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Improved calculation of CRC32 #46936

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Improved calculation of CRC32 #46936

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7 changes: 2 additions & 5 deletions DataFormats/Provenance/src/BranchID.cc
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Original file line number Diff line number Diff line change
@@ -1,13 +1,10 @@
#include "DataFormats/Provenance/interface/BranchID.h"
#include "FWCore/Utilities/interface/CRC32Calculator.h"
#include "FWCore/Utilities/interface/calculateCRC32.h"
#include <ostream>

namespace edm {

BranchID::value_type BranchID::toID(std::string const& branchName) {
cms::CRC32Calculator crc32(branchName);
return crc32.checksum();
}
BranchID::value_type BranchID::toID(std::string const& branchName) { return cms::calculateCRC32(branchName); }

std::ostream& operator<<(std::ostream& os, BranchID const& id) {
os << id.id();
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16 changes: 8 additions & 8 deletions EventFilter/L1TRawToDigi/src/AMC13Spec.cc
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Expand Up @@ -3,11 +3,11 @@

#include "FWCore/Framework/interface/Event.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/Utilities/interface/CRC32Calculator.h"
#include "FWCore/Utilities/interface/calculateCRC32.h"

#include "EventFilter/L1TRawToDigi/interface/AMC13Spec.h"

#define EDM_ML_DEBUG 1
//#define EDM_ML_DEBUG 1

namespace amc13 {
Header::Header(unsigned int namc, unsigned int orbit) {
Expand Down Expand Up @@ -38,8 +38,8 @@ namespace amc13 {
}

void Trailer::writeCRC(const uint64_t* start, uint64_t* end) {
std::string dstring(reinterpret_cast<const char*>(start), reinterpret_cast<const char*>(end) + 4);
auto crc = cms::CRC32Calculator(dstring).checksum();
std::string_view dstring(reinterpret_cast<const char*>(start), reinterpret_cast<const char*>(end) + 4);
auto crc = cms::calculateCRC32(dstring);

*end = ((*end) & ~(uint64_t(CRC_mask) << CRC_shift)) | (static_cast<uint64_t>(crc & CRC_mask) << CRC_shift);
}
Expand Down Expand Up @@ -128,8 +128,8 @@ namespace amc13 {

int crc = 0;
if (check_crc) {
std::string check(reinterpret_cast<const char*>(start), reinterpret_cast<const char*>(data) - 4);
crc = cms::CRC32Calculator(check).checksum();
std::string_view check(reinterpret_cast<const char*>(start), reinterpret_cast<const char*>(data) - 4);
crc = cms::calculateCRC32(check);

LogDebug("L1T") << "checking data checksum of " << std::hex << crc << std::dec;
}
Expand All @@ -156,8 +156,8 @@ namespace amc13 {
t = Trailer(data++);

if (check_crc) {
std::string check(reinterpret_cast<const char*>(start), reinterpret_cast<const char*>(data) - 4);
crc = cms::CRC32Calculator(check).checksum();
std::string_view check(reinterpret_cast<const char*>(start), reinterpret_cast<const char*>(data) - 4);
crc = cms::calculateCRC32(check);

LogDebug("L1T") << "checking data checksum of " << std::hex << crc << std::dec;
} else {
Expand Down
12 changes: 6 additions & 6 deletions EventFilter/L1TRawToDigi/src/AMCSpec.cc
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Original file line number Diff line number Diff line change
@@ -1,11 +1,11 @@
#include <iomanip>

#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/Utilities/interface/CRC32Calculator.h"
#include "FWCore/Utilities/interface/calculateCRC32.h"

#include "EventFilter/L1TRawToDigi/interface/AMCSpec.h"

#define EDM_ML_DEBUG 1
//#define EDM_ML_DEBUG 1

namespace amc {
BlockHeader::BlockHeader(unsigned int amc_no, unsigned int board_id, unsigned int size, unsigned int block) {
Expand Down Expand Up @@ -92,8 +92,8 @@ namespace amc {
}

void Trailer::writeCRC(const uint64_t *start, uint64_t *end) {
std::string dstring(reinterpret_cast<const char *>(start), reinterpret_cast<const char *>(end) + 4);
auto crc = cms::CRC32Calculator(dstring).checksum();
std::string_view dstring(reinterpret_cast<const char *>(start), reinterpret_cast<const char *>(end) + 4);
auto crc = cms::calculateCRC32(dstring);

