Intel® FPGA SDK for OpenCL™ Pro Edition: Programming Guide

ID 683846
Date 10/04/2021

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11.1.6. Specifying an OpenCL Library when Compiling an OpenCL Kernel

To use an OpenCL™ library in an OpenCL kernel, specify the library file name and directory when you compile the kernel.
Important: Using a library does not reduce kernel compilation time.
To specify an OpenCL library to the Intel® FPGA SDK for OpenCL™ Offline Compiler, invoke the following command: aoc -l <library_file_name>.aoclib [-L <library directory>] <kernel file name>.cl
where the -l <library_file_name>.aoclib command option specifies the library file name, and the -L <library directory> command option specifies the directory containing the library files.

You may include multiple instances of -l <library file name> and -L <library directory> in the offline compiler command.

For example, if you create a library that includes the functions my_div_fd(), my_sqrtfd(), and myrsqrtfd(), the OpenCL kernel code might resemble the following:

#include “lib_header.hcl”

kernel void test_lib (
    global double * restrict in,
    global double * restrict out,
    int N) {
        int i = get_global_id(0);
        for (int k =0; k < N; k++) {
            double x = in[i*N + k];
            out[i*N + k] = my_divfd
                my_sqrtfd(my_rsqrtfd (x)));
Note: Library-related lines are highlighted in bold.

The corresponding lib_header.h file might resemble the following:

double my_sqrtfd (double x);
double my_rsqrtfd(double x);
double my_divfd(double a, double b);