From 7740bfbae4b9211303dfc1e9d535d1d73dfc7e03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mamy=20Andr=C3=A9-Ratsimbazafy?= <mamy_github@numforge.co>
Date: Sun, 16 Feb 2020 12:32:34 +0100
Subject: [PATCH] print montgomery magics at compile-time

---
 constantine/config/curves.nim | 29 +++++++++++++++++++++++++++++
 constantine/io/io_bigints.nim |  1 -
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/constantine/config/curves.nim b/constantine/config/curves.nim
index 46c5e84..226d099 100644
--- a/constantine/config/curves.nim
+++ b/constantine/config/curves.nim
@@ -131,3 +131,32 @@ macro getR2modP*(C: static Curve): untyped =
 macro getNegInvModWord*(C: static Curve): untyped =
   ## Get the Montgomery "-1/P[0] mod 2^WordBitSize" constant associated to a curve field modulus
   result = bindSym($C & "_NegInvModWord")
+
+# ############################################################
+#
+#                Debug info printed at compile-time
+#
+# ############################################################
+
+macro debugConsts(): untyped =
+  let curves = bindSym("Curve")
+  let E = curves.getImpl[2]
+
+  result = newStmtList()
+  for i in 1 ..< E.len:
+    let curve = E[i]
+    let curveName = $curve
+    let modulus = bindSym(curveName & "_Modulus")
+    let r2modp = bindSym(curveName & "_R2modP")
+    let negInvModWord = bindSym(curveName & "_NegInvModWord")
+
+    result.add quote do:
+      echo "Curve ", `curveName`,':'
+      echo "  Field Modulus:                 ", `modulus`
+      echo "  Montgomery R² (mod P):         ", `r2modp`
+      echo "  Montgomery -1/P[0] (mod 2^", WordBitSize, "): ", `negInvModWord`
+  result.add quote do:
+    echo "----------------------------------------------------------------------------"
+
+debug:
+  debugConsts()
diff --git a/constantine/io/io_bigints.nim b/constantine/io/io_bigints.nim
index a1f48d5..1a8b660 100644
--- a/constantine/io/io_bigints.nim
+++ b/constantine/io/io_bigints.nim
@@ -330,7 +330,6 @@ func fromHex*(T: type BigInt, s: string): T =
   # 1. Convert to canonical uint
   const canonLen = (T.bits + 8 - 1) div 8
   var bytes: array[canonLen, byte]
-  debugEcho "canonLen: ", canonLen
   hexToPaddedByteArray(s, bytes, littleEndian)
 
   # 2. Convert canonical uint to Big Int