Provided by: opencl-1.2-man-doc_1.0~svn33624-5_all 
NAME
clCreateBuffer - Creates a buffer object.
cl_mem clCreateBuffer(cl_context context, cl_mem_flags flags, size_t size, void *host_ptr,
cl_int *errcode_ret);
PARAMETERS
context
A valid OpenCL context used to create the buffer object.
flags
A bit-field that is used to specify allocation and usage information such as the
memory arena that should be used to allocate the buffer object and how it will be
used. The following table describes the possible values for flags. If value specified
for flags is 0, the default is used which is CL_MEM_READ_WRITE.
┌───────────────────────┬──────────────────────────────────┐
│cl_mem_flags │ Description │
├───────────────────────┼──────────────────────────────────┤
│CL_MEM_READ_WRITE │ This flag specifies that the │
│ │ memory object will be read and │
│ │ written by a kernel. This is the │
│ │ default. │
├───────────────────────┼──────────────────────────────────┤
│CL_MEM_WRITE_ONLY │ This flags specifies that the │
│ │ memory object will be written │
│ │ but not read by a kernel. │
│ │ │
│ │ Reading from a buffer or image │
│ │ object created with │
│ │ CL_MEM_WRITE_ONLY inside a │
│ │ kernel is undefined. │
│ │ │
│ │ CL_MEM_READ_WRITE and │
│ │ CL_MEM_WRITE_ONLY are mutually │
│ │ exclusive. │
├───────────────────────┼──────────────────────────────────┤
│CL_MEM_READ_ONLY │ This flag specifies that the │
│ │ memory object is a read-only │
│ │ memory object when used inside a │
│ │ kernel. │
│ │ │
│ │ Writing to a buffer or image │
│ │ object created with │
│ │ CL_MEM_READ_ONLY inside a kernel │
│ │ is undefined. │
│ │ │
│ │ CL_MEM_READ_WRITE or │
│ │ CL_MEM_WRITE_ONLY and │
│ │ CL_MEM_READ_ONLY are mutually │
│ │ exclusive. │
├───────────────────────┼──────────────────────────────────┤
│CL_MEM_USE_HOST_PTR │ This flag is valid only if │
│ │ host_ptr is not NULL. If │
│ │ specified, it indicates that the │
│ │ application wants the OpenCL │
│ │ implementation to use memory │
│ │ referenced by host_ptr as the │
│ │ storage bits for the memory │
│ │ object. │
│ │ │
│ │ OpenCL implementations are │
│ │ allowed to cache the buffer │
│ │ contents pointed to by host_ptr │
│ │ in device memory. This cached │
│ │ copy can be used when kernels │
│ │ are executed on a device. │
│ │ │
│ │ The result of OpenCL commands │
│ │ that operate on multiple buffer │
│ │ objects created with the same │
│ │ host_ptr or overlapping host │
│ │ regions is considered to be │
│ │ undefined. │
│ │ │
│ │ Refer to the dataTypes(3clc) for │
│ │ host_ptr for memory objects │
│ │ (buffer and images) created │
│ │ using CL_MEM_USE_HOST_PTR. │
├───────────────────────┼──────────────────────────────────┤
│CL_MEM_ALLOC_HOST_PTR │ This flag specifies that the │
│ │ application wants the OpenCL │
│ │ implementation to allocate │
│ │ memory from host accessible │
│ │ memory. │
│ │ │
│ │ CL_MEM_ALLOC_HOST_PTR and │
│ │ CL_MEM_USE_HOST_PTR are mutually │
│ │ exclusive. │
├───────────────────────┼──────────────────────────────────┤
│CL_MEM_COPY_HOST_PTR │ This flag is valid only if │
│ │ host_ptr is not NULL. If │
│ │ specified, it indicates that the │
│ │ application wants the OpenCL │
│ │ implementation to allocate │
│ │ memory for the memory object and │
│ │ copy the data from memory │
│ │ referenced by host_ptr. │
│ │ │
│ │ CL_MEM_COPY_HOST_PTR and │
│ │ CL_MEM_USE_HOST_PTR are mutually │
│ │ exclusive. │
│ │ │
│ │ CL_MEM_COPY_HOST_PTR can be used │
│ │ with CL_MEM_ALLOC_HOST_PTR to │
│ │ initialize the contents of the │
