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Update keyboard.c

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some issues with keyboard buffer fixed and interrupt greater than 32 would cause EOI to get sent to PIC 2x
This commit is contained in:
Gregory Kenneth Bowne
2025-11-10 05:09:30 -08:00
committed by GitHub
parent 70539f72b8
commit 95f0507c24
1 changed files with 27 additions and 21 deletions
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48
kernel/keyboard.c
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@@ -4,8 +4,12 @@
#include "terminal.h"
#define KEYBOARD_DATA_PORT 0x60
#define KEY_BUFFER_SIZE 256
static char key_buffer[256];
static char key_buffer[KEY_BUFFER_SIZE];
static uint8_t buffer_head = 0; // Write position (interrupt)
static uint8_t buffer_tail = 0; // Read position (get_char)
static uint8_t buffer_count = 0;
static uint8_t buffer_index = 0;
// Basic US QWERTY keymap (scancode to ASCII)
@@ -21,39 +25,41 @@ static const char scancode_map[128] = {
// Interrupt handler for IRQ1
void keyboard_callback(void) {
uint8_t scancode = inb(0x60);
uint8_t scancode = inb(KEYBOARD_DATA_PORT);
// Only handle key press (ignore key release)
if (!(scancode & 0x80)) {
char c = scancode_map[scancode];
if (c && buffer_index < sizeof(key_buffer) - 1) {
key_buffer[buffer_index++] = c;
terminal_putchar(c);
}
}
if (scancode & 0x80) return; // Ignore key release
// Send End of Interrupt (EOI) to the PIC
outb(0x20, 0x20);
char c = scancode_map[scancode];
if (!c) return;
uint8_t next_head = (buffer_head + 1) % KEY_BUFFER_SIZE;
// Drop key if buffer full
if (next_head == buffer_tail) return;
key_buffer[buffer_head] = c;
buffer_head = next_head;
buffer_count++;
terminal_putchar(c);
}
void keyboard_init() {
register_interrupt_handler(33, keyboard_callback); // IRQ1 = int 33 (0x21)
}
// Blocking read (returns one char)
char keyboard_get_char() {
while (buffer_index == 0); // Busy wait
char keyboard_get_char(void) {
while (buffer_count == 0) {
__asm__ __volatile__("hlt"); // Better than busy loop
}
char c;
__asm__ __volatile__("cli");
c = key_buffer[0];
for (uint8_t i = 1; i < buffer_index; i++) {
key_buffer[i - 1] = key_buffer[i];
}
buffer_index--;
c = key_buffer[buffer_tail];
buffer_tail = (buffer_tail + 1) % KEY_BUFFER_SIZE;
buffer_count--;
__asm__ __volatile__("sti");
return c;
}