From ddb084e9a8a0cba10536951236cde824526e8071 Mon Sep 17 00:00:00 2001 From: gatecat Date: Sun, 19 Dec 2021 16:41:34 +0000 Subject: archapi: Use arbitrary rather than actual placement in predictDelay This makes predictDelay be based on an arbitrary belpin pair rather than a arc of a net based on cell placement. This way 'what-if' decisions can be evaluated without actually changing placement; potentially useful for parallel placement. A new helper predictArcDelay behaves like the old predictDelay to minimise the impact on existing passes; only arches need be updated. Signed-off-by: gatecat --- docs/coding.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'docs/coding.md') diff --git a/docs/coding.md b/docs/coding.md index dc09bb3f..db2ec079 100644 --- a/docs/coding.md +++ b/docs/coding.md @@ -80,7 +80,7 @@ As nextpnr allows arbitrary constraints on bels for more advanced packer-free fl There are several routes for timing information in the placer: - sink `PortRef`s have a `budget` value annotated by calling `assign_budget` which is an estimate of the maximum delay that an arc may have - sink ports can have a criticality (value between 0 and 1 where 1 is the critical path) associated with them by using `get_criticalities` and a `NetCriticalityMap` - - `predictDelay` returns an estimated delay for a sink port based on placement information + - `predictDelay` and its derivative `predictArcDelay` returns an estimated delay for a sink port based on placement information ### Bel Buckets -- cgit v1.2.3