SPNU151W January   1998  – March 2023 66AK2E05 , 66AK2H06 , 66AK2H12 , 66AK2H14 , AM1705 , AM1707 , AM1802 , AM1806 , AM1808 , AM1810 , AM5K2E04 , OMAP-L132 , OMAP-L137 , OMAP-L138 , SM470R1B1M-HT , TMS470R1A288 , TMS470R1A384 , TMS470R1A64 , TMS470R1B1M , TMS470R1B512 , TMS470R1B768

 

  1.   Read This First
    1.     About This Manual
    2.     Notational Conventions
    3.     Related Documentation
    4.     Related Documentation From Texas Instruments
    5.     Trademarks
  2. 1Introduction to the Software Development Tools
    1. 1.1 Software Development Tools Overview
    2. 1.2 Compiler Interface
    3. 1.3 ANSI/ISO Standard
    4. 1.4 Output Files
    5. 1.5 Utilities
  3. 2Using the C/C++ Compiler
    1. 2.1  About the Compiler
    2. 2.2  Invoking the C/C++ Compiler
    3. 2.3  Changing the Compiler's Behavior with Options
      1. 2.3.1  Linker Options
      2. 2.3.2  Frequently Used Options
      3. 2.3.3  Miscellaneous Useful Options
      4. 2.3.4  Run-Time Model Options
      5. 2.3.5  Symbolic Debugging and Profiling Options
      6. 2.3.6  Specifying Filenames
      7. 2.3.7  Changing How the Compiler Interprets Filenames
      8. 2.3.8  Changing How the Compiler Processes C Files
      9. 2.3.9  Changing How the Compiler Interprets and Names Extensions
      10. 2.3.10 Specifying Directories
      11. 2.3.11 Assembler Options
      12. 2.3.12 Deprecated Options
    4. 2.4  Controlling the Compiler Through Environment Variables
      1. 2.4.1 Setting Default Compiler Options (TI_ARM_C_OPTION)
      2. 2.4.2 Naming One or More Alternate Directories (TI_ARM_C_DIR)
    5. 2.5  Controlling the Preprocessor
      1. 2.5.1  Predefined Macro Names
      2. 2.5.2  The Search Path for #include Files
        1. 2.5.2.1 Adding a Directory to the #include File Search Path (--include_path Option)
      3. 2.5.3  Support for the #warning and #warn Directives
      4. 2.5.4  Generating a Preprocessed Listing File (--preproc_only Option)
      5. 2.5.5  Continuing Compilation After Preprocessing (--preproc_with_compile Option)
      6. 2.5.6  Generating a Preprocessed Listing File with Comments (--preproc_with_comment Option)
      7. 2.5.7  Generating Preprocessed Listing with Line-Control Details (--preproc_with_line Option)
      8. 2.5.8  Generating Preprocessed Output for a Make Utility (--preproc_dependency Option)
      9. 2.5.9  Generating a List of Files Included with #include (--preproc_includes Option)
      10. 2.5.10 Generating a List of Macros in a File (--preproc_macros Option)
    6. 2.6  Passing Arguments to main()
    7. 2.7  Understanding Diagnostic Messages
      1. 2.7.1 Controlling Diagnostic Messages
      2. 2.7.2 How You Can Use Diagnostic Suppression Options
    8. 2.8  Other Messages
    9. 2.9  Generating Cross-Reference Listing Information (--gen_cross_reference_listing Option)
    10. 2.10 Generating a Raw Listing File (--gen_preprocessor_listing Option)
    11. 2.11 Using Inline Function Expansion
      1. 2.11.1 Inlining Intrinsic Operators
      2. 2.11.2 Inlining Restrictions
    12. 2.12 Using Interlist
    13. 2.13 Controlling Application Binary Interface
    14. 2.14 VFP Support
    15. 2.15 Enabling Entry Hook and Exit Hook Functions
  4. 3Optimizing Your Code
    1. 3.1  Invoking Optimization
    2. 3.2  Controlling Code Size Versus Speed
    3. 3.3  Performing File-Level Optimization (--opt_level=3 option)
      1. 3.3.1 Creating an Optimization Information File (--gen_opt_info Option)
    4. 3.4  Program-Level Optimization (--program_level_compile and --opt_level=3 options)
      1. 3.4.1 Controlling Program-Level Optimization (--call_assumptions Option)
      2. 3.4.2 Optimization Considerations When Mixing C/C++ and Assembly
    5. 3.5  Automatic Inline Expansion (--auto_inline Option)
    6. 3.6  Link-Time Optimization (--opt_level=4 Option)
      1. 3.6.1 Option Handling
      2. 3.6.2 Incompatible Types
    7. 3.7  Using Feedback Directed Optimization
      1. 3.7.1 Feedback Directed Optimization
        1. 3.7.1.1 Phase 1 -- Collect Program Profile Information
        2. 3.7.1.2 Phase 2 -- Use Application Profile Information for Optimization
        3. 3.7.1.3 Generating and Using Profile Information
        4. 3.7.1.4 Example Use of Feedback Directed Optimization
        5. 3.7.1.5 The .ppdata Section
        6. 3.7.1.6 Feedback Directed Optimization and Code Size Tune
        7. 3.7.1.7 Instrumented Program Execution Overhead
        8. 3.7.1.8 Invalid Profile Data
      2. 3.7.2 Profile Data Decoder
      3. 3.7.3 Feedback Directed Optimization API
      4. 3.7.4 Feedback Directed Optimization Summary
    8. 3.8  Using Profile Information to Analyze Code Coverage
      1. 3.8.1 Code Coverage
        1. 3.8.1.1 Phase1 -- Collect Program Profile Information
        2. 3.8.1.2 Phase 2 -- Generate Code Coverage Reports
      2. 3.8.2 Related Features and Capabilities
        1. 3.8.2.1 Path Profiler
        2. 3.8.2.2 Analysis Options
        3. 3.8.2.3 Environment Variables
    9. 3.9  Accessing Aliased Variables in Optimized Code
    10. 3.10 Use Caution With asm Statements in Optimized Code
    11. 3.11 Using the Interlist Feature With Optimization
    12. 3.12 Debugging and Profiling Optimized Code
      1. 3.12.1 Profiling Optimized Code
    13. 3.13 What Kind of Optimization Is Being Performed?