*end = ((*end) & ~(uint64_t(CRC_mask) << CRC_shift)) | (static_cast<uint64_t>(crc & CRC_mask) << CRC_shift);
}
Expand Down Expand Up @@ -133,8 +133,8 @@ namespace amc {
header_ = Header(payload_.data());
trailer_ = Trailer(&payload_.back());

std::string check(reinterpret_cast<const char *>(payload_.data()), payload_.size() * 8 - 4);
auto crc = cms::CRC32Calculator(check).checksum();
std::string_view check(reinterpret_cast<const char *>(payload_.data()), payload_.size() * 8 - 4);
auto crc = cms::calculateCRC32(check);

trailer_.check(crc, lv1, header_.getSize(), mtf7_mode);
}
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16 changes: 4 additions & 12 deletions FWCore/Utilities/interface/CRC32Calculator.h → FWCore/Utilities/interface/calculateCRC32.h
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
#ifndef FWCore_Utilities_CRC32Calculator_h
#define FWCore_Utilities_CRC32Calculator_h
#ifndef FWCore_Utilities_calculateCRC32_h
#define FWCore_Utilities_calculateCRC32_h

/*
Code to calculate a CRC32 checksum on a string. This code is based
Expand Down Expand Up @@ -55,18 +55,10 @@ from the original code follow below to attribute the source.

#include <cstdint>

#include <string>
#include <string_view>

namespace cms {

class CRC32Calculator {
public:
CRC32Calculator(std::string const& message);

std::uint32_t checksum() { return checksum_; }

private:
std::uint32_t checksum_;
};
std::uint32_t calculateCRC32(std::string_view message);
} // namespace cms
#endif
21 changes: 9 additions & 12 deletions FWCore/Utilities/src/CRC32Calculator.cc → FWCore/Utilities/src/calculateCRC32.cc
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@@ -1,14 +1,14 @@

#include "FWCore/Utilities/interface/CRC32Calculator.h"
#include "FWCore/Utilities/interface/calculateCRC32.h"

namespace cms {

namespace {

const std::uint32_t CRC32_XINIT = 0xFFFFFFFFL;
const std::uint32_t CRC32_XOROT = 0xFFFFFFFFL;
constexpr std::uint32_t CRC32_XINIT = 0xFFFFFFFFL;
constexpr std::uint32_t CRC32_XOROT = 0xFFFFFFFFL;

const std::uint32_t crctable[256] = {
constexpr std::uint32_t crctable[256] = {
0x00000000L, 0x77073096L, 0xEE0E612CL, 0x990951BAL, 0x076DC419L, 0x706AF48FL, 0xE963A535L, 0x9E6495A3L,
0x0EDB8832L, 0x79DCB8A4L, 0xE0D5E91EL, 0x97D2D988L, 0x09B64C2BL, 0x7EB17CBDL, 0xE7B82D07L, 0x90BF1D91L,
0x1DB71064L, 0x6AB020F2L, 0xF3B97148L, 0x84BE41DEL, 0x1ADAD47DL, 0x6DDDE4EBL, 0xF4D4B551L, 0x83D385C7L,
Expand Down Expand Up @@ -43,19 +43,16 @@ namespace cms {
0xB3667A2EL, 0xC4614AB8L, 0x5D681B02L, 0x2A6F2B94L, 0xB40BBE37L, 0xC30C8EA1L, 0x5A05DF1BL, 0x2D02EF8DL};
} // namespace

CRC32Calculator::CRC32Calculator(std::string const& message) {
std::uint32_t calculateCRC32(std::string_view message) {
/* initialize value */
checksum_ = CRC32_XINIT;
uint32_t checksum = CRC32_XINIT;

/* process each byte prior to checksum field */
auto length = message.length();
char const* p = message.data();
for (size_t j = 0; j < length; j++) {
unsigned char uc = *p++;
checksum_ = cms::crctable[(checksum_ ^ uc) & 0xFFL] ^ (checksum_ >> 8);
for (auto uc : message) {
checksum = cms::crctable[(checksum ^ uc) & 0xFFL] ^ (checksum >> 8);
}

/* return XOR out value */
checksum_ = checksum_ ^ CRC32_XOROT;
return checksum ^ CRC32_XOROT;
}
} // namespace cms
16 changes: 0 additions & 16 deletions FWCore/Utilities/test/test_catch2_CRC32Calculator.cc
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This file was deleted.

16 changes: 16 additions & 0 deletions FWCore/Utilities/test/test_catch2_calculateCRC32.cc
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Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
#include "catch.hpp"
#include "FWCore/Utilities/interface/calculateCRC32.h"

TEST_CASE("test cms::calculateCRC32", "[calculateCRC32]") {
SECTION("known") {
auto crc32 = cms::calculateCRC32("type_label_instance_process");

// This known result was calculated using python as a cross check
unsigned int knownResult = 1215348599;
REQUIRE(crc32 == knownResult);
}
SECTION("empty") {
auto emptyString_crc32 = cms::calculateCRC32("");
REQUIRE(emptyString_crc32 == 0);
}
}