passthrough_stream_fifo: gate ptr updates on full handshake (#264 #313)#322
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The read and write pointer updates previously fired on valid_i/ready_i alone, without checking the other side of the handshake. With assertions disabled or in synthesized netlists this corrupted the FIFO pointers whenever a push happened while full, or a pop happened while empty. Fix: gate read-pointer advance on (ready_i && valid_o) and write-pointer advance on (valid_i && ready_o). The SameCycleRW mechanism is unaffected — ready_o already includes the (SameCycleRW && ready_i && valid_o) term, so simultaneous push+pop when full continues to work correctly (#313). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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This was referenced Jun 30, 2026
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Addresses #264 and #313.
The read and write pointer updates previously fired on valid_i/ready_i alone, without checking the other side of the handshake. With assertions disabled or in synthesized netlists this corrupted the FIFO pointers whenever a push happened while full, or a pop happened while empty.
Fix: gate read-pointer advance on (ready_i && valid_o) and write-pointer advance on (valid_i && ready_o). The SameCycleRW mechanism is unaffected — ready_o already includes the (SameCycleRW && ready_i && valid_o) term, so simultaneous push+pop when full continues to work correctly.