frontend: Model status/done_id as internal status registers#135
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frontend: Model status/done_id as internal status registers#135DanielKellerM wants to merge 1 commit into
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…otype) status and done_id have no read side-effect, so they need not be external. Drop 'external' in the RDL and drive the registered value via hwif .next; PeakRDL then emits internal storage with no external read handshake and no assert_bad_ext_rd_ack for them. next_id keeps its external read-launch + arb_ready-gated ack. Trade-off: status/done_id reads are now registered (<=1-cycle-delayed) rather than live-combinational.
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Refines the external-register read-ack fix (#134) by modeling the two observational registers correctly instead of gating their ack.
`status` (busy) and `done_id` have no read side-effect, so they need not be `external`. This drops `external` on them in the RDL and drives the registered value through the PeakRDL `hwif .next` input; PeakRDL then emits plain internal storage with no external read handshake and no `assert_bad_ext_rd_ack` for those registers. `next_id` keeps its external read-launch interface with the `arb_ready`-gated ack from #134 (its read launches a transfer and must back-pressure).
Net effect: the external read handshake/assertion now governs only `next_id` (the one register that genuinely needs it); the change removes logic rather than gating it.
Trade-off: `status`/`done_id` reads are now registered (≤1-cycle-delayed) rather than live-combinational. This is benign for busy/done polling (you never read a value that was not true, just up to a cycle late) and the SW-facing register map is unchanged (offsets, width, `sw=r` access identical).
Status: verified structurally — regenerates cleanly, the generated reg block elaborates (slang, 0 errors), and `external_rd_ack` now ORs only `next_id`. Draft pending the same cluster/UVM sim validation #134 had (assertion clears + a SW polling read returns the expected registered value).