AS6812 Assembler


   The   AS6812  assembler  supports  the  68HC(S)12  series  of
microprocessors which includes  the  68HC(S)8xx  and  68HC(S)9xx

.hc12 Directive 



The  .hc12 directive selects the HC12 core specific cycles count
output when the -c command line option is specified.  

.hcs12 Directive 



The  .hcs12  directive  selects  the  HCS12 core specific cycles
count output when the -c command line option is specified.  

The .__.CPU.  Variable 

   The value of the pre-defined symbol '.__.CPU.' corresponds to
the selected processor type.  The default value is 0 which  cor-
responds  to  the  default  processor type.  The following table
lists the processor types and associated values for  the  AS6812

        Processor Type            .__.CPU. Value
        --------------            --------------
            .hc12                        0
            .hcs12                       1

   The  variable  '.__.CPU.'  is by default defined as local and
will not be output to the created .rel file.  The assembler com-
mand line options -g or -a will not cause the local symbol to be
output to the created .rel file.  

   The  assembler  .globl  directive  may  be used to change the
variable type to global causing its definition to be  output  to
the  .rel file.  The inclusion of the definition of the variable
'.__.CPU.' might be a useful means of validating that seperately
assembled  files have been compiled for the same processor type.
The linker will report an error for variables with multiple  non
equal definitions.  


The  following  is a list of the  68HC(S)12  registers  used  by

        a,b     -       8-bit accumulators
        d       -       16-bit accumulator <a:b>
        x,y     -       index registers
        sp,s    -       stack pointer
        pc      -       program counter
        ccr,cc  -       condition code register


   The  following tables list all 68HC(S)12 mnemonics recognized
by the AS6812 assembler.  The designation []  refers  to  a  re-
quired  addressing  mode argument.  The following list specifies
the format for each addressing mode supported by AS6812:  

        #data           immediate data
                        byte or word data

        ext             extended addressing

        pg              memory page number

        *dir            direct page addressing
                        (see .setdp directive)
                        0 <= dir <= 255 

        label           branch label

        r,r1,r2         registers

        -x      x-      register indexed, pre or
        ,-x     ,x-     post autodecrement by 1

        n,-x    n,x-    register indexed, pre or
                        post autodecrement by 1 - 8

        +x      x+      register indexed, pre or
        ,+x     ,x+     post autoincrement by 1

        n,+x    n,x+    register indexed, pre or
                        post autoincrement by 1 - 8

        offset,x        register indexed addressing
                           -16 <= offset <= 15    ---  5-bit
                          -256 <= offset <= -17   ---  9-bit
                            16 <= offset <= 255   ---  9-bit
                        -32768 <= offset <= -257  --- 16-bit
                           256 <= offset <= 32767 --- 16-bit
                        (external definition of offset
                         uses 16-bit mode)

        [offset,x]      register indexed indirect addressing
                        -32768 <= offset <= 32767 --- 16-bit

        [,x]            register indexed indirect addressing
                        zero offset

        a,x             accumulator offset indexed addressing

        [d,x]           d accumulator offset indexed
                        indirect addressing

The  terms  data, dir, label, offset, and ext may all be expres-

   Note  that  not all addressing modes are valid with every in-
struction, refer to the 68HC(S)12 technical data for valid modes.  

Inherent Instructions 

        aba             bgnd            cba
        daa             dex             dey
        ediv            edivs           emul
        emuls           fdiv            idiv
        idivs           inx             iny
        mem             mul             nop
        psha            pshb            pshc
        pshd            pshx            pshy
        pula            pulb            pulc
        puld            pulx            puly
        rev             revw            rtc
        rti             rts             sba
        stop            swi             tab
        tba             wai             wav

Short Branch Instructions 

        bcc     label           bcs     label
        beq     label           bge     label
        bgt     label           bhi     label
        bhis    label           bhs     label
        ble     label           blo     label
        blos    label           bls     label
        blt     label           bmi     label
        bne     label           bpl     label
        bra     label           brn     label
        bvc     label           bvs     label
        bsr     label

Long Branch Instructions 

        lbcc    label           lbcs    label
        lbeq    label           lbge    label
        lbgt    label           lbhi    label
        lbhis   label           lbhs    label
        lble    label           lblo    label
        lblos   label           lbls    label
        lblt    label           lbmi    label
        lbne    label           lbpl    label
        lbra    label           lbrn    label
        lbvc    label           lbvs    label

Branch on Decrement, Test, or Increment 

        dbeq    r,label         dbne    r,label
        ibeq    r,label         ibne    r,label
        tbeq    r,label         tbne    r,label

Bit Clear and Set Instructions 

        bclr    [],#data
        bset    [],#data

Branch on Bit Clear or Set 

        brclr   [],#data,label
        brset   [],#data,label

Single Operand Instructions 

        asla            aslb
        asl     []

        asra            asrb
        asr     []

        clra            clrb
        clr     []

        coma            comb
        com     []

        deca            decb
        dec     []

        inca            incb
        inc     []

        lsla            lslb
        lsl     []

        lsra            lsrb
        lsr     []

        nega            negb
        neg     []

        rola            rolb
        rol     []

        rora            rorb
        ror     []

        tsta            tstb
        tst     []

Double Operand Instructions 

        adca    []              adcb    []

        adda    []              addb    []

        anda    []              andb    []

        bita    []              bitb    []

        cmpa    []              cmpb    []

        eora    []              eorb    []

        ldaa    []      <=>     lda     []

        ldab    []      <=>     ldb     []

        oraa    []      <=>     ora     []

        orab    []      <=>     orb     []

        sbca    []              sbcb    []

        staa    []      <=>     sta     []

        stab    []      <=>     stb     []

        suba    []              subb    []

Move Instructions 

        movb    [],[]           movw    [],[]

D-register Instructions 

        addd    []              subd    []
        cpd     []      <=>     cmpd    []
        ldd     []              std     []

Index/Stack Register Instructions 

        cps     []      <=>     cmps    []
        cpx     []      <=>     cmpx    []
        cpy     []      <=>     cmpy    []

        lds     []
        ldx     []              ldy     []

        leas    []
        leax    []              leay    []

        sts     []
        stx     []              sty     []

Jump and Jump/Call to Subroutine Instructions 

        call    [],pg
        jmp     []              jsr     []

Other Special Instructions 

        emacs   []
        emaxd   []              emaxm   []
        emind   []              eminm   []
        etbl    []
        maxa    []              maxm    []
        mina    []              minm    []
        tbl     []              trap    #data

H.2.14  Register - Register Instructions 

        exg     r1,r2           sex     r1,r2
        tfr     r1,r2

Condition Code Register Instructions 

        andcc   #data           orcc    #data

M68HC11 Compatibility Mode Instructions 

        abx             aby             clc
        cli             clv             des
        ins             sec             sei
        sev             tap             tpa
        tsx             tsy             txs
        tys             xgdx            xgdy

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Last Updated: March 2021