From 7e18c0f46bbc2c380e670ba1ad36a600d9aa41e7 Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Mon, 13 Nov 2023 13:17:22 +0100
Subject: [PATCH] Move merkleRoot() into its own module

---
 poseidon2.nim                                 | 39 +------------------
 poseidon2/merkle.nim                          | 34 ++++++++++++++++
 .../{testPoseidon2.nim => testMerkle.nim}     |  6 ++-
 tests/test.nim                                |  2 +-
 4 files changed, 41 insertions(+), 40 deletions(-)
 create mode 100644 poseidon2/merkle.nim
 rename tests/poseidon2/{testPoseidon2.nim => testMerkle.nim} (93%)

diff --git a/poseidon2.nim b/poseidon2.nim
index bdee038..f071913 100644
--- a/poseidon2.nim
+++ b/poseidon2.nim
@@ -1,47 +1,12 @@
-import std/sequtils
-import constantine/math/arithmetic
-
 import poseidon2/types
-import poseidon2/permutation
 import poseidon2/io
 import poseidon2/sponge
 import poseidon2/compress
+import poseidon2/merkle
 
 export sponge
 export compress
+export merkle
 export toBytes
 export elements
 export types
-
-#-------------------------------------------------------------------------------
-
-func merkleRoot*(xs: openArray[F]) : F =
-  let a = low(xs)
-  let b = high(xs)
-  let m = b-a+1
-
-  if m==1:
-    return xs[a]
-
-  else:
-    let halfn  : int  = m div 2
-    let n      : int  = 2*halfn
-    let isOdd : bool = (n != m)
-
-    var ys : seq[F]
-    if not isOdd:
-      ys = newSeq[F](halfn)
-    else:
-      ys = newSeq[F](halfn+1)
-
-    for i in 0..<halfn:
-      ys[i] = compress( xs[a+2*i], xs[a+2*i+1] )
-    if isOdd:
-      ys[halfn] = compress( xs[n], zero )
-
-    return merkleRoot(ys)
-
-func merkleRoot*(bytes: openArray[byte]): F =
-  merkleRoot(toSeq bytes.elements(F))
-
-#-------------------------------------------------------------------------------
diff --git a/poseidon2/merkle.nim b/poseidon2/merkle.nim
new file mode 100644
index 0000000..fe18210
--- /dev/null
+++ b/poseidon2/merkle.nim
@@ -0,0 +1,34 @@
+import std/sequtils
+import constantine/math/arithmetic
+import ./types
+import ./io
+import ./compress
+
+func merkleRoot*(xs: openArray[F]) : F =
+  let a = low(xs)
+  let b = high(xs)
+  let m = b-a+1
+
+  if m==1:
+    return xs[a]
+
+  else:
+    let halfn  : int  = m div 2
+    let n      : int  = 2*halfn
+    let isOdd : bool = (n != m)
+
+    var ys : seq[F]
+    if not isOdd:
+      ys = newSeq[F](halfn)
+    else:
+      ys = newSeq[F](halfn+1)
+
+    for i in 0..<halfn:
+      ys[i] = compress( xs[a+2*i], xs[a+2*i+1] )
+    if isOdd:
+      ys[halfn] = compress( xs[n], zero )
+
+    return merkleRoot(ys)
+
+func merkleRoot*(bytes: openArray[byte]): F =
+  merkleRoot(toSeq bytes.elements(F))
diff --git a/tests/poseidon2/testPoseidon2.nim b/tests/poseidon2/testMerkle.nim
similarity index 93%
rename from tests/poseidon2/testPoseidon2.nim
rename to tests/poseidon2/testMerkle.nim
index 6a149d9..cff8677 100644
--- a/tests/poseidon2/testPoseidon2.nim
+++ b/tests/poseidon2/testMerkle.nim
@@ -8,9 +8,11 @@ import constantine/math/io/io_bigints
 import constantine/serialization/codecs
 
 import poseidon2/types
-import poseidon2
+import poseidon2/io
+import poseidon2/compress
+import poseidon2/merkle
 
-suite "poseidon2":
+suite "merkle root":
 
   test "merkle root of field elements":
     let m = 17
diff --git a/tests/test.nim b/tests/test.nim
index da47d22..dea2668 100644
--- a/tests/test.nim
+++ b/tests/test.nim
@@ -1,7 +1,7 @@
 import ./poseidon2/testPermutation
 import ./poseidon2/testSponge
 import ./poseidon2/testCompress
-import ./poseidon2/testPoseidon2
+import ./poseidon2/testMerkle
 import ./poseidon2/testIo
 import ./poseidon2/testReadme