From b1bc89ecdd570fe01225ad0487d503186b60aea3 Mon Sep 17 00:00:00 2001
From: Timofey Solomko <tsolomko@gmail.com>
Date: Sat, 29 Jul 2017 23:24:54 +0300
Subject: [PATCH] Add update-crc version for crc32 function with Data argument

---
 Sources/CheckSums.swift | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Sources/CheckSums.swift b/Sources/CheckSums.swift
index 5384eebb..8080b66d 100644
--- a/Sources/CheckSums.swift
+++ b/Sources/CheckSums.swift
@@ -18,8 +18,8 @@ struct CheckSums {
         return ~crc
     }
 
-    static func crc32(_ data: Data) -> UInt32 {
-        var crc: UInt32 = ~0
+    static func crc32(_ data: Data, prevValue: UInt32 = 0) -> UInt32 {
+        var crc = ~prevValue
         for i in 0..<data.count {
             let index = (crc & 0xFF) ^ (UInt32(data[i]))
             crc = CheckSums.crc32table[Int(index)] ^ (crc >> 8)