Ps/2 Compatible Mouse | Driver

if (mouse_cycle == 0) // Byte 0: verify bit 3 = 1 (always set in standard packet) if ((data & 0x08) == 0x08) mouse_packet[0] = data; mouse_cycle = 1; else if (mouse_cycle == 1) mouse_packet[1] = data; mouse_cycle = 2; else if (mouse_cycle == 2) = 0xFFFFFF00; mouse_x += dx; mouse_y -= dy; // Invert Y for screen coordinates mouse_buttons = mouse_packet[0] & 0x07;

// Enable devices again outb(0x64, 0xAE); // Enable keyboard outb(0x64, 0xA8); // Enable mouse PS/2 commands are sent via port 0x64 , then data via 0x60 . The mouse acknowledges each command with 0xFA . Helper function: mouse_send_command int mouse_send_command(uint8_t cmd) // Wait until input buffer is empty while (inb(0x64) & 2); outb(0x64, 0xD4); // Tell controller next byte is for mouse while (inb(0x64) & 2); outb(0x60, cmd); // Wait for ACK uint8_t ack = 0; int timeout = 100000; while (timeout-- && !(inb(0x64) & 1)); if (timeout <= 0) return -1; ack = inb(0x60); return (ack == 0xFA) ? 0 : -1; Enabling the Mouse mouse_send_command(0xF4); // Enable data reporting Optional: Set sample rate, resolution, scaling. 5. Interrupt Handling The mouse fires IRQ12 every time a byte is ready. We must read 3 bytes, then assemble the packet. ISR (Interrupt Service Routine) skeleton: volatile uint8_t mouse_cycle = 0; volatile uint8_t mouse_packet[4]; // We use 3 for standard volatile int mouse_x = 0, mouse_y = 0; volatile uint8_t mouse_buttons = 0; void mouse_isr() uint8_t status = inb(0x64); if (!(status & 1)) return; // No data ps/2 compatible mouse driver

// Send EOI to PIC outb(0x20, 0x20); In real mode or protected mode, you must set up the IDT (Interrupt Descriptor Table) for IRQ12 (vector 0x2C if PIC is in standard remap). Example for 32-bit protected mode: if (mouse_cycle == 0) // Byte 0: verify