\ Plan9 a.out generation  \ Steps to build a.out binary:\\ 1. compute .data size (pdict + dict)\ 2. generate a.out header\ 3. copy .text\ 4. copy .data (only primitives) \ 5. fixup "h", "dp", "heaptop" and "tib" in copied primitive-dictionary\ 6. copy generated dictionary\ 7. write-out completed executable  \ image addresses variable textbase   variable textsize   variable textaddrvariable pdictbase  variable pdictsize  variable pdictaddrvariable stackbase  variable theaptop _start textbase !_end _start - textsize !c" @" findname drop 1 cells - pdictbase !dictbase @ pdictbase @ - pdictsize !s0 @ stackbase ! textbase @ textaddr ! \ identical, unless cross-compilingpdictbase @ pdictaddr ! \ same hereheaptop @ theaptop ! variable datasize     variable imgbase    variable bsssize 4096 constant pagesize : calc-datasize  ( -- )    malign mhere mdictbase @ - pdictsize @ + datasize ! ; : calc-sizes  ( -- )    calc-datasize    here imgbase !                      \  where image is generated    stackbase @ mhere mreloc - bsssize ! ; : dump-sizes  ( -- )    ."  text section size:       " textsize @ . cr    ."  data section size:       " datasize @ . cr    ."  bss section size:        " bsssize @ . cr ; \ Big-endian comma: big,  ( n -- )  dup 24 rshift c, dup 16 rshift 255 and c, dup 8 rshift 255 and c,   255 and c, ;   hex 000001eb constant a.out-magic-i3861020 constant a.out-entry-point-i386decimal : gen-a.out-header  ( entrypoint -- )  a.out-magic-i386 big,  textsize @ big, datasize @ big, bsssize @ big,  0 , big, 0 , 0 ,  ;   \ syms, entry, spsz, pcsz        : copy-bytes  ( a n -- )  >r here r@ cmove r> allot ;: copy-text  ( -- )  textbase @ textsize @ copy-bytes ;: copy-pdict  ( -- a )  here >r pdictbase @ pdictsize @ copy-bytes r> ;: copy-dict  ( -- )  mdictbase @ mhere mdictbase @ - copy-bytes ; \ location in generated core-dict for system-variable values4 constant #sysvars   variable sysvars : valoffset  ( xt -- offset ) pmap pdictaddr @ - cell+ ; : fixup-const  ( pdict val xt -- ) over . cr valoffset rot + ! ; : fixup  ( pdict xt index -- )    cells sysvars @ + mreloc swap ( pdict sysvaraddr xt ) fixup-const ; : fixup-vars  ( pdict -- )    mhere mreloc sysvars @ !                         \ h    mdp @ mreloc sysvars @ cell+ !                   \ dp    theaptop @ sysvars @ 2 cells + !                 \ heaptop    hex    ."   h:       " dup ['] h 0 fixup    ."   dp:      " dup ['] dp 1 fixup    ."   heaptop: " dup ['] heaptop 2 fixup    ."   tib:     " dup ['] tib 3 fixup    ."   _start:  " dup textaddr @ ['] _start fixup-const    ."   _end:    " textaddr @ textsize @ + ['] _end fixup-const     decimal ; : unexec ( | <fname> -- )    bl word count w/o open-file ?fcheck >r    imgbase @ dup here swap - r@ write-file ?fcheck    r> close-file ?fcheck ; : .offset ( -- ) here imgbase @ - . ; \ invoke after metacompilation: msave  ( <fname> -- )    describe-endianness    ." calculating sizes" cr    mhere sysvars ! #sysvars cells mallot  \ h, dp, heaptop, tib, _start, _end    tibsize wordbufsize + mallot           \ tib + wordbuf    calc-sizes dump-sizes    ." generating a.out header" cr    a.out-entry-point-i386 gen-a.out-header    ." generating .text section" cr    copy-text    ." generating .data section" cr    ."  generating primitive dictionary" cr    copy-pdict    ."  fixing up system variables" cr    fixup-vars    ."  copying core dictionary" cr    copy-dict    ." saving image" cr    unexec    ." done" cr ;