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author | Thiago Macieira <thiago.macieira@nokia.com> | 2009-10-22 16:57:53 (GMT) |
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committer | Thiago Macieira <thiago.macieira@nokia.com> | 2009-10-28 14:27:36 (GMT) |
commit | 3f0b969772cf3056ed54349bfe6837d9de2995ea (patch) | |
tree | 95b88cb55e66b3f4b2933e41939fb3ec1e8a46ee /src/corelib/global | |
parent | 0283ca4cf2ad1c9e642b24f8376aa7179fa54599 (diff) | |
download | Qt-3f0b969772cf3056ed54349bfe6837d9de2995ea.zip Qt-3f0b969772cf3056ed54349bfe6837d9de2995ea.tar.gz Qt-3f0b969772cf3056ed54349bfe6837d9de2995ea.tar.bz2 |
Add the aligned versions of qMalloc/qRealloc/qFree
Diffstat (limited to 'src/corelib/global')
-rw-r--r-- | src/corelib/global/qglobal.h | 3 | ||||
-rw-r--r-- | src/corelib/global/qmalloc.cpp | 100 |
2 files changed, 103 insertions, 0 deletions
diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h index 5ee1815..cbb8fda 100644 --- a/src/corelib/global/qglobal.h +++ b/src/corelib/global/qglobal.h @@ -2065,6 +2065,9 @@ Q_DECLARE_TYPEINFO(long double, Q_PRIMITIVE_TYPE); Q_CORE_EXPORT void *qMalloc(size_t size); Q_CORE_EXPORT void qFree(void *ptr); Q_CORE_EXPORT void *qRealloc(void *ptr, size_t size); +Q_CORE_EXPORT void *qMallocAligned(size_t size, size_t alignment); +Q_CORE_EXPORT void *qReallocAligned(void *ptr, size_t size, size_t oldsize, size_t alignment); +Q_CORE_EXPORT void qFreeAligned(void *ptr); Q_CORE_EXPORT void *qMemCopy(void *dest, const void *src, size_t n); Q_CORE_EXPORT void *qMemSet(void *dest, int c, size_t n); diff --git a/src/corelib/global/qmalloc.cpp b/src/corelib/global/qmalloc.cpp index a9f103c..db5e519 100644 --- a/src/corelib/global/qmalloc.cpp +++ b/src/corelib/global/qmalloc.cpp @@ -42,6 +42,7 @@ #include "qplatformdefs.h" #include <stdlib.h> +#include <malloc.h> /* Define the container allocation functions in a separate file, so that our @@ -65,4 +66,103 @@ void *qRealloc(void *ptr, size_t size) return ::realloc(ptr, size); } +#if ((defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L) || (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 600)) +# define HAVE_POSIX_MEMALIGN +#endif + +void *qMallocAligned(size_t size, size_t alignment) +{ +#if defined(Q_OS_WIN) + return _aligned_malloc(size, alignment); +#elif defined(HAVE_POSIX_MEMALIGN) + if (alignment <= sizeof(void*)) + return qMalloc(size); + + // we have posix_memalign + void *ptr = 0; + if (posix_memalign(&ptr, alignment, size) == 0) + return ptr; + return 0; +#else + return qReallocAligned(0, size, 0, alignment); +#endif +} + +void *qReallocAligned(void *oldptr, size_t newsize, size_t oldsize, size_t alignment) +{ +#if defined(Q_OS_WIN) + Q_UNUSED(oldsize); + return _aligned_realloc(oldptr, newsize, alignment); +#elif defined(HAVE_POSIX_MEMALIGN) + if (alignment <= sizeof(void*)) + return qRealloc(oldptr, newsize); + + void *newptr = qMallocAligned(newsize, alignment); + if (!newptr) + return 0; + qMemCopy(newptr, oldptr, qMin(oldsize, newsize)); + qFree(oldptr); + return newptr; +#else + // fake an aligned allocation + Q_UNUSED(oldsize); + + void *actualptr = oldptr ? static_cast<void **>(oldptr)[-1] : 0; + if (alignment <= sizeof(void*)) { + // special, fast case + void **newptr = static_cast<void **>(qRealloc(actualptr, newsize + sizeof(void*))); + if (!newptr) + return 0; + if (newptr == actualptr) { + // realloc succeeded without reallocating + return oldptr; + } + + *newptr = newptr; + return newptr + 1; + } + + union { void *ptr; void **pptr; quintptr n; } real, faked; + + // qMalloc returns pointers aligned at least at sizeof(size_t) boundaries + // but usually more (8- or 16-byte boundaries). + // So we overallocate by alignment-sizeof(size_t) bytes, so we're guaranteed to find a + // somewhere within the first alignment-sizeof(size_t) that is properly aligned. + + // However, we need to store the actual pointer, so we need to allocate actually size + + // alignment anyway. + + real.ptr = qRealloc(actualptr, newsize + alignment); + if (!real.ptr) + return 0; + + faked.n = real.n + alignment; + faked.n &= ~(alignment - 1); + + // now save the value of the real pointer at faked-sizeof(void*) + // by construction, alignment > sizeof(void*) and is a power of 2, so + // faked-sizeof(void*) is properly aligned for a pointer + faked.pptr[-1] = real.ptr; + + // and save the actual size just before the pointer + //reinterpret_cast<size_t *>(faked.pptr - 1)[-1] = size; + + return faked.ptr; +#endif +} + +void qFreeAligned(void *ptr) +{ +#if defined(Q_OS_WIN) + _aligned_free(ptr); +#elif defined(HAVE_POSIX_MEMALIGN) + ::free(ptr); +#else + if (!ptr) + return; + void **ptr2 = static_cast<void **>(ptr); + free(ptr2[-1]); +#endif +} + QT_END_NAMESPACE |