Category : C Source Code
Archive   : LHA211S.ZIP
Filename : CRCIO_.ASM

;***********************************************
; crcio_.asm -- input/output
;***********************************************
page 0, 128

include amscls.inc
$_init GEN

CGROUP GROUP TEXT
DGROUP GROUP DATA,BSS

TEXT segment byte public 'CODE'
assume cs:CGROUP, ds:DGROUP, ss:DGROUP
TEXT ends

DATA segment byte public 'DATA'
DATA ends

BSS segment byte public 'DATA'
public infile_
infile_ dw 1 dup (?)
public outfile_
outfile_ dw 1 dup (?)
public dispflg_
dispflg_ dw 1 dup (?)

crctable_ dw 100h dup (?)
public crc_
crc_ dw 1 dup (?)
public bitbuf_
bitbuf_ dw 1 dup (?)

subbitbuf_ db 1 dup (?)
bitcount_ db 1 dup (?)


BSS ends
TEXT segment byte public 'CODE'
assume cs:CGROUP, ds:DGROUP, ss:DGROUP

;
;void make_crctable(uchar crcpoly)
;

public make_crctable_
make_crctable_:
cld
push ds
pop es
push cx
push dx
push di
mov bx, ax
mov di, offset DGROUP:crctable_
xor dx, dx
$_do
mov ax, dx
mov cx, 8
$_do
$_if , C
xor ax, bx
$_endif
$_until
stosw
$_until , Z
pop di
pop dx
pop cx
ret

;
;ushort calccrc(uchar *p, uint n)
;

public calccrc_
calccrc_:
push cx
push si
mov si, ax
mov cx, bx
mov bx, crc_
jcxz nofile
xor ah, ah
cld
$_do
lodsb
xor bl, al
mov al, bh
mov bh, ah
shl bx, 1
mov bx, crctable_[bx]
xor bx, ax
$_until
nofile:
mov ax, bx
mov crc_, ax
pop si
pop cx
ret

;
;ushort getbits(uchar n)
;

public getbits_
getbits_:
push cx
mov cl, 16
sub cl, al
push bitbuf_
call fillbuf_
pop ax
shr ax, cl
pop cx
ret

;
; stream control structure of LSI C-86
;

iob struc
mode db ?
ptr dw ?
rcount dw ?
wcount dw ?
base dw ?
bufsiz dw ?
fd dw ?
smallbuf db ?
iob ends

;
;void fillbuf(uchar n) /* Shift bitbuf n bits left, read n bits */
;

public fillbuf_
fillbuf_:
push cx
push dx
mov ch, al
mov cl, bitcount_

mov dx, bitbuf_
mov al, subbitbuf_
$_if , A
sub ch, cl
shl dx, cl
rol al, cl
add dl, al
mov cl, 8
fb1:
xor ax, ax
sub word ptr compsize_, 1
sbb word ptr compsize_ + 2, ax
$_if , NS
mov bx, infile_
$_if , NS
inc ptr[bx]
mov bx, ptr[bx]
mov al, [bx - 1]
$_else
mov ax, bx
push bx
call fgetc_
pop bx
$_if , S
mov ax, offset DGROUP:RDERR_
jmp fileerror_
$_endif
$_endif
$_endif
$_if , A
sub ch, cl
mov dh, dl
mov dl, al
jmp fb1
$_endif
$_endif
sub cl, ch
mov bitcount_, cl
mov cl, ch
xor ah, ah
shl dx, cl
shl ax, cl
add dl, ah
mov bitbuf_, dx
mov subbitbuf_, al
pop dx
pop cx
ret


;
;void putbits(uchar n, ushort x) /* Write rightmost n bits of x */
;

public putbits_
putbits_:
push cx
mov cl, 16
sub cl, al
shl bx, cl
pop cx


;
;void putcode(uchar n, ushort x) /* Write rightmost n bits of x */
;
public putcode_
putcode_:

push cx
push dx
mov ch, al
mov cl, bitcount_
mov al, subbitbuf_
$_if , B
rol bh, cl
or al, bh
mov subbitbuf_, al
sub cl, ch
mov bitcount_, cl
pop dx
pop cx
ret
$_endif
sub ch, cl

xor dh, dh
mov dl, bh
shl dx, cl

shl bx, cl
or al, dh
mov dx, bx
mov cl, 8
pc1:
sub word ptr compsize_, 1
sbb word ptr compsize_ + 2, 0
jb disable
mov bx, outfile_
$_if , NS
inc ptr[bx]
mov bx, ptr[bx]
mov [bx - 1], al
$_else
xor ah, ah
inc wcount[bx]
call fputc_
$_if , S
mov ax, offset DGROUP:WTERR_
mov bx, outfile_
jmp fileerror_
$_endif
$_endif
$_if , AE
sub ch, cl
mov al, dh
mov dh, dl
jmp pc1
$_endif
mov subbitbuf_, dh
sub cl, ch
mov bitcount_, cl
pop dx
pop cx
ret

disable:
mov unpackable_, 1
inc word ptr compsize_
inc word ptr compsize_ + 2
pop dx
pop cx
ret


;
;int fread_crc(uchar *p, int n, FILE *f)
;

public fread_crc_
fread_crc_:
push cx
push dx
mov dx, ax
xchg bx, cx
mov bx, fd[bx]
mov ah, 3fh
int 21h
mov bx, ax
xchg ax, dx
$_if , NZ
call calccrc_
$_endif
mov ax, dx
pop dx
pop cx
ret


;
;void fwrite_crc(uchar *p, int n, FILE *f)
;

public fwrite_crc_
fwrite_crc_:
push cx
push dx
mov dx, ax
push bx
call calccrc_
pop bx
jcxz fc0
xchg bx, cx
push bx
mov bx, fd[bx]
mov ah, 40h
int 21h
pop dx
$_if , NE, AND
mov ax, bx
call isatty_
$_c , Z
mov ax, offset DGROUP:WTERR_
mov bx, dx
jmp fileerror_
$_endif
fc0:
pop dx
pop cx
ret


;
;void init_getbits(void)
;

public init_getbits_
init_getbits_:
xor ax, ax
mov word ptr DGROUP:[bitbuf_], ax
mov byte ptr DGROUP:[subbitbuf_], al
mov byte ptr DGROUP:[bitcount_], al
mov al,16
jmp fillbuf_


;
;void init_putbits(void)
;

public init_putbits_
init_putbits_:
mov byte ptr DGROUP:[bitcount_], 8
mov byte ptr DGROUP:[subbitbuf_], 0
RET


EXTRN fileerror_:near
EXTRN WTERR_:near
EXTRN RDERR_:near
EXTRN fgetc_:near
EXTRN fwrite_:near
EXTRN fread_:near
EXTRN fputc_:near
EXTRN isatty_:near
EXTRN dispmark_:near
TEXT ends

EXTRN unpackable_:word
EXTRN origsize_:dword
EXTRN compsize_:dword
EXTRN _iob_:byte

END