refactor SHA1 and SHA2

src/commonMain/kotlin/com/infendro/hash/sha1/SHA1.kt

@@ -21,42 +21,44 @@ object SHA1 : 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()
+    }
+
+    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())
-        }
-
-        // process
-        val blocks = paddedValue
-            .chunked(64) { it.toUByteArray() }
-        for (block in blocks) {
-            val w = buildList {
-                addAll(block.toUIntArray())
-                for (i in 16..<80) {
-                    val word = (get(i - 3) xor get(i - 8) xor get(i - 14) xor get(i - 16)).rotateLeft(1)
-                    add(word)
-                }
-            }.toUIntArray()
-            process(h, w)
-        }
-
-        return h.toUByteArray()
+        }.toUByteArray()
     }
 
     private fun process(
         h: UIntArray,
-        w: UIntArray,
+        block: UByteArray,
     ) {
+        val w = buildList {
+            addAll(block.toUIntArray())
+            for (i in 16..79) {
+                val word = (get(i - 3) xor get(i - 8) xor get(i - 14) xor get(i - 16)).rotateLeft(1)
+                add(word)
+            }
+        }.toUIntArray()
         val v = h.copyOf()
 
-        for (i in 0..<80) {
+        repeat(80) { i ->
             val f = when (i) {
                 in 0..<20 -> (v[1] and v[2]) or (v[1].inv() and v[3])
                 in 20..<40 -> v[1] xor v[2] xor v[3]