How to convert between keyboard scan code and USB keyboard usage index?

Question

I'm working with a Windows virtual keyboard driver to generate keystrokes, and it requires specifying keys using the USB keyboard usage index. (See "Windows Platform Design Notes - Keyboard Scan Code Specification" appendix C for a list of usage indices and corresponding keys.) However, the keys I need to type will be specified by virtual key code.

Windows provides functions for converting between virtual key codes and scan codes, but I haven't found any way of converting between scan codes and these usage indices. Other than writing my own function that converts the hundred-and-change possible scan codes that my virtual keyboard driver may need to type, does Microsoft provide a function for doing this?

Answer 1

The following hash table will convert from scan code to USB usage ID. Note that it only includes page IDs with a corresponding usage page of 7.

The translations were acquired from the Microsoft document USB HID to PS/2 Scan Code Translation Table and from this pastebin that conveniently already has all that information formatted into a Python data structure.

std::unordered_map<WORD, BYTE> scanCodeToUSBUsageIndex({
    {0x00FF, 0x01}, // Overrun Error
    {0x00FC, 0x02}, // POST Fail
    {0x001E, 0x04}, // a A
    {0x0030, 0x05}, // b B
    {0x002E, 0x06}, // c C
    {0x0020, 0x07}, // d D
    {0x0012, 0x08}, // e E
    {0x0021, 0x09}, // f F
    {0x0022, 0x0A}, // g G
    {0x0023, 0x0B}, // h H
    {0x0017, 0x0C}, // i I
    {0x0024, 0x0D}, // j J
    {0x0025, 0x0E}, // k K
    {0x0026, 0x0F}, // l L
    {0x0032, 0x10}, // m M
    {0x0031, 0x11}, // n N
    {0x0018, 0x12}, // o O
    {0x0019, 0x13}, // p P
    {0x0010, 0x14}, // q Q
    {0x0013, 0x15}, // r R
    {0x001F, 0x16}, // s S
    {0x0014, 0x17}, // t T
    {0x0016, 0x18}, // u U
    {0x002F, 0x19}, // v V
    {0x0011, 0x1A}, // w W
    {0x002D, 0x1B}, // x X
    {0x0015, 0x1C}, // y Y
    {0x002C, 0x1D}, // z Z
    {0x0002, 0x1E}, // 1 !
    {0x0003, 0x1F}, // 2 @
    {0x0004, 0x20}, // 3 #
    {0x0005, 0x21}, // 4 $
    {0x0006, 0x22}, // 5 %
    {0x0007, 0x23}, // 6 ^
    {0x0008, 0x24}, // 7 &
    {0x0009, 0x25}, // 8 *
    {0x000A, 0x26}, // 9 (
    {0x000B, 0x27}, // 0 )
    {0x001C, 0x28}, // Return
    {0x0001, 0x29}, // Escape
    {0x000E, 0x2A}, // Backspace
    {0x000F, 0x2B}, // Tab
    {0x0039, 0x2C}, // Space
    {0x000C, 0x2D}, // - _
    {0x000D, 0x2E}, // = +
    {0x001A, 0x2F}, // [ {
    {0x001B, 0x30}, // ] }
    {0x002B, 0x31}, // \ |
    {0x002B, 0x32}, // Europe 1 (Note 2)
    {0x0027, 0x33}, // ; :
    {0x0028, 0x34}, // ' "
    {0x0029, 0x35}, // ` ~