      1. 3.13.1  Cost-Based Register Allocation
      2. 3.13.2  Alias Disambiguation
      3. 3.13.3  Branch Optimizations and Control-Flow Simplification
      4. 3.13.4  Data Flow Optimizations
      5. 3.13.5  Expression Simplification
      6. 3.13.6  Inline Expansion of Functions
      7. 3.13.7  Function Symbol Aliasing
      8. 3.13.8  Induction Variables and Strength Reduction
      9. 3.13.9  Loop-Invariant Code Motion
      10. 3.13.10 Loop Rotation
      11. 3.13.11 Instruction Scheduling
      12. 3.13.12 Tail Merging
      13. 3.13.13 Autoincrement Addressing
      14. 3.13.14 Block Conditionalizing
        1. 3.13.14.1 Block Conditionalizing C Source
        2. 3.13.14.2 C/C++ Compiler Output for
      15. 3.13.15 Epilog Inlining
      16. 3.13.16 Removing Comparisons to Zero
      17. 3.13.17 Integer Division With Constant Divisor
      18. 3.13.18 Branch Chaining
  5. 4Linking C/C++ Code
    1. 4.1 Invoking the Linker Through the Compiler (-z Option)
      1. 4.1.1 Invoking the Linker Separately
      2. 4.1.2 Invoking the Linker as Part of the Compile Step
      3. 4.1.3 Disabling the Linker (--compile_only Compiler Option)
    2. 4.2 Linker Code Optimizations
      1. 4.2.1 Generate List of Dead Functions (--generate_dead_funcs_list Option)
      2. 4.2.2 Generating Aggregate Data Subsections (--gen_data_subsections Compiler Option)
    3. 4.3 Controlling the Linking Process
      1. 4.3.1 Including the Run-Time-Support Library
        1. 4.3.1.1 Automatic Run-Time-Support Library Selection
          1. 4.3.1.1.1 Using the --issue_remarks Option
        2. 4.3.1.2 Manual Run-Time-Support Library Selection
        3. 4.3.1.3 Library Order for Searching for Symbols
      2. 4.3.2 Run-Time Initialization
      3. 4.3.3 Initialization of Cinit and Watchdog Timer Hold
      4. 4.3.4 Global Object Constructors
      5. 4.3.5 Specifying the Type of Global Variable Initialization
      6. 4.3.6 Specifying Where to Allocate Sections in Memory
      7. 4.3.7 A Sample Linker Command File
  6. 5C/C++ Language Implementation
    1. 5.1  Characteristics of ARM C
      1. 5.1.1 Implementation-Defined Behavior
    2. 5.2  Characteristics of ARM C++
    3. 5.3  Using MISRA C 2004
    4. 5.4  Using the ULP Advisor
    5. 5.5  Data Types
      1. 5.5.1 Size of Enum Types
    6. 5.6  File Encodings and Character Sets
    7. 5.7  Keywords
      1. 5.7.1 The const Keyword
      2. 5.7.2 The __interrupt Keyword
      3. 5.7.3 The volatile Keyword
    8. 5.8  C++ Exception Handling
    9. 5.9  Register Variables and Parameters
      1. 5.9.1 Local Register Variables and Parameters
      2. 5.9.2 Global Register Variables
    10. 5.10 The __asm Statement
    11. 5.11 Pragma Directives
      1. 5.11.1  The CALLS Pragma
      2. 5.11.2  The CHECK_MISRA Pragma
      3. 5.11.3  The CHECK_ULP Pragma
      4. 5.11.4  The CODE_SECTION Pragma
      5. 5.11.5  The CODE_STATE Pragma
      6. 5.11.6  The DATA_ALIGN Pragma
      7. 5.11.7  The DATA_SECTION Pragma
        1. 5.11.7.1 Using the DATA_SECTION Pragma C Source File
        2. 5.11.7.2 Using the DATA_SECTION Pragma C++ Source File
        3. 5.11.7.3 Using the DATA_SECTION Pragma Assembly Source File
      8. 5.11.8  The Diagnostic Message Pragmas
      9. 5.11.9  The DUAL_STATE Pragma
      10. 5.11.10 The FORCEINLINE Pragma
      11. 5.11.11 The FORCEINLINE_RECURSIVE Pragma
      12. 5.11.12 The FUNC_ALWAYS_INLINE Pragma
      13. 5.11.13 The FUNC_CANNOT_INLINE Pragma
      14. 5.11.14 The FUNC_EXT_CALLED Pragma
      15. 5.11.15 The FUNCTION_OPTIONS Pragma
      16. 5.11.16 The INTERRUPT Pragma
      17. 5.11.17 The LOCATION Pragma
      18. 5.11.18 The MUST_ITERATE Pragma
        1. 5.11.18.1 The MUST_ITERATE Pragma Syntax
        2. 5.11.18.2 Using MUST_ITERATE to Expand Compiler Knowledge of Loops
      19. 5.11.19 The NOINIT and PERSISTENT Pragmas
      20. 5.11.20 The NOINLINE Pragma
      21. 5.11.21 The NO_HOOKS Pragma
      22. 5.11.22 The once Pragma
      23. 5.11.23 The pack Pragma
      24. 5.11.24 The PROB_ITERATE Pragma
      25. 5.11.25 The RESET_MISRA Pragma
      26. 5.11.26 The RESET_ULP Pragma
      27. 5.11.27 The RETAIN Pragma
      28. 5.11.28 The SET_CODE_SECTION and SET_DATA_SECTION Pragmas
