CMakeLists.txt

cmake_minimum_required(VERSION 3.10)
project(cppgen VERSION 0.0.1 LANGUAGES CXX)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

add_executable(remapping remapping.cc)
target_link_libraries(remapping stdc++ "-framework Foundation" "-framework IOKit" objc)

hidutil-remapping.py

# See https://developer.apple.com/library/archive/technotes/tn2450/_index.html
# and
#   https://www.nanoant.com/mac/macos-function-key-remapping-with-hidutil
#   https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf#page=56
#   https://opensource.apple.com/source/IOHIDFamily/IOHIDFamily-1090.260.23/IOHIDEventSystemPlugIns/
#   https://opensource.apple.com/source/IOHIDFamily/IOHIDFamily-1090.260.23/IOHIDFamily/IOHIDUsageTables.h.auto.html


import os

TABLE = {
    "Keyboard a and A": 0x04,
    "Keyboard 5 and %": 0x22,
    "Keyboard F7": 0x40,
    "Keypad 6 and Right Arrow": 0x5E,
    "Keyboard b and B": 0x05,
    "Keyboard 6 and ^": 0x23,
    "Keyboard F8": 0x41,
    "Keypad 7 and Home": 0x5F,
    "Keyboard c and C": 0x06,
    "Keyboard 7 and&": 0x24,
    "Keyboard F9": 0x42,
    "Keypad 8 and Up Arrow": 0x60,
    "Keyboard d and D": 0x07,
    "Keyboard 8 and *": 0x25,
    "Keyboard F10": 0x43,
    "Keypad 9 and Page Up": 0x61,
    "Keyboard e and E": 0x08,
    "Keyboard 9 and (": 0x26,
    "Keyboard F11": 0x44,
    "Keypad 0 and Insert": 0x62,
    "Keyboard f and F": 0x09,
    "Keyboard 0 and )": 0x27,
    "Keyboard F12": 0x45,
    "Keypad . and Delete": 0x63,
    "Keyboard g and G": 0x0A,
    "Keyboard Return (Enter)": 0x28,
    "Keyboard Print Screen": 0x46,
    "Keyboard Non-US \\ and |": 0x64,
    "Keyboard h and H": 0x0B,
    "Keyboard Escape": 0x29,
    "Keyboard Scroll Lock": 0x47,
    "Keyboard Application": 0x65,
    "Keyboard i and I": 0x0C,
    "Keyboard Delete (Backspace)": 0x2A,
    "Keyboard Pause": 0x48,
    "Keyboard Power": 0x66,
    "Keyboard j and J": 0x0D,
    "Keyboard Tab": 0x2B,
    "Keyboard Insert": 0x49,
    "Keypad =": 0x67,
    "Keyboard k and K": 0x0E,
    "Keyboard Spacebar": 0x2C,
    "Keyboard Home": 0x4A,
    "Keyboard F13": 0x68,
    "Keyboard l and L": 0x0F,
    "Keyboard - and _": 0x2D,
    "Keyboard Page Up": 0x4B,
    "Keyboard F14": 0x69,
    "Keyboard m and M": 0x10,
    "Keyboard = and +": 0x2E,
    "Keyboard Delete Forward": 0x4C,
    "Keyboard F15": 0x6A,
    "Keyboard n and N": 0x11,
    "Keyboard [ and {": 0x2F,
    "Keyboard End": 0x4D,
    "Keyboard F16": 0x6B,
    "Keyboard o and O": 0x12,
    "Keyboard ] and }": 0x30,
    "Keyboard Page Down": 0x4E,
    "Keyboard F17": 0x6C,
    "Keyboard p and P": 0x13,
    "Keyboard \\ and |": 0x31,
    "Keyboard Right Arrow": 0x4F,
    "Keyboard F18": 0x6D,
    "Keyboard q and Q": 0x14,
    "Keyboard Non-US # and ~": 0x32,
    "Keyboard Left Arrow": 0x50,
    "Keyboard F19": 0x6E,
    "Keyboard r and R": 0x15,
    "Keyboard ; and :": 0x33,
    "Keyboard Down Arrow": 0x51,
    "Keyboard F20": 0x6F,
    "Keyboard s and S": 0x16,
    "Keyboard ' and \"": 0x34,
    "Keyboard Up Arrow": 0x52,
    "Keyboard F21": 0x70,
    "Keyboard t and T": 0x17,
    "Keyboard Grave Accent and Tilde": 0x35,
    "Keypad Num Lock and Clear": 0x53,
    "Keyboard F22": 0x71,
    "Keyboard u and U": 0x18,
    'Keyboard , and "<"': 0x36,
    "Keypad /": 0x54,
    "Keyboard F23": 0x72,
    "Keyboard v and V": 0x19,
    'Keyboard . and ">"': 0x37,
    "Keypad *": 0x55,
    "Keyboard F24": 0x73,
    "Keyboard w and W": 0x1A,
    "Keyboard / and ?": 0x38,
    "Keypad -": 0x56,
    "Keyboard Left Control": 0xE0,
    "Keyboard x and X": 0x1B,
    "Keyboard Caps Lock": 0x39,
    "Keypad +": 0x57,
    "Keyboard Left Shift": 0xE1,
    "Keyboard y and Y": 0x1C,
    "Keyboard F1": 0x3A,
    "Keypad Enter": 0x58,
    "Keyboard Left Alt": 0xE2,
    "Keyboard z and Z": 0x1D,
    "Keyboard F2": 0x3B,
    "Keypad 1 and End": 0x59,
    "Keyboard Left GUI": 0xE3,
    "Keyboard 1 and !": 0x1E,
    "Keyboard F3": 0x3C,
    "Keypad 2 and Down Arrow": 0x5A,
    "Keyboard Right Control": 0xE4,
    "Keyboard 2 and @": 0x1F,
    "Keyboard F4": 0x3D,
    "Keypad 3 and Page Down": 0x5B,
    "Keyboard Right Shift": 0xE5,
    "Keyboard 3 and #": 0x20,
    "Keyboard F5": 0x3E,
    "Keypad 4 and Left Arrow": 0x5C,
    "Keyboard Right Alt": 0xE6,
    "Keyboard 4 and $": 0x21,
    "Keyboard F6": 0x3F,
    "Keypad 5": 0x5D,
    "Keyboard Right GUI": 0xE7,
}


