/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2005-2008 H. Peter Anvin - All Rights Reserved
 *
 *   Permission is hereby granted, free of charge, to any person
 *   obtaining a copy of this software and associated documentation
 *   files (the "Software"), to deal in the Software without
 *   restriction, including without limitation the rights to use,
 *   copy, modify, merge, publish, distribute, sublicense, and/or
 *   sell copies of the Software, and to permit persons to whom
 *   the Software is furnished to do so, subject to the following
 *   conditions:
 *
 *   The above copyright notice and this permission notice shall
 *   be included in all copies or substantial portions of the Software.
 *
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 *   OTHER DEALINGS IN THE SOFTWARE.
 *
 * ----------------------------------------------------------------------- */

/*
 * idle.c
 *
 * What to do in a busy loop...
 */

#include <stddef.h>
#include <com32.h>
#include <sys/cpu.h>
#include <syslinux/idle.h>

void syslinux_idle(void)
{
    static int do_idle = 1;
    static const com32sys_t sys_idle = {
	.eax.l = 0x0013,
    };
    com32sys_t idle_result;

    /* This call isn't supported on SYSLINUX < 3.08, but all it does
       is return an error, so we don't care. */

    if (do_idle) {
	__intcall(0x22, &sys_idle, &idle_result);

	do_idle = ~idle_result.eflags.l & EFLAGS_CF;
    }

    cpu_relax();
}