      29. 5.11.29 The SWI_ALIAS Pragma
      30. 5.11.30 The TASK Pragma
      31. 5.11.31 The UNROLL Pragma
      32. 5.11.32 The WEAK Pragma
    12. 5.12 The _Pragma Operator
    13. 5.13 Application Binary Interface
    14. 5.14 ARM Instruction Intrinsics
    15. 5.15 Object File Symbol Naming Conventions (Linknames)
    16. 5.16 Changing the ANSI/ISO C/C++ Language Mode
      1. 5.16.1 C99 Support (--c99)
      2. 5.16.2 C11 Support (--c11)
      3. 5.16.3 Strict ANSI Mode and Relaxed ANSI Mode (--strict_ansi and --relaxed_ansi)
    17. 5.17 GNU , Clang, and ACLE Language Extensions
      1. 5.17.1 Extensions
      2. 5.17.2 Function Attributes
      3. 5.17.3 For Loop Attributes
      4. 5.17.4 Variable Attributes
      5. 5.17.5 Type Attributes
      6. 5.17.6 Built-In Functions
    18. 5.18 AUTOSAR
    19. 5.19 Compiler Limits
  7. 6Run-Time Environment
    1. 6.1  Memory Model
      1. 6.1.1 Sections
      2. 6.1.2 C/C++ System Stack
      3. 6.1.3 Dynamic Memory Allocation
    2. 6.2  Object Representation
      1. 6.2.1 Data Type Storage
        1. 6.2.1.1 char and short Data Types (signed and unsigned)
        2. 6.2.1.2 float, int, and long Data Types (signed and unsigned)
        3. 6.2.1.3 double, long double, and long long Data Types (signed and unsigned)
        4. 6.2.1.4 Pointer to Data Member Types
        5. 6.2.1.5 Pointer to Member Function Types
        6. 6.2.1.6 Structure and Array Alignment
      2. 6.2.2 Bit Fields
      3. 6.2.3 Character String Constants
    3. 6.3  Register Conventions
    4. 6.4  Function Structure and Calling Conventions
      1. 6.4.1 How a Function Makes a Call
      2. 6.4.2 How a Called Function Responds
      3. 6.4.3 C Exception Handler Calling Convention
      4. 6.4.4 Accessing Arguments and Local Variables
    5. 6.5  Accessing Linker Symbols in C and C++
    6. 6.6  Interfacing C and C++ With Assembly Language
      1. 6.6.1 Using Assembly Language Modules With C/C++ Code
      2. 6.6.2 Accessing Assembly Language Functions From C/C++
        1. 6.6.2.1 Calling an Assembly Language Function From a C/C++ Program
        2. 6.6.2.2 Assembly Language Program Called by
        3.       237
      3. 6.6.3 Accessing Assembly Language Variables From C/C++
        1. 6.6.3.1 Accessing Assembly Language Global Variables
          1. 6.6.3.1.1 Assembly Language Variable Program
          2. 6.6.3.1.2 C Program to Access Assembly Language From
        2.       242
        3. 6.6.3.2 Accessing Assembly Language Constants
          1. 6.6.3.2.1 Accessing an Assembly Language Constant From C
          2. 6.6.3.2.2 Assembly Language Program for
          3.        246
      4. 6.6.4 Sharing C/C++ Header Files With Assembly Source
      5. 6.6.5 Using Inline Assembly Language
      6. 6.6.6 Modifying Compiler Output
    7. 6.7  Interrupt Handling
      1. 6.7.1 Saving Registers During Interrupts
      2. 6.7.2 Using C/C++ Interrupt Routines
      3. 6.7.3 Using Assembly Language Interrupt Routines
      4. 6.7.4 How to Map Interrupt Routines to Interrupt Vectors
        1. 6.7.4.1 Sample intvecs.asm File
      5. 6.7.5 Using Software Interrupts
      6. 6.7.6 Other Interrupt Information
    8. 6.8  Intrinsic Run-Time-Support Arithmetic and Conversion Routines
      1. 6.8.1 CPSR Register and Interrupt Intrinsics
    9. 6.9  Built-In Functions
    10. 6.10 System Initialization
      1. 6.10.1 Boot Hook Functions for System Pre-Initialization
      2. 6.10.2 Run-Time Stack
      3. 6.10.3 Automatic Initialization of Variables
        1. 6.10.3.1 Zero Initializing Variables
        2. 6.10.3.2 Direct Initialization
        3. 6.10.3.3 Autoinitialization of Variables at Run Time
        4. 6.10.3.4 Autoinitialization Tables
          1. 6.10.3.4.1 Length Followed by Data Format
          2. 6.10.3.4.2 Zero Initialization Format
          3. 6.10.3.4.3 Run Length Encoded (RLE) Format
          4. 6.10.3.4.4 Lempel-Ziv-Storer-Szymanski Compression (LZSS) Format
          5. 6.10.3.4.5 Sample C Code to Process the C Autoinitialization Table
        5. 6.10.3.5 Initialization of Variables at Load Time
        6. 6.10.3.6 Global Constructors
      4. 6.10.4 Initialization Tables
    11. 6.11 Dual-State Interworking Under TIABI (Deprecated)
