driver.hid.usb.keyboard

USB HID boot-protocol keyboard driver.

Overview

This unit implements a USB HID keyboard class driver. It targets the HID boot protocol (subclass $01, protocol $01), which uses fixed 8-byte input reports without requiring HID report descriptor parsing. During load, it configures the device for boot protocol and idle mode, locates the interrupt IN endpoint, and submits an initial interrupt transfer. The kernel polling loop calls poll_keyboards each frame to process completed reports.

Dependencies

• driver.bus.usb.core
• driver.bus.usb.types
• driver.mgr
• driver.hid.keyboard
• driver.hid.ps2.keyboard
• syslog

Types

TUSBKeyboardData

Per-device state record:

Field	Type	Description
device	PUSBDevice	Pointer to the enumerated USB device
endpoint	TUSBEndpoint	Interrupt IN endpoint descriptor
report	array[0..7] of uint8	Current 8-byte HID boot report buffer
prev_report	array[0..7] of uint8	Previous report for change detection
transfer	PUSBTransfer	Handle to the pending interrupt transfer
active	boolean	Whether this keyboard slot is in use
fail_count	uint8	Consecutive transfer failure counter

Constants

HID_TO_ASCII / HID_TO_ASCII_SHIFT

Two lookup tables of 104 entries mapping HID usage IDs (keycodes 0–103) to ASCII characters, for unshifted and shifted states respectively.

Functions and Procedures

init

procedure init;

Registers the USB keyboard class driver with driver.mgr for USB devices with class $03 (HID), subclass $01 (Boot), protocol $01 (Keyboard).

load

function load(ptr: pointer): boolean;

Driver load callback. Sends SET_PROTOCOL(Boot) and SET_IDLE(0) control requests, finds the first interrupt IN endpoint, allocates a TUSBKeyboardData slot, submits the first interrupt transfer, and disables the PS/2 keyboard driver to prevent duplicate input.

poll_keyboards

procedure poll_keyboards;

Called each kernel frame. For each active keyboard slot, checks the pending transfer status: - tsSuccess: compares report to previous report, translates changed keycodes via HID_TO_ASCII/HID_TO_ASCII_SHIFT, fires events through driver.hid.keyboard.reportKeyEvent, saves current report as previous, and resubmits the transfer. - Error status: increments fail_count; deactivates the slot after 3 consecutive failures and attempts to clear the endpoint halt.

UnitTest

procedure UnitTest;

Verifies HID-to-ASCII table coverage and key tracking logic.

Notes

• The 8-byte boot report layout is: byte 0 = modifier bitmask (Ctrl/Shift/Alt/GUI), byte 1 = reserved, bytes 2–7 = up to 6 simultaneous key usage IDs.
• A usage ID of $00 in bytes 2–7 indicates no key; $01 indicates rollover error.
• Modifier keys (Shift, Ctrl, Alt) are extracted from byte 0 bit fields and passed to driver.hid.keyboard.reportKeyEvent in the TKeyInfo modifier fields.