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RFC: Add a HID report composition helper macros

Peter Hutterer requested to merge whot/udev-hid-bpf:wip/hid-report-helpers into main

These macros make it slightly easier and more modular to create a HID report descriptor from scratch. Since they carry the annotation we don't need to comment it and they cannot get stale.

For comparison, before we had this:

0x15, 0x00,                    //   Logical Minimum (0)
0x25, 0x01,                    //   Logical Maximum (1)
0x95, 0x04,                    //   Report Count (4)
0x75, 0x01,                    //   Report Size (1)

Now we can write this as:

    LOGICAL_RANGE_i8(0, 1)
    REPORT_COUNT(4)
    REPORT_SIZE(1)

Because these macros are for creating new report descriptors, some bits aren't directly exposed. e.g in the example above: there is a logical range as one macro that sets both min and max. There is seldom a good use case for skipping either anyway.

These macros will need to be expanded over time.

Filing as RFC for comments and bikeshedding on style, not yet content, I may expand those as needed.

These are the macros from !87 (merged) factored into a separate header file (and slightly cleaned up/improved).

tbh, reading this I wouldn't mind using the HID notation instead of the screaming capitals, things like ReportId(4) would be nicer to read than REPORT_ID(4).

cc @bentiss, @JoseExposito

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