      1. 6.11.1 Level of Dual-State Support
      2. 6.11.2 Implementation
        1. 6.11.2.1 Naming Conventions for Entry Points
        2. 6.11.2.2 Indirect Calls
          1. 6.11.2.2.1 C Code Compiled for 16-BIS State: sum( )
          2. 6.11.2.2.2 16-Bit Assembly Program for
          3. 6.11.2.2.3 C Code Compiled for 32-BIS State: sum( )
          4. 6.11.2.2.4 32-Bit Assembly Program for
          5.        286
  8. 7Using Run-Time-Support Functions and Building Libraries
    1. 7.1 C and C++ Run-Time Support Libraries
      1. 7.1.1 Linking Code With the Object Library
      2. 7.1.2 Header Files
      3. 7.1.3 Modifying a Library Function
      4. 7.1.4 Support for String Handling
      5. 7.1.5 Minimal Support for Internationalization
      6. 7.1.6 Support for Time and Clock Functions
      7. 7.1.7 Allowable Number of Open Files
      8. 7.1.8 Nonstandard Header Files in the Source Tree
      9. 7.1.9 Library Naming Conventions
    2. 7.2 The C I/O Functions
      1. 7.2.1 High-Level I/O Functions
        1. 7.2.1.1 Formatting and the Format Conversion Buffer
      2. 7.2.2 Overview of Low-Level I/O Implementation
        1.       open
        2.       close
        3.       read
        4.       write
        5.       lseek
        6.       unlink
        7.       rename
      3. 7.2.3 Device-Driver Level I/O Functions
        1.       DEV_open
        2.       DEV_close
        3.       DEV_read
        4.       DEV_write
        5.       DEV_lseek
        6.       DEV_unlink
        7.       DEV_rename
      4. 7.2.4 Adding a User-Defined Device Driver for C I/O
        1. 7.2.4.1 Mapping Default Streams to Device
      5. 7.2.5 The device Prefix
        1.       add_device
        2.       321
        3. 7.2.5.1 Program for C I/O Device
    3. 7.3 Handling Reentrancy (_register_lock() and _register_unlock() Functions)
    4. 7.4 Library-Build Process
      1. 7.4.1 Required Non-Texas Instruments Software
      2. 7.4.2 Using the Library-Build Process
        1. 7.4.2.1 Automatic Standard Library Rebuilding by the Linker
        2. 7.4.2.2 Invoking mklib Manually
          1. 7.4.2.2.1 Building Standard Libraries
          2. 7.4.2.2.2 Shared or Read-Only Library Directory
          3. 7.4.2.2.3 Building Libraries With Custom Options
          4. 7.4.2.2.4 The mklib Program Option Summary
      3. 7.4.3 Extending mklib
        1. 7.4.3.1 Underlying Mechanism
        2. 7.4.3.2 Libraries From Other Vendors
  9. 8C++ Name Demangler
    1. 8.1 Invoking the C++ Name Demangler
    2. 8.2 Sample Usage of the C++ Name Demangler
  10.   A Glossary
    1.     A.1 Terminology
  11.   B Revision History
  12.   B Earlier Revisions

5.14 ARM Instruction Intrinsics

Assembly instructions can be generated using the intrinsics in the following tables. Table 5-3 shows which intrinsics are available on the different ARM targets. Table 5-4 shows the calling syntax for each intrinsic, along with the corresponding assembly instruction and a description. Additional intrinsices for getting and setting the CPSR register and to enable/disable interrupts are provided in Section 6.8.1.

Table 5-3 ARM Intrinsic Support by Target
C/C++ Compiler IntrinsicARM V5e (ARM9E)ARM V6 (ARM11)ARM V6M0 (Cortex-M0)ARM V7M3 (Cortex-M3)ARM V7M4 (Cortex-M4)ARM V7R (Cortex-R4)ARM V7A8 (Cortex-A8)
_ _clzyesyesyesyesyesyes
_ _delay_cyclesyesyesyesyes
_ _get_MSPyesyesyes
_ _get_PRIMASKyesyesyes
_ _ldrexyesyesyesyesyes
_ _ldrexbyesyesyesyesyes
_ _ldrexdyesyesyes
_ _ldrexhyesyesyesyesyes
_ _MCRyesyesyesyesyesyes
_ _MRCyesyesyesyesyesyes
_ _ nopyesyesyesyesyesyesyes
_normyesyesyesyesyesyes
_ _revyesyesyesyesyes
_ _rev16yesyesyesyesyes
_ _revshyesyesyesyesyes
_ _rbityesyesyesyes
_ _roryesyesyesyesyesyesyes
_pkhbtyesyesyesyes
_pkhtbyesyesyesyes
_qadd16yesyesyesyes
_qadd8yesyesyesyes
_qaddsubxyesyesyesyes
_qsub16yesyesyesyes
_qsub8yesyesyesyes
_qsubaddxyesyesyesyes
_saddyesyesyesyesyes
_sadd16yesyesyesyes
_sadd8yesyesyesyes
_saddsubxyesyesyesyes
_sdaddyesyesyesyesyes
_sdsubyesyesyesyesyes
_selyesyesyesyes
_ _set_MSPyesyesyes
_ _set_PRIMASKyesyesyes
_shadd16yesyesyesyes
_shadd8yesyesyesyes
_shsub16yesyesyesyes
_shsub8yesyesyesyes
_smacyesyesyesyesyes
_smlabbyesyesyesyesyes
_smlabtyesyesyesyesyes
_smladyesyesyesyes
