Describes an allocation on the heap. More...

#include <allocation.h>

Public Member Functions
	Allocation ()
	Constructs a new zero-sized allocation.

	~Allocation ()
	Destroys the allocation.

uint8_t *	GetBuffer () const
	Gets the pointer to the start of the allocation.

Bytes	GetLength () const
	Gets the length of the allocation.

Bytes	GetReservedLength () const
	Gets the reserved length of the allocation. Calls to truncate may be ignored till the length exceeds the reserved length.

bool	Truncate (Bytes length, bool npot=true)
	Resize the underlying allocation to at least given number of bytes.

Static Public Member Functions
static absl::StatusOr< uint64_t >	NextPowerOfTwoSize (uint64_t x)
	Gets the next power of two size.

Detailed Description

Describes an allocation on the heap.

        Managing allocations through this utility makes it harder to
        miss allocation failures.

Definition at line 23 of file allocation.h.

Constructor & Destructor Documentation

◆ Allocation()

impeller::Allocation::Allocation ( )

default

Constructs a new zero-sized allocation.

◆ ~Allocation()

impeller::Allocation::~Allocation ( )

Destroys the allocation.

Definition at line 16 of file allocation.cc.

                        {
  ::free(buffer_);
}

Member Function Documentation

◆ GetBuffer()

uint8_t * impeller::Allocation::GetBuffer ( ) const

Gets the pointer to the start of the allocation.

        This pointer is only valid till the next call to `Truncate`.

Returns: The pointer to the start of the allocation.

Definition at line 20 of file allocation.cc.

                                     {
  return buffer_;
}

Referenced by impeller::ProcTableGLES::GetProgramInfoLogString(), impeller::testing::TEST(), and impeller::interop::testing::TEST_P().

◆ GetLength()

Bytes impeller::Allocation::GetLength ( ) const

Gets the length of the allocation.

Returns: The length.

Definition at line 24 of file allocation.cc.

                                  {
  return length_;
}

◆ GetReservedLength()

Bytes impeller::Allocation::GetReservedLength ( ) const

Gets the reserved length of the allocation. Calls to truncate may be ignored till the length exceeds the reserved length.

Returns: The reserved length.

Definition at line 28 of file allocation.cc.

                                          {
  return reserved_;
}

◆ NextPowerOfTwoSize()

absl::StatusOr< uint64_t > impeller::Allocation::NextPowerOfTwoSize ( uint64_t x )

static

Gets the next power of two size.

Parameters

[in] x The size.

Returns: The smallest power of two that is greater than or equal to x.

Definition at line 42 of file allocation.cc.

                                                                {
  if (x > (static_cast<uint64_t>(1) << 63)) {
    return absl::InvalidArgumentError("Out of range");
  }
  if (x == 0) {
    return 1;
  }
 
  --x;
 
  x |= x >> 1;
  x |= x >> 2;
  x |= x >> 4;
  x |= x >> 8;
  x |= x >> 16;
  x |= x >> 32;
 
  return x + 1;
}

References x.

Referenced by impeller::testing::TEST().

◆ Truncate()

bool impeller::Allocation::Truncate	(	Bytes	length,
		bool	npot = `true`
	)

Resize the underlying allocation to at least given number of bytes.

In case of failure, false is returned and the underlying allocation remains unchanged.

Warning: Pointers to buffers obtained via previous calls to GetBuffer may become invalid at this point.