reducing gate (#13)

field/quadratic_extension.go

@@ -15,11 +15,21 @@ type QuadraticExtensionAPI struct {
 
 	ONE_QE  QuadraticExtension
 	ZERO_QE QuadraticExtension
+
+	ZERO_QE_ALGEBRA QEAlgebra
 }
 
 func NewQuadraticExtensionAPI(fieldAPI frontend.API, degreeBits uint64) *QuadraticExtensionAPI {
 	// TODO:  Should degreeBits be verified that it fits within the field and that degree is within uint64?
 
+	var ZERO_QE = QuadraticExtension{ZERO_F, ZERO_F}
+
+	var ZERO_QE_ALGEBRA QEAlgebra
+
+	for i := 0; i < D; i++ {
+		ZERO_QE_ALGEBRA[i] = ZERO_QE
+	}
+
 	return &QuadraticExtensionAPI{
 		fieldAPI: fieldAPI,
 
@@ -27,7 +37,9 @@ func NewQuadraticExtensionAPI(fieldAPI frontend.API, degreeBits uint64) *Quadrat
 		DTH_ROOT: NewFieldElement(18446744069414584320),
 
 		ONE_QE:  QuadraticExtension{ONE_F, ZERO_F},
-		ZERO_QE: QuadraticExtension{ZERO_F, ZERO_F},
+		ZERO_QE: ZERO_QE,
+
+		ZERO_QE_ALGEBRA: ZERO_QE_ALGEBRA,
 	}
 }
 

plonky2_verifier/gate.go

@@ -140,6 +140,24 @@ func GateInstanceFromId(gateId string) gate {
 		return NewReducingExtensionGate(uint64(numCoeffs))
 	}
 
+	if strings.HasPrefix(gateId, "ReducingGate") {
+		// Has the format "ReducingGate { num_coeffs: 33 }"
+
+		regEx := "ReducingGate { num_coeffs: (?P<numCoeffs>[0-9]+) }"
+		r, err := regexp.Compile(regEx)
+		if err != nil {
+			panic("Invalid ReducingGate regular expression")
+		}
+
+		matches := getRegExMatches(r, gateId)
+		numCoeffs, hasNumCoeffs := matches["numCoeffs"]
+		if !hasNumCoeffs {
+			panic("Invalid ReducingGate ID")
+		}
+
+		return NewReducingGate(uint64(numCoeffs))
+	}
+
 	return nil
 	//panic(fmt.Sprintf("Unknown gate ID %s", gateId))
 }

plonky2_verifier/gate_test.go

@@ -415,7 +415,6 @@ var poseidonGateExpectedConstraints = []QuadraticExtension{
 	{NewFieldElement(3134481789780853760), NewFieldElement(10023938129020275945)},
 }
 
-// ReducingExtensionGate { num_coeffs: 33 }
 var reducingExtensionGateExpectedConstraints = []QuadraticExtension{
 	{NewFieldElement(12512260201049243975), NewFieldElement(5104620179714279781)},
 	{NewFieldElement(13013016297591764071), NewFieldElement(3905565448987160512)},
@@ -770,6 +769,7 @@ func TestGates(t *testing.T) {
 		{&ArithmeticExtensionGate{numOps: 10}, arithmeticExtensionGateExpectedConstraints},
 		{&MultiplicationExtensionGate{numOps: 13}, mulExtensionGateExpectedConstraints},
 		{&ReducingExtensionGate{numCoeffs: 33}, reducingExtensionGateExpectedConstraints},
+		{&ReducingGate{numCoeffs: 44}, reducingGateExpectedConstraints},
 	}
 
 	for _, test := range gateTests {

plonky2_verifier/reducing_extension_gate.go

@@ -9,7 +9,7 @@ type ReducingExtensionGate struct {
 	numCoeffs uint64
 }
 
-const START_COEFFS = 3 * D
+const START_COEFFS_REDUCING_EXTENSION_GATE = 3 * D
 
 func NewReducingExtensionGate(numCoeffs uint64) *ReducingExtensionGate {
 	return &ReducingExtensionGate{
@@ -34,11 +34,11 @@ func (g *ReducingExtensionGate) wiresOldAcc() Range {
 }
 