│ │ cl_mem object allocated using │
│ │ host-accessible (e.g. PCIe) │
│ │ memory. │
├───────────────────────┼──────────────────────────────────┤
│CL_MEM_HOST_WRITE_ONLY │ This flag specifies that the │
│ │ host will only write to the │
│ │ memory object (using OpenCL APIs │
│ │ that enqueue a write or a map │
│ │ for write). This can be used to │
│ │ optimize write access from the │
│ │ host (e.g. enable write combined │
│ │ allocations for memory objects │
│ │ for devices that communicate │
│ │ with the host over a system bus │
│ │ such as PCIe). │
├───────────────────────┼──────────────────────────────────┤
│CL_MEM_HOST_READ_ONLY │ This flag specifies that the │
│ │ host will only read the memory │
│ │ object (using OpenCL APIs that │
│ │ enqueue a read or a map for │
│ │ read). │
│ │ │
│ │ CL_MEM_HOST_WRITE_ONLY and │
│ │ CL_MEM_HOST_READ_ONLY are │
│ │ mutually exclusive. │
├───────────────────────┼──────────────────────────────────┤
│CL_MEM_HOST_NO_ACCESS │ This flag specifies that the │
│ │ host will not read or write the │
│ │ memory object. │
│ │ │
│ │ CL_MEM_HOST_WRITE_ONLY or │
│ │ CL_MEM_HOST_READ_ONLY and │
│ │ CL_MEM_HOST_NO_ACCESS are │
│ │ mutually exclusive. │
└───────────────────────┴──────────────────────────────────┘
size
The size in bytes of the buffer memory object to be allocated.
host_ptr
A pointer to the buffer data that may already be allocated by the application. The
size of the buffer that host_ptr points to must be ≥ size bytes.
errcode_ret
Returns an appropriate error code. If errcode_ret is NULL, no error code is returned.
ERRORS
Returns a valid non-zero buffer object and errcode_ret is set to CL_SUCCESS if the buffer
object is created successfully. Otherwise, it returns a NULL value with one of the
following error values returned in errcode_ret:
• CL_INVALID_CONTEXT if context is not a valid context.
• CL_INVALID_VALUE if values specified in flags are not valid as defined in the table
above.
• CL_INVALID_BUFFER_SIZE if size is 0. Implementations may return
CL_INVALID_BUFFER_SIZE if size is greater than the CL_DEVICE_MAX_MEM_ALLOC_SIZE value
specified in the table of allowed values for param_name for clGetDeviceInfo(3clc) for
all devices in context.
• CL_INVALID_HOST_PTR if host_ptr is NULL and CL_MEM_USE_HOST_PTR or
CL_MEM_COPY_HOST_PTR are set in flags or if host_ptr is not NULL but
CL_MEM_COPY_HOST_PTR or CL_MEM_USE_HOST_PTR are not set in flags.
• CL_MEM_OBJECT_ALLOCATION_FAILURE if there is a failure to allocate memory for buffer
object.
• CL_OUT_OF_RESOURCES if there is a failure to allocate resources required by the OpenCL
implementation on the device.
• CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the
OpenCL implementation on the host.
SPECIFICATION
OpenCL Specification[1]
SEE ALSO
clEnqueueReadBuffer(3clc), clEnqueueWriteBuffer(3clc), clEnqueueCopyBuffer(3clc),
clCreateSubBuffer(3clc), classDiagram(3clc)
AUTHORS
The Khronos Group
COPYRIGHT
Copyright © 2007-2011 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and/or associated documentation files (the "Materials"), to deal in the Materials
without restriction, including without limitation the rights to use, copy, modify, merge,
publish, distribute, sublicense, and/or sell copies of the Materials, and to permit
persons to whom the Materials are furnished to do so, subject to the condition that this
copyright notice and permission notice shall be included in all copies or substantial
portions of the Materials.
NOTES
1. OpenCL Specification
page 66, section 5.2.1 - Creating Buffer Objects