_smladxyesyesyesyes
_smlalbbyesyesyesyesyes
_smlalbtyesyesyesyesyes
_smlaldyesyesyesyes
_smlaldxyesyesyesyes
_smlaltbyesyesyesyesyes
_smlalttyesyesyesyesyes
_smlatbyesyesyesyesyes
_smlattyesyesyesyesyes
_smlawbyesyesyesyesyes
_smlawtyesyesyesyesyes
_smlsdyesyesyesyes
_smlsdxyesyesyesyes
_smlsldyesyesyesyes
_smlsldxyesyesyesyes
_smmlayesyesyesyes
_smmlaryesyesyesyes
_smmlsyesyesyesyes
_smmlsryesyesyesyes
_smmulyesyesyesyes
_smmulryesyesyesyes
_smuadyesyesyesyes
_smuadxyesyesyesyes
_smusdyesyesyesyes
_smusdxyesyesyesyes
_smpyyesyesyesyesyes
_smsubyesyesyesyesyes
_smulbbyesyesyesyesyes
_smulbtyesyesyesyesyes
_smultbyesyesyesyesyes
_smulttyesyesyesyesyes
_smulwbyesyesyesyesyes
_smulwtyesyesyesyesyes
_ _sqrtyesyesyesyes
_ _sqrtfyesyesyesyesyes
_ssat16yesyesyesyes
_ssatayesyesyesyesyesyes
_ssatlyesyesyesyesyesyes
_ssubyesyesyesyesyes
_ssub16yesyesyesyes
_ssub8yesyesyesyes
_ssubaddxyesyesyesyes
_ _strexyesyesyesyesyes
_ _strexbyesyesyesyesyes
_ _strexdyesyesyes
_ _strexhyesyesyesyesyes
_subcyesyesyesyesyes
_sxtabyesyesyesyes
_sxtab16yesyesyesyes
_sxtahyesyesyesyes
_sxtbyesyesyesyesyesyes
_sxtb16yesyesyesyes
_sxthyesyesyesyesyesyes
_uadd16yesyesyesyes
_uadd8yesyesyesyes
_uaddsubxyesyesyesyes
_uhadd16yesyesyesyes
_uhadd8yesyesyesyes
_uhsub16yesyesyesyes
_uhsub8yesyesyesyes
_umaalyesyesyesyes
_uqadd16yesyesyesyes
_uqadd8yesyesyesyes
_uqaddsubxyesyesyesyes
_uqsub16yesyesyesyes
_uqsub8yesyesyesyes
_uqsubaddxyesyesyesyes
_usad8yesyesyesyes
_usat16yesyesyesyes
_usatayesyesyesyesyesyes
_usatlyesyesyesyesyesyes
_usub16yesyesyesyes
_usub8yesyesyesyes
_usubaddxyesyesyesyes
_uxtabyesyesyesyes
_uxtab16yesyesyesyes
_uxtahyesyesyesyes
_uxtbyesyesyesyesyesyes
_uxtb16yesyesyesyes
_uxthyesyesyesyesyesyes
_ _wfeyesyesyesyesyes
_ _wfiyesyesyesyesyes

Table 5-4 shows the calling syntax for each intrinsic, along with the corresponding assembly instruction and a description. See Table 5-3 for a list of which intrinsics are available on the different ARM targets. Additional intrinsices for getting and setting the CPSR register and to enable/disable interrupts are provided in Section 6.8.1.

Table 5-4 ARM Compiler Intrinsics
C/C++ Compiler IntrinsicAssembly
Instruction		Description
int count = _ _clz(int src );CLZcount , srcReturns the count of leading zeros.
void _ _delay_cycles( unsigned int cycles );variesDelays execution for the specified number of cycles. The number of cycles must be a constant.

The __delay_cycles intrinsic inserts code to consume precisely the number of specified cycles with no side effects. The number of cycles delayed must be a compile-time constant.

Note: Cycle timing is based on 0 wait states. Results vary with additional wait states. The implementation does not account for dynamic prediction. Lower delay cycle counts may be less accurate given pipeline flush behaviors.

unsigned int dst = _ _get_MSP(void );MRS dst, MSPReturns the current value of the Main Stack Pointer.
unsigned int dst = _ _get_PRIMASK(void );MRS dst, PRIMASKReturns the current value of the Priority Mask Register. If this value is 1, activation of all exceptions with configurable priority is prevented.
unsigned int dest = _ _ldrex(void* src );LDREXdst , srcLoads data from memory address containing word (32-bit) data
unsigned int dest= _ _ldrexb(void* src );LDREXBdst , srcLoads data from memory address containing byte data
unsigned long long dest = _ _ldrexd(void* src );LDREXDdst , srcLoads data from memory address with long long support
unsigned int dest = _ _ldrexh(void* src );LDREXHdst , srcLoads data from memory address containing halfword (16-bit) data
void __MCR (unsigned int coproc, unsigned int opc1, unsigned int src, unsigned int coproc_reg1, unsigned int coproc_reg2, unsigned int opc2);MCRcoproc, opc1, src, CR<coproc_reg1>, CR<coproc_reg2>, opc2Access the coprocessor registers
unsigned int __MRC(unsigned int coproc, unsigned int opc1, unsigned int coproc_reg1, unsigned int coproc_reg2, unsigned int opc2);MRCcoproc, opc1, src, CR<coproc_reg1>, CR<coproc_reg2>, opc2Access the coprocessor registers
void _ _nop( void );NOPPerform an instruction that does nothing.
int dst = _norm(int src );CLZ dst , srcCount leading zero bits. This intrinsic can be used when implementing integer normalization.
