Abstract
The disclosure describes a tiered prefix-sum canonical key gather unit that forms a canonical match key of selectable size (8, 16, 24, or 48 bytes) into a fixed-width canonical_key storage without using a key-wide barrel shifter and without cross-register-group gather. Up to six operands are decoded from a bank of key-generation registers, including packet header vector registers, metadata registers, and routing/result registers. Operands are organized into tiers of non-increasing width, including naturally aligned wide runs spanning 1, 2, or 4 registers, word operands spanning one register, and byte operands extracting 1 to 4 bytes from a register using a sub-word right shift. A prefix-sum placement computes byte positions from the most-significant byte downward, concatenates valid operands in order, zero-fills the tail, and applies a mask for the selected key size. A legality gate detects violations (e.g., alignment, range, mask, or budget) and can convert the operation to a no-operation result.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Anonymous, "Tiered Prefix-Sum Canonical Key Gather for Match-Stage Lookup Keys", Technical Disclosure Commons, ()
https://www.tdcommons.org/dpubs_series/12563