 func (g *ReducingExtensionGate) wiresCoeff(i uint64) Range {
-	return Range{START_COEFFS + D*i, START_COEFFS + D*(i+1)}
+	return Range{START_COEFFS_REDUCING_EXTENSION_GATE + D*i, START_COEFFS_REDUCING_EXTENSION_GATE + D*(i+1)}
 }
 
 func (g *ReducingExtensionGate) startAccs() uint64 {
-	return START_COEFFS + g.numCoeffs*D
+	return START_COEFFS_REDUCING_EXTENSION_GATE + g.numCoeffs*D
 }
 
 func (g *ReducingExtensionGate) wiresAccs(i uint64) Range {

plonky2_verifier/reducing_gate.go

@@ -0,0 +1,89 @@
+package plonky2_verifier
+
+import (
+	"fmt"
+	. "gnark-plonky2-verifier/field"
+)
+
+type ReducingGate struct {
+	numCoeffs uint64
+}
+
+const START_COEFFS_REDUCING_GATE = 3 * D
+
+func NewReducingGate(numCoeffs uint64) *ReducingGate {
+	return &ReducingGate{
+		numCoeffs: numCoeffs,
+	}
+}
+
+func (g *ReducingGate) Id() string {
+	return fmt.Sprintf("ReducingExtensionGate { num_ops: %d }", g.numCoeffs)
+}
+
+func (g *ReducingGate) wiresOutput() Range {
+	return Range{0, D}
+}
+
+func (g *ReducingGate) wiresAlpha() Range {
+	return Range{D, 2 * D}
+}
+
+func (g *ReducingGate) wiresOldAcc() Range {
+	return Range{2 * D, 3 * D}
+}
+
+func (g *ReducingGate) wiresCoeff() Range {
+	return Range{START_COEFFS_REDUCING_GATE, START_COEFFS_REDUCING_GATE + g.numCoeffs}
+}
+
+func (g *ReducingGate) startAccs() uint64 {
+	return START_COEFFS_REDUCING_GATE + g.numCoeffs
+}
+
+func (g *ReducingGate) wiresAccs(i uint64) Range {
+	if i >= g.numCoeffs {
+		panic("Accumulator index out of bounds")
+	}
+
+	if i == g.numCoeffs-1 {
+		return g.wiresOutput()
+	}
+
+	return Range{g.startAccs() + D*i, g.startAccs() + D*(i+1)}
+}
+
+func (g *ReducingGate) EvalUnfiltered(p *PlonkChip, vars EvaluationVars) []QuadraticExtension {
+	alpha := vars.GetLocalExtAlgebra(g.wiresAlpha())
+	oldAcc := vars.GetLocalExtAlgebra(g.wiresOldAcc())
+
+	coeffs := []QuadraticExtension{}
+	coeffsRange := g.wiresCoeff()
+	for i := coeffsRange.start; i < coeffsRange.end; i++ {
+		coeffs = append(coeffs, vars.localWires[i])
+	}
+
+	accs := []QEAlgebra{}
+	for i := uint64(0); i < g.numCoeffs; i++ {
+		accs = append(accs, vars.GetLocalExtAlgebra(g.wiresAccs(i)))
+	}
+
+	constraints := []QuadraticExtension{}
+	acc := oldAcc
+	for i := uint64(0); i < g.numCoeffs; i++ {
+		var coeff QEAlgebra
+		for j := 0; j < D; j++ {
+			coeff[j] = p.qeAPI.ZERO_QE
+		}
+		coeff[0] = coeffs[i]
+		tmp := p.qeAPI.MulExtensionAlgebra(acc, alpha)
+		tmp = p.qeAPI.AddExtensionAlgebra(tmp, coeff)
+		tmp = p.qeAPI.SubExtensionAlgebra(tmp, accs[i])
+		for j := 0; j < D; j++ {
+			constraints = append(constraints, tmp[j])
+		}
+		acc = accs[i]
+	}
+
+	return constraints
+}