micheleandClaude Sonnet 5
932aec2490
Adds packed_pe.v (packed_slot.v's compute+activation-fetch+writeback subsystem, reusing ddr_prefetch_mgr.v/neural_processor_packed.v/ result_writeback.v completely unmodified, with its own private weight-fetch removed) and systolic_group.v (one real layer_prefetch_ ctrl.v+layer_weight_buffer.v+weight_tile_gather.v shared by 4x packed_pe.v via a real, barrier-synchronized broadcast bus). Real design choice confirmed with the user before writing any RTL (AskUserQuestion, concrete topology preview): shared-weight broadcast, not a literal PE-to-PE systolic shift register -- achieves the real, quantified rationale (4x reduction in redundant weight-fetch DDR3 traffic per group of 4 PEs) with much lower real risk than genuine inter-PE pipeline fill/drain. The real new design is the barrier: each PE's own tcnt is the join key against the group's broadcast tcnt, self-synchronizing regardless of which PE is momentarily ahead/behind (e.g. a real DDR3 row-switch stall on one PE's own activation fetch). Found and fixed a real bug during verification (not by inspection): the first full test run reported every result as undefined despite every control-flow signal tracing correctly -- root-caused via real signal tracing down to a 5-way test arbiter bus mis-sliced at the wrong slot offset (single-bit handshake buses happened to use a correct range and masked it from the control-flow trace; only the wide, byte-offset buses were wrong). Verified in isolation (tb_systolic_group.v, real Icarus xsim, real sdram_arbiter_n.v generalized to NUM_REQ=5 with zero changes): 8/8 PASS across 2 consecutive group jobs (exercising the barrier's own per-job reset path, not just cold start). Deliberately scoped to the isolated mechanism only, per this project's "one variable at a time" discipline -- Director/SPI job dispatch for group jobs, a real N=16 top-level, and real P&R are real, disclosed next steps, not done here. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC