Intel® High Level Synthesis Compiler Standard Edition: Reference Manual

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ID 683310
Date 12/18/2019
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Document Table of Contents
Document Table of Contents x
1. Intel® HLS Compiler Standard Edition Reference Manual 2. Compiler 3. C Language and Library Support 4. Component Interfaces 5. Component Memories (Memory Attributes) 6. Loops in Components 7. Component Concurrency 8. Arbitrary Precision Math Support 9. Component Target Frequency 10. Intel® High Level Synthesis Compiler Standard Edition Compiler Reference Summary A. Supported Math Functions B. Intel® HLS Compiler Standard Edition Reference Manual Archives C. Document Revision History of the Intel® HLS Compiler Standard Edition Reference Manual
2. Compiler x
2.1. Intel® HLS Compiler Standard Edition Command Options 2.2. Using Libraries in Your Component 2.3. Compiler Interoperability 2.4. Intel® HLS Compiler Pipeline Approach
3. C Language and Library Support x
3.1. Supported C and C++ Subset for Component Synthesis 3.2. C and C++ Libraries 3.3. Intel® HLS Compiler Standard Edition Compiler-Defined Preprocessor Macros
4. Component Interfaces x
4.1. Component Invocation Interface 4.2. Avalon® Streaming Interfaces 4.3. Avalon® Memory-Mapped Master Interfaces 4.4. Slave Interfaces 4.5. Component Invocation Interface Arguments 4.6. Unstable and Stable Component Arguments 4.7. Global Variables 4.8. Structs in Component Interfaces 4.9. Reset Behavior
4.1. Component Invocation Interface x
4.1.1. Scalar Parameters 4.1.2. Pointer and Reference Parameters 4.1.3. Interface Definition Example: Component with Both Scalar and Pointer Arguments
4.3. Avalon® Memory-Mapped Master Interfaces x
4.3.1. Memory-Mapped Master Testbench Constructor 4.3.2. Implicit and Explicit Examples of Describing a Memory Interface
4.4. Slave Interfaces x
4.4.1. Control and Status Register (CSR) Slave 4.4.2. Slave Memories
5. Component Memories (Memory Attributes) x
5.1. Static Variables
6. Loops in Components x
6.1. Loop Initiation Interval (ii Pragma) 6.2. Loop-Carried Dependencies (ivdep Pragma) 6.3. Loop Coalescing (loop_coalesce Pragma) 6.4. Loop Concurrency (max_concurrency Pragma) 6.5. Loop Unrolling (unroll Pragma)
7. Component Concurrency x
7.1. Serial Equivalence within a Memory Space or I/O 7.2. Concurrency Control (hls_max_concurrency Attribute)
8. Arbitrary Precision Math Support x
Advantages of Arbitrary Precision Data Types Limitations of AC Data Types 8.1. Declaring ac_int Data Types 8.2. Integer Promotion and ac_int Data Types 8.3. Debugging Your Use of the ac_int Data Type 8.4. Declaring ac_fixed Data Types 8.5. AC Data Types and Native Compilers
8.1. Declaring ac_int Data Types x
8.1.1. Important Usage Information on the ac_int Data Type
10. Intel® High Level Synthesis Compiler Standard Edition Compiler Reference Summary x
10.1. Intel® HLS Compiler Standard Edition i++ Command-Line Arguments 10.2. Intel® HLS Compiler Standard Edition Header Files 10.3. Intel® HLS Compiler Standard Edition Compiler-Defined Preprocessor Macros 10.4. Intel® HLS Compiler Standard Edition Keywords 10.5. Intel® HLS Compiler Standard Edition Simulation API (Testbench Only) 10.6. Intel® HLS Compiler Standard Edition Component Memory Attributes 10.7. Intel® HLS Compiler Standard Edition Loop Pragmas 10.8. Intel® HLS Compiler Standard Edition Component Attributes 10.9. Intel® HLS Compiler Standard Edition Component Default Interfaces 10.10. Intel® HLS Compiler Standard Edition Component Invocation Interface Arguments 10.11. Intel® HLS Compiler Standard Edition Component Macros 10.12. Intel® HLS Compiler Standard Edition Streaming Input Interfaces 10.13. Intel® HLS Compiler Standard Edition Streaming Output Interfaces 10.14. Intel® HLS Compiler Standard Edition Memory-Mapped Interfaces 10.15. Intel® HLS Compiler Standard Edition Arbitrary Precision Data Types
A. Supported Math Functions x
A.1. Math Functions Provided by the math.h Header File A.2. Math Functions Provided by the extendedmath.h Header File A.3. Math Functions Provided by the ac_fixed_math.h Header File
1. Intel® HLS Compiler Standard Edition Reference Manual
2. Compiler
3. C Language and Library Support
4. Component Interfaces
5. Component Memories (Memory Attributes)
6. Loops in Components
7. Component Concurrency
8. Arbitrary Precision Math Support
9. Component Target Frequency
10. Intel® High Level Synthesis Compiler Standard Edition Compiler Reference Summary
A. Supported Math Functions
B. Intel® HLS Compiler Standard Edition Reference Manual Archives
C. Document Revision History of the Intel® HLS Compiler Standard Edition Reference Manual

