84 lines
1.6 KiB
C
84 lines
1.6 KiB
C
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#include "kbd.h"
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#include "process.h"
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#include "scheduler.h"
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#include "common.h"
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#include <lib/tasks.h>
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#include <lib/print.h>
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#include <stddef.h>
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#define KBD_BUFFER_SIZE 256
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static spinlock_t kbd_lock = {0};
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static process_t* kbd_waiting_task = NULL;
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static char kbd_buffer[KBD_BUFFER_SIZE];
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static int kbd_head = 0;
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static int kbd_tail = 0;
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static void lock_kbd() {
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disable_interrupts();
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spin_lock(&kbd_lock);
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}
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static void unlock_kbd() {
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spin_unlock(&kbd_lock);
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enable_interrupts();
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}
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static void kbd_set_waiting(process_t* task) {
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lock_kbd();
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if (kbd_head == kbd_tail) {
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kbd_waiting_task = task;
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}
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unlock_kbd();
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}
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static char kbd_pop() {
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char c = 0;
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lock_kbd();
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if (kbd_head != kbd_tail) {
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c = kbd_buffer[kbd_tail];
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kbd_tail = (kbd_tail + 1) % KBD_BUFFER_SIZE;
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}
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unlock_kbd();
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return c;
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}
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void kbd_push(char c) {
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spin_lock(&kbd_lock);
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// push to buffer first, very important
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int next_head = (kbd_head + 1) % KBD_BUFFER_SIZE;
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if (next_head != kbd_tail) {
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kbd_buffer[kbd_head] = c;
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kbd_head = next_head;
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}
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if (kbd_waiting_task != NULL) {
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wake(kbd_waiting_task);
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kbd_waiting_task = NULL;
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}
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spin_unlock(&kbd_lock);
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}
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int kbd_ready() {
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int ready = 0;
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lock_kbd();
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ready = (kbd_head != kbd_tail);
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unlock_kbd();
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return ready;
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}
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void kbd_wait() {
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process_t* task = current_task();
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while (!kbd_ready()) {
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task->state = STATE_BLOCKED;
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kbd_set_waiting(task);
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yield();
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}
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}
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char kbd_read() {
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return kbd_pop();
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}
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