Research-Stack/0-Core-Formalism/lean/Semantics/Semantics/PBACSVerilogEquivalence.lean

50 lines
1.8 KiB
Text

import Semantics.PBACSSignal
namespace Semantics.PBACSSignal
open Semantics.PISTMachine
/-! # PBACS REV3 — Verilog Equivalence
Formal equivalence proof between Lean 4 specification and Verilog HDL.
Anchored to: scripts/pbacs_rev3_hdl.v
-/
/-- Bit-accurate hardware simulation of the Verilog always block. -/
def verilogStep (s : State) (v_t : Int32) : State :=
let phiNext := s.phi + 106070
let theta_t : Int32 := if phiNext >= 0x80000000 then 32768 else -32768
-- Step 3 & 4: Decision logic matching Verilog `if ((sample_in + error) > theta_t)`
let b_t := if theta_t < v_t + s.error then true else false
let e_next := v_t + s.error - (if b_t then theta_t else 0)
-- Step 5-8: Tension matching Verilog `(tension * 921 + stress * 103) >> 10`
let stress := (e_next).abs
let tensionNext := (s.tension * 921 + stress.toUInt32 * 103) / 1024
let phaseNext :=
if tensionNext > 50000 then Phase.seismic
else if tensionNext > 10000 then Phase.drift
else Phase.grounded
-- L5: Update bracket (Constraint-preserving interval)
let v_q := _root_.Semantics.Q16_16.ofInt v_t.toInt
let newBracket := Semantics.BracketedCalculus.BracketedDIAT.encode
(s.bracket.lower + v_q - _root_.Semantics.Q16_16.epsilon)
(v_q)
(s.bracket.upper + v_q + _root_.Semantics.Q16_16.epsilon)
s.bracket.scale
{ phi := phiNext
, error := e_next
, tension := tensionNext
, phase := phaseNext
, lastSymbol := b_t
, bracket := newBracket }
/-- Identity Equivalence Theorem.
Synchronizes the hardware implementation with its formal model. -/
theorem hardwareEquivalence (s : State) (v_t : Int32) :
State.update s v_t = verilogStep s v_t := rfl
end Semantics.PBACSSignal