Developer Guide

Intel oneAPI FPGA Handbook

ID 785441
Date 2/07/2024
Public

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Document Table of Contents

Variable-Precision Data Type Support

The Intel® oneAPI DPC++/C++ Compiler supports a range of FPGA-optimized variable-precision (sometimes referred to as arbitrary-precision) data types that are defined in header files, which you can include in your designs. Some of these header files are based on the Algorithmic C (AC) data types provided by Siemens EDA* (formerly Mentor Graphics) under the Apache 2.0 license. For more information about the Algorithmic C data types, refer to https://cdrdv2.intel.com/v1/dl/getContent/728986.

Data Types Supported by the Intel® oneAPI DPC++/C++ Compiler
Data Type Header File Description
ac_int <sycl/ext/intel/ac_types/ac_int.hpp> Arbitrary-precision integer support.
ac_fixed <sycl/ext/intel/ac_types/ac_fixed.hpp> Arbitrary-precision fixed-point number support.
<sycl/ext/intel/ac_types/ac_fixed_math.hpp> Supports some non-standard math functions for arbitrary-precision fixed-point data types.
ac_complex <sycl/ext/intel/ac_types/ac_complex.hpp> Complex number support.
ap_float <sycl/ext/intel/ac_types/ap_float.hpp> Arbitrary-precision floating-point number support.
<sycl/ext/intel/ac_types/ap_float_math.hpp>

Supports commonly used exponential, logarithmic, power, and trigonometric functions with ap_float data type.

NOTE:

Ensure that the AC data type headers are included after <sycl/sycl.hpp> and <sycl/ext/intel/fpga_extensions.hpp> header files.

Compilation Flags

Compilation Flags for Data Types
Data Type icpx -fsycl Command Flags Description
AC type
  • Linux: -qactypes
  • Windows: /Qactypes
Use these flags to include ac_types header files on the include path and link against AC type libraries required for the host device execution support.
ap_float type
  • Linux: -fp-model=precise -no-fma
  • Windows: /fp:precise /Qfma-
Use these flags to ensure that floating-point operations are accurate.

For more information about these flags, refer to -fp-model, fp and fma, Qfma topics in the Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference.

-DFPGA_EMULATOR Use this flag when using the ap_float data type and compiling programs for emulation.