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/
/ copyright 1972 bell telephone laboratories inc.
/

/  a7 -- pdp-11 assembler

expres:
       clr     xsymbol
expres1:
       mov     r5,-(sp)
       mov     $'+,-(sp)
       clr     r2
       mov     $1,r3
       br      1f
advanc:
       jsr     pc,readop
1:
       mov     r4,r0
       jsr     r5,betwen; 0; 177
               br .+4
       br      7f
       movb    (r4),r0
       tst     r0
       bne     1f
       tstb    passno
       beq     1f
       jsr     r5,error; 'u
1:
       cmp     r0,$40
       bne     1f
       mov     r4,xsymbol
       clr     r1
       br      oprand
1:
       mov     2(r4),r1
       br      oprand
7:
       cmp     r4,$141
       blo     1f
       asl     r4
       mov     curfb-[2*141](r4),r0
       mov     2(r0),r1
       movb    (r0),r0
       br      oprand
1:
       mov     $esw1,r1
1:
       cmp     (r1)+,r4
       beq     1f
       tst     (r1)+
       bne     1b
       tst     (sp)+
       mov     (sp)+,r5
       rts     pc
1:
       jmp     *(r1)

esw1:
       '+;     binop
       '-;     binop
       '*;     binop
       '/;     binop
       '&;     binop
       037;    binop
       035;    binop
       036;    binop
       '%;     binop
       '[;     brack
       '^;     binop
       1;      exnum
       2;      exnum1
       '!;     binop
       200;    0

binop:
       cmpb    (sp),$'+
       beq     1f
       jsr     pc,errore
1:
       movb    r4,(sp)
       br      advanc

exnum1:
       mov     numval,r1
       br      1f

exnum:
       jsr     pc,getw
       mov     r4,r1
1:
       mov     $1,r0
       br      oprand

brack:
       mov     r2,-(sp)
       mov     r3,-(sp)
       jsr     pc,readop
       jsr     pc,expres1
       cmp     r4,$']
       beq     1f
       jsr     r5,error; ']
1:
       mov     r3,r0
       mov     r2,r1
       mov     (sp)+,r3
       mov     (sp)+,r2

oprand:
       mov     $exsw2,r5
1:
       cmp     (sp),(r5)+
       beq     1f
       tst     (r5)+
       bne     1b
       br      eoprnd
1:
       jmp     *(r5)

exsw2:
       '+; exadd
       '-; exsub
       '*; exmul
       '/; exdiv
       037; exor
       '&; exand
       035;exlsh
       036;exrsh
       '%; exmod
       '^; excmbin
       '!; exnot
       200;  0

excmbin:
       mov     r0,r3
       br      eoprnd

exrsh:
       neg     r1
       beq     exlsh
       inc     r1
       clc
       ror     r2
exlsh:
       jsr     r5,combin; relte2
       als     r1,r2
       br      eoprnd

exmod:
       jsr     r5,combin; relte2
       mov     r3,r0
       mov     r2,r3
       clr     r2
       dvd     r1,r2
       mov     r3,r2
       mov     r0,r3
       br      eoprnd

exadd:
       jsr     r5,combin; reltp2
       add     r1,r2
       br      eoprnd

exsub:
       jsr     r5,combin; reltm2
       sub     r1,r2
       br      eoprnd

exand:
       jsr     r5,combin; relte2
       com     r1
       bic     r1,r2
       br      eoprnd

exor:
       jsr     r5,combin; relte2
       bis     r1,r2
       br      eoprnd

exmul:
       jsr     r5,combin; relte2
       mpy     r2,r1
       mov     r1,r2
       br      eoprnd

exdiv:
       jsr     r5,combin; relte2
       mov     r3,r0
       mov     r2,r3
       clr     r2
       dvd     r1,r2
       mov     r0,r3
       br      eoprnd

exnot:
       jsr     r5,combin; relte2
       com     r1
       add     r1,r2
       br      eoprnd

eoprnd:
       mov     $'+,(sp)
       jmp     advanc

combin:
       tstb    passno
       bne     combin1
       mov     r0,-(sp)
       bis     r3,(sp)
       bic     $!40,(sp)
       bic     $!37,r0
       bic     $!37,r3
       cmp     r0,r3
       ble     1f
       mov     r0,-(sp)
       mov     r3,r0
       mov     (sp)+,r3
1:
       tst     r0
       beq     1f
       cmp     (r5)+,$reltm2
       bne     2f
       cmp     r0,r3
       bne     2f
       mov     $1,r3
       br      2f
1:
       tst     (r5)+
       clr     r3
2:
       bis     (sp)+,r3
       rts     r5
combin1:
       mov     r1,-(sp)
       clr     maxtyp
       jsr     pc,maprel
       mov     r0,r1
       mpy     $6,r1
       mov     r3,r0
       jsr     pc,maprel
       add     (r5)+,r0
       add     r1,r0
       movb    (r0),r3
       bpl     1f
       cmp     r3,$-1
       beq     2f
       jsr     r5,error; 'r
2:
       mov     maxtyp,r3
1:
       mov     (sp)+,r1
       rts     r5

maprel:
       cmp     r0,$40
       bne     1f
       mov     $5,r0
       rts     pc
1:
       bic     $!37,r0
       cmp     r0,maxtyp
       blos    1f
       mov     r0,maxtyp
1:
       cmp     r0,$5
       blos    1f
       mov     $1,r0
1:
       rts     pc

X = -2
M = -1
reltp2:
       .byte 0, 0, 0, 0, 0, 0
       .byte 0, M, 2, 3, 4,40
       .byte 0, 2, X, X, X, X
       .byte 0, 3, X, X, X, X
       .byte 0, 4, X, X, X, X
       .byte 0,40, X, X, X, X

reltm2:
       .byte 0, 0, 0, 0, 0, 0
       .byte 0, M, 2, 3, 4,40
       .byte 0, X, 1, X, X, X
       .byte 0, X, X, 1, X, X
       .byte 0, X, X, X, 1, X
       .byte 0, X, X, X, X, X

relte2:
       .byte 0, 0, 0, 0, 0, 0
       .byte 0, M, X, X, X, X
       .byte 0, X, X, X, X, X
       .byte 0, X, X, X, X, X
       .byte 0, X, X, X, X, X
       .byte 0, X, X, X, X, X