! Copyright (C) 2004, 2005 Slava Pestov.
! See http://factor.sf.net/license.txt for BSD license.

! This library allows one to generate a new set of bootstrap
! images (boot.image.{le32,le64,be32,be64}.
!
! It does this by parsing the set of source files needed to
! generate the minimal image, and writing the cons cells, words,
! strings etc to the image file in the CFactor object memory
! format.

IN: image
USING: errors generic hashtables kernel lists
math namespaces parser prettyprint sequences sequences io
strings vectors words ;

! If true in current namespace, we are bootstrapping.
SYMBOL: bootstrapping?

! The image being constructed; a vector of word-size integers
SYMBOL: image

! Object cache
SYMBOL: objects

! Image output format
SYMBOL: big-endian
SYMBOL: 64-bits

SYMBOL: t-object

: emit ( cell -- ) image get push ;

: emit-seq ( seq -- ) image get swap nappend ;

: fixup ( value offset -- ) image get set-nth ;

( Object memory )

: image-magic HEX: 0f0e0d0c ;
: image-version 0 ;

: cell 64-bits get 8 4 ? ;
: char 64-bits get 4 2 ? ;

: untag ( cell tag -- ) tag-mask bitnot bitand ;
: tag ( cell -- tag ) tag-mask bitand ;

: t-type         7  ; inline
: array-type     8  ; inline
: hashtable-type 10 ; inline
: vector-type    11 ; inline
: string-type    12 ; inline
: wrapper-type   14 ; inline
: word-type      17 ; inline
: tuple-type     18 ; inline

: immediate ( x tag -- tagged ) swap tag-bits shift bitor ;
: >header ( id -- tagged ) object-tag immediate ;

( Image header )

: base 1024 ;

: header ( -- )
    image-magic emit
    image-version emit
    ( relocation base at end of header ) base emit
    ( bootstrap quotation set later ) 0 emit
    ( global namespace set later ) 0 emit
    ( pointer to t object ) 0 emit
    ( pointer to bignum 0 ) 0 emit
    ( pointer to bignum 1 ) 0 emit
    ( pointer to bignum -1 ) 0 emit
    ( size of heap set later ) 0 emit ;

: boot-quot-offset 3 ;
: global-offset    4 ;
: t-offset         5 ;
: 0-offset         6 ;
: 1-offset         7 ;
: -1-offset        8 ;
: heap-size-offset 9 ;
: header-size      10 ;

GENERIC: ' ( obj -- ptr )
#! Write an object to the image.

( Allocator )

: here ( -- size ) 
    image get length header-size - cell * base + ;

: here-as ( tag -- pointer )
    here swap bitor ;

: align-here ( -- )
    here 8 mod 4 = [ 0 emit ] when ;

( Fixnums )

: emit-fixnum ( n -- ) fixnum-tag immediate emit ;

M: fixnum ' ( n -- tagged ) fixnum-tag immediate ;

( Bignums )

M: bignum ' ( bignum -- tagged )
    #! This can only emit 0, -1 and 1.
    bignum-tag here-as >r
    bignum-tag >header emit
    {{
        [[ 0  [ 1 0   ] ]]
        [[ -1 [ 2 1 1 ] ]]
        [[ 1  [ 2 0 1 ] ]]
    }} hash unswons emit-fixnum emit-seq align-here r> ;

( Special objects )

! Padded with fixnums for 8-byte alignment

: t,
    object-tag here-as
    dup t-offset fixup t-object set
    t-type >header emit
    0 ' emit ;

M: t ' ( obj -- ptr ) drop t-object get ;
M: f ' ( obj -- ptr )
    #! f is #define F RETAG(0,OBJECT_TYPE)
    drop object-tag ;

:  0,  0 >bignum '  0-offset fixup ;
:  1,  1 >bignum '  1-offset fixup ;
: -1, -1 >bignum ' -1-offset fixup ;

( Beginning of the image )
! The image begins with the header, then T,
! and the bignums 0, 1, and -1.

