call CLEARLCD            ; Clears the LCD
   ld bc,0                  ; 0 -> c, 0 -> b
   ld (CURSOR_ROW),bc       ; Set cursor at position (0,0)
   ld hl,Text               ; Address of Text -> hl
   ld de,(PROGRAM_ADDR)     ; (PROGRAM_ADDR) -> de
   add hl,de                ; hl = hl + de

   ld bc,D_ZT_STR
   ld (FINAL_ADDR),bc
   call (FINAL_ADDR)
 GetkeyLoop:
   call GET_KEY             ; Get the keyboard scan code
   cp $37                   ; Check to see if [MODE] was pressed
   ret Z                    ; If so, return to caller
   jr GetkeyLoop            ; Goto GetkeyLoop

 Text: .DB "Hello World!!!",0

 .END


 However, this code works (it gets to be REAL weird after fooling with the
 code for a while):

 #include "ti-82.h"
 FINAL_ADDR = $8C2B         ; Word

 .ORG 0
 .DB "Test Ver",0

   call CLEARLCD            ; Clears the LCD
   ld bc,0                  ; 0 -> c, 0 -> b
   ld (CURSOR_ROW),bc       ; Set cursor at position (0,0)
   ld hl,Text               ; Address of Text -> hl
   ld de,(PROGRAM_ADDR)     ; (PROGRAM_ADDR) -> de
   add hl,de                ; hl = hl + de

   call D_ZT_STR
 GetkeyLoop:
   call GET_KEY             ; Get the keyboard scan code
   cp $37                   ; Check to see if [MODE] was pressed
   ret Z                    ; If so, return to caller
   jr GetkeyLoop            ; Goto GetkeyLoop

 Text: .DB "Hello World!!!",0

 .END

 Both programs should be compiled under OShell-82.  This is a very confusing
 problem and I really would like any hint to an answer.
  >>

ever heard of a ROM_CALL?  call CLEARLCD should not work, and niether should
call D_ZT_STR (and of course not that junk in the first program!!!)

but yes, call does exist.


~Adamman