unicorn-engine/unicorn is a lightweight emulator framework that executes CPU instruction sets in software. It supports the ARM, AArch64, M68K, Mips, Sparc, PowerPC, RiscV, S390x, TriCore, and X86 architectures, and was created on August 20, 2015. The latest release is 2.1.4, and the provided information contains no changes for this version.
This framework was built on top of QEMU. Its architecture-neutral API allows instructions from different CPUs to be handled through a single interface. Instrumentation is the feature for observing the emulated execution flow in fine detail. Thread safety is provided as well. It is implemented in pure C, supports bindings for multiple languages, and runs on Windows and *nix. The distribution is under the GPL-2.0 license, and the GitHub star count is 9472.
Still, the scope of what can be judged from this information alone is narrow. No performance figures, benchmarks, or real-world adoption cases are presented. On the evaluation side, only the momentum item has a score of 2.8, while the freshness, technical, and quality items are empty. The linking conditions of the GPL-2.0 license are also not contained in this information. The composition of lightly bundling multiple architectures and providing instrumentation features is practical. What exactly changed in 2.1.4 can only be known by checking the release notes.