uhd

/* -*- c++ -*- */

/*

 * Copyright 2003 Free Software Foundation, Inc.

 * 

 * This file is part of GNU Radio

 * 

 * GNU Radio is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 3, or (at your option)

 * any later version.

 * 

 * GNU Radio is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 * 

 * You should have received a copy of the GNU General Public License

 * along with GNU Radio; see the file COPYING.  If not, write to

 * the Free Software Foundation, Inc., 51 Franklin Street,

 * Boston, MA 02110-1301, USA.

 */

/*

 * Delay approximately 1 microsecond (including overhead in udelay).

 */

static void

udelay1 (void) _naked

{

  _asm                                ; lcall that got us here took 4 bus cycles

        ret                        ; 4 bus cycles

  _endasm;

}

/*

 * delay for approximately usecs microseconds

 */

void

udelay (unsigned char usecs)

{

  do {

    udelay1 ();

  } while (--usecs != 0);

}

/*

 * Delay approximately 1 millisecond.

 * We're running at 48 MHz, so we need 48,000 clock cycles.

 *

 * Note however, that each bus cycle takes 4 clock cycles (not obvious,

 * but explains the factor of 4 problem below).

 */

static void

mdelay1 (void) _naked

{

  _asm

        mov        dptr,#(-1200 & 0xffff)

002$:        

        inc        dptr                ; 3 bus cycles

        mov        a, dpl                ; 2 bus cycles

        orl        a, dph                ; 2 bus cycles

        jnz        002$                ; 3 bus cycles

        ret

  _endasm;

}

void

mdelay (unsigned int msecs)

{

  do {

    mdelay1 ();

  } while (--msecs != 0);

}