URL
https://opencores.org/ocsvn/gecko3/gecko3/trunk
Subversion Repositories gecko3
[/] [gecko3/] [trunk/] [GECKO3COM/] [gecko3com-fw/] [firmware/] [lib/] [delay.c] - Rev 12
Go to most recent revision | Compare with Previous | Blame | View Log
/* -*- 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); }
Go to most recent revision | Compare with Previous | Blame | View Log