int dst = _pkhbt(int src1 , int src2 , int shift );PKHBTdst , src1 , src2 , #shiftCombine bottom halfword of src1 with shifted top halfword of src2
nt dst = _pkhtb(int src1 , int src2 , int shift );PKHTBdst , src1 , src2 , #shiftCombine top halfword of src1 with shifted bottom halfword of src2
int dst = _qadd16(int src1 , int src2 );QADD16dst , src1 , src2Performs two signed halfword saturated additions
int dst = _qadd8(int src1 , int src2 );QADD8dst , src1 , src2Performs four signed saturated 8-bit additions
int dst = _qaddsubx(int src1 , int src2 );QASXdst , src1 , src2Exchange halfwords of src2, perform signed saturated addition on the top halfwords and signed saturated subtraction on the bottom halfwords.
int dst = _qsub16(int src1 , int src2 );QSUB16dst , src1 , src2Performs two signed saturated halfword subtractions
int dst = _qsub8(int src1 , int src2 );QSUB8dst , src1 , src2Performs four signed saturated 8-bit subtractions
int dst = _qsubaddx(int src1 , int src2 );QSAXdst , src1 , src2Exchange halfwords of src2, perform signed saturated subtraction on top halfwords and signed saturated addition on bottom halfwords
int dst = _ _rbit(int src );RBITdst , srcReverses the bit order in a word.
int dst = _ _rev(int src );REVdst , srcReverses byte order in a word. That is, converts 32-bit data between big-endian and little-endian or vice versa.
int dst = _ _rev16(int src );REV16dst , srcReverses byte order in each byte in a word independently. That is, converts 16-bit data between big-endian and little-endian or vice versa.
int dst = _ _revsh(int src );REVSHdst , srcReverses byte order in the lower byte of a word, and extends the sign to 32 bits. That is, converts 16-bit signed data to 32-bit signed data, while also converting between big-endian and little-endian or vice versa.
int dst = _ _ror(int src , int shift );RORdst , src , shiftRotates the value to the right by the number of bits specified. Bits rotated off the right end are placed into empty bits on the left.
int dst =_sadd(int src1 , int src2 );QADDdst , src1 , src2Saturated add
int dst = _sadd16(int src1 , int src2 );SADD16 dst , src1 , src2Performs two signed halfword additions
int dst = _sadd8(int src1 , int src2 );SADD8dst , src1 , src2Performs four signed 8-bit additions
int dst = _saddsubx(int src1 , int src2 );SASXdst , src1 , src2Exchange halfwords of src2, add the top halfwords and subtract the bottom halfwords
int dst =_sdadd(int src1 , int src2 );QDADDdst , src1 , src2Saturated double-add
int dst =_sdsub(int src1 , int src2 );QDSUBdst , src1 , src2Saturated double-subtract
int dst = _sel(int src1 , int src2 );SELdst , src1 , src2Selects byte n from src1 if GE bit n is set or from src2 if GE bit n is not set, where n ranges from 0 to 3.
void _ _set_MSP(unsigned int src);MSR MSP,srcSets the value of the Main Stack Pointer to src.
unsigned int dst = _ _set_PRIMASK(unsigned int src);MRSdst , PRIMASK (optional)
MSR PRIMASK, src		Sets the Priority Mask Register to the src value and returns the value as it was prior to being set as dst. Setting this register to 1 prevents the activation of all exceptions with configurable priority.
int dst = _shadd16(int src1 , int src2 );SHADD16dst , src1 , src2Performs two signed halfword additions and halves the results
int dst = _shadd8(int src1 , int src2 );SHADD8 dst , src1 , src2Performs four signed 8-bit additions and halves the results
int dst = _shsub16(int src1 , int src2 );SHSUB16dst , src1 , src2Performs two signed halfword subtractions and halves the results
int dst = _shsub8int src1 , int src2 );SHSUB8dst , src1 , src2Performs four signed 8-bit subtractions and halves the results
int dst =_smac(int dst, int src1 , int src2 );SMULBB tmp , src1 , src2
QDADD dst, dst , tmp		Saturated multiply-accumulate
int dst =_smlabb(int dst , short src1 , short src2 );SMLABB dst , src1 , src2Signed multiply-accumulate bottom halfwords
int dst =_smlabt(int dst , short src1 , int src2 );SMLABT dst , src1 , src2Signed multiply-accumulate bottom and top halfwords
int dst _smlad(int src1 , int src2 , int acc );SMLADdst , src1 , src2 , accPerforms two signed 16-bit multiplications on the top and bottom halfwords of src1 and src2 and adds the results to acc.
int dst _smladx(int src1 , int src2 , int acc );SMLADXdst , src1 , src2 , accSame as _smlad except the halfwords in src2 are exchange before the multiplication.
long long dst =_smlalbb(long long dst , short src1 , short src2 );SMLALBB dstlo , dsthi , src1 , src2Signed multiply-long and accumulate bottom halfwords
long long dst =_smlalbt(long long dst , short src1 , int src2 );SMLALBT dstlo , dsthi , src1 , src2Signed multiply-long and accumulate bottom and top halfwords
long long dst _smlald(long long acc , int src1 , int src2 );SMLALDdst , src1 , src2Performs two 16-bit multiplication on the top and bottom halfwords of src1 and src2 and adds the results to the 64-bit acc operand
long long dst _smlaldx(long long acc , int src1 , int src2 );SMLALDX dst , src1 , src2Same as _smlald except the halfwords in src2 are exchanged.
