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Diffstat (limited to 'Source/Internal/checksum.cpp')
-rw-r--r-- | Source/Internal/checksum.cpp | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/Source/Internal/checksum.cpp b/Source/Internal/checksum.cpp new file mode 100644 index 00000000..2e74a378 --- /dev/null +++ b/Source/Internal/checksum.cpp @@ -0,0 +1,118 @@ +//----------------------------------------------------------------------------- +// Name: checksum.cpp +// Developer: Wolfire Games LLC +// Description: +// License: Read below +//----------------------------------------------------------------------------- +// +// Copyright 2022 Wolfire Games LLC +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// +//----------------------------------------------------------------------------- +#include "checksum.h" + +#include <Internal/error.h> +#include <Internal/profiler.h> +#include <Internal/common.h> + +#include <Compat/fileio.h> +#include <Memory/allocation.h> + +#include <stdio.h> +#include <string> + +using std::string; +using std::endl; + +class ProfilerContext; + +//TODO: Maybe modifying this to be Adler32 would be a little better CRC32 even more so, lowering the risk for collisions for small changes. +//(If you make a 'b' a 'c' and another 'b' an 'a' in a file, this function will give you the same checksum value, i would consider this a possible common change) +unsigned short Checksum(const string& abs_path) { + PROFILER_ZONE(g_profiler_ctx, "Checksum"); + unsigned short sum = 0; + + FILE * pFile; + long lSize; + unsigned char * buffer; + size_t result; + + pFile = my_fopen ( abs_path.c_str() , "rb" ); + +#ifndef NO_ERR + const int kBufSize = 512; + char error_msg[kBufSize]; + while (pFile==NULL) { + FormatString(error_msg, kBufSize, "Could not open file: %s. Retry?", abs_path.c_str()); + DisplayError("Error", error_msg, _ok_cancel); + pFile = my_fopen ( abs_path.c_str() , "rb" ); + } +#endif + + if( pFile ) { + // obtain file size: + fseek (pFile , 0 , SEEK_END); + lSize = ftell (pFile); + rewind (pFile); + + // allocate memory to contain the whole file: + buffer = (unsigned char*) alloc.stack.Alloc(sizeof(char)*lSize); + + if( buffer ) { + #ifndef NO_ERR + if (buffer == NULL) { + FormatString(error_msg, kBufSize, "Could not allocate memory to checksum: %s.", abs_path.c_str()); + FatalError("Error", error_msg); + } + #endif + + // copy the file into the buffer: + result = fread (buffer,1,lSize,pFile); + #ifndef NO_ERR + if (result != (size_t)lSize) { + FormatString(error_msg, kBufSize, "Could not read data from file: %s.", abs_path.c_str()); + FatalError("Error", error_msg); + } + #endif + + { + PROFILER_ZONE(g_profiler_ctx, "Actual summation"); + size_t short_count = lSize/2; + for (size_t i = 0; i < short_count; i++){ + // Might have trouble on wrong-endian machines, but those should probably just have different checksums built in anyhow, to keep this fast + sum += ((uint16_t*)buffer)[i]; + } + } + alloc.stack.Free(buffer); + } else { + LOGE << "Failed to allocate data from stack allocator, size: " << lSize << endl; + } + // terminate + fclose (pFile); + } else { + LOGE << "Failed to open file " << abs_path << endl; + } + return sum; +} + +// From http://www.cse.yorku.ca/~oz/hash.html +unsigned long djb2_string_hash(const char *cstr){ + unsigned long hash = 5381; + int c; + + while ((c = *cstr++)) + hash = ((hash << 5) + hash) + c; /* hash * 33 + c */ + + return hash; +} |