Install Now
clCreateSubBuffer - Creates a new buffer object (referred to as a sub-buffer object) from an existing
Contents
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.
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 one of the following error in errcode_ret:
• CL_INVALID_MEM_OBJECT if buffer is not a valid buffer object or is a sub-buffer object.
• CL_INVALID_VALUE if buffer was created with CL_MEM_WRITE_ONLY and flags specifies CL_MEM_READ_WRITE
or CL_MEM_READ_ONLY, or if buffer was created with CL_MEM_READ_ONLY and flags specifies
CL_MEM_READ_WRITE or CL_MEM_WRITE_ONLY, or if flags specifies CL_MEM_USE_HOST_PTR or
CL_MEM_ALLOC_HOST_PTR or CL_MEM_COPY_HOST_PTR.
• CL_INVALID_VALUE if buffer was created with CL_MEM_HOST_WRITE_ONLY and flags specifies
CL_MEM_HOST_READ_ONLY or if buffer was created with CL_MEM_HOST_READ_ONLY and flags specifies
CL_MEM_HOST_WRITE_ONLY, or if buffer was created with CL_MEM_HOST_NO_ACCESS and flags specifies
CL_MEM_HOST_READ_ONLY or CL_MEM_HOST_WRITE_ONLY.
• CL_INVALID_VALUE if value specified in buffer_create_type is not valid.
• CL_INVALID_VALUE if value(s) specified in buffer_create_info (for a given buffer_create_type) is not
valid or if buffer_create_info is NULL.
• CL_INVALID_BUFFER_SIZE if size is 0.
• CL_MEM_OBJECT_ALLOCATION_FAILURE if there is a failure to allocate memory for sub-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.
Name
clCreateSubBuffer - Creates a new buffer object (referred to as a sub-buffer object) from an existing
buffer object.
cl_memclCreateSubBuffer(cl_membuffer,cl_mem_flagsflags,cl_buffer_create_typebuffer_create_type,constvoid*buffer_create_info,cl_int*errcode_ret);Notes
1. OpenCL Specification
page 69, section 5.2.1 - Creating Buffer Objects
The Khronos Group 11/18/2024 CLCREATESUBBUFFER(3clc)
Parameters
buffer
A valid object and cannot be a sub-buffer object.
flags
A bit-field that is used to specify allocation and usage information about the sub-buffer memory
object being created and is described in the table below. If the CL_MEM_READ_WRITE, CL_MEM_READ_ONLY
or CL_MEM_WRITE_ONLY values are not specified in flags, they are inherited from the corresponding
memory access qualifers associated with buffer. The CL_MEM_USE_HOST_PTR, CL_MEM_ALLOC_HOST_PTR and
CL_MEM_COPY_HOST_PTR values cannot be specified in flags but are inherited from the corresponding
memory access qualifiers associated with buffer. If CL_MEM_COPY_HOST_PTR is specified in the memory
access qualifier values associated with buffer it does not imply any additional copies when the
sub-buffer is created from buffer. If the CL_MEM_HOST_WRITE_ONLY, CL_MEM_HOST_READ_ONLY or
CL_MEM_HOST_NO_ACCESS values are not specified in flags, they are inherited from the corresponding
memory access qualifiers associated with buffer.
┌────────────────────────┬───────────────────────────────────────┐
│ 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. │
└────────────────────────┴───────────────────────────────────────┘
buffer_create_type and buffer_create_info
Describes the type of buffer object to be created. The list of supported values for
buffer_create_type and corresponding descriptor that buffer_create_info points to is described below.
┌──────────────────────────────┬───────────────────────────────────────────────────┐
│ cl_buffer_create_type │ Description │
├──────────────────────────────┼───────────────────────────────────────────────────┤
│ CL_BUFFER_CREATE_TYPE_REGION │ Create a buffer object that │
│ │ represents a specific region in │
│ │ buffer. │
│ │ │
│ │ buffer_create_info is a pointer to │
│ │ the following structure: │
│ │ │
│ │ │
│ │ typedef struct _cl_buffer_region { │
│ │ size_t origin; │
│ │ size_t size; │
│ │ } cl_buffer_region; │
│ │ │
│ │ │
│ │ (origin,size) defines the │
│ │ offset and size in bytes │
│ │ in buffer. │
│ │ │
│ │ If buffer is created with │
│ │ CL_MEM_USE_HOST_PTR, the │
│ │ host_ptr associated with │
│ │ the buffer object returned │
│ │ is host_ptr + origin. │
│ │ │
│ │ The buffer object returned │
│ │ references the data store │
│ │ allocated for buffer and │
│ │ points to a specific │
│ │ region given by (origin, │
│ │ size) in this data store. │
│ │ │
│ │ CL_INVALID_VALUE is │
│ │ returned in errcode_ret if │
│ │ the region specified by │
│ │ (origin,size) is out of │
│ │ bounds in buffer. │
│ │ │
│ │ CL_INVALID_BUFFER_SIZE if │
│ │ size is 0. │
│ │ │
│ │ CL_MISALIGNED_SUB_BUFFER_OFFSET │
│ │ is returned in errcode_ret │
│ │ if there are no devices in │
│ │ context associated with │
│ │ buffer for which the │
│ │ origin value is aligned to │
│ │ the │
│ │ CL_DEVICE_MEM_BASE_ADDR_ALIGN │
│ │ value. │
└──────────────────────────────┴───────────────────────────────────────────────────┘
See Also
clCreateBuffer(3clc), clEnqueueReadBuffer(3clc), clEnqueueWriteBuffer(3clc), clEnqueueCopyBuffer(3clc)
Specification
OpenCLSpecification[1]
PNG Icons
