Mega CD-ROM 1/megacd_rom_1.zip/megacd_rom_1/MAGAZINE/PROGJOUR/PJ_9_4.ZIP/MISC.ASM

Assembly Source File | 1991-04-18 | 4KB | 266 lines

    title    miscellaneous
    include    asm.inc


    public    close_file
    public    exit_program
    public    get_input_state
    public    open_input_file
    public    open_output_file
    public    move_file_pointer
    public    putchar_newline
    public    putchar_space
    public    put_hex_byte
    public    put_hex_word
    public    read_from_file
    public    save_most
    public    select_min_count
    public    write_to_file


    .code
    extn    putchar,ms_dos,ms_dos_strerror


;;    close file
;
;    entry    BX    handle
;    exit    Cf    0
;    uses    AX
;
close_file proc
    mov    ah,3Eh
    jmp    ms_dos_strerror
close_file endp


;;    exit program
;
exit_program proc
    mov    ax,4C00h
    jmp    ms_dos
exit_program endp


;;    get input state
;
;    exit    Zf    if no key waiting
;    uses    AX
;    note    returns TRUE for keyboard, mouse, and timer under Windows
;
get_input_state proc
    mov    ah,1
    int    16h
    ret
get_input_state endp


;;    open input file
;
;    entry    DS:SI    string
;    exit    AX,BX    handle
;        Cf    if error, error text set
;    calls    offset_dos_error, ms_dos
;
open_input_file proc
    mov    ax,3D00h        ; (use 3D20 for shared access read)
    xchg    dx,si
    call    ms_dos_strerror
    xchg    dx,si
    mov    bx,ax
    ret
open_input_file endp


;;    open output file
;
;    entry    DS:SI    string
;    exit    AX,BX    handle
;        Cf    if error, error text set
;    calls    offset_dos_error, ms_dos
;
open_output_file proc
    push    cx
    mov    ax,3C00h
    xor    cx,cx
    xchg    dx,si
    call    ms_dos_strerror
    xchg    dx,si
    mov    bx,ax
    pop    cx
    ret
open_output_file endp


;;    move file pointer
;
;    entry    BX    file handle
;        DX AX    file position
;    exit    Cf    if error
;    uses    AX
;
move_file_pointer proc
    push    cx
    mov    cx,dx
    mov    dx,ax
    mov    ax,4200h
    call    ms_dos
    pop    cx
    ret
move_file_pointer endp


;;    put hex byte
;
;    entry    AL    byte
;    uses    AX
;    note    calls putchar to write chrs
;
put_hex_byte proc
    push    ax
    sar    al,1
    sar    al,1
    sar    al,1
    sar    al,1
    call    ohb1
    pop    ax
ohb1:    and    al,0Fh
    add    al,90h
    daa
    adc    al,40h
    daa
    jmp    putchar
put_hex_byte endp


;;    put hex word
;
;    entry    AX    word
;    uses    AX
;
put_hex_word proc
    push    ax
    mov    al,ah
    call    put_hex_byte
    pop    ax
    jmp    put_hex_byte
put_hex_word endp


;;    putchar newline
;
;    uses    AX
;
putchar_newline proc
    mov    al,13
    call    putchar
    mov    al,10
    jmp    putchar
putchar_newline endp


;;    putchar space
;
;    uses    AX
;
putchar_space proc
    mov    al,' '
    jmp    putchar
putchar_space endp


;;    read from file
;
;    entry    BX    file handle
;        CX    byte count
;        ES:DI    destination
;    exit    AX    number of bytes read
;        Cf    if error
;
read_from_file proc
    push    ds
    mov    ah,3Fh
    push    es
    pop    ds
    xchg    dx,di
    call    ms_dos
    xchg    di,dx
    pop    ds
    ret
read_from_file endp


    even
;;    restore most
;
;    note    never call this routine
;
restore_most proc
    popm    bp,es,ds,si,di,dx,cx,bx
    ret
restore_most endp

    even
;;    save most
;
;    note    saves all registers except AX and BP.  however, the current
;        version also saves BP because the code works out that way.
;        the registers are automatically restored.  this routine is
;        called with a return address as the top of stack.
;
save_most proc                ; +16 inner ret adr, +18 outer ret adr
    push    cx            ; +14
    push    dx            ; +12
    push    di            ; +10
    push    si            ; +8
    push    ds            ; +6
    push    es            ; +4
    push    bp            ; +2
    lea    bp,restore_most        ;     after execution of inner
    push    bp            ; +0  routine, return to restore_most
    mov    bp,sp
    xchg    bx,[bp+16]        ;    bx above cx
    push    bx            ; -2    setup return to inner routine
    mov    bx,[bp+16]        ;    restore original BX and BP
    mov    bp,[bp+2]
    ret
save_most endp


;;    select min count
;
;    entry    CX    count1
;        DX AX    count2
;    exit    CX    minimum of count1 and count2
;
select_min_count proc
    or    dx,dx
    jnz    smc1            ; if count2 > 64k
    cmp    ax,cx
    ja    smc1            ; if count2 > count1
    mov    cx,ax
smc1:    ret
select_min_count endp


;;    write to file
;
;    entry    BX    file handle
;        CX    byte count
;        ES:DI    buffer
;    exit    Cf    if error
;
write_to_file proc
    push    ds
    mov    ah,40h
    push    es
    pop    ds
    xchg    dx,di
    call    ms_dos
    xchg    di,dx
    pop    ds
    ret
write_to_file endp

    end