Move rebaseLE to its own module

fq.lua

@@ -3,36 +3,9 @@
 -- @module ccryptolib.fq
 --
 
-local unpack = unpack or table.unpack
+local util = require "ccryptolib.util"
 
---- Converts a little-endian array from one power-of-two base to another.
+local unpack = unpack or table.unpack
---
--- @tparam {number...} a The array to convert, in little-endian.
--- @tparam number base1 The base to convert from. Must be a power of 2.
--- @tparam number base2 The base to convert to. Must be a power of 2.
--- @treturn {number...}
---
-local function rebaseLE(a, base1, base2)
-    local out = {}
-    local outlen = 1
-    local acc = 0
-    local mul = 1
-    for i = 1, #a do
-        acc = acc + a[i] * mul
-        mul = mul * base1
-        while mul >= base2 do
-            local rem = acc % base2
-            acc = (acc - rem) / base2
-            mul = mul / base2
-            out[outlen] = rem
-            outlen = outlen + 1
-        end
-    end
-    if mul > 0 then
-        out[outlen] = acc
-    end
-    return out
-end
 
 --- The scalar field's order, q.
 local Q = {
@@ -53,7 +26,7 @@ local INVEXP_BITS = nil
 do
     local Q2 = {unpack(Q)}
     Q2[1] = Q2[1] - 2
-    INVEXP_BITS = rebaseLE(Q2, 2 ^ 24, 2)
+    INVEXP_BITS = util.rebaseLE(Q2, 2 ^ 24, 2)
 end
 
 --- The first Montgomery precomputed constant, -q⁻¹ mod 2²⁶⁴.
@@ -313,7 +286,7 @@ end
 -- @treturn {number...} 2⁻²⁶⁴ * a mod q as limbs in [0..2).
 --
 local function bits(a)
-    return rebaseLE(demontgomery(a), 2 ^ 24, 2)
+    return util.rebaseLE(demontgomery(a), 2 ^ 24, 2)
 end
 
 return {

util.lua

@@ -0,0 +1,32 @@
+local mod = {}
+
+--- Converts a little-endian array from one power-of-two base to another.
+--
+-- @tparam {number...} a The array to convert, in little-endian.
+-- @tparam number base1 The base to convert from. Must be a power of 2.
+-- @tparam number base2 The base to convert to. Must be a power of 2.
+-- @treturn {number...}
+--
+function mod.rebaseLE(a, base1, base2)
+    local out = {}
+    local outlen = 1
+    local acc = 0
+    local mul = 1
+    for i = 1, #a do
+        acc = acc + a[i] * mul
+        mul = mul * base1
+        while mul >= base2 do
+            local rem = acc % base2
+            acc = (acc - rem) / base2
+            mul = mul / base2
+            out[outlen] = rem
+            outlen = outlen + 1
+        end
+    end
+    if mul > 0 then
+        out[outlen] = acc
+    end
+    return out
+end
+
+return mod