The PC-SIG Library 10/The PC-Sig Library - Shareware for the IBM PC and Compatibles (PC-SIG)(Tenth Edition Disks 1-2804)(1991).iso/PC_SIGCD/03/4/DISK0341.ZIP/IOS1_20.ASM

Assembly Source File | 1983-10-27 | 8KB | 318 lines

title    Level 1 I/O Functions for Lattice 'c' Version 1.04
page    64,132
name    IOS1_20 ;DOS function calls 3DH, 3EH, 3FH, 40H, AND 42H.
comment |
   These functions take advantage of DOS 2.0 and will directly
replace the original level 1 I/O except that 'text mode' is
not supported.    DOS error numbers are saved at ERRNO and may be
checked by including: "extern short errno;" in your source files.
Note that the pmode parameter in creat is forced to zero, due to
a problem with Lattice's freopen which passes a 1A4H to creat.

            Ted Reuss     c/o South Texas Software, Inc.
          Home: 713/961-3926      4544 Post Oak Place, Suite 176
          Offi: 713/877-8205      Houston, Tx 77027
    |
    public    CREAT, OPEN, CLOSE, READ, WRITE, LSEEK
dgroup    group    data
data    segment word public 'data'
    assume    ds:dgroup

    public    ERRNO
ERRNO    dw    0    ; DOS error number (DOS Manual page D-14)
data    ends

pgroup    group    prog
prog    segment byte public 'prog'
    assume    cs:pgroup

    subttl    CREAT -- create a new file
    page
;
; NAME
;    creat -- create a new file
;
; SYNOPSIS
;
;    file = creat(name, pmode);
;    int file;    file number or error code
;    char *name;    file name (valid drive\path\filespec)
;    int pmode;    access privilege mode bits, DOS attribute
;            NOTE: forced to zero in current version.
;
; DESCRIPTION
;
;    Creates a new file with the specified name and prepares is
;    for access via the level 1 I/O functions.  The file name
;    may consist of a valid drive and path name.  All I/O is
;    done via DOS calls 3fh (READ) and 40h (WRITE).    If the file
;    already exists, it's contents are discarded.  The current file
;    position and the end of file are both zero. (indicating an
;    empty file) if the function is successful. ERRNO is set to
;    the error number returned by DOS in the event of an error.
;
; RETURNS
;    file = file number to access file, if successful
;         = -1 if error  (ERRNO get DOS error number)
;

    public    CREAT
CREAT    proc    near
    push    bp
    mov    bp,sp
    mov    dx,[bp+4]    ;get ptr to drive\path\filespec
    xor    cx,cx
    mov    ah,3CH        ;DOS create function
    int    21H
    jnc    cre10
    mov    dgroup:errno,ax
    mov    ax,-1
cre10:    mov    sp,bp
    pop    bp
    ret
CREAT    endp

    subttl    OPEN -- open a file
    page
;
; NAME
;    open -- open a file
;
; SYNOPSIS
;
;    file = open(name, rwmode);
;    int file;    file number or error code
;    char *name;    file name (valid drive\path\filespec)
;    int rwmode;    read/write mode, where 0=read, 1=write,
;            2=read/write
;
; DESCRIPTION
;
;    Opens a file for access using the level 1 I/O functions.
;    The file name may contain a valid drive and path name.    All
;    I/O is done via DOS functions 3fh (READ) and 40h (WRITE).
;    The mode word determines the type of I/O which will be
;    performed on the file.    The low order bits specify whether
;    read or write operations (or both) are to be allowed.
;    In the event of an error the error code passed by DOS is
;    saved at ERRNO.
;
; RETURNS
;
;    file = file number to access file, if successful
;         = -1 if error  (ERRNO get DOS error number)
;

    public    OPEN
OPEN    proc    near
    push    bp
    mov    bp,sp
    mov    dx,[bp+4]    ;get ptr to drive\path\filespec
    mov    ax,[bp+6]    ;get mode
    mov    ah,3DH        ;DOS open function
    int    21H
    jnc    opn10
    mov    dgroup:errno,ax
    mov    ax,-1
opn10:    mov    sp,bp
    pop    bp
    ret
OPEN    endp

    subttl    CLOSE -- close a file
    page
;
; NAME
;
;    close -- close a file
;
; SYNOPSIS
;
;    status = close(file);
;    int status;    status code: 0 if successful
;    int file;    file number for file
;
; DESCRIPTION
;
;    Close a file and frees the file number for use in accessing
;    another file.  Any buffers allocated when the file was
;    opened are released.
;
; RETURNS
;
;    status = 0 if successful
;           = -1 if error  (ERRNO get DOS error number)
;

