PC World 1997 November/PCWorld_1997-11_cd.bin/software/sharware/utility/PACKERS/LZH/LHASRC.EXE/MAKETBL_.ASM

Assembly Source File | 1991-02-11 | 3KB | 198 lines

;***********************************************
;    maketbl_.asm -- makes decoding table
;***********************************************
            page    0, 128

include    amscls.inc
$_init    GEN

TEXT    segment    byte    public    'CODE'
TEXT    ends

DATA    segment word    public    'DATA'
DATA    ends

BSS        segment word    public    'DATA'
extrn    nchar:word
extrn    bitlen:word
extrn    tablebits:word
extrn    table:word
extrn    avail_mt:word
extrn    len_cnt:word
extrn    start:word
extrn    weight:word

extrn    right_:word
extrn    left_:word
extrn    BROKENARC_:byte
extrn    error_:near
BSS        ends

DGROUP    group    DATA, BSS

TEXT    segment    byte    public    'CODE'
        assume    cs:TEXT, ds:DGROUP
;---------------------------------------------------------------
;    void make_table(short nchar, uchar bitlen[],
;                             ax            bx
;                    short tablebits, ushort table[])
;                                 cx            dx
;---------------------------------------------------------------
    public    make_table_
make_table_    proc    near
    push    cx
    push    dx
    push    si
    push    di
    push    bp

    mov        nchar, ax
    shl        ax, 1
    mov        avail_mt, ax
    mov        bitlen, bx
    mov        tablebits, cx
    mov        table, dx

    push    ds
    pop        es
    cld

;    /* clear len_cnt */
    xor        ax, ax
    mov        cx, 16
    mov        di, offset DGROUP:len_cnt + 2
    rep        stosw

;    /* count bitlen into len_cnt */
    xor        bx, bx
    mov        cx, nchar
    mov        si, bitlen
    $_do
        mov        bl, [si]
        inc        si
        shl        bx, 1
        inc        len_cnt[bx]
    $_until <LOOP>

;    /* initialize weight, start, table */
    mov        cx, tablebits
    mov        bp, 1
    shl        bp, cl
    mov        bx, offset DGROUP:len_cnt + 2
    mov        si, offset DGROUP:weight + 2
    mov        di, offset DGROUP:start + 2
    mov        ax, table
    $_do
        stosw
        mov        dx, [bx]
        add        bx, 2
        shl        dx, cl
        add        ax, dx
        shr        bp, 1
        mov        [si], bp
        add        si, 2
    $_until <LOOP>
    push    ax
    sub        ax, table
    mov        cl, 15
    sub        cx, tablebits
    shl        ax, cl
    shl        bp, cl
    $_do
        stosw
        mov        dx, [bx]
        add        bx, 2
        shl        dx, cl
        add        ax, dx
        mov        [si], bp
        add        si, 2
        dec        cx
    $_until <shr bp, 1>, Z
    $_if <or ax, ax>, NZ
        mov        ax, offset DGROUP:BROKENARC_
        xor        bx, bx
        call    error_
    $_endif
    pop        di
    mov        ax, di
    sub        ax, table
    shr        ax, 1
    mov        bx, 1
    mov        cx, tablebits
    shl        bx, cl
    mov        cx, bx
    sub        cx, ax
    xor        ax, ax
    rep        stosw

;    /* make table & additional tree */
    xor        ax, ax
    $_do
        mov        si, ax
        add        si, bitlen
        mov        bl, [si]

        or        bl, bl
        jz        make_table_1
        xor        bh, bh

        mov        dx, bx
        shl        bx, 1
        mov        di, start[bx]
        mov        cx, weight[bx]
        $_if <cmp dx, tablebits>, BE
            rep        stosw
            mov        start[bx], di
        $_else
            add        start[bx], cx

            mov        si, di
            mov        bx, tablebits
            mov        cl, 16
            sub        cl, bl

            shr        di, cl
            shl        di, 1
            add        di, table

            mov        cl, bl
            shl        si, cl

            xor        cx, cx
            mov        cl, dl
            sub        cx, tablebits
;        /* ìéé│ n é╠ tree é≡ì∞éΘ */
            $_do
                $_if <cmp word ptr [di], 0>, E
;                /* Ä}é¬é▄é╛ëäé╤é─éóé╚é»éΩé╬ì∞éΘ */
                    mov        bx, avail_mt
                    mov        right_[bx], 0
                    mov        left_[bx], 0
;;                    shr        bx, 1
                    mov        [di], bx
                    add        avail_mt, 2
                $_endif
                mov        di, [di]
;;                shl        di, 1
                $_if <shl si, 1>, C
                    add        di, offset DGROUP:right_
                $_else
                    add        di, offset DGROUP:left_
                $_endif
            $_until <LOOP>
            mov        [di], ax
        $_endif
make_table_1:
        inc        ax
    $_until <cmp ax, nchar>, AE

    pop        bp
    pop        di
    pop        si
    pop        dx
    pop        cx
    ret
make_table_    endp
TEXT    ends
        end