From 7b584fbfb8cd9451ecb798c5f27c56b1216b9ca2 Mon Sep 17 00:00:00 2001
From: Vegard Storheil Eriksen <zyp@jvnv.net>
Date: Sun, 25 Aug 2013 19:22:45 +0200
Subject: Added basic HID descriptors.

---
 usb/hid.h | 227 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 227 insertions(+)
 create mode 100644 usb/hid.h

diff --git a/usb/hid.h b/usb/hid.h
new file mode 100644
index 0000000..eac3f07
--- /dev/null
+++ b/usb/hid.h
@@ -0,0 +1,227 @@
+#ifndef HID_H
+#define HID_H
+
+struct HID_desc {
+	uint8_t bLength;
+	uint8_t bDescriptorType;
+	uint16_t bcdHID;
+	uint8_t bCountryCode;
+	uint8_t bNumDescriptors;
+	uint8_t bDescriptorType0;
+	uint16_t wDescriptorLength0;
+} __attribute__((packed));
+
+constexpr HID_desc hid_desc(
+		uint16_t bcdHID,
+		uint8_t bCountryCode,
+		uint8_t bNumDescriptors,
+		uint8_t bDescriptorType,
+		uint16_t wDescriptorLength
+	) {
+	
+	return {
+		sizeof(HID_desc),
+		0x21,
+		bcdHID,
+		bCountryCode,
+		bNumDescriptors,
+		bDescriptorType,
+		wDescriptorLength
+	};
+}
+
+template <typename T>
+struct HID_Item {
+	uint8_t tag;
+	T data;
+} __attribute__((packed));
+
+template <>
+struct HID_Item<void> {
+	uint8_t tag;
+} __attribute__((packed));
+
+constexpr HID_Item<void> hid_item(uint8_t tag) {
+	return {tag};
+}
+
+template <typename T>
+constexpr uint8_t hid_item_data_size() {
+	static_assert(sizeof(T) == 1 || sizeof(T) == 2 || sizeof(T) == 4, "item has invalid size");
+	
+	return sizeof(T) == 1 ? 1 : sizeof(T) == 2 ? 2 : 3;
+}
+
+template <typename T>
+constexpr HID_Item<T> hid_item(uint8_t tag, T data) {
+	return HID_Item<T>{uint8_t(tag | hid_item_data_size<T>()), data};
+}
+
+namespace UsagePage {
+	enum _8 : uint8_t {
+		Undefined,
+		Desktop,
+		Simulation,
+		VR,
+		Sport,
+		Game,
+		Generic,
+		Keyboard,
+		LED,
+		Button,
+		Ordinal,
+	};
+}
+
+constexpr HID_Item<UsagePage::_8> usage_page(UsagePage::_8 page) {
+	return hid_item(0x04, page);
+}
+
+constexpr HID_Item<uint16_t> usage_page(uint16_t page) {
+	return hid_item(0x04, page);
+}
+
+namespace DesktopUsage {
+	enum _8 : uint8_t {
+		Undefined,
+		Gamepad = 0x05,
+		X = 0x30,
+		Y,
+		Z,
+		Rx,
+		Ry,
+		Rz,
+	};
+}
+
+enum class Collection : uint8_t {
+	Physical,
+	Application,
+	Logical,
+};
+
+constexpr HID_Item<DesktopUsage::_8> usage(DesktopUsage::_8 usage) {
+	return hid_item(0x08, usage);
+}
+
+constexpr HID_Item<uint16_t> usage(uint16_t usage) {
+	return hid_item(0x08, usage);
+}
+
+template <typename... R>
+constexpr auto collection(Collection type, R... r) -> decltype(pack(HID_Item<Collection>(), r..., HID_Item<void>())) {
+	return pack(hid_item(0xa0, type), r..., hid_item(0xc0));
+}
+
+constexpr HID_Item<int16_t> usage_minimum(int16_t x) {
+	return hid_item(0x18, x);
+}
+
+constexpr HID_Item<int16_t> usage_maximum(int16_t x) {
+	return hid_item(0x28, x);
+}
+
+constexpr HID_Item<int32_t> logical_minimum(int32_t x) {
+	return hid_item(0x14, x);
+}
+
+constexpr HID_Item<int32_t> logical_maximum(int32_t x) {
+	return hid_item(0x24, x);
+}
+
+constexpr HID_Item<uint8_t> report_count(uint8_t x) {
+	return hid_item(0x94, x);
+}
+
+constexpr HID_Item<uint8_t> report_size(uint8_t x) {
+	return hid_item(0x74, x);
+}
+
+constexpr HID_Item<uint8_t> input(uint8_t x) {
+	return hid_item(0x80, x);
+}
+
+constexpr HID_Item<uint8_t> output(uint8_t x) {
+	return hid_item(0x90, x);
+}
+
+constexpr HID_Item<uint8_t> feature(uint8_t x) {
+	return hid_item(0xb0, x);
+}
+
+constexpr HID_Item<uint8_t> report_id(uint8_t id) {
+	return hid_item(0x84, id);
+}
+
+template <typename... R>
+constexpr auto gamepad(R... r) -> decltype(
+	pack(
+		usage_page(UsagePage::Desktop),
+		usage(DesktopUsage::Gamepad),
+		collection(Collection::Application,
+			collection(Collection::Physical,
+				r...
+			)
+		)
+	)) {
+	return pack(
+		usage_page(UsagePage::Desktop),
+		usage(DesktopUsage::Gamepad),
+		collection(Collection::Application,
+			collection(Collection::Physical,
+				r...
+			)
+		)
+	);
+}
+
+constexpr auto buttons(uint8_t num) -> decltype(
+	pack(
+		usage_page(UsagePage::Button),
+		usage_minimum(1),
+		usage_maximum(num),
+		logical_minimum(0),
+		logical_maximum(1),
+		report_count(num),
+		report_size(1),
+		input(0x02)
+	)) {
+	return pack(
+		usage_page(UsagePage::Button),
+		usage_minimum(1),
+		usage_maximum(num),
+		logical_minimum(0),
+		logical_maximum(1),
+		report_count(num),
+		report_size(1),
+		input(0x02)
+	);
+}
+
+constexpr auto padding_in(uint8_t size) -> decltype(
+	pack(
+		report_count(1),
+		report_size(size),
+		input(0x01)
+	)) {
+	return pack(
+		report_count(1),
+		report_size(size),
+		input(0x01)
+	);
+}
+
+constexpr auto padding_out(uint8_t size) -> decltype(
+	pack(
+		report_count(1),
+		report_size(size),
+		output(0x01)
+	)) {
+	return pack(
+		report_count(1),
+		report_size(size),
+		output(0x01)
+	);
+}
+
+#endif
-- 
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