long long dst =_smlaltb(long long dst , int src1 , short src2 );SMLALTB dstlo , dsthi , src1 , src2Signed multiply-long and accumulate top and bottom halfwords
long long dst =_smlaltt(long long dst , int src1 , int src2 );SMLALTT dstlo , dsthi , src1 , src2Signed multiply-long and accumulate top halfwords
int dst =_smlatb(int dst , int src1 , short src2 );SMLATB dst , src1 , src2Signed multiply-accumulate top and bottom halfwords
int dst =_smlatt(int dst , int src1 , int src2 );SMLATT dst , src1 , src2Signed multiply-accumulate top halfwords
int dst _smlawb(int src1 , short src2 , int acc );SMLAWB dst , src1 , src2Signed multiply-accumulate word and bottom halfword
int dst _smlawt(int src1 , short src2 , int acc );SMLAWT dst , src1 , src2Signed multiply-accumulate word and top halfword
int dst _smlsd(int src1 , int src2 , int acc );SMLSDdst , src1 , src2 , accPerforms two signed 16-bit multiplications on the top and bottom halfwords of src1 and src2 and adds the difference of the results to acc.
int dst _smlsdx(int src1 , int src2 , int acc );SMLSDXdst , src1 , src2 , accSame as _smlsd except the halfwords in src2 are exchange before the multiplication.
long long dst _smlsld(long long acc , int src1 , int src2 );SMLSLDdst , src1 , src2Performs two 16-bit multiplication on the top and bottom halfwords of src1 and src2 and adds the difference of the results to the 64-bit acc operand.
long long dst _smlsldx(long long acc , int src1 , int src2 );SMLSLDX dst , src1 , src2Same as _smlsld except the halfwords in src2 are exchanged.
int dst _smmla(int src1 , int src2 , int acc );SMMLAdst , src1 , src2 , accPerforms a signed multiplication on src1 and src2, extracts the most significant 32 bits of the result, and adds an accumulate value.
int dst _smmlar(int src1 , int src2 , int acc );SMMLARdst , src1 , src2 , accSame as _smmla execpt the result is rounded instead of being truncated.
int dst _smmls(int src1 , int src2 , int acc );SMMLSdst , src1 , src2 , accPerforms a signed multiplication on src1 and src2, subtracts the result from an accumulate value that is shifted left by 32 bits, and extracts the most significant 32 bits of the result of the subtraction.
int dst _smmlsr(int src1 , int src2 , int acc );SMMLSRdst , src1 , src2 , accSame as _smmls except the result is rounded instead of being truncated.
int dst _smmul(int src1 , int src2 , int acc );SMMULdst , src1 , src2 , accPerforms a signed 32-bit multiplication on src1 and src2 and extracts the most significant 32-bits of the result.
int dst _smmulr(int src1 , int src2 , int acc );SMMULRdst , src1 , src2 , accSame as _smmul except the result is rounded instead of being truncated.
int dst =_smpy(int src1 , int src2 );SMULBB dst , src1 , src2
QADD dst, dst , dst		Saturated multiply
int dst =_smsub(int src1 , int src2 );SMULBB tmp , src1 , src2
QDSUB dst, dst , tmp		Saturated multiply-subtract
int dst _smuad(int src1 , int src2 );SMUADdst , src1 , src2Performs two signed 16-bit multiplications on the top and bottom halfwords and adds the products.
int dst _smuadx(int src1 , int src2 );SMUADXdst , src1 , src2Same as _smuad except the halfwords in src2 are exchange before the multiplication.
int dst =_smulbb(int src1 , int src2 );SMULBB dst , src1 , src2Signed multiply bottom halfwords
int dst =_smulbt(int src1 , int src2 );SMULBT dst , src1 , src2Signed multiply bottom and top halfwords
int dst =_smultb(int src1 , int src2 );SMULTB dst , src1 , src2Signed multiply top and bottom halfwords
int dst =_smultt(int src1 , int src2 );SMULTT dst , src1 , src2Signed multiply top halfwords
int dst _smulwb(int src1 , short src2 , int acc );SMULWB dst , src1 , src2Signed multiply word and bottom halfword
int dst _smulwt(int src1 , short src2 , int acc );SMULWT dst , src1 , src2Signed multiply word and top halfword
int dst _smusd(int src1 , int src2 );SMUSDdst , src1 , src2Performs two signed 16-bit multiplications on the top and bottom halfwords and subtracts the products.
int dst _smusdx(int src1 , int src2 );SMUSDXdst , src1 , src2Same as _smusd except the halfwords in src2 are exchanged before the multiplication.
double __sqrt( double );VSQRTdst , src1Return the square root of the specified double. This intrinsic is directly replaced with the VSQRT instruction if --fp_mode=relaxed. If strict floating point mode is used, the function must also set an errno if a domain error occurs.
float __sqrtf( float );VSQRTdst , src1Return the square root of the specified float. This intrinsic is directly replaced with the VSQRT instruction if --fp_mode=relaxed. If strict floating point mode is used, the function must also set an errno if a domain error occurs.
