OpenCL 1.0 Specification阅读笔记（3）

5. The OpenCL Runtime

5.2 Memory Objects

(1) buffer objects: 1-dim: scalar, vector, user-defined structure

(2) image objects: 2-dims or 3-dims texture, frame buffer and image: image format

memory object的元素至少为1

buffer的结构是显式的，指针访问，类型一致；image的结构是隐式的，不能用指针访问，类型可以隐式转换

cl_mem clCreateBuffer(
cl_context    context,
cl_mem_flag   flags,
size_t        size,
void         *host_ptr,
cl_int       *errcode_ret);

cl_mem_flag:

read_write/read_only/write_only buffer,

(1) use_host_ptr: mapping device memory ptr or pcie memory ptr to host ptr

(2) copy_host_ptr: allocate memory on device or pcie and then copy host_ptr's content to

(3) alloc_host_ptr: allocate memory on host memory

read/write buffer command should be enqueued into command queue

(1) clEnqueueReadBuffer

(2) clEnqueueWriteBuffer

(3) clEnqueueCopyBuffer

概念：

(1) blocking or non-blocking: 同步读写或异步读写的问题，当异步时，使用event来query是否完成

(2) event_wait_list and num_event_in_wait_list: 当列表中的事件都完成时，才可执行读（写）操作

clRetainMemObject

clReleaseMemObject

cl_mem clCreateImage2D(
cl_context              context,
cl_mem_flag             flags,
const cl_image_format  *image_format,
size_t                  image_width,
size_t                  image_height,
size_t                  image_row_pitch,
void                   *host_ptr,
cl_int                 *errcode_ret );

注意：image中每个元素的字节数是2的平方数

clCreateImage3D与clCreateImage2D差不多

而Image Format Descriptor结构分成两部分：

(1) image_channel_order: channel数和Layout，即memory layout

(2) image_channel_data_type: channel数据类型的大小

to be continued .....