def key2hex(k):
    return 0x700000000 | TABLE[k]


def fromto(fromk, tok):
    return {
        "HIDKeyboardModifierMappingSrc": key2hex(fromk),
        "HIDKeyboardModifierMappingDst": key2hex(tok),
    }


def user_key_mapping(mapping):
    """Hex version of return str({"UserKeyMapping": mapping})."""
    m = []
    for d in mapping:
        m.append("{%s}" % ",".join('"%s":%s' % (k, hex(d[k])) for k in d))

    return '{"UserKeyMapping":[%s]}' % ",".join(m)


def main():
    # Settings for Razer Huntsman Tournament Edition Keyboard.
    # (ioreg -lw0 | less).
    matching = {"ProductID": 579, "VendorID": 5426}
    mapping = [
        fromto("Keyboard Left Alt", "Keyboard Left GUI"),
        fromto("Keyboard Left GUI", "Keyboard Left Alt"),
        fromto("Keyboard Right Alt", "Keyboard Right GUI"),
        fromto("Keyboard Application", "Keyboard Right Alt"),
    ]
    command = "hidutil property --matching '%s' --set '%s'" % (
        str(matching).replace("'", '"'),
        user_key_mapping(mapping),
    )
    print(command)
    os.system(command)


if __name__ == "__main__":
    main()

remapping.cc

// Cf.
// https://opensource.apple.com/source/IOHIDFamily/IOHIDFamily-1090.260.23/tools/hidutil/property.m.auto.html
// https://opensource.apple.com/source/IOHIDFamily/IOHIDFamily-1090.260.23/IOHIDFamily/IOHIDUsageTables.h.auto.html

#include <iostream>

#include <IOKit/hid/IOHIDKeys.h>
#include <IOKit/hid/IOHIDUsageTables.h>
#include <IOKit/hidsystem/IOHIDEventSystemClient.h>
#include <IOKit/hidsystem/IOHIDParameter.h>
#include <IOKit/hidsystem/IOHIDServiceClient.h>

int main(int argc, char *argv[]) {
  uint64_t aKey = 0x700000004;
  uint64_t bKey = 0x700000005;

  CFStringRef keys[2] = {CFSTR(kIOHIDKeyboardModifierMappingSrcKey),
                         CFSTR(kIOHIDKeyboardModifierMappingDstKey)};
  CFNumberRef values[2] = {
      CFNumberCreate(NULL, kCFNumberSInt64Type, &aKey),
      CFNumberCreate(NULL, kCFNumberSInt64Type, &bKey),
  };

  CFDictionaryRef dicts[2];
  dicts[0] = CFDictionaryCreate(
      NULL, (const void **)keys, (const void **)values, 2,
      &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);

  CFArrayRef map =
      CFArrayCreate(NULL, (const void **)dicts, 1, &kCFTypeArrayCallBacks);

  int product = 579;
  int vendor = 5426;

  CFStringRef keys2[2] = {CFSTR(kIOHIDProductIDKey), CFSTR(kIOHIDVendorIDKey)};
  CFNumberRef values2[2] = {
      CFNumberCreate(NULL, kCFNumberSInt64Type, &product),
      CFNumberCreate(NULL, kCFNumberSInt64Type, &vendor),
  };
  dicts[1] = CFDictionaryCreate(
      NULL, (const void **)keys2, (const void **)values2, 2,
      &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);

  IOHIDEventSystemClientRef system =
      IOHIDEventSystemClientCreateSimpleClient(kCFAllocatorDefault);
  // IOHIDEventSystemClientSetMatchingMultiple(system, dicts[1]);

  CFArrayRef services = IOHIDEventSystemClientCopyServices(system);
  for (CFIndex i = 0; i < CFArrayGetCount(services); i++) {
    IOHIDServiceClientRef service =
        (IOHIDServiceClientRef)CFArrayGetValueAtIndex(services, i);
    if (IOHIDServiceClientConformsTo(service, kHIDPage_GenericDesktop,
                                     kHIDUsage_GD_Keyboard)) {
      CFTypeRef product_ref =
          IOHIDServiceClientCopyProperty(service, CFSTR(kIOHIDProductIDKey));
      CFShow(product_ref);
      int64_t value = 0;
      CFNumberGetValue((CFNumberRef)product_ref, kCFNumberSInt64Type, &value);
      std::cout << value << std::endl;
      /*IOHIDServiceClientSetProperty(service, CFSTR(kIOHIDUserKeyUsageMapKey),
                                    map);
      */
    }
  }

  CFRelease(services);
  CFRelease(system);

  return 0;
}