llvm/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 #include <stdlib.h>
  17
  18 using namespace llvm;
  19
  20 namespace {
  21
  22 TEST(CRCTest, CRC32) {
  23   EXPECT_EQ(0x414FA339U, llvm::crc32(arrayRefFromStringRef(
  24                              "The quick brown fox jumps over the lazy dog")));
  25
  26   // CRC-32/ISO-HDLC test vector
  27   // http://reveng.sourceforge.net/crc-catalogue/17plus.htm#crc.cat.crc-32c
  28   EXPECT_EQ(0xCBF43926U, llvm::crc32(arrayRefFromStringRef("123456789")));
  29
  30   // Check the CRC-32 of each byte value, exercising all of CRCTable.
  31   for (int i = 0; i < 256; i++) {
  32     // Compute CRCTable[i] using Hacker's Delight (2nd ed.) Figure 14-7.
  33     uint32_t crc = i;
  34     for (int j = 7; j >= 0; j--) {
  35       uint32_t mask = -(crc & 1);
  36       crc = (crc >> 1) ^ (0xEDB88320 & mask);
  37     }
  38
  39     // CRCTable[i] is the CRC-32 of i without the initial and final bit flips.
  40     uint8_t byte = i;
  41     EXPECT_EQ(crc, ~llvm::crc32(0xFFFFFFFFU, byte));
  42   }
  43
  44   EXPECT_EQ(0x00000000U, llvm::crc32(arrayRefFromStringRef("")));
  45 }
  46
  47 #if (SIZE_MAX > UINT32_MAX) && defined(EXPENSIVE_CHECKS)
  48 TEST(CRCTest, LargeCRC32) {
  49   // Check that crc32 can handle inputs with sizes larger than 32 bits.
  50   size_t TestSize = (size_t)UINT32_MAX + 42;
  51   uint8_t *TestData = (uint8_t*)calloc(TestSize, 1);
  52   if (!TestData)
  53     GTEST_SKIP();
  54
  55   // Test expectation generated with:
  56   // $ truncate --size=`echo 2^32-1+42 | bc` /tmp/foo
  57   // $ crc32 /tmp/foo
  58   EXPECT_EQ(0xE46F28FBU, llvm::crc32(ArrayRef(TestData, TestSize)));
  59
  60   free(TestData);
  61 }
  62 #endif
  63
  64 } // end anonymous namespace