8. Arbitrary Precision Math Support

The Intel® HLS Compiler supports a range of FPGA-optimized arbitrary-precision data types that are defined in header files that you can include in your designs.

Some of these header files are based on the Algorithmic C (AC) data types that Mentor Graphics* provides under the Apache license. For more information about the Algorithmic C data types, refer to Mentor Graphics Algorithmic C (AC) Datatypes, which is available as a part of your Intel® HLS Compiler installation: <quartus_installdir>/hls/include/ref/ac_datatypes_ref.pdf.

The Intel® HLS Compiler also supports arbitrary-precision IEEE 754 compliant floating point data types that is not based on the AC data types.

The Intel® HLS Compiler supports the following arbitrary precision data types:
Table 16.  Arbitrary Precision Data Types Supported by the Intel® HLS Compiler Standard Edition
Data Type Intel Header File Description
ac_int HLS/ac_int.h Arbitrary-width integer support
To learn more, review the following tutorials:
  • <quartus_installdir>/hls/examples/tutorials/ac_datatypes/ac_int_basic_ops
  • <quartus_installdir>/hls/examples/tutorials/ac_datatypes/ac_int_overflow
  • <quartus_installdir>/hls/examples/tutorials/best_practices/struct_interfaces
ac_fixed HLS/ac_fixed.h Arbitrary-precision fixed-point number support

To learn more, review the tutorial: <quartus_installdir>/hls/examples/tutorials/ac_datatypes/ac_fixed_constructor

HLS/ac_fixed_math.h Support for some nonstandard math functions for arbitrary-precision fixed-point data types

To learn more, review the tutorial: <quartus_installdir>/hls/examples/tutorials/ac_datatypes/ac_fixed_math_library

The Intel® HLS Compiler also supports some nonstandard math functions for the following data types when you include an additional header file:
  • ac_fixed data type

    Include the HLS/ac_fixed_math.h header file

Advantages of Arbitrary Precision Data Types

The arbitrary precision data types have the following advantages over using standard C/C++ data types in your components:

  • You can achieve narrower data paths and processing elements for various operations in the circuit.
  • The data types ensure that all operations are carried out in a size guaranteed not to lose any data. However, you can still lose data if you store data into a location where the data type is too narrow.

Limitations of AC Data Types

The AC data types have the following limitations:

  • Multipliers are limited to generating 512-bit results.
  • Dividers are limited to consuming a maximum of 64 bits.
  • The FPGA-optimized header files provided by the Intel® HLS Compiler are not compatible with GCC or MSVC. When you use the Intel® HLS Compiler header files, you cannot use GCC or MSVC to compile your testbench. Both your component and testbench must be compiled with the Intel® HLS Compiler.

    To compile AC data types with GCC or MSVC, use the reference AC data types headers also provided with he Intel® HLS Compiler. For details, see AC Data Types and Native Compilers.

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