usr/src/cmd/as/as13.s

/
/

/ a3 -- pdp-11 assembler pass 1

assem:
        jsr     pc,readop
        jsr     pc,checkeos
                br ealoop
        tst     ifflg
        beq     3f
        cmp     r4,$200
        blos    assem
        cmpb    (r4),$21        /if
        bne     2f
        inc     ifflg
2:
        cmpb    (r4),$22   /endif
        bne     assem
        dec     ifflg
        br      assem
3:
        mov     r4,-(sp)
        jsr     pc,readop
        cmp     r4,$'=
        beq     4f
        cmp     r4,$':
        beq     1f
        mov     r4,savop
        mov     (sp)+,r4
        jsr     pc,opline
        br      ealoop
1:
        mov     (sp)+,r4
        cmp     r4,$200
        bhis    1f
        cmp     r4,$1           / digit
        beq     3f
        jsr     r5,error; 'x
        br      assem
1:
        bitb    $37,(r4)
        beq     1f
        jsr     r5,error; 'm
1:
        bisb    dot-2,(r4)
        mov     dot,2(r4)
        br      assem
3:
        mov     numval,r0
        jsr     pc,fbcheck
        movb    dotrel,curfbr(r0)
        asl     r0
        movb    dotrel,nxtfb
        mov     dot,nxtfb+2
        movb    r0,nxtfb+1
        mov     dot,curfb(r0)
        movb    fbfil,r0
        sys     write; nxtfb; 4
        jes     wrterr
        br      assem
4:
        jsr     pc,readop
        jsr     pc,expres
        mov     (sp)+,r1
        cmp     r1,$200
        bhis    1f
        jsr     r5,error; 'x
        br      ealoop
1:
        cmp     r1,$dotrel
        bne     2f
        bic     $40,r3
        cmp     r3,dotrel
        bne     1f
2:
        bicb    $37,(r1)
        bic     $!37,r3
        bne     2f
        clr     r2
2:
        bisb    r3,(r1)
        mov     r2,2(r1)
        br      ealoop
1:
        jsr     r5,error; '.
        movb    $2,dotrel
ealoop:
        cmp     r4,$';
        beq     assem1
        cmp     r4,$'\n
        bne     1f
        inc     line
        br      assem1
1:
        cmp     r4,$'\e
        bne     2f
        tst     ifflg
        beq     1f
        jsr     r5,error; 'x
1:
        rts     pc
2:
        jsr     r5,error; 'x
2:
        jsr     pc,checkeos
                br assem1
        jsr     pc,readop
        br      2b
assem1:
        jmp     assem

fbcheck:
        cmp     r0,$9.
        bhi     1f
        rts     pc
1:
        jsr     r5,error; 'f
        clr     r0
        rts     pc

checkeos:
        cmp     r4,$'\n
        beq     1f
        cmp     r4,$';
        beq     1f
        cmp     r4,$'\e
        beq     1f
        add     $2,(sp)
1:
        rts     pc