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(svn r19468) -Codechange: make ptr_u union in Blob anonymous (skidd13)

This commit is contained in:
yexo 2010-03-19 20:04:24 +00:00
parent 1834e0edb5
commit 0d29c5aff2
1 changed files with 20 additions and 20 deletions
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40
src/misc/blob.hpp
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@ -27,13 +27,13 @@
* - no thread synchronization at all
*
* Internal member layout:
* 1. The only class member is pointer to the first item (see union ptr_u).
* 1. The only class member is pointer to the first item (see union).
* 2. Allocated block contains the blob header (see CHdr) followed by the raw byte data.
* Always, when it allocates memory the allocated size is:
* sizeof(CHdr) + <data capacity>
* 3. Two 'virtual' members (m_size and m_max_size) are stored in the CHdr at beginning
* of the alloated block.
* 4. The pointter (in ptr_u) pobsize_ts behind the header (to the first data byte).
* 4. The pointer of the union pobsize_ts behind the header (to the first data byte).
* When memory block is allocated, the sizeof(CHdr) it added to it.
* 5. Benefits of this layout:
* - items are accessed in the simplest possible way - just dereferencing the pointer,
@ -55,9 +55,9 @@ protected:
/** type used as class member */
union {
byte *m_pData; ///< ptr to the first byte of data
CHdr *m_pHdr_1; ///< ptr just after the CHdr holding m_size and m_max_size
} ptr_u;
byte *m_pData; ///< ptr to the first byte of data
CHdr *m_pHdr_1; ///< ptr just after the CHdr holding m_size and m_max_size
};
private:
/**
@ -90,7 +90,7 @@ public:
FORCEINLINE CBlobBaseSimple(CHdr * const & pHdr_1)
{
assert(pHdr_1 != NULL);
ptr_u.m_pHdr_1 = pHdr_1;
m_pHdr_1 = pHdr_1;
*const_cast<CHdr**>(&pHdr_1) = NULL;
}
@ -101,29 +101,29 @@ public:
}
protected:
/** initialize the empty blob by setting the ptr_u.m_pHdr_1 pointer to the static CHdr with
/** initialize the empty blob by setting the m_pHdr_1 pointer to the static CHdr with
* both m_size and m_max_size containing zero */
FORCEINLINE void InitEmpty()
{
ptr_u.m_pHdr_1 = const_cast<CHdr *>(&CBlobBaseSimple::hdrEmpty[1]);
m_pHdr_1 = const_cast<CHdr *>(&CBlobBaseSimple::hdrEmpty[1]);
}
/** initialize blob by attaching it to the given header followed by data */
FORCEINLINE void Init(CHdr *hdr)
{
ptr_u.m_pHdr_1 = &hdr[1];
m_pHdr_1 = &hdr[1];
}
/** blob header accessor - use it rather than using the pointer arithmetics directly - non-const version */
FORCEINLINE CHdr& Hdr()
{
return *(ptr_u.m_pHdr_1 - 1);
return *(m_pHdr_1 - 1);
}
/** blob header accessor - use it rather than using the pointer arithmetics directly - const version */
FORCEINLINE const CHdr& Hdr() const
{
return *(ptr_u.m_pHdr_1 - 1);
return *(m_pHdr_1 - 1);
}
/** return reference to the actual blob size - used when the size needs to be modified */
@ -154,13 +154,13 @@ public:
/** return pointer to the first byte of data - non-const version */
FORCEINLINE byte *RawData()
{
return ptr_u.m_pData;
return m_pData;
}
/** return pointer to the first byte of data - const version */
FORCEINLINE const byte *RawData() const
{
return ptr_u.m_pData;
return m_pData;
}
/** return the 32 bit CRC of valid data in the blob */
@ -195,15 +195,15 @@ public:
FORCEINLINE void MoveFrom(CBlobBaseSimple& src)
{
Free();
ptr_u.m_pData = src.ptr_u.m_pData;
m_pData = src.m_pData;
src.InitEmpty();
}
/** swap buffers (with data) between two blobs (this and source blob) */
FORCEINLINE void Swap(CBlobBaseSimple& src)
{
byte *tmp = ptr_u.m_pData; ptr_u.m_pData = src.ptr_u.m_pData;
src.ptr_u.m_pData = tmp;
byte *tmp = m_pData; m_pData = src.m_pData;
src.m_pData = tmp;
}
/** append new bytes at the end of existing data bytes - reallocates if necessary */
@ -228,7 +228,7 @@ public:
{
uint new_size = RawSize() + num_bytes;
if (new_size > MaxRawSize()) SmartAlloc(new_size);
return ptr_u.m_pData + RawSize();
return m_pData + RawSize();
}
/** Increase RawSize() by num_bytes.
@ -269,7 +269,7 @@ public:
pNewHdr->m_max_size = alloc_size - (sizeof(CHdr) + Ttail_reserve);
/* copy existing data */
if (RawSize() > 0)
memcpy(pNewHdr + 1, ptr_u.m_pData, pNewHdr->m_size);
memcpy(pNewHdr + 1, m_pData, pNewHdr->m_size);
/* replace our block with new one */
CHdr *pOldHdr = &Hdr();
Init(pNewHdr);
@ -315,7 +315,7 @@ public:
FORCEINLINE void FixTail() const
{
if (MaxRawSize() > 0) {
byte *p = &ptr_u.m_pData[RawSize()];
byte *p = &m_pData[RawSize()];
for (uint i = 0; i < Ttail_reserve; i++) {
p[i] = 0;
}
@ -341,7 +341,7 @@ public:
struct OnTransfer {
typename base::CHdr *m_pHdr_1;
OnTransfer(const OnTransfer& src) : m_pHdr_1(src.m_pHdr_1) {assert(src.m_pHdr_1 != NULL); *const_cast<typename base::CHdr**>(&src.m_pHdr_1) = NULL;}
OnTransfer(CBlobT& src) : m_pHdr_1(src.ptr_u.m_pHdr_1) {src.InitEmpty();}
OnTransfer(CBlobT& src) : m_pHdr_1(src.m_pHdr_1) {src.InitEmpty();}
~OnTransfer() {assert(m_pHdr_1 == NULL);}
};