unittests/Support/CRCTest.cpp

   1 //===- llvm/unittest/Support/CRCTest.cpp - CRC tests ----------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements unit tests for CRC calculation functions.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/Support/CRC.h"
  14 #include "llvm/ADT/StringExtras.h"
  15 #include "gtest/gtest.h"
  16
  17 using namespace llvm;
  18
  19 namespace {
  20
  21 TEST(CRCTest, CRC32) {
  22   EXPECT_EQ(0x414FA339U, llvm::crc32(arrayRefFromStringRef(
  23                              "The quick brown fox jumps over the lazy dog")));
  24
  25   // CRC-32/ISO-HDLC test vector
  26   // http://reveng.sourceforge.net/crc-catalogue/17plus.htm#crc.cat.crc-32c
  27   EXPECT_EQ(0xCBF43926U, llvm::crc32(arrayRefFromStringRef("123456789")));
  28
  29   // Check the CRC-32 of each byte value, exercising all of CRCTable.
  30   for (int i = 0; i < 256; i++) {
  31     // Compute CRCTable[i] using Hacker's Delight (2nd ed.) Figure 14-7.
  32     uint32_t crc = i;
  33     for (int j = 7; j >= 0; j--) {
  34       uint32_t mask = -(crc & 1);
  35       crc = (crc >> 1) ^ (0xEDB88320 & mask);
  36     }
  37
  38     // CRCTable[i] is the CRC-32 of i without the initial and final bit flips.
  39     uint8_t byte = i;
  40     EXPECT_EQ(crc, ~llvm::crc32(0xFFFFFFFFU, byte));
  41   }
  42 }
  43
  44 } // end anonymous namespace