diff options
Diffstat (limited to 'src/corelib')
-rw-r--r-- | src/corelib/tools/qbytearray.cpp | 37 |
1 files changed, 19 insertions, 18 deletions
diff --git a/src/corelib/tools/qbytearray.cpp b/src/corelib/tools/qbytearray.cpp index 90069b112d..559ba193d1 100644 --- a/src/corelib/tools/qbytearray.cpp +++ b/src/corelib/tools/qbytearray.cpp @@ -69,24 +69,25 @@ int qFindByteArray( int qAllocMore(int alloc, int extra) { - if (alloc == 0 && extra == 0) - return 0; - const int page = 1 << 12; - int nalloc; - alloc += extra; - if (alloc < 1<<6) { - nalloc = (1<<3) + ((alloc >>3) << 3); - } else { - // don't do anything if the loop will overflow signed int. - if (alloc >= INT_MAX/2) - return INT_MAX; - nalloc = (alloc < page) ? 1 << 3 : page; - while (nalloc < alloc) { - if (nalloc <= 0) - return INT_MAX; - nalloc *= 2; - } - } + Q_ASSERT(alloc >= 0 && extra >= 0); + Q_ASSERT(alloc < (1 << 30) - extra); + + unsigned nalloc = alloc + extra; + + // Round up to next power of 2 + + // Assuming container is growing, always overshoot + //--nalloc; + + nalloc |= nalloc >> 1; + nalloc |= nalloc >> 2; + nalloc |= nalloc >> 4; + nalloc |= nalloc >> 8; + nalloc |= nalloc >> 16; + ++nalloc; + + Q_ASSERT(nalloc > unsigned(alloc + extra)); + return nalloc - extra; } |