llvm/Support/DJB.h

0001 //===-- llvm/Support/DJB.h ---DJB Hash --------------------------*- C++ -*-===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008 //
0009 // This file contains support for the DJ Bernstein hash function.
0010 //
0011 //===----------------------------------------------------------------------===//
0012
0013 #ifndef LLVM_SUPPORT_DJB_H
0014 #define LLVM_SUPPORT_DJB_H
0015
0016 #include "llvm/ADT/StringRef.h"
0017
0018 namespace llvm {
0019
0020 /// The Bernstein hash function used by the DWARF accelerator tables.
0021 inline uint32_t djbHash(StringRef Buffer, uint32_t H = 5381) {
0022   for (unsigned char C : Buffer.bytes())
0023     H = (H << 5) + H + C;
0024   return H;
0025 }
0026
0027 /// Computes the Bernstein hash after folding the input according to the Dwarf 5
0028 /// standard case folding rules.
0029 uint32_t caseFoldingDjbHash(StringRef Buffer, uint32_t H = 5381);
0030 } // namespace llvm
0031
0032 #endif // LLVM_SUPPORT_DJB_H