opencl(五)----缓存对象

创建缓存对象

参考：https://www.khronos.org/registry/OpenCL/sdk/1.0/docs/man/xhtml/clCreateBuffer.html

// 创建缓存对象
cl_mem clCreateBuffer (    
        cl_context context,      //上下文
     cl_mem_flags flags,    //内存对象性质标签
     size_t size,                //大小
     void *host_ptr,          //主机地址
     cl_int *errcode_ret   //错误码
)

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_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_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.
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.

 创建子缓存对象

// 创建子缓存对象
cl_mem clCreateSubBuffer (    
        cl_mem buffer,         //缓存对象
     cl_mem_flags flags,    // 性质标签
     cl_buffer_create_type buffer_create_type,   //必须为 CL_BUFFER_CREATE_TYPE_REGION
     const void *buffer_create_info,     //缓存创建信息数据
     cl_int *errcode_ret       //错误代码
)


//  缓存创建信息结构数据
typedef struct _cl_buffer_region (
        size_t origin; //开始位置
        size_t  size;   //大小
)cl_buffer_region;

获取缓存对象相关信息

// 获取缓存对象相关信息

cl_int clGetMemObjectInfo (    
        cl_mem  memobj ,           //缓存对象
     cl_mem_info  param_name ,   //信息类型名称
     size_t  param_value_size ,
     void  *param_value ,
     size_t  *param_value_size_ret 
)
// 详情参考  https://www.khronos.org/registry/OpenCL/sdk/1.2/docs/man/xhtml/clGetMemObjectInfo.html