Made the aligned malloc templated.

BUG=N/A

Review URL: https://webrtc-codereview.appspot.com/865004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@2866 4adac7df-926f-26a2-2b94-8c16560cd09d
This commit is contained in:
henrike@webrtc.org 2012-10-03 16:50:37 +00:00
parent 2e5192fa6a
commit 46d4073a64
3 changed files with 52 additions and 39 deletions

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@ -34,7 +34,19 @@ void* GetRightAlign(const void* ptr, size_t alignment);
// be de-allocated using AlignedFree. // be de-allocated using AlignedFree.
void* AlignedMalloc(size_t size, size_t alignment); void* AlignedMalloc(size_t size, size_t alignment);
// De-allocates memory created using the AlignedMalloc() API. // De-allocates memory created using the AlignedMalloc() API.
void AlignedFree(void* memBlock); void AlignedFree(void* mem_block);
// Templated versions to facilitate usage of aligned malloc without casting
// to and from void*.
template<typename T>
T* GetRightAlign(const T* ptr, size_t alignment) {
return reinterpret_cast<T*>(GetRightAlign(reinterpret_cast<const void*>(ptr),
alignment));
}
template<typename T>
T* AlignedMalloc(size_t size, size_t alignment) {
return reinterpret_cast<T*>(AlignedMalloc(size, alignment));
}
// Scoped pointer to AlignedMalloc-memory. // Scoped pointer to AlignedMalloc-memory.
template<typename T> template<typename T>

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@ -27,14 +27,14 @@ namespace webrtc {
// TODO(henrike): better to create just one memory block and interpret the // TODO(henrike): better to create just one memory block and interpret the
// first sizeof(AlignedMemory) bytes as an AlignedMemory struct. // first sizeof(AlignedMemory) bytes as an AlignedMemory struct.
struct AlignedMemory { struct AlignedMemory {
void* alignedBuffer; void* aligned_buffer;
void* memoryPointer; void* memory_pointer;
}; };
uintptr_t GetRightAlign(uintptr_t startPos, size_t alignment) { uintptr_t GetRightAlign(uintptr_t start_pos, size_t alignment) {
// The pointer should be aligned with |alignment| bytes. The - 1 guarantees // The pointer should be aligned with |alignment| bytes. The - 1 guarantees
// that it is aligned towards the closest higher (right) address. // that it is aligned towards the closest higher (right) address.
return (startPos + alignment - 1) & ~(alignment - 1); return (start_pos + alignment - 1) & ~(alignment - 1);
} }
// Alignment must be an integer power of two. // Alignment must be an integer power of two.
@ -52,8 +52,8 @@ void* GetRightAlign(const void* ptr, size_t alignment) {
if (!ValidAlignment(alignment)) { if (!ValidAlignment(alignment)) {
return NULL; return NULL;
} }
uintptr_t startPos = reinterpret_cast<uintptr_t>(ptr); uintptr_t start_pos = reinterpret_cast<uintptr_t>(ptr);
return reinterpret_cast<void*>(GetRightAlign(startPos, alignment)); return reinterpret_cast<void*>(GetRightAlign(start_pos, alignment));
} }
void* AlignedMalloc(size_t size, size_t alignment) { void* AlignedMalloc(size_t size, size_t alignment) {
@ -64,8 +64,8 @@ void* AlignedMalloc(size_t size, size_t alignment) {
return NULL; return NULL;
} }
AlignedMemory* returnValue = new AlignedMemory(); AlignedMemory* return_value = new AlignedMemory();
if (returnValue == NULL) { if (return_value == NULL) {
return NULL; return NULL;
} }
@ -73,46 +73,46 @@ void* AlignedMalloc(size_t size, size_t alignment) {
// alignment - 1 bytes needs to be allocated. // alignment - 1 bytes needs to be allocated.
// A pointer to AlignedMemory must be stored so that it can be retreived for // A pointer to AlignedMemory must be stored so that it can be retreived for
// deletion, ergo the sizeof(uintptr_t). // deletion, ergo the sizeof(uintptr_t).
returnValue->memoryPointer = malloc(size + sizeof(uintptr_t) + return_value->memory_pointer = malloc(size + sizeof(uintptr_t) +
alignment - 1); alignment - 1);
if (returnValue->memoryPointer == NULL) { if (return_value->memory_pointer == NULL) {
delete returnValue; delete return_value;
return NULL; return NULL;
} }
// Aligning after the sizeof(header) bytes will leave room for the header // Aligning after the sizeof(header) bytes will leave room for the header
// in the same memory block. // in the same memory block.
uintptr_t alignStartPos = uintptr_t align_start_pos =
reinterpret_cast<uintptr_t>(returnValue->memoryPointer); reinterpret_cast<uintptr_t>(return_value->memory_pointer);
alignStartPos += sizeof(uintptr_t); align_start_pos += sizeof(uintptr_t);
uintptr_t alignedPos = GetRightAlign(alignStartPos, alignment); uintptr_t aligned_pos = GetRightAlign(align_start_pos, alignment);
returnValue->alignedBuffer = reinterpret_cast<void*>(alignedPos); return_value->aligned_buffer = reinterpret_cast<void*>(aligned_pos);
// Store the address to the AlignedMemory struct in the header so that a // Store the address to the AlignedMemory struct in the header so that a
// it's possible to reclaim all memory. // it's possible to reclaim all memory.
uintptr_t headerPos = alignedPos; uintptr_t header_pos = aligned_pos;
headerPos -= sizeof(uintptr_t); header_pos -= sizeof(uintptr_t);
void* headerPtr = reinterpret_cast<void*>(headerPos); void* header_ptr = reinterpret_cast<void*>(header_pos);
uintptr_t headerValue = reinterpret_cast<uintptr_t>(returnValue); uintptr_t header_value = reinterpret_cast<uintptr_t>(return_value);
memcpy(headerPtr,&headerValue,sizeof(uintptr_t)); memcpy(header_ptr, &header_value, sizeof(uintptr_t));
return returnValue->alignedBuffer; return return_value->aligned_buffer;
} }
void AlignedFree(void* memBlock) { void AlignedFree(void* mem_block) {
if (memBlock == NULL) { if (mem_block == NULL) {
return; return;
} }
uintptr_t alignedPos = reinterpret_cast<uintptr_t>(memBlock); uintptr_t aligned_pos = reinterpret_cast<uintptr_t>(mem_block);
uintptr_t headerPos = alignedPos - sizeof(uintptr_t); uintptr_t header_pos = aligned_pos - sizeof(uintptr_t);
// Read out the address of the AlignedMemory struct from the header. // Read out the address of the AlignedMemory struct from the header.
uintptr_t* headerPtr = reinterpret_cast<uintptr_t*>(headerPos); uintptr_t* header_ptr = reinterpret_cast<uintptr_t*>(header_pos);
AlignedMemory* deleteMemory = reinterpret_cast<AlignedMemory*>(*headerPtr); AlignedMemory* delete_memory = reinterpret_cast<AlignedMemory*>(*header_ptr);
if (deleteMemory->memoryPointer != NULL) { if (delete_memory->memory_pointer != NULL) {
free(deleteMemory->memoryPointer); free(delete_memory->memory_pointer);
} }
delete deleteMemory; delete delete_memory;
} }
} // namespace webrtc } // namespace webrtc

