clirc

clirc (Clinical Lightweight Interoperability Resources in C) is a lightweight, bidirectional FHIR R4 library written in pure C. It parses FHIR JSON into C structs and serializes C structs back into FHIR JSON — with zero heap allocation and zero dependencies.

Built for medical devices, surgical robots, and embedded gateways that need to interoperate with EHRs without heavyweight runtimes. Fixed-size structs, no malloc on the hot path, explicit error codes, and roughly 2K lines of auditable, hand-written C99.

Supports Observation, Device, and Patient resources, including component arrays for complex observations like blood pressure. Designed and implemented the entire library, test suite, and validation CLI end-to-end.