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AS78K0 Assembler

PROCESSOR SPECIFIC DIRECTIVES 

.setdp Directive 

Format:  

        .setdp [base [,area]] 

The set direct page directive has a common format in all the as-
semblers supporting a paged mode.  The .setdp directive is  used
to  inform  the  AS78K0 assembler of the current SFR page region
and the offset address within the selected area.  The normal in-
vocation methods are:  

       .area   SFR  (PAG)
       .setdp

       or

       .setdp  0xFF00,SFR


The  directives  specify that the direct page is in area SFR and
its offset address is 0xFF00 (the only valid value for all r78k0
microprocessor  variations).   Be  sure to place the SFR area at
address 0xFF00 during linking.  When the base address  and  area
are  not  specified,  then  0xFF00  and the current area are the
defaults.  If a .setdp directive is  not  issued  the  assembler
defaults the direct page to the area "CODE" at offset 0xFF00.  

   The assembler verifies that any local variable used in an SFR
variable reference is located in this area.  Local variable  and
constant  value direct access addresses are checked to be within
the address range from 0xFF00 to 0xFFFF.  

   External SFR references are assumed by the assembler to be in
the correct area and have valid offsets.  The linker will  check
all SFR page relocations to verify that they are within the cor-
rect area.  


.xerr Directive 

Format:  

        .xerr [n] 


   The expanded error directive outputs alternate error messages
for the <a> error at the commmand line and in the listing  files
created by the assembler.  The modes are:  

       .xerr [0]

           Restores the default <a> error reporting.

       .xerr 1

           Replaces the <a> error with the <x> error which
           lists the source line containing the error on
           the stdout device.

       .xerr 2

           Replaces the <a> error with the <x> error which
           lists the source line containing the error on
           the stdout device and also outputs an additional
           <x> error describing the detected error.

       .xerr 3

           Replaces the <a> error with the <x> error which
           lists the source line containing the error on
           the stdout device and also outputs an additional
           <x> error describing the detected error.  The
           additional <x> error describing the detected
           error is inserted into the optional listing file.

78K/0 REGISTER SET 

The following is a list of the 78K/0 registers used by AS78K0:  

       x(r0), a(r1),   8-bit registers
       c(r2), b(r3),
       e(r4), d(r5),
       l(r6), h(r7)

       ax(rp0),        16-bit registers
       bc(rp1),
       de(rp2),
       hl(rp3)

       rb0, rb1,       register bank selection
       rb2, rb3

       sp              Stack pointer
       psw             Program status word
       cy              Carry flag

       Register names are NOT case sensitive.

78K/0 INSTRUCTION SET 

   The  following  tables list all 78K/0 mnemonics recognized by
the AS78K0 assembler.  The designation [] refers to  a  required
addressing  mode  argument.  The first list specifies the format
for each addressing mode supported by AS78K0:  

        addr16          direct addressing
                        via a 16-bit address

        !addr16         immediate addressing
                        only required for the
                        long br instruction

        addr11          direct addressing
                        via an 11-bit address

        [addr5]         indirect addressing
                        via a 5-bit address

        @saddr          short direct addressing
                        0xFE20 <= saddr <= 0xFF1F

        @saddr.bit      short direct addressing
        @saddr,bit      with bit addressing (0-7)
                        0xFE20 <= saddr <= 0xFF1F

        *sfr            special function registers
                        0xFF00 <= sfr <= 0xFFCF  or
                        0xFFE0 <= sfr <= 0xFFFF

        *sfr.bit        special function registers
        *sfr,bit        wiht bit addressing (0-7)
                        0xFF00 <= sfr <= 0xFFCF  or
                        0xFFE0 <= sfr <= 0xFFFF

        label           branch label
                        (pc relative addressing)

        #byte           immediate data (8  bit)
        #word           immediate data (16 bit)

        rn              registers (8 bit)
                        x, a, c, b, e, d, l, h
                        r0-r7

        rpn             registers (16 bit)
                        ax, bc, de, hl
                        rp0-rp3

        rbn             register bank
                        rb0-rb3

        sp              stack pointer

        psw             program status register

        cy              carry flag

        [DE], [HL]      register indirect addressing

        [HL+byte]       based register indirect addressing
        [HL,byte]
        [HL+B]
        [HL,B]
        [HL+C]
        [HL,C]

        [HL].bit        register indirect addressing
                        with bit addressing


   The  terms  addr16,  addr11,  addr5,  saddr, sfr, bit, label,
byte, and word may all be expressions.  

   Absolute  addresses  (CONSTANTS)  will be checked as being in
the 'saddr' range first and then as being in the 'sfr' range  if
no explicit @ or * is specified.  

   The  bit addressing modes *sfr.bit and @saddr.bit use the '.'
as a seperator from the address and  the  bit  value.   The  bit
value  can  be  a numeric constant, a named constant, an expres-
sion, or a combination of these.  Because the '.' is also a  le-
gal  character  in a name or label the assembler may not be able
to resolve the address and bit value.  The  optional  method  of
using a ',' to seperate the address and bit value may be used in
this case.  

   If  the 'sfr' or 'saddr' address is external then the user is
responsible to ensure the addresses are in  the  proper  ranges.
Paging ERRORS for 'sfr' may be reported by the linker.  

   Note  that  not all addressing modes are valid with every in-
struction, refer to the 78K/0 technical data for valid modes.  

Inherent Instructions 

        nop     halt    stop
        ret     retb    reti
        di      ei      brk
        adjba   adjbs

Branch Instructions 

        bc      label                   bnc     label
        bz      label                   bnz     label

        br      []                      dbnz    [],addr16

        bt      [],addr16               bf      [],addr16
        btclr   [],addr16

Single Operand Instructions 

        inc     []                      dec     []
        incw    rpn                     dec     rpn

        set1    []                      clr1    []

        set1    cy                      clr1    cy
        not1    cy

        ror4    [HL]                    rol4    [HL]

        call    addr16                  callt   [addr5]
        callf   addr11

        mulu    x                       divuw   c

        push    []                      pop     []

Double Operand Instructions 

        movw    sp,ax                   movw    ax,sp
        movw    [],[]                   xchw    ax,rpn

        add     a,[]                    add     saddr,#byte
        addc    a,[]                    addc    saddr,#byte
        sub     a,[]                    sub     saddr,#byte
        subc    a,[]                    subc    saddr,#byte
        and     a,[]                    and     saddr,#byte
        or      a,[]                    or      saddr,#byte
        xor     a,[]                    xor     saddr,#byte
        cmp     a,[]                    cmp     saddr,#byte

        mov1    cy,[]                   mov1    [],cy
        and1    cy,[]                   and1    [],cy
        or1     cy,[]                   or1     [],cy
        xor1    cy,[]                   xor1    [],cy

        adddw   ax,#word                subw    ax,#word
        cmpw    ax,#word
        
                ror     a,1                     rol     a,1
                rorc    a,1                     rolc    a,1

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Last Updated: January 2019