coreclr/src/utilcode/sbuffer.cpp at master · dotnet/coreclr · GitHub

Name: coreclr/src/utilcode/sbuffer.cpp at master · dotnet/coreclr · GitHub
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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
// ---------------------------------------------------------------------------

//
// Buffer.cpp
// ---------------------------------------------------------------------------

#include"stdafx.h"
#include"sbuffer.h"
#include"ex.h"
#include"holder.h"
#include"stdmacros.h"

// Try to minimize the performance impact of contracts on CHK build.
#if defined(_MSC_VER)
#pragma inline_depth (20)
#endif

const DWORD g_garbageFillBuffer[GARBAGE_FILL_BUFFER_ITEMS] =
{
 GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD,
 GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD,
 GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD,
 GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD, GARBAGE_FILL_DWORD,
};

//----------------------------------------------------------------------------
// ReallocateBuffer
// Low level buffer reallocate routine
//----------------------------------------------------------------------------
voidSBuffer::ReallocateBuffer(COUNT_T allocation, Preserve preserve)
{
 CONTRACT_VOID
 {
PRECONDITION(CheckPointer(this));
PRECONDITION(CheckBufferClosed());
PRECONDITION(CheckAllocation(allocation));
PRECONDITION(allocation >= m_size);
POSTCONDITION(m_allocation == allocation);
if (allocation > 0) THROWS; else NOTHROW;
 GC_NOTRIGGER;
 SUPPORTS_DAC_HOST_ONLY;
 }
 CONTRACT_END;

 BYTE *newBuffer = NULL;
if (allocation > 0)
 {
 newBuffer = NewBuffer(allocation);

if (preserve == PRESERVE)
 {
// Copy the relevant contents of the old buffer over
DebugMoveBuffer(newBuffer, m_buffer, m_size);
 }
 }

if (IsAllocated())
DeleteBuffer(m_buffer, m_allocation);

 m_buffer = newBuffer;
 m_allocation = allocation;

if (allocation > 0)
SetAllocated();
else
ClearAllocated();

ClearImmutable();

 RETURN;
}

voidSBuffer::Replace(const Iterator &i, COUNT_T deleteSize, COUNT_T insertSize)
{
 CONTRACT_VOID
 {
 THROWS;
 GC_NOTRIGGER;
PRECONDITION(CheckPointer(this));
PRECONDITION(CheckIteratorRange(i, deleteSize));
 SUPPORTS_DAC_HOST_ONLY;
 }
 CONTRACT_END;

 COUNT_T startRange = (COUNT_T) (i.m_ptr - m_buffer);
// The PRECONDITION(CheckIterationRange(i, deleteSize)) should check this in
// contract-checking builds, but this ensures we don't integer overflow if someone
// passes in an egregious deleteSize by capping it to the remaining length in the
// buffer.
if ((COUNT_T)(m_buffer + m_size - i.m_ptr) < deleteSize)
 {
_ASSERTE(!"Trying to replace more bytes than are remaining in the buffer.");
 deleteSize = (COUNT_T)(m_buffer + m_size - i.m_ptr);
 }
 COUNT_T endRange = startRange + deleteSize;
 COUNT_T end = m_size;

 SCOUNT_T delta = insertSize - deleteSize;

if (delta < 0)
 {
// Buffer is shrinking

DebugDestructBuffer(i.m_ptr, deleteSize);

DebugMoveBuffer(m_buffer + endRange + delta,
 m_buffer + endRange,
 end - endRange);

Resize(m_size+delta, PRESERVE);

 i.Resync(this, m_buffer + startRange);

 }
elseif (delta > 0)
 {
// Buffer is growing

ResizePadded(m_size+delta);

 i.Resync(this, m_buffer + startRange);

DebugDestructBuffer(i.m_ptr, deleteSize);

DebugMoveBuffer(m_buffer + endRange + delta,
 m_buffer + endRange,
 end - endRange);

 }
else
 {
// Buffer stays the same size. We need to DebugDestruct it first to keep
// the invariant that the new space is clean.

DebugDestructBuffer(i.m_ptr, insertSize);
 }

DebugConstructBuffer(i.m_ptr, insertSize);

 RETURN;
}