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/
/

/ a21 -- pdp-11 assembler pass 2 

main:
       sys     signal; 2; 1
       ror     r0
       bcs     1f
       sys     signal; 2; saexit
1:
       jmp     start

/ set up sizes and origins

go:

/ read in symbol table

       mov     $usymtab,r1
1:
       jsr     pc,getw
       bvs     1f
       add     $14,symsiz              / count symbols
       jsr     pc,getw
       jsr     pc,getw
       jsr     pc,getw
       jsr     pc,getw
       mov     r4,r0
       bic     $!37,r0
       cmp     r0,$2                   /text
       blo     2f
       cmp     r0,$3                   /data
       bhi     2f
       add     $31,r4                  /mark "estimated"
       mov     r4,(r1)+
       jsr     pc,getw
       mov     r4,(r1)+
       br      3f
2:
       clr     (r1)+
       clr     (r1)+
       jsr     pc,getw
3:
       jsr     pc,setbrk
       br      1b
1:

/ read in f-b definitions

       mov     r1,fbbufp
       movb    fbfil,fin
       clr     ibufc
1:
       jsr     pc,getw
       bvs     1f
       add     $31,r4                  / "estimated"
       mov     r4,(r1)+
       jsr     pc,getw
       mov     r4,(r1)+
       jsr     pc,setbrk
       br      1b
1:
       mov     r1,endtable
       mov     $100000,(r1)+

/ set up input text file; initialize f-b table

       jsr     pc,setup
/ do pass 1

       jsr     pc,assem

/ prepare for pass 2
       cmp     outmod,$777
       beq     1f
       jmp     aexit
1:
       clr     dot
       mov     $2,dotrel
       mov     $..,dotdot
       clr     brtabp
       movb    fin,r0
       sys     close
       jsr     r5,ofile; a.tmp1
       movb    r0,fin
       clr     ibufc
       jsr     pc,setup
       inc     passno
       inc     bsssiz
       bic     $1,bsssiz
       mov     txtsiz,r1
       inc     r1
       bic     $1,r1
       mov     r1,txtsiz
       mov     datsiz,r2
       inc     r2
       bic     $1,r2
       mov     r2,datsiz
       mov     r1,r3
       mov     r3,datbase      / txtsiz
       mov     r3,savdot+2
       add     r2,r3
       mov     r3,bssbase      / txtsiz+datsiz
       mov     r3,savdot+4
       clr     r0
       asl     r3
       adc     r0
       add     $20,r3
       adc     r0
       mov     r3,symseek+2    / 2*txtsiz+2*datsiz+20
       mov     r0,symseek
       sub     r2,r3
       sbc     r0
       mov     r3,drelseek+2   / 2*txtsiz+datsiz
       mov     r0,drelseek
       sub     r1,r3
       sbc     r0
       mov     r3,trelseek+2   / txtsiz+datsiz+20
       mov     r0,trelseek
       sub     r2,r3
       sbc     r0
       mov     r0,datseek
       mov     r3,datseek+2    / txtsiz+20
       mov     $usymtab,r1
1:
       jsr     pc,doreloc
       add     $4,r1
       cmp     r1,endtable
       blo     1b
       clr     r0
       clr     r1
       jsr     r5,oset; txtp
       mov     trelseek,r0
       mov     trelseek+2,r1
       jsr     r5,oset; relp
       mov     $8.,r2
       mov     $txtmagic,r1
1:
       mov     (r1)+,r0
       jsr     r5,putw; txtp
       dec     r2
       bne     1b
       jsr     pc,assem

/polish off text and relocation

       jsr     r5,flush; txtp
       jsr     r5,flush; relp

/ append full symbol table

       mov     symf,r0
       mov     r0,fin
       sys     lseek; 0; 0; 0
       clr     ibufc
       mov     symseek,r0
       mov     symseek+2,r1
       jsr     r5,oset; txtp
       mov     $usymtab,r1
1:
       jsr     pc,getw
       bvs     1f
       mov     r4,r0
       jsr     r5,putw; txtp
       jsr     pc,getw
       mov     r4,r0
       jsr     r5,putw; txtp
       jsr     pc,getw
       mov     r4,r0
       jsr     r5,putw; txtp
       jsr     pc,getw
       mov     r4,r0
       jsr     r5,putw; txtp
       mov     (r1)+,r0
       jsr     r5,putw; txtp
       mov     (r1)+,r0
       jsr     r5,putw; txtp
       jsr     pc,getw
       jsr     pc,getw
       br      1b
1:
       jsr     r5,flush; txtp
       jmp     aexit

       .data
saexit:
       mov     pc,errflg

aexit:
       mov     a.tmp1,0f
       sys     unlink; 0:..
       mov     a.tmp2,0f
       sys     unlink; 0:..
       mov     a.tmp3,0f
       sys     unlink; 0:..
       tst     errflg
       bne     2f
       sys     umask; 0
       bic     r0,outmod
       sys     chmod; a.outp2:a.out; outmod: 777
       clr     r0
       br      1f
2:
       mov     $2,r0
1:
       sys     exit
       .text

filerr:
       mov     *(r5),r5
1:
       movb    (r5)+,ch
       beq     1f
       mov     $1,r0
       sys     write; ch; 1
       br      1b
1:
       mov     $1,r0
       sys     write; qnl; 2
       jmp     saexit

doreloc:
       movb    (r1),r0
       bne     1f
       bisb    defund,(r1)
1:
       bic     $!37,r0
       cmp     r0,$5
       bhis    1f
       cmp     r0,$3
       blo     1f
       beq     2f
       add     bssbase,2(r1)
       rts     pc
2:
       add     datbase,2(r1)
1:
       rts     pc

setbrk:
       mov     r1,-(sp)
       add     $20,r1
       cmp     r1,0f
       blo     1f
       add     $512.,0f
       sys     indir; 9f
       .data
9:      sys     break; 0: end
       .text
1:
       mov     (sp)+,r1
       rts     pc

setup:
       mov     $curfb,r4
1:
       clr     (r4)+
       cmp     r4,$curfb+40.
       blo     1b
       mov     txtfil,fin
       clr     ibufc
       clr     r4
1:
       jsr     pc,fbadv
       tstb    (r4)+
       cmp     r4,$10.
       blt     1b
       rts     pc

ofile:
       mov     *(r5),0f
       sys     indir; 9f
       .data
9:      sys     open; 0:..; 0
       .text
       bes     1f
       tst     (r5)+
       rts     r5
1:
       jmp     filerr