Need Assembly Help

PhatiteM — Fri, 08 Jun 2007 07:57:16 GMT

Hello everyone, I am a teaching assistant and i am in need of some help. Our students used to use a 68k chip and there are numerous labs that go along with it.

My job is to test these labs using the mcf5211DEMO board. I am unfamiliar with CodeWarrior 6.4 Coldfire and I am unable to even get the option to create a project in assembly. Can someone direct me as to how to test to make sure the programs (each instruction) will still run on the board? I've included an example of a previous lab.

TIA!
~M

*******************************************************************************
*
* Program that performs BCD arithmetic on data from the parallel port.
*
*******************************************************************************

* Set the assembler options, cre turns on cross-reference in the listing file
* and mex turns on macro expansion in the listing file.
    opt     cre,mex

*******************************************************************************
* Definitions for access to and control of the ACIA chip
ACIA_CR    equ    $E0000        ; Control Register address
ACIA_DR    equ    $E0002        ; Data Register address
* Control Register (7..0) Bit definitions:
* 7    Receive Interrupt Enable
* 6..5    RTS control / Transmit interrupt control
*    00 = RTS=Low, Transmit interrupt disabled
*          01 = RTS=Low, Transmit interrupt enabled
*          10 = RTS=High, Transmit interrupt disabled
*          11 = RTS=Low, TxD=Break, Transmit interrupt disabled
* 4..2    Communication configuration
*    000 = 7E2
*    001 = 7O2
*    010 = 7E1
*    011 = 7O1
*    100 = 8N2
*    101 = 8N1
*    110 = 8E1
*    111 = 8O1
* 1..0    Clock divider / Master Reset
*    00 = Divide by 1
*    01 = Divide by 16
*    10 = Divide by 64
*    11 = Master Reset
* Control register values:
SER_RST    equ    $03        ; CR1=CR0=1 causes master reset
SER_8N1    equ    $15        ; 4..2=8N1, Divide by 16
*******************************************************************************
* Definitions for access to and control of the PIA chip
* Port A Data Register
PIA_DRA     equ    ($E8001+$0)
* Port A Data Direction Register
PIA_DDRA     equ    ($E8001+$0)
* Port A Control Register
PIA_CRA     equ    ($E8001+$2)

* Port B Data Register
PIA_DRB     equ    ($E8001+$4)
* Port B Data Direction Register
PIA_DDRB     equ    ($E8001+$4)
* Port B Control Register
PIA_CRB     equ    ($E8001+$6)

* Control Register - Select Data Direction Register
SEL_DDR     equ    $00
* Control Register - Select Data Register
SEL_DR       equ    $04

* Data Direction Register - Select Input Port
SEL_INP     equ    $00
* Control Register - Select Output Port
SEL_OUTP     equ    $FF
*******************************************************************************

* Set the starting address of the program.
    org        $20000

start
* Initialize the stack
    MOVEA.L    #$23C00,A7

* Waste some time ~1sec. (wait for ACIA to be inactive)
           MOVE.L     #$0002FF00,D0
DELAY:     SUBQ.L     #1,D0
           BNE        DELAY

* Initialize ACIA #1 chip
* Reset the chip using "master reset"
           MOVE.B     #SER_RST,ACIA_CR
* Setup the communication protocol
           MOVE.B     #SER_8N1,ACIA_CR

