71 lines
2.1 KiB
C
71 lines
2.1 KiB
C
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/*
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File: machine.C
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Author: R. Bettati
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Department of Computer Science
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Texas A&M University
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Date : 12/09/04
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LOW-LEVEL MACHINE FUNCTIONS.
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*/
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/*--------------------------------------------------------------------------*/
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/* INCLUDES */
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/*--------------------------------------------------------------------------*/
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#include "machine.H"
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#include "machine_low.H"
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#include "assert.H"
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/*--------------------------------------------------------------------------*/
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/* INTERRUPTS */
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/*--------------------------------------------------------------------------*/
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bool Machine::interrupts_enabled() {
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/* We check the IF flag (INTERRUPT ENABLE) in the EFLAGS status register. */
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return get_EFLAGS() & (1 << 9);
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}
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void Machine::enable_interrupts() {
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assert(!interrupts_enabled());
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__asm__ __volatile__ ("sti");
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}
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void Machine::disable_interrupts() {
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assert(interrupts_enabled());
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__asm__ __volatile__ ("cli");
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}
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/*--------------------------------------------------------------------------*/
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/* PORT I/O OPERATIONS */
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/*--------------------------------------------------------------------------*/
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/* We will use this later on for reading from the I/O ports to get data
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* from devices such as the keyboard. We are using what is called
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* 'inline assembly' in these routines to actually do the work */
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char Machine::inportb (unsigned short _port) {
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unsigned char rv;
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__asm__ __volatile__ ("inb %1, %0" : "=a" (rv) : "dN" (_port));
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return rv;
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}
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unsigned short Machine::inportw (unsigned short _port) {
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unsigned short rv;
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__asm__ __volatile__ ("inw %1, %0" : "=a" (rv) : "dN" (_port));
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return rv;
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}
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/* We will use this to write to I/O ports to send bytes to devices. This
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* will be used in the next tutorial for changing the textmode cursor
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* position. Again, we use some inline assembly for the stuff that simply
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* cannot be done in C */
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void Machine::outportb (unsigned short _port, char _data) {
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__asm__ __volatile__ ("outb %1, %0" : : "dN" (_port), "a" (_data));
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}
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void Machine::outportw (unsigned short _port, unsigned short _data) {
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__asm__ __volatile__ ("outw %1, %0" : : "dN" (_port), "a" (_data));
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}
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