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04e0dc4a7a
Imported from https://www.nuget.org/packages/Microsoft.Windows.SDK.CRTSource/10.0.22621.3 License: MIT
80 lines
2.3 KiB
C++
80 lines
2.3 KiB
C++
//
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// lfind.cpp
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//
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//
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// Defines _lfind(), which performs a linear search over an array.
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//
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#include <corecrt_internal.h>
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#include <search.h>
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#ifdef _M_CEE
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#define __fileDECL __clrcall
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#else
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#define __fileDECL __cdecl
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#endif
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#ifdef __USE_CONTEXT
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#define __COMPARE(context, p1, p2) (*compare)(context, p1, p2)
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#else
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#define __COMPARE(context, p1, p2) (*compare)(p1, p2)
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#endif
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// Performs a linear search over the array, looking for the value 'key' in an
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// array of 'num' elements of 'width' bytes in size. Returns a pointer to the
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// matching element if found. Otherwise, returns nullptr.
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//
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// Parameters:
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// * key: The key for which to search
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// * base: A pointer to the initial element of the array to be searched
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// * num: The number of elements in the array.
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// * width: The size of each element, in bytes.
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// * comp: Pointer to a function returning analog of strcmp for strings, but
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// supplied by the caller for comparing the array elements. It
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// accepts two pointers to elements; returns negative if 1 < 2;
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// zero if 1 == 2, and positive if 1 > 2.
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#ifndef _M_CEE
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extern "C"
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#endif
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#ifdef __USE_CONTEXT
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void* __fileDECL _lfind_s(
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void const* const key,
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void const* const base,
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unsigned int* const num,
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size_t const width,
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int (__fileDECL* const compare)(void*, void const*, void const*),
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void* const context
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)
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#else // __USE_CONTEXT
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void* __fileDECL _lfind(
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void const* const key,
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void const* const base,
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unsigned int* const num,
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unsigned int const width,
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int (__fileDECL* const compare)(void const*, void const*)
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)
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#endif // __USE_CONTEXT
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{
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_VALIDATE_RETURN(key != nullptr, EINVAL, nullptr);
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_VALIDATE_RETURN(num != nullptr, EINVAL, nullptr);
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_VALIDATE_RETURN(base != nullptr || *num == 0, EINVAL, nullptr);
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_VALIDATE_RETURN(width > 0, EINVAL, nullptr);
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_VALIDATE_RETURN(compare != nullptr, EINVAL, nullptr);
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char const* const first = static_cast<char const*>(base);
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char const* const last = first + *num * width;
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for (char const* p = first; p != last; p += width)
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{
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if (__COMPARE(context, key, const_cast<char*>(p)) == 0)
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{
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return const_cast<char*>(p);
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}
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}
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return nullptr;
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}
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#undef __COMPARE
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