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Differential-pair length/skew evidence

ZapTrace emits a machine-readable report for differential-pair and length-match constraints. The report is based on routed trace segment lengths and is conservative: missing route evidence blocks supported high-speed profiles.

Inputs

The report consumes:

Net.constraints.length_match_group
Net.constraints.diff_pair_partner
RoutingIntent.differential_pair
RoutingIntent.length_match_mm
Design.routing.traces

Report

build_diffpair_length_report(design) returns:

schema_version
pair_count
violation_count
missing_route_count
blocked
entries[]

Each entry records:

group_name
net_ids
net_names
lengths_mm
delta_mm
tolerance_mm
supported_profile
status
blocking
message

Policy

  • If a supported differential/high-speed profile exceeds its length-match tolerance, the entry is blocking.
  • If a supported profile has no routed trace evidence, the entry is blocking.
  • Unrouted or partial route data is treated as insufficient evidence, not a pass.

Proof-pack sign-off

Proof manifests can attach diffpair_length evidence. It maps to autonomous sign-off as:

passed=false -> diff-pair-length blocks autonomous-pass
passed=true  -> diff-pair-length passes