47 lines
1.9 KiB
C++
47 lines
1.9 KiB
C++
// Copyright (c) 1999 Microsoft Corporation. All rights reserved.
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//
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// Misc tiny helper functions.
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//
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#pragma once
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// Releases a COM pointer and then sets it to NULL. No effect if pointer already was NULL.
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template<class T>
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void SafeRelease(T *&t) { if (t) t->Release(); t = NULL; }
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// Returns the number of elements in an array determined at compile time.
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// Note: Only works for variables actually declared as arrays. Don't try this with a pointer to an array. There's no way to determine the size at that point.
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#define ARRAY_SIZE(array) (sizeof(array) / sizeof(*(array)))
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// Zeros memory of struct pointed to.
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// Note: This is statically typed. Don't use it with a pointer to void, pointer to an array, or a pointer to a base class because the size will be too small.
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template<class T> void Zero(T *pT) { ZeroMemory(pT, sizeof(*pT)); }
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// Zeros memory of the struct pointed to and sets its dwSize field.
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template<class T> void ZeroAndSize(T *pT) { Zero(pT); pT->dwSize = sizeof(*pT); }
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// Copies one dwSize struct to another dwSize struct without reading/writing beyond either struct
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template<class T> void CopySizedStruct(T *ptDest, const T *ptSrc)
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{
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assert(ptDest && ptSrc);
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DWORD dwDestSize = ptDest->dwSize;
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memcpy(ptDest, ptSrc, std::_cpp_min(ptDest->dwSize, ptSrc->dwSize));
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ptDest->dwSize = dwDestSize;
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}
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// Copy pwszSource to pwszDest where pwszDest is a buffer of size uiBufferSize.
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// Returns S_OK if successful or DMUS_S_STRING_TRUNCATED if the string had to be truncated.
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// Faster then wcsncpy for short strings because the entire buffer isn't padded with nulls.
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inline HRESULT wcsTruncatedCopy(WCHAR *pwszDest, const WCHAR *pwszSource, UINT uiBufferSize)
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{
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for (UINT i = 0; i < uiBufferSize; ++i)
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{
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if (!(pwszDest[i] = pwszSource[i])) // assign and check for null
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return S_OK; // the whole string copied
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}
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// string needs to be truncated
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pwszDest[uiBufferSize - 1] = L'\0';
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return DMUS_S_STRING_TRUNCATED;
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}
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