* Initialize the PIA #1 chip
* Select the Data Direction Register for Port A
    MOVE.B    #SEL_DDR,PIA_CRA
* Setup Port A for output to LEDs
    MOVE.B    #SEL_OUTP,PIA_DDRA
* Select the Data Register for Port A
    MOVE.B    #SEL_DR,PIA_CRA
* Select the Data Direction Register for Port B
    MOVE.B    #SEL_DDR,PIA_CRB
* Setup Port B for input from switches
    MOVE.B    #SEL_INP,PIA_DDRB
* Select the Data Register for Port B
    MOVE.B    #SEL_DR,PIA_CRB
REPEAT:
* Prompt the user to set the switches for A
            MOVE.B     #0,d0
    LEA        M0,A1
    MOVEQ     #LENM0,D1
    BSR    SBC_IO
* Wait for a key to be pressed...
    MOVE.B     #5,D0
    BSR    SBC_IO
* Read the switches
    MOVE.B    PIA_DRB,D0
           MOVE.B     D0,BCD_A
* Prompt the user to set the switches for B
           MOVE.B     #0,d0
    LEA        M1,A1
    MOVEQ     #LENM1,D1
    BSR    SBC_IO
* Wait for a key to be pressed...
    MOVE.B     #5,D0
    BSR    SBC_IO
* Read the switches
    MOVE.B    PIA_DRB,D0
    MOVE.B    D0,BCD_B
* Calculate the BCD sum A-23+B
        MOVE.B     #$23,D0
    MOVE.B    BCD_A,D1
    MOVE.B    BCD_B,D2
* Initialize the CCR, X=0 and Z=1
    MOVE.W    #%00100,CCR
* Compute A-23
        SBCD       D0,D1
* Check to see if result is less than 0 (indicated by a carry-out)
    BCS    OUT_RANGE
* Compute A-23+B
           ABCD       D2,D1
* Check to see if result is greater than 99 (indicated by a carry-out)
    BCC    IN_RANGE
* Display 'out of range' message
OUT_RANGE:
           MOVE.B     #1,d0
    LEA        M3,A1
    MOVEQ     #LENM3,D1
    BSR    SBC_IO
* Clear the result (and the LEDs) since it is not correct
    CLR.B    D1
IN_RANGE:
* Display the result on the LEDs
    MOVE.B    D1,PIA_DRA
* Prompt the user to contiue
           MOVE.B     #0,d0
    LEA        M2,A1
    MOVEQ     #LENM2,D1
    BSR    SBC_IO
* Get the user response
    MOVE.B     #5,D0
    BSR    SBC_IO
* Compare the response - repeat if it was 'Y'
    CMP.B    #'Y',D1
    BEQ    REPEAT

* Stop executing
            JMP         $48C

*******************************************************************************
* This subroutine implements *some* of the Teesside simulator TRAP I/O
*
* D0.B : Description (blank descriptions are not implemented)
*
* 0: Print string pointed at by A1 and D1.W characters long with CRLF
* 1: Print string pointed at by A1 and D1.W characters long without CRLF
* 2: Read the string pointed at by A1. Length returned in D1.W (maximum 80)
* 3:
* 4:
* 5: Read a single character in D1.B
* 6: Print a single character in D1.B
* 7:
* 8:
* 9:
*
*******************************************************************************
sbc_io:
* Save registers
        MOVEM.L D0,-(SP)
* Dispatch table / switch() statement
    CMP.B    #0,D0
    BEQ    SUB_0
            CMP.B       #1,D0
            BEQ         SUB_1
    CMP.B    #2,D0
    BEQ    SUB_2
    CMP.B    #5,D0
            BEQ         SUB_5
    CMP.B    #6,D0
            BEQ         SUB_6
* Default for unimplemented subfunctions is to simply exit, an error is better
    JMP    EXIT_IO
*******************************************************************************
* Print the string pointed at by A1 and D1.W characters long with CRLF
SUB_0:
* setup loop by decrementing LCV
    SUBI.W    #1,D1
    CMP.W    #-1,D1
    BEQ    CRLF
NEXT_0:
* Check to see if the ACIA is ready for a character
    MOVE.B    ACIA_CR,D0
    BTST.B    #1,D0
    BEQ    NEXT_0
* The ACIA is ready, send it the character
    MOVE.B    (A1)+,ACIA_DR
    DBF    D1,NEXT_0
CRLF:
CR_WAIT:
* Check to see if the ACIA is ready for a character
    MOVE.B    ACIA_CR,D0
    BTST.B    #1,D0
    BEQ    CR_WAIT
* The ACIA is ready, send it the CR
    MOVE.B    #$0D,ACIA_DR
* Check to see if the ACIA is ready for a character
LF_WAIT:
    MOVE.B    ACIA_CR,D0
    BTST.B    #1,D0
    BEQ    LF_WAIT
* The ACIA is ready, send it the LF
    MOVE.B    #$0A,ACIA_DR
* Done. Go to the subroutine exit
    JMP    EXIT_IO
*******************************************************************************
* Print the string pointed at by A1 and D1.W characters long without CRLF
SUB_1:
* setup loop by decrementing LCV
    SUBI.W    #1,D1
    CMP.W    #-1,D1
            BEQ         DONE_1
NEXT_1:
* Check to see if the ACIA is ready for a character
    MOVE.B    ACIA_CR,D0
    BTST.B    #1,D0
            BEQ         NEXT_1
* The ACIA is ready, send it the character
    MOVE.B    (A1)+,ACIA_DR
            DBF         D1,NEXT_1
DONE_1:
    JMP    EXIT_IO
*******************************************************************************
* Read the string pointed at by A1. Length resturned in D1.W (max 80)
SUB_2:
* Clear Count register
    CLR.W    D1
NEXT_2:
* Check to see if the ACIA has a character
    MOVE.B    ACIA_CR,D0
    BTST.B    #0,D0
            BEQ         NEXT_2
* The ACIA has a character, get it the character
            MOVE.B     ACIA_DR,D0
* See if the character is "enter"
    CMP.B    #$0D,D0
    BEQ    DONE_2
* Save the character
            MOVE.B     D0,(A1)+
    ADDI.W    #1,D1
    JMP    NEXT_2
DONE_2:
            JMP         EXIT_IO
*******************************************************************************
* Read a single character in D1.B
SUB_5:
* Check to see if the ACIA has a character
    MOVE.B    ACIA_CR,D0
    BTST.B    #0,D0
    BEQ    SUB_5
* The ACIA has a character, get it the character
    MOVE.B    ACIA_DR,D1
    JMP    EXIT_IO
*******************************************************************************
* Print single character in D1.B
SUB_6:
* Check to see if the ACIA is ready for a character
    MOVE.B    ACIA_CR,D0
    BTST.B    #1,D0
    BEQ    SUB_6
* The ACIA is ready, send it the character
    MOVE.B    D1,ACIA_DR
    JMP    EXIT_IO
EXIT_IO:
* Restore Resisters
            MOVEM.L     (SP)+,D0
* Return from subroutine
    RTS

