From b41debf94877eab05aeae0bff5cc20b0dc93ac1c Mon Sep 17 00:00:00 2001
From: Infendro <infendro@noreply.infendro.com>
Date: Thu, 4 Dec 2025 19:13:43 +0100
Subject: [PATCH] refactor MD5

---
 .../kotlin/com/infendro/hash/md/MD5.kt        | 34 ++++++++++---------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/src/commonMain/kotlin/com/infendro/hash/md/MD5.kt b/src/commonMain/kotlin/com/infendro/hash/md/MD5.kt
index 41dfa9c..a34127c 100644
--- a/src/commonMain/kotlin/com/infendro/hash/md/MD5.kt
+++ b/src/commonMain/kotlin/com/infendro/hash/md/MD5.kt
@@ -51,36 +51,38 @@ object MD5 : HashFunction() {
         value: UByteArray,
     ): UByteArray {
         val h = initial.copyOf()
-        val l = value.size.toULong() * 8UL
 
-        // padding
-        val paddedValue = buildList {
+        val blocks = pad(value)
+            .chunked(64) { it.toUByteArray() }
+        for (block in blocks) {
+            process(h, block)
+        }
+
+        return h.toUByteArray(LITTLE_ENDIAN)
+    }
+
+    private fun pad(
+        value: UByteArray,
+    ): UByteArray {
+        val l = value.size.toULong() * 8UL
+        return buildList {
             addAll(value)
             add(0x80U)
             while (size % 64 != 56) {
                 add(0x00U)
             }
             addAll(l.toUByteArray(LITTLE_ENDIAN))
-        }
-
-        // process
-        val blocks = paddedValue
-            .chunked(64) { it.toUByteArray() }
-        for (block in blocks) {
-            val w = block.toUIntArray(LITTLE_ENDIAN)
-            process(h, w)
-        }
-
-        return h.toUByteArray(LITTLE_ENDIAN)
+        }.toUByteArray()
     }
 
     private fun process(
         h: UIntArray,
-        w: UIntArray,
+        block: UByteArray,
     ) {
+        val w = block.toUIntArray(LITTLE_ENDIAN)
         val v = h.copyOf()
 
-        for (i in 0..<64) {
+        repeat(64) { i ->
             var f = when (i) {
                 in 0..15 -> (v[1] and v[2]) or (v[1].inv() and v[3])
                 in 16..31 -> (v[3] and v[1]) or (v[3].inv() and v[2])