The HAL Interface Description Language (HIDL) specifies the interface between a HAL and its users. It defines types and method calls, collected into interfaces and packages. HIDL is a system for communicating between codebases that may be compiled independently and is intended for inter-process communication. See the HIDL guides.
The autogenerated documentation for the HIDL (.hal) files have been deprecated. For the details of the interface specifications, consult the HIDL source files in AOSP.
HIDL interface files are in four different locations in AOSP:
See the sections below for links to the HIDL source files in each location.