Every call dispatches to the fastest kernel among the CPU’s enabled capabilities, a bitmask with one bit per SIMD capability.
A StringZilla.Device reports those masks for the host CPU, or for a GPU by its runtime’s own ordinal:
StringZilla.Device cpu = StringZilla.Device.cpu();
long enabled = cpu.capabilitiesEnabled(); // what dispatch uses
System.out.println(StringZilla.capabilitiesName(enabled)); // e.g. "serial,haswell,skylake,icelake"
System.out.println(StringZilla.version());capabilitiesEnabled() is the one you usually want, and derives from two independent axes:
capabilitiesDetected(): what this device can execute.capabilitiesCompiled(): what this build contains for devices of its kind, from the ISA probes at build time.capabilitiesEnabled(): what dispatch uses, both axes at once.
capabilitiesDetected() describes the machine and says nothing about whether a kernel was compiled in, so a build whose ISA probes failed still reports your CPU’s full feature set while containing no SIMD kernels at all.
The enabled set always keeps the serial fallback, bit 1. capabilitiesName(mask) spells any mask as comma-separated capability names, like "serial,neon". configureThread(capabilities) prepares the calling thread for the kernels of capabilities, usually capabilitiesEnabled(), and belongs at the start of every thread that runs them.
GPUs only report their masks here, since no call of this binding runs on one:
long gpus = StringZilla.Device.count(StringZilla.DeviceKind.METAL); // throws without a Metal device
StringZilla.Device gpu = new StringZilla.Device(StringZilla.DeviceKind.METAL, 0);
System.out.println(StringZilla.capabilitiesName(gpu.capabilitiesEnabled())); // e.g. "metal"Device.count(kind) is one for the CPU and whatever the GPU runtime counts otherwise.
Constructing a Device past the last ordinal of its kind throws a StatusException with sz_missing_gpu_k. configureThread on a GPU throws one with sz_missing_kernel_k, as GPUs keep no thread state of their own.