hardware.c

/*
 * hardware.c 
 */


#include <types.h>

DWord
get_eflags (void)
{
  register DWord flags;
  __asm__ __volatile__ ("pushfl\n\t" "popl %0":"=q" (flags));

  return flags;
}

void
set_eflags (void)
{
  __asm__ __volatile__ ("pushl $0\n\t" "popfl");
}

void
set_idt_reg (Register * idt)
{
  __asm__ __volatile__ ("lidtl (%0)":	/*no output */
			:"r" (idt));
}

void
set_gdt_reg (Register * gdt)
{
  __asm__ __volatile__ ("lgdtl (%0)":	/*no output */
			:"r" (gdt));
}

void
set_ldt_reg (Selector ldt)
{
  __asm__ __volatile__ ("lldtw %0":	/*no output */
			:"r" (ldt));
}

void
set_task_reg (Selector tr)
{
  __asm__ __volatile__ ("ltrw %0":	/*no output */
			:"r" (tr));
}


void
return_gate (Word ds, Word ss, DWord esp, Word cs, DWord eip)
{
  __asm__ __volatile__ ("mov %0,%%es\n\t" "mov %0,%%ds\n\t" "pushl %1\n\t"	/* user ss */
			"pushl %2\n\t"	/* user esp */
			"pushl %3\n\t"	/* user cs */
			"pushl %4\n\t"	/* user eip */
			"lret":	/*no output */
			:"r" (ds), "g" (ss), "g" (esp), "g" (cs), "g" (eip));
}

/*
 * enable_int: Set interruput mask
 *
 *    register 0x21:
 *    7 6 5 4 3 2 1 0
 *    x x x x x x x x
 *    
 *    bit 0 : Timer
 *    bit 1 : Keyboard
 *    bit 2 : PIC cascading
 *    bit 3 : 2nd Serial Port
 *    bit 4 : 1st Serial Port
 *    bit 5 : Reserved
 *    bit 6 : Floppy disk
 *    bit 7 : Reserved
 * 
 *
 *   x = 0 -> enabled
 *   x = 1 -> disabled
 */

void
enable_int (void)
{
  __asm__ __volatile__ ("movb %0,%%al\n\t" "outb %%al,$0x21\n\t" "call delay\n\t" "sti":	/*no output */
			:"i" (0xfc)	/* 0xFF = 11111111 -> all bits disabled */
			:"%al");
}

void
delay (void)
{
  __asm__ __volatile__ ("jmp a\na:\t"::);
}