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@ -23,7 +23,7 @@
// Returns true if |size| and |alignment| are valid combinations. // Returns true if |size| and |alignment| are valid combinations.
bool CorrectUsage(size_t size, size_t alignment) { bool CorrectUsage(size_t size, size_t alignment) {
webrtc::Allocator<char>::scoped_ptr_aligned scoped( webrtc::Allocator<char>::scoped_ptr_aligned scoped(
static_cast<char*> (webrtc::AlignedMalloc(size, alignment))); webrtc::AlignedMalloc<char>(size, alignment));
if (scoped.get() == NULL) { if (scoped.get() == NULL) {
return false; return false;
} }
@ -36,14 +36,15 @@ TEST(AlignedMalloc, GetRightAlign) {
const size_t alignment = 32; const size_t alignment = 32;
const size_t left_missalignment = 8; const size_t left_missalignment = 8;
webrtc::Allocator<char>::scoped_ptr_aligned scoped( webrtc::Allocator<char>::scoped_ptr_aligned scoped(
static_cast<char*> (webrtc::AlignedMalloc(size, alignment))); webrtc::AlignedMalloc<char>(size, alignment));
EXPECT_TRUE(scoped.get() != NULL); EXPECT_TRUE(scoped.get() != NULL);
const uintptr_t aligned_address = reinterpret_cast<uintptr_t> (scoped.get()); const uintptr_t aligned_address = reinterpret_cast<uintptr_t> (scoped.get());
const uintptr_t missaligned_address = aligned_address - left_missalignment; const uintptr_t missaligned_address = aligned_address - left_missalignment;
const void* missaligned_ptr = reinterpret_cast<void*> (missaligned_address); const char* missaligned_ptr = reinterpret_cast<const char*>(
const void* realignedPtr = webrtc::GetRightAlign( missaligned_address);
missaligned_ptr, alignment); const char* realigned_ptr = webrtc::GetRightAlign(
EXPECT_EQ(scoped.get(), realignedPtr); missaligned_ptr, alignment);
EXPECT_EQ(scoped.get(), realigned_ptr);
} }
TEST(AlignedMalloc, IncorrectSize) { TEST(AlignedMalloc, IncorrectSize) {