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When to use input event codes in Linux?
Used to describe absolute axis value changes, e.g. describing the coordinates of a touch on a touchscreen. Used to describe miscellaneous input data that do not fit into other types. Used to describe binary state input switches. Used to turn LEDs on devices on and off. Used to output sound to devices.
How are special event types used in Linux?
A special event type, EV_SYN, is used to separate input events into packets of input data changes occurring at the same moment in time. In the following, the term “event” refers to a single input event encompassing a type, code, and value.
How is the input protocol used in Linux?
The input protocol uses a map of types and codes to express input device values to userspace. This document describes the types and codes and how and when they may be used. A single hardware event generates multiple input events. Each input event contains the new value of a single data item.
What are the events in the input protocol?
Each input event contains the new value of a single data item. A special event type, EV_SYN, is used to separate input events into packets of input data changes occurring at the same moment in time. In the following, the term “event” refers to a single input event encompassing a type, code, and value. The input protocol is a stateful protocol.
How are EV _ syn event values used in evdev?
EV_SYN event values are undefined. Their usage is defined only by when they are sent in the evdev event stream. Used to synchronize and separate events into packets of input data changes occurring at the same moment in time. For example, motion of a mouse may set the REL_X and REL_Y values for one motion, then emit a SYN_REPORT.
How are input events separated into data packets?
A single hardware event generates multiple input events. Each input event contains the new value of a single data item. A special event type, EV_SYN, is used to separate input events into packets of input data changes occurring at the same moment in time.