: begin ( -- ) header t, 0, 1, -1, ;

( Words )

: emit-word ( word -- )
    dup word-props ' >r
    dup word-def ' >r
    object-tag here-as over objects get set-hash
    word-type >header emit
    dup hashcode emit-fixnum
    0 emit
    word-primitive emit
    r> emit
    r> emit ;

: word-error ( word msg -- )
    [ % dup word-vocabulary % " " % word-name % ] "" make
    throw ;

: transfer-word ( word -- word )
    #! This is a hack. See doc/bootstrap.txt.
    dup dup word-name swap word-vocabulary lookup
    [ ] [ dup "Missing DEFER: " word-error ] ?ifte ;

: pooled-object ( object -- ptr ) objects get hash ;

: fixup-word ( word -- offset )
    transfer-word dup pooled-object dup
    [ nip ] [ "Not in image: " word-error ] ifte ;

: fixup-words ( -- )
    image get [ dup word? [ fixup-word ] when ] nmap ;

M: word ' ( word -- pointer ) ;

( Wrappers )

M: wrapper ' ( wrapper -- pointer )
    wrapped '
    object-tag here-as >r
    wrapper-type >header emit
    emit r> ;

( Conses )

M: cons ' ( c -- tagged )
    uncons ' swap '
    cons-tag here-as
    -rot emit emit ;

( Strings )

: emit-chars ( seq -- )
    big-endian get [ [ reverse ] map ] unless
    [ 0 [ swap 16 shift + ] reduce emit ] each ;

: pack-string ( string -- seq )
    dup length 1 + char align CHAR: \0 pad-right char swap group ;

: emit-string ( string -- ptr )
    object-tag here-as swap
    string-type >header emit
    dup length emit-fixnum
    dup hashcode emit-fixnum
    pack-string emit-chars
    align-here ;

M: string ' ( string -- pointer )
    #! We pool strings so that each string is only written once
    #! to the image
    objects get [ emit-string ] cache ;

( Arrays and vectors )

: emit-array ( list type -- pointer )
    >r [ ' ] map r>
    object-tag here-as >r
    >header emit
    dup length emit-fixnum
    ( elements -- ) emit-seq
    align-here r> ;

M: tuple ' ( tuple -- pointer )
    <mirror> tuple-type emit-array ;

M: vector ' ( vector -- pointer )
    dup array-type emit-array swap length
    object-tag here-as >r
    vector-type >header emit
    emit-fixnum ( length )
    emit ( array ptr )
    align-here r> ;

( Hashes )

M: hashtable ' ( hashtable -- pointer )
    dup buckets>vector array-type emit-array
    swap hash-size
    object-tag here-as >r
    hashtable-type >header emit
    emit-fixnum ( length )
    emit ( array ptr )
    align-here r> ;

( End of the image )

: words, ( -- )
    all-words [ emit-word ] each ;

: global, ( -- )
    [
        { vocabularies typemap builtins } [ [ ] change ] each
    ] make-hash '
    global-offset fixup ;

: boot, ( quot -- ) ' boot-quot-offset fixup ;

: heap-size image get length header-size - cell * ;

: end ( quot -- )
    "Generating words..." print
    words,
    "Generating global namespace..." print
    global,
    "Generating boot quotation..." print
    boot,
    "Performing some word fixups..." print
    fixup-words
    heap-size heap-size-offset fixup ;

( Image output )

: (write-image) ( image -- )
    64-bits get 8 4 ? swap big-endian get [
        [ swap >be write ] each-with
    ] [
        [ swap >le write ] each-with
    ] ifte ;

: write-image ( image file -- )
    "Writing image to " write dup write "..." print
    <file-writer> [ (write-image) ] with-stream ;

: with-image ( quot -- image )
    [
        bootstrapping? on
        800000 <vector> image set
        20000 <hashtable> objects set
        call
        "Image length: " write image get length .
        "Object cache size: " write objects get hash-size .
        image get
    ] with-scope ;

: make-image ( name -- )
    #! Make a bootstrap image.
    [
        begin
        "/library/bootstrap/boot-stage1.factor" run-resource
        namespace global [ "foobar" set ] bind
        end
    ] with-image

    swap write-image ;

: make-images ( -- )
    64-bits off
    big-endian off "boot.image.le32" make-image
    big-endian on  "boot.image.be32" make-image
    64-bits on
    big-endian off "boot.image.le64" make-image
    big-endian on  "boot.image.be64" make-image
    64-bits off ;