*******************************************************************************
* Constants are placed at the end of the program.
*******************************************************************************
m0        dc.b        'Enter the BCD value for A on the switches'
lenm0     equ         *-m0
m1        dc.b        'Enter the BCD value for B on the switches'
lenm1     equ         *-m1
m2        dc.b        'Enter Y to continue: '
lenm2     equ         *-m2
m3        dc.b        'The result is out of range (0-99) and cannot be displayed!'
lenm3     equ         *-m3

*******************************************************************************
* Variables are placed in RAM
*******************************************************************************
* Set the starting address of RAM data
          org         $22000
BCD_A     ds.b        1
BCD_B     ds.b        1
          end         start

Re: Need Assembly Help

SimonMarsden_de — Fri, 08 Jun 2007 16:22:04 GMT

Hi

If you name the file with extension ".s" and include it in the CodeWarrior project, the assembler will automatically be invoked to handle it.

However, I'm afraid you have got three problems...

(a) The code is written in 68K assembler, and not all assembler dialects are the same. CodeWarrior uses the same mnemonics for instructions as your example (Some assemblers like Gnu do not), but some of the assembler directives are different.

For example, the CodeWarrior assembler requires everything to be in a section (text, data), etc, so you'll need to add suitable directives. You'll also need to add explicit "extern" statements for all external labels.

If you try to assemble your example, you'll get quite a few errors...

There is a preference panel for the assembler options. Make sure that you have "Labels must end with :" unchecked, and "Directives begin with ." unchecked. If you then start the file with:

    text
    option   processor=mcf5211

...then you'll get down to a large but manageable number of assembler errors.

(b) The code is written for a 68K processor and hence uses the 68K instruction set. Some of the instructions which were valid for 68K are not valid for ColdFire. For example:

    ABCD
    SBCD
    MOVEM.L    D0,-(SP)

You will need to recode these.

(c) The code is written for a 68K processor with 68K-specific peripherals. For example, it is accessing a 'PIA #1' chip. Since the same hardware probably doesn't exist on the ColdFire Demo board, this code will need rewriting too.

In summary, you might be better off understanding what this code does, and rewriting it for ColdFire.

Sorry this is not more encouraging.

Simon

topic Need Assembly Help in ColdFire/68K Microcontrollers and Processors

Need Assembly Help

Re: Need Assembly Help