returnBuffer.cpp

Detailed Description

 1
 2//-----------------------------------------------------------------------------
 3// Copyright (c) 2012 GarageGames, LLC
 4//
 5// Permission is hereby granted, free of charge, to any person obtaining a copy
 6// of this software and associated documentation files (the "Software"), to
 7// deal in the Software without restriction, including without limitation the
 8// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 9// sell copies of the Software, and to permit persons to whom the Software is
10// furnished to do so, subject to the following conditions:
11//
12// The above copyright notice and this permission notice shall be included in
13// all copies or substantial portions of the Software.
14//
15// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21// IN THE SOFTWARE.
22//-----------------------------------------------------------------------------
23
24#include "returnBuffer.h"
25
26ReturnBuffer::ReturnBuffer()
27{
28   mBuffer = nullptr;
29   mBufferSize = 0;
30   mStart = 0;
31
32   //Decent starting alloc of ~1 page = 4kb
33   ensureSize(4 * 1024);
34}
35
36ReturnBuffer::~ReturnBuffer()
37{
38   if (mBuffer)
39   {
40      dFree(mBuffer);
41   }
42}
43
44void ReturnBuffer::ensureSize(U32 newSize)
45{
46   //Round up to nearest multiple of 16 bytes
47   if (newSize & 0xF)
48   {
49      newSize = (newSize & ~0xF) + 0x10;
50   }
51   if (mBuffer == NULL)
52   {
53      //First alloc
54      mBuffer = (char *)dMalloc(newSize * sizeof(char));
55      mBufferSize = newSize;
56   }
57   else if (mBufferSize < newSize)
58   {
59      //Just use the expected size
60      mBuffer = (char *)dRealloc(mBuffer, newSize * sizeof(char));
61      mBufferSize = newSize;
62   }
63}
64
65char *ReturnBuffer::getBuffer(U32 size, U32 alignment)
66{
67   ensureSize(size);
68
69   //Align the start if necessary
70   if (mStart % alignment != 0)
71   {
72      mStart += alignment - (mStart % alignment);
73   }
74
75   if (size + mStart > mBufferSize)
76   {
77      //Restart
78      mStart = 0;
79   }
80   char *buffer = mBuffer + mStart;
81   mStart += size;
82
83   return buffer;
84}
85