| /************************************************************************** |
| * |
| * tmpbuf.cpp - definition of the __rw_tmpbuf() helper |
| * |
| * $Id$ |
| * |
| *************************************************************************** |
| * |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed |
| * with this work for additional information regarding copyright |
| * ownership. The ASF licenses this file to you under the Apache |
| * License, Version 2.0 (the "License"); you may not use this file |
| * except in compliance with the License. You may obtain a copy of |
| * the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or |
| * implied. See the License for the specific language governing |
| * permissions and limitations under the License. |
| * |
| * Copyright 2005-2006 Rogue Wave Software. |
| * |
| **************************************************************************/ |
| |
| #define _RWSTD_LIB_SRC |
| |
| #include "podarray.h" // for __rw_aligned_buffer |
| #include <rw/_allocator.h> // for __rw_allocate(), ... |
| #include <rw/_mutex.h> // for _RWSTD_THREAD_XXX() |
| |
| #include <stddef.h> // for size_t |
| |
| #include <rw/_defs.h> |
| |
| |
| _RWSTD_NAMESPACE (__rw) { |
| |
| // make sure buffer size is greater than zero |
| typedef char _CharBuf [_RWSTD_TMPBUF_SIZE + !_RWSTD_TMPBUF_SIZE]; |
| |
| // use `aligned_buffer' to guarantee proper buffer alignment |
| static _RWSTD_THREAD __rw_aligned_buffer<_CharBuf> |
| __rw_buffer; |
| |
| static _RWSTD_THREAD unsigned long |
| __rw_buffer_busy /* = 0 */; // > 0 when buffer in use |
| |
| |
| // extern "C" to avoid binary incompatibility due to changes |
| // in function arguments (e.g., their sign) |
| extern "C" { |
| |
| |
| // used by std::get_temporary_buffer<>() |
| _RWSTD_EXPORT size_t |
| __rw_tmpbuf (void **pptr, _RWSTD_PTRDIFF_T nelems, size_t size) |
| { |
| _RWSTD_ASSERT (0 != pptr); |
| _RWSTD_ASSERT (0 != size); |
| |
| // detect overflow and fail |
| size_t nbytes = nelems * size; |
| |
| if ( nelems < 0 |
| || nbytes / size != _RWSTD_STATIC_CAST (size_t, nelems) |
| || (nelems && nbytes / nelems != size)) { |
| *pptr = 0; |
| return 0; |
| } |
| |
| // implicit initialization used to prevent a g++ 2.95.2 warning on Tru64 |
| // sorry: semantics of inline function static data are wrong (you'll wind |
| // up with multiple copies) |
| |
| void* const buffer = __rw_buffer._C_data (); |
| |
| if (*pptr == buffer) { |
| |
| // static buffer being returned, decrement its usage counter |
| _RWSTD_THREAD_PREDECREMENT (__rw_buffer_busy, false); |
| |
| return 0; |
| } |
| |
| if (*pptr) { |
| // dynamically allocated buffer being returned |
| __rw_deallocate (*pptr, 0); |
| return 0; |
| } |
| |
| // allocating a new buffer |
| |
| if (!nbytes) { |
| // don't waste memory for 0-size requests |
| *pptr = 0; |
| return 0; |
| } |
| |
| if (nbytes <= _RWSTD_TMPBUF_SIZE) { |
| |
| if (1 == _RWSTD_THREAD_PREINCREMENT (__rw_buffer_busy, false)) { |
| |
| *pptr = buffer; |
| |
| // static buffer used, its usage counter stays non-zero |
| return _RWSTD_TMPBUF_SIZE / size; |
| } |
| |
| // static buffer not used, decrement its usage counter |
| _RWSTD_THREAD_PREDECREMENT (__rw_buffer_busy, false); |
| } |
| |
| _TRY { |
| *pptr = __rw_allocate (nbytes, 0); |
| } |
| _CATCH (...) { |
| *pptr = 0; |
| nbytes = 0; |
| } |
| |
| return nbytes / size; |
| } |
| |
| } // extern "C" |
| |
| |
| } // namespace __rw |