feat: remove dependency on internal package in ecc.go (#693)

Author: gbotrel

ecc/ecc.go

@@ -13,14 +13,6 @@
 //   - EdDSA (on the "companion" twisted edwards curves)
 package ecc
 
-import (
-	"errors"
-	"math/big"
-	"strings"
-
-	"github.com/consensys/gnark-crypto/internal/generator/config"
-)
-
 // ID represent a unique ID for a curve
 type ID uint16
 
@@ -39,75 +31,6 @@ const (
 	GRUMPKIN
 )
 
-// Implemented return the list of curves fully implemented in gnark-crypto
-func Implemented() []ID {
-	return []ID{BN254, BLS12_377, BLS12_381, BW6_761, BLS24_315, BW6_633, BLS24_317, STARK_CURVE, SECP256K1, GRUMPKIN}
-}
-
-func IDFromString(s string) (ID, error) {
-	s = strings.ToLower(s)
-	for _, id := range Implemented() {
-		if s == id.String() {
-			return id, nil
-		}
-	}
-	return UNKNOWN, errors.New("unknown curve ID")
-}
-
-func (id ID) String() string {
-	cfg := id.config()
-	return strings.ToLower(cfg.EnumID)
-}
-
-// ScalarField returns the scalar field of the curve
-func (id ID) ScalarField() *big.Int {
-	cfg := id.config()
-	return modulus(cfg, true)
-}
-
-// BaseField returns the base field of the curve
-func (id ID) BaseField() *big.Int {
-	cfg := id.config()
-	return modulus(cfg, false)
-}
-
-func (id ID) config() *config.Curve {
-	// note to avoid circular dependency these are hard coded
-	// values are checked for non regression in code generation
-	switch id {
-	case BLS12_377:
-		return &config.BLS12_377
-	case BLS12_381:
-		return &config.BLS12_381
-	case BN254:
-		return &config.BN254
-	case BW6_761:
-		return &config.BW6_761
-	case BW6_633:
-		return &config.BW6_633
-	case BLS24_315:
-		return &config.BLS24_315
-	case BLS24_317:
-		return &config.BLS24_317
-	case STARK_CURVE:
-		return &config.STARK_CURVE
-	case SECP256K1:
-		return &config.SECP256K1
-	case GRUMPKIN:
-		return &config.GRUMPKIN
-	default:
-		panic("unimplemented ecc ID")
-	}
-}
-
-func modulus(c *config.Curve, scalarField bool) *big.Int {
-	if scalarField {
-		return new(big.Int).Set(c.FrInfo.Modulus())
-	}
-
-	return new(big.Int).Set(c.FpInfo.Modulus())
-}
-
 // MultiExpConfig enables to set optional configuration attribute to a call to MultiExp
 type MultiExpConfig struct {
 	NbTasks int // go routines to be used in the multiexp. can be larger than num cpus.

ecc/ecc_field.go

@@ -0,0 +1,61 @@
+import (
+	"math/big"
+	"errors"
+	"strings"
+)
+
+var mID = map[string]ID{
+	{{- range $curve := .}}
+	"{{toLower $curve.EnumID}}": {{toUpper $curve.EnumID}},
+	{{- end}}
+}
+
+// ScalarField returns the scalar field of the curve
+func (id ID) ScalarField() *big.Int {
+	f := new(big.Int)
+	switch id {
+	{{- range $curve := .}}
+	case {{toUpper $curve.EnumID}}:
+		f.SetString("{{$curve.FrModulus}}", 10)
+	{{- end}}
+	default:
+		panic("unimplemented ecc ID")
+	}
+	return f
+}
+
+// BaseField returns the base field of the curve
+func (id ID) BaseField() *big.Int {
+	f := new(big.Int)
+	switch id {
+	{{- range $curve := .}}
+	case {{toUpper $curve.EnumID}}:
+		f.SetString("{{$curve.FpModulus}}", 10)
+	{{- end}}
+	default:
+		panic("unimplemented ecc ID")
+	}
+	return f
+}
+
+// String returns the string representation of the ID
+func (id ID) String() string {
+	switch id {
+	{{- range $curve := .}}
+	case {{toUpper $curve.EnumID}}:
+		return "{{toLower $curve.EnumID}}"
+	{{- end}}
+	default:
+		panic("unimplemented ecc ID")
+	}
+}
+
+// IDFromString returns the ID corresponding to the string representation of the curve ID.
+// It returns UNKNOWN if the string does not match any known curve ID.
+func IDFromString(s string) (ID, error) {
+	s = strings.ToLower(s)
+	if id, ok := mID[s]; ok {
+		return id, nil
+	}
+	return UNKNOWN, errors.New("unknown curve ID")
+}

internal/generator/config/template/ecc_field.go.tmpl

@@ -187,6 +187,15 @@ func main() {
 
 	wg.Wait()
 
+	// generate the ecc_field.go file
+	{
+		entries := []bavard.Entry{
+			{File: filepath.Join(baseDir, "ecc", "ecc_field.go"), Templates: []string{"ecc_field.go.tmpl"}},
+		}
+
+		assertNoError(bgen.Generate(config.Curves, "ecc", "./config/template", entries...))
+	}
+
 	// format the whole directory
 
 	cmd := exec.Command("gofmt", "-s", "-w", baseDir)