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Decoding Input Device (evdev) Capabilities on Linux

Introduction

Input devices (whether physically present, or emulated) may produce any "kind" of input. In other words there is no clear distinction between a keyboard and a mouse, other than the data they (i.e., their drivers) write to their corresponding /dev/input/eventX file (where X is an integer). That can be problematic sometimes, for example if a program in userspace consumes input data from a device and expects that data to only contain certain keycodes, event types, etc. Another example could be a video game which displays different sprites/text when a gamepad is used instead of a keyboard, like key/button prompts in a tutorial or a settings menu. Luckily, most devices only write a strict set of event types and codes to their eventX file, because well, most hardware is only a keyboard, or mouse, or gamepad, or touchscreen, etc. and not a wild combination. The kernel calls these the input device's capabilities, as documented [here](ht

TriceHelix

    // float32
    // Martin Kallman
    //
    // Fast half-precision to single-precision floating point conversion
    //  - Supports signed zero and denormals-as-zero (DAZ)
    //  - Does not support infinities or NaN
    //  - Few, partially pipelinable, non-branching instructions,
    //  - Core opreations ~6 clock cycles on modern x86-64
    void float32(float* __restrict out, const uint16_t in) {
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