Module hadamard 

Fast Walsh-Hadamard Transform (FWHT) GPU kernel dispatch.

Applies an in-place, normalized FWHT to a flat buffer shaped [num_heads, head_dim]. One Metal threadgroup is dispatched per head; each threadgroup has head_dim threads that cooperate through shared memory using the standard butterfly pattern.

The transform is normalized so that H·H = I (applying it twice returns the original vector), which is required for the random-feature / scrambled Hadamard use-case in Gemma-4 attention.

Statics

HADAMARD_SHADER_SOURCE

MSL source for the Hadamard transform kernel (embedded at compile time).

Functions

dispatch_hadamard_transform

Dispatch an in-place normalized Fast Walsh-Hadamard Transform on the GPU.

register

Register the Hadamard transform shader source with the given kernel registry.