    {0x0033, 0x36}, // , <
    {0x0034, 0x37}, // . >
    {0x0035, 0x38}, // / ?
    {0x003A, 0x39}, // Caps Lock
    {0x003B, 0x3A}, // F1
    {0x003C, 0x3B}, // F2
    {0x003D, 0x3C}, // F3
    {0x003E, 0x3D}, // F4
    {0x003F, 0x3E}, // F5
    {0x0040, 0x3F}, // F6
    {0x0041, 0x40}, // F7
    {0x0042, 0x41}, // F8
    {0x0043, 0x42}, // F9
    {0x0044, 0x43}, // F10
    {0x0057, 0x44}, // F11
    {0x0058, 0x45}, // F12
    {0xE037, 0x46}, // Print Screen (Note 1)
    {0x0046, 0x47}, // Scroll Lock
    {0xE052, 0x49}, // Insert (Note 1)
    {0xE047, 0x4A}, // Home (Note 1)
    {0xE049, 0x4B}, // Page Up (Note 1)
    {0xE053, 0x4C}, // Delete (Note 1)
    {0xE04F, 0x4D}, // End (Note 1)
    {0xE051, 0x4E}, // Page Down (Note 1)
    {0xE04D, 0x4F}, // Right Arrow (Note 1)
    {0xE04B, 0x50}, // Left Arrow (Note 1)
    {0xE050, 0x51}, // Down Arrow (Note 1)
    {0xE048, 0x52}, // Up Arrow (Note 1)
    {0x0045, 0x53}, // Num Lock
    {0xE035, 0x54}, // Keypad / (Note 1)
    {0x0037, 0x55}, // Keypad *
    {0x004A, 0x56}, // Keypad -
    {0x004E, 0x57}, // Keypad +
    {0xE01C, 0x58}, // Keypad Enter
    {0x004F, 0x59}, // Keypad 1 End
    {0x0050, 0x5A}, // Keypad 2 Down
    {0x0051, 0x5B}, // Keypad 3 PageDn
    {0x004B, 0x5C}, // Keypad 4 Left
    {0x004C, 0x5D}, // Keypad 5
    {0x004D, 0x5E}, // Keypad 6 Right
    {0x0047, 0x5F}, // Keypad 7 Home
    {0x0048, 0x60}, // Keypad 8 Up
    {0x0049, 0x61}, // Keypad 9 PageUp
    {0x0052, 0x62}, // Keypad 0 Insert
    {0x0053, 0x63}, // Keypad . Delete
    {0x0056, 0x64}, // Europe 2 (Note 2)
    {0xE05D, 0x65}, // App
    {0x0059, 0x67}, // Keypad =
    {0x005D, 0x68}, // F13
    {0x005E, 0x69}, // F14
    {0x005F, 0x6A}, // F15
    {0x007E, 0x85}, // Keypad , (Brazilian Keypad .)
    {0x0073, 0x87}, // Keyboard Int'l 1 ろ (Ro)
    {0x0070, 0x88}, // Keyboard Int'l 2 かたかな ひらがな ローマ字 (Katakana/Hiragana)
    {0x007D, 0x89}, // Keyboard Int'l 3 ￥ (Yen)
    {0x0079, 0x8A}, // Keyboard Int'l 4 前候補 変換 (次候補) 全候補 (Henkan)
    {0x007B, 0x8B}, // Keyboard Int'l 5 無変換 (Muhenkan)
    {0x005C, 0x8C}, // Keyboard Int'l 6 (PC9800 Keypad , )
    {0x00F2, 0x90}, // Keyboard Lang 1 한/영 (Hanguel/English)
    {0x00F1, 0x91}, // Keyboard Lang 2 한자 (Hanja)
    {0x0078, 0x92}, // Keyboard Lang 3 かたかな (Katakana)
    {0x0077, 0x93}, // Keyboard Lang 4 ひらがな (Hiragana)
    {0x0076, 0x94}, // Keyboard Lang 5 半角/全角 (Zenkaku/Hankaku)
    {0x001D, 0xE0}, // Left Control
    {0x002A, 0xE1}, // Left Shift
    {0x0038, 0xE2}, // Left Alt
    {0xE05B, 0xE3}, // Left GUI
    {0xE01D, 0xE4}, // Right Control
    {0x0036, 0xE5}, // Right Shift
    {0xE038, 0xE6}, // Right Alt
    {0xE05C, 0xE7}  // Right GUI
});