Data commit

Task/CRC-32/Nim/crc-32.nim

@@ -0,0 +1,23 @@
+import strutils
+
+type TCrc32* = uint32
+const InitCrc32* = TCrc32(0xffffffff)
+
+proc createCrcTable(): array[0..255, TCrc32] =
+  for i in 0..255:
+    var rem = TCrc32(i)
+    for j in 0..7:
+      if (rem and 1) > 0: rem = (rem shr 1) xor TCrc32(0xedb88320)
+      else: rem = rem shr 1
+    result[i] = rem
+
+# Table created at compile time
+const crc32table = createCrcTable()
+
+proc crc32(s: string): TCrc32 =
+  result = InitCrc32
+  for c in s:
+    result = (result shr 8) xor crc32table[(result and 0xff) xor byte(c)]
+  result = not result
+
+echo crc32("The quick brown fox jumps over the lazy dog").int64.toHex(8)