    public    CLOSE
CLOSE    proc    near
    push    bp
    mov    bp,sp
    mov    bx,[bp+4]    ;get file handle
    mov    ah,3EH        ;DOS close function
    int    21H
    jc     clo10
    xor    ax,ax
    jmp    short clo20
clo10:    mov    dgroup:errno,ax
    mov    ax,-1
clo20:    mov    sp,bp
    pop    bp
    ret
CLOSE    endp

    subttl    READ -- read data from file
    page
;
; NAME
;
;    read -- read data from file
;
; SYNOPSIS
;
;    status = read(file, buffer, length);
;    int status;    status code or actual length
;    int file;    file number for file
;    char *buffer;    input buffer
;    int length;    number of bytes requested
;
; DESCRIPTION
;
;    Reads the next set of bytes from a file.  The return count
;    is always equal to the number of bytes placed in the buffer
;    and will never exceed the "length" parameter, except in the
;    case of an error, where -1 is returned.  The file position
;    is advanced accordingly.
;
; RETURNS
;
;    status = 0 if end of file
;           = -1 if error  (ERRNO get DOS error number)
;           = number of bytes actually read, otherwise
;

    public    READ
READ    proc    near
    push    bp
    mov    bp,sp
    mov    bx,[bp+4]    ;get file handle
    mov    dx,[bp+6]    ;get buffer address
    mov    cx,[bp+8]    ;get byte count
    mov    ah,3FH        ;DOS read function
    int    21H
    jnc    red10
    mov    dgroup:errno,ax
    mov    ax,-1
red10:    mov    sp,bp
    pop    bp
    ret
READ    endp

    subttl    WRITE -- write data to file
    page
;
; NAME
;
;    write -- write data to file
;
; SYNOPSIS
;
;    status = write(file, buffer, length);
;    int status;    status code or actual length
;    int file;    file number for file
;    char *buffer;    output buffer
;    int length;    number of bytes in buffer
;
; DESCRIPTION
;
;    Writes the next set of bytes to a file.  The return count is
;    equal to the number of bytes written, unless an error
;    occurred.  The file position is advanced accordingly.
;
; RETURNS
;
;    status = -1 if error  (ERRNO get DOS error number)
;           = number of bytes actually written otherwise
;

    public    WRITE
WRITE    proc    near
    push    bp
    mov    bp,sp
    mov    bx,[bp+4]    ;get file handle
    mov    dx,[bp+6]    ;get buffer address
    mov    cx,[bp+8]    ;get byte count
    mov    ah,40H        ;DOS write function
    int    21H
    jnc    wrt10
    mov    dgroup:errno,ax
    mov    ax,-1
wrt10:    mov    sp,bp
    pop    bp
    ret
WRITE    endp

    subttl    LSEEK -- seek to specified file position
    page
;
; NAME
;
;    lseek -- seek to specified file position
;
; SYNOPSIS
;
;    pos = lseek(file, offset, mode);
;    long pos;    returned file position or error code
;    int file;    file number for file
;    long offset;    desired position
;    int mode;    offset mode relative to:
;            0 = beginning of file        BOFM
;            1 = current file position   CURM
;            2 = end of file         EOFM
;
; DESCRIPTION
;
;    Changes the current file position to a new position in the
;    file.  The offset is specified as a long int and is added to
;    the current position (mode 1) or to the logical end of file
;    (mode 2).  Use DOS function 42h (LSEEK).
;
; RETURNS
;
;    pos = -1L if error occurred (ERRNO get DOS error number)
;    = new file position if successful
;

    public    LSEEK
LSEEK    proc    near
    push    bp
    mov    bp,sp
    mov    bx,[bp+4]    ;get file handle
    mov    dx,[bp+6]    ;get low word of pos
    mov    cx,[bp+8]    ;get high word of pos
    mov    ax,[bp+10]    ;get seek mode
    mov    ah,42H        ;DOS lseek function
    int    21H
    jnc    lsk10
    mov    dgroup:errno,ax
    mov    ax,-1
    mov    dx,ax
lsk10:    mov    bx,ax
    mov    ax,dx
    mov    sp,bp
    pop    bp
    ret
LSEEK    endp

prog    ends
    end
roup:errno,ax
    mov    ax,-1
    mov    dx,ax
lsk10:    mov    bx,ax
    mov    ax,dx
    mov    sp,bp
    pop    bp
    ret
LSEEK    endp