From 9db77ad0eb181e4430f8650d284697e547277bc0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mamy=20Andr=C3=A9-Ratsimbazafy?= <mamy_github@numforge.co>
Date: Sun, 9 Feb 2020 00:52:24 +0100
Subject: [PATCH] Prepare for testing finite fields, comment cleanups

---
 constantine.nimble                         | 13 ++++++------
 constantine/bigints.nim                    | 11 ++++++++++-
 constantine/curves_config.nim              | 23 ++++++++++++++--------
 constantine/field_fp.nim                   |  2 --
 tests/{all_tests.nim => test_field_fp.nim} |  6 ++----
 5 files changed, 34 insertions(+), 21 deletions(-)
 rename tests/{all_tests.nim => test_field_fp.nim} (85%)

diff --git a/constantine.nimble b/constantine.nimble
index bf151d8..30d5fdb 100644
--- a/constantine.nimble
+++ b/constantine.nimble
@@ -6,16 +6,17 @@ license       = "MIT or Apache License 2.0"
 srcDir        = "src"
 
 ### Dependencies
-requires "nim >= 0.18.0"
+requires "nim >= 1.0.6"
 
 ### Helper functions
-proc test(name: string, defaultLang = "c") =
+proc test(fakeCurves: string, path: string, lang = "c") =
   if not dirExists "build":
     mkDir "build"
-  --run
-  switch("out", ("./build/" & name))
-  setCommand defaultLang, "tests/" & name & ".nim"
+  exec "nim " & lang & fakeCurves & " --outdir:build -r --hints:off --warnings:off " & path
 
 ### tasks
 task test, "Run all tests":
-  test "all_tests"
+  test "",                 "tests/test_word_types.nim"
+  test "",                 "tests/test_io.nim"
+  test "",                 "tests/test_bigints.nim"
+  test "-d:testingCurves", "tests/test_field_fp.nim"
diff --git a/constantine/bigints.nim b/constantine/bigints.nim
index 22ddeba..2f8fa98 100644
--- a/constantine/bigints.nim
+++ b/constantine/bigints.nim
@@ -36,7 +36,6 @@
 # We internally order the limbs in little-endian
 # So the least significant limb is limb[0]
 # This is independent from the base type endianness.
-# TODO: hexdumps
 
 import ./word_types
 
@@ -49,6 +48,16 @@ const WordBitSize* = sizeof(Word) * 8 - 1
 func wordsRequired(bits: int): int {.compileTime.}=
   (bits + WordBitSize - 1) div WordBitSize
 
+# TODO: Currently the library is instantiation primitives like "add"
+#       for each "bits" size supported. This will lead to duplication
+#       if many sizes (for example for scp256k1, bn254 and BLS12-381)
+#       are required.
+#       It could be avoided by having the bitsize be a runtime field
+#       of the bigint. However the tradeoff would be:
+#       - overhead of this additional field
+#       - limbs have to be stored in an UncheckedArray instead of an array
+#         introducing memory management issues
+
 type
   BigInt*[bits: static int] = object
     ## Fixed-precision big integer
diff --git a/constantine/curves_config.nim b/constantine/curves_config.nim
index 616924a..670e76b 100644
--- a/constantine/curves_config.nim
+++ b/constantine/curves_config.nim
@@ -35,11 +35,18 @@ import
 # - proc MontyMagic(curve: static Curve): static Word =
 #   which returns the Montgomery magic constant
 #   associated with the curve modulus
-declareCurves:
-  # Barreto-Naehrig curve, Prime 254 bit, 128-bit security, https://eprint.iacr.org/2013/879.pdf
-  # Usage: Zero-Knowledge Proofs / zkSNARKs in ZCash and Ethereum 1
-  #        https://eips.ethereum.org/EIPS/eip-196
-  curve BN254:
-    bitsize: 254
-    modulus: "0x30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47"
-    # Equation: Y^2 = X^3 + 3
+when not defined(testingCurves):
+  declareCurves:
+    # Barreto-Naehrig curve, Prime 254 bit, 128-bit security, https://eprint.iacr.org/2013/879.pdf
+    # Usage: Zero-Knowledge Proofs / zkSNARKs in ZCash and Ethereum 1
+    #        https://eips.ethereum.org/EIPS/eip-196
+    curve BN254:
+      bitsize: 254
+      modulus: "0x30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47"
+      # Equation: Y^2 = X^3 + 3
+else:
+  # Fake curve for testing field arithmetic
+  declareCurves:
+    curve Fake101:
+      bitsize: 101
+      modulus: "0x65" # 101 in hex
diff --git a/constantine/field_fp.nim b/constantine/field_fp.nim
index 78bb5cb..7e845e6 100644
--- a/constantine/field_fp.nim
+++ b/constantine/field_fp.nim
@@ -17,8 +17,6 @@
 import ./word_types, ./bigints, ./curves_config
 from ./private/word_types_internal import unsafe_div2n1n
 
-static: echo CurveBitSize
-
 type
   Fp*[C: static Curve] = object
     ## P is the prime modulus of the Curve C
diff --git a/tests/all_tests.nim b/tests/test_field_fp.nim
similarity index 85%
rename from tests/all_tests.nim
rename to tests/test_field_fp.nim
index 20a28b1..702e1e7 100644
--- a/tests/all_tests.nim
+++ b/tests/test_field_fp.nim
@@ -6,7 +6,5 @@
 #   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
-import
-  test_word_types,
-  test_io,
-  test_bigints
+import  unittest, random,
+        ../constantine/[io, bigints, word_types, field_fp]