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| author | gatecat <gatecat@ds0.me> | 2021-02-19 10:39:57 +0000 |
|---|---|---|
| committer | gatecat <gatecat@ds0.me> | 2021-02-19 11:31:33 +0000 |
| commit | 7922b3bfc4ef93b8f67194c05e1a236b4c83c3da (patch) | |
| tree | b2b21259e030edd0adc7cc944322e3e9186d3a71 /docs | |
| parent | 8376db94a7519406444988be3628a4dadfb8d742 (diff) | |
| download | nextpnr-7922b3bfc4ef93b8f67194c05e1a236b4c83c3da.tar.gz nextpnr-7922b3bfc4ef93b8f67194c05e1a236b4c83c3da.tar.bz2 nextpnr-7922b3bfc4ef93b8f67194c05e1a236b4c83c3da.zip | |
Replace DelayInfo with DelayPair/DelayQuad
This replaces the arch-specific DelayInfo structure with new DelayPair
(min/max only) and DelayQuad (min/max for both rise and fall) structures
that form part of common code.
This further reduces the amount of arch-specific code; and also provides
useful data structures for timing analysis which will need to delay
with pairs/quads of delays as it is improved.
While there may be a small performance cost to arches that didn't
separate the rise/fall cases (arches that aren't currently separating
the min/max cases just need to be fixed...) in DelayInfo, my expectation
is that inlining will mean this doesn't make much difference.
Signed-off-by: gatecat <gatecat@ds0.me>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/archapi.md | 25 |
1 files changed, 5 insertions, 20 deletions
diff --git a/docs/archapi.md b/docs/archapi.md index 96d96e80..9ecb1bf1 100644 --- a/docs/archapi.md +++ b/docs/archapi.md @@ -43,21 +43,6 @@ With the exception of `ArchNetInfo` and `ArchCellInfo`, the following types shou A scalar type that is used to represent delays. May be an integer or float type. -### DelayInfo - -A struct representing the delay across a timing arc. Must provide a `+` operator for getting the combined delay of two arcs, and the following methods to access concrete timings: - -``` -delay_t minRaiseDelay() const { return delay; } -delay_t maxRaiseDelay() const { return delay; } - -delay_t minFallDelay() const { return delay; } -delay_t maxFallDelay() const { return delay; } - -delay_t minDelay() const { return delay; } -delay_t maxDelay() const { return delay; } -``` - ### BelId A type representing a bel name. `BelId()` must construct a unique null-value. Must provide `==`, `!=`, and `<` operators and a specialization for `std::hash<BelId>`. @@ -332,7 +317,7 @@ will make the given wire available. *BaseArch default: returns `getBoundWireNet(wire)`* -### DelayInfo getWireDelay(WireId wire) const +### DelayQuad getWireDelay(WireId wire) const Get the delay for a wire. @@ -448,7 +433,7 @@ Get the destination wire for a pip. Bi-directional switches (transfer gates) are modeled using two anti-parallel pips. -### DelayInfo getPipDelay(PipId pip) const +### DelayQuad getPipDelay(PipId pip) const Get the delay for a pip. @@ -541,9 +526,9 @@ actual penalty used is a multiple of this value (i.e. a weighted version of this Convert an `delay_t` to an actual real-world delay in nanoseconds. -### DelayInfo getDelayFromNS(float v) const +### delay_t getDelayFromNS(float v) const -Convert a real-world delay in nanoseconds to a DelayInfo with equal min/max rising/falling values. +Convert a real-world delay in nanoseconds to a `delay_t`. ### uint32\_t getDelayChecksum(delay\_t v) const @@ -609,7 +594,7 @@ Return the decal and X/Y position for the graphics representing a group. Cell Delay Methods ------------------ -### bool getCellDelay(const CellInfo \*cell, IdString fromPort, IdString toPort, DelayInfo &delay) const +### bool getCellDelay(const CellInfo \*cell, IdString fromPort, IdString toPort, DelayQuad &delay) const Returns the delay for the specified path through a cell in the `&delay` argument. The method returns false if there is no timing relationship from `fromPort` to `toPort`. |