Wide Memory Read/Write (OpenCL Kernel)

This is simple example of vector addition to demonstrate Wide Memory Access using uint16 data type. Based on input argument type, V++ compiler will figure our the memory datawidth between Global Memory and Kernel. For this example, uint16 datatype is used, so Memory datawidth will be 16 x (integer bit size) = 16 x 32 = 512 bit.

KEY CONCEPTS: Kernel to DDR, wide memory access, burst read and write

KEYWORDS: uint16, xcl_pipeline_loop

This example demonstrates the use of ap_uint<> datatype which enables V++ to figure out the memory datawidth for the kernel to global memory transfers.Using this datatype, larger chunks of data can be transferred as compared to conventional datatypes such as int.

For efficient use of this bandwidth, ap_uint<16> is used. User must include ap_int.h to use these datatypes. ```c++ #define DATAWIDTH 512 typedef ap_uint uint512_dt;

local uint16 v1_local[LOCAL_MEM_SIZE]; local uint16 result_local[LOCAL_MEM_SIZE];

A maximum of 512 bits can be transferred b/w kernel and global memory, attribute `xcl_pipeline_loop` is used to infer the burst read/write.
```c++
 v1_rd: __attribute__((xcl_pipeline_loop(1)))
        __attribute__((xcl_loop_tripcount(c_size, c_size)))
        for (int j = 0 ; j <  chunk_size; j++){
            v1_local[j] = in1 [i + j];
        }

EXCLUDED PLATFORMS:

• Embedded ZC702

• All NoDMA Platforms, i.e u50 nodma etc

• Samsung U.2 SmartSSD

DESIGN FILES

Application code is located in the src directory. Accelerator binary files will be compiled to the xclbin directory. The xclbin directory is required by the Makefile and its contents will be filled during compilation. A listing of all the files in this example is shown below

src/host.cpp
src/vadd.cl

Access these files in the github repo by clicking here.

COMMAND LINE ARGUMENTS

Once the environment has been configured, the application can be executed by

./cl_wide_mem_rw <vadd XCLBIN>