diff options
| author | Edward Welbourne <edward.welbourne@qt.io> | 2019-05-29 12:22:09 +0200 |
|---|---|---|
| committer | Edward Welbourne <edward.welbourne@qt.io> | 2019-05-29 13:29:12 +0200 |
| commit | c7e6407f84eb51db64871a001dc44010d822061c (patch) | |
| tree | ce4cc09883bc3330a3ba46bce8aa5ada2d0dcfbe /src/corelib/tools/qbytearray.cpp | |
| parent | a3b931e7c4a5702da5fd99df0746f9ff511b7fdc (diff) | |
Move container block-size calculations to qarraydata.cpp
These were in qbytearray.cpp, which doesn't use them, is big and I
intend to move it to a different directory than the header,
qtools_p.h, that declares them. So move them to a small file that does
use them.
Change-Id: I5a4684f8c7628e617546019cc3f01d92d829f085
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Diffstat (limited to 'src/corelib/tools/qbytearray.cpp')
| -rw-r--r-- | src/corelib/tools/qbytearray.cpp | 102 |
1 files changed, 1 insertions, 101 deletions
diff --git a/src/corelib/tools/qbytearray.cpp b/src/corelib/tools/qbytearray.cpp index 9816b5cb320..5c2af7e058b 100644 --- a/src/corelib/tools/qbytearray.cpp +++ b/src/corelib/tools/qbytearray.cpp @@ -1,6 +1,6 @@ /**************************************************************************** ** -** Copyright (C) 2016 The Qt Company Ltd. +** Copyright (C) 2019 The Qt Company Ltd. ** Copyright (C) 2016 Intel Corporation. ** Contact: https://www.qt.io/licensing/ ** @@ -130,106 +130,6 @@ int qFindByteArray( const char *haystack0, int haystackLen, int from, const char *needle0, int needleLen); -/* - * This pair of functions is declared in qtools_p.h and is used by the Qt - * containers to allocate memory and grow the memory block during append - * operations. - * - * They take size_t parameters and return size_t so they will change sizes - * according to the pointer width. However, knowing Qt containers store the - * container size and element indexes in ints, these functions never return a - * size larger than INT_MAX. This is done by casting the element count and - * memory block size to int in several comparisons: the check for negative is - * very fast on most platforms as the code only needs to check the sign bit. - * - * These functions return SIZE_MAX on overflow, which can be passed to malloc() - * and will surely cause a NULL return (there's no way you can allocate a - * memory block the size of your entire VM space). - */ - -/*! - \internal - \since 5.7 - - Returns the memory block size for a container containing \a elementCount - elements, each of \a elementSize bytes, plus a header of \a headerSize - bytes. That is, this function returns \c - {elementCount * elementSize + headerSize} - - but unlike the simple calculation, it checks for overflows during the - multiplication and the addition. - - Both \a elementCount and \a headerSize can be zero, but \a elementSize - cannot. - - This function returns SIZE_MAX (~0) on overflow or if the memory block size - would not fit an int. -*/ -size_t qCalculateBlockSize(size_t elementCount, size_t elementSize, size_t headerSize) noexcept -{ - unsigned count = unsigned(elementCount); - unsigned size = unsigned(elementSize); - unsigned header = unsigned(headerSize); - Q_ASSERT(elementSize); - Q_ASSERT(size == elementSize); - Q_ASSERT(header == headerSize); - - if (Q_UNLIKELY(count != elementCount)) - return std::numeric_limits<size_t>::max(); - - unsigned bytes; - if (Q_UNLIKELY(mul_overflow(size, count, &bytes)) || - Q_UNLIKELY(add_overflow(bytes, header, &bytes))) - return std::numeric_limits<size_t>::max(); - if (Q_UNLIKELY(int(bytes) < 0)) // catches bytes >= 2GB - return std::numeric_limits<size_t>::max(); - - return bytes; -} - -/*! - \internal - \since 5.7 - - Returns the memory block size and the number of elements that will fit in - that block for a container containing \a elementCount elements, each of \a - elementSize bytes, plus a header of \a headerSize bytes. This function - assumes the container will grow and pre-allocates a growth factor. - - Both \a elementCount and \a headerSize can be zero, but \a elementSize - cannot. - - This function returns SIZE_MAX (~0) on overflow or if the memory block size - would not fit an int. - - \note The memory block may contain up to \a elementSize - 1 bytes more than - needed. -*/ -CalculateGrowingBlockSizeResult -qCalculateGrowingBlockSize(size_t elementCount, size_t elementSize, size_t headerSize) noexcept -{ - CalculateGrowingBlockSizeResult result = { - std::numeric_limits<size_t>::max(),std::numeric_limits<size_t>::max() - }; - - unsigned bytes = unsigned(qCalculateBlockSize(elementCount, elementSize, headerSize)); - if (int(bytes) < 0) // catches std::numeric_limits<size_t>::max() - return result; - - unsigned morebytes = qNextPowerOfTwo(bytes); - if (Q_UNLIKELY(int(morebytes) < 0)) { - // catches morebytes == 2GB - // grow by half the difference between bytes and morebytes - bytes += (morebytes - bytes) / 2; - } else { - bytes = morebytes; - } - - result.elementCount = (bytes - unsigned(headerSize)) / unsigned(elementSize); - result.size = bytes; - return result; -} - /***************************************************************************** Safe and portable C string functions; extensions to standard string.h *****************************************************************************/ |