Load and Store Using Pointers - 2023.1 English

AI Engine Kernel and Graph Programming Guide (UG1079)

Document ID
UG1079
Release Date
2023-06-23
Version
2023.1 English

It is mandatory to use the window API in the kernel function prototype as inputs and outputs. However, in the kernel code, it is possible to use a direct pointer reference to read/write data.

void func(input_window_int16 *w_input, 
			output_window_cint16 *w_output){
	.....
	v16int16 *ptr_in  = (v16int16 *)w_input->ptr;
	v8cint16 *ptr_out = (v8cint16 *)w_output->ptr;
	......
}

The window structure is responsible for managing buffer locks tracking buffer type (ping/pong) and this can add to the cycle count. This is especially true when load/store are out-of-order (scatter-gather). Using pointers may help reduce the cycle count required for load and store.

Note: If using pointers to load and store data, it is the designer’s responsibility to avoid out-of-bound memory access.