int dst =_ssat16(int src , int bitpos );SSAT16dst , #bitposPerforms two halfword saturations to a selectable signed range specified by bitpos
int dst =_ssata(int src , int shift , int bitpos );SSAT dst , #bitpos, src, ASR #shiftRight shifts src and saturates to a selectable signed range specified by bitpos
int dst =_ssatl(int src , int shift , int bitpos );SSAT dst , #bitpos, src, LSL #shiftLeft shifts src and saturates to a selectable signed range specified by bitpos
int dst =_ssub(int src1 , int src2 );QSUBdst , src1 , src2Saturated subtract
int dst = _ssub16(int src1 , int src2 );SSUB16 dst , src1 , src2Performs two signed halfword subtractions
int dst = _ssub8(int src1 , int src2 );SSUB8dst , src1 , src2Performs four signed 8-bit subtractions
int dst = _ssubaddx(int src1 , int src2 );SSAXdst , src1 , src2Exchange halfwords of src2, subtract the top halfwords and add the bottom halfwords
int status = _ _strex(unsigned int src, void* dst );STREXstatus , src , destStores word (32-bit) data in memory address
int status = _ _strexb(unsigned char src, void* dst );STREXBstatus , src , destStores byte data in memory address
int status = _ _strexd(unsigned long long src, void* dst );STREXDstatus , src , destStores long long data in memory address
int status = _ _strexh(unsigned short src, void* dst );STREXHstatus , src , destStores halfword (16-bit) data in memory address
int dst = _subc(int src1 , int src2 );SUBCdst , src1 , src2Subtract with carry
int dst _sxtab(int src1 , int src2 , int rotamt );SXTABdst , src1 , src2 , ROR #rotamtExtracts an optionally rotated 8-bit value from src2 and sign extends it to 32 bits, then adds the value to src1. The rotation amount can be 0, 8, 16, or 24.
int dst _sxtab16(int src1 , int src2 , int rotamt );SXTAB16 dst , src1 , src2 , ROR #rotamtExtracts two optionally rotated 8-bit values from src2 and sign extends them to 16 bits each, then adds the values to the two 16-bit values in src1. The rotation amount should be 0, 8, 16, or 24.
int dst _sxtah(int src1 , int src2 , int rotamt );SXTAHdst , src1 , src2 , ROR #rotamtExtracts an optionally rotated 16-bit value from src2 and sign extends it to 32 bits, then adds the result to src1. The rotation amount can be 0, 8, 16, or 32.
int dst _sxtb(int src1 , int rotamt );SXTB dst , src1 , ROR #rotamtExtracts an optionally rotated 8-bit value from src1 and sign extends it to 32 bits. The rotation amount can be 0, 8, 16, or 24.
int dst _sxtb16(int src1 , int rotamt );SXTAB16 dst , src1 , ROR #rotamtExtracts two optionally rotated 8-bit values from src1 and sign extends them to 16-bits. The rotation amount can be 0, 8, 16, or 24.
int dst _sxth(int src1 , int rotamt );SXTHdst , src1 , ROR #rotamtExtracts an optionally rotated 16-bit value from src2 and sign extends it to 32 bits. The rotation amount can be 0, 8, 16, or 24.
int dst = _uadd16(int src1 , int src2 );UADD16 dst , src1 , src2Performs two unsigned halfword additions
int dst = _uadd8(int src1 , int src2 );UADD8dst , src1 , src2Performs four unsigned 8-bit additions
int dst = _uaddsubx(int src1 , int src2 );UASXdst , src1 , src2Exchange halfwords of src2, add the top halfwords and subtract the bottom halfwords
int dst = _uhadd16(int src1 , int src2 );UHADD16dst , src1 , src2Performs two unsigned halfword additions and halves the results
int dst = _uhadd8(int src1 , int src2 );UHADD8 dst , src1 , src2Performs four unsigned 8-bit additions and halves the results
int dst = _uhsub16(int src1 , int src2 );UHSUB16dst , src1 , src2Performs two unsigned halfword subtractions and halves the results
int dst = _uhsub8(int src1 , int src2 );UHSUB8 dst , src1 , src2Performs four unsigned 8-bit subtractions and halves the results
int dst = _umaal(long long acc , int src1 , int src2 );UMAALdst1 , dst2 , src1 , src2Performs an unsigned 32-bit multiplication on src1 and src2, then adds two unsigned 32-bit values in acc.
int dst = _uqadd16(int src1 , int src2 );UQADD16dst , src1 , src2Performs two unsigned halfword saturated additions
int dst = _uqadd8(int src1 , int src2 );UQADD8 dst , src1 , src2Performs four unsigned saturated 8-bit additions
int dst = _uqaddsubx(int src1 , int src2 );UQASXdst , src1 , src2Exchange halfwords of src2, perform unsigned saturated addition on the top halfwords and unsigned saturated subtraction on the bottom halfwords.
int dst = _uqsub16(int src1 , int src2 );UQSUB16dst , src1 , src2Performs two unsigned saturated halfword subtractions
int dst = _uqsub8(int src1 , int src2 );UQSUB8 dst , src1 , src2Performs four unsigned saturated 8-bit subtractions
int dst = _uqsubaddx(int src1 , int src2 );UQSAXdst , src1 , src2Exchange halfwords of src2, perform unsigned saturated subtraction on top halfwords and unsigned saturated addition on bottom halfwords
int dst = _usad8(int src1 , int src2 );USAD8dst , src1 , src2Performs four unsigned 8-bit subtractions, and adds the absolute value of the differences together.
int dst =_usat16(int src , int bitpos );USAT16 dst , #bitposPerforms two halfword saturations to a selectable unsigned range specified by bitpos
int dst =_usata(int src , int shift , int bitpos );USAT dst , #bitpos, src, ASR #shiftRight shifts src and saturates to a selectable unsigned range specified by bitpos
int dst =_usatl(int src , int shift , int bitpos );USAT dst , #bitpos, src, LSL #shiftLeft shifts src and saturates to a selectable unsigned range specified by bitpos
int dst = _usub16(int src1 , int src2 );USUB16 dst , src1 , src2Performs two unsigned halfword subtractions
int dst = _usub8(int src1 , int src2 );USUB8dst , src1 , src2Performs four unsigned 8-bit subtractions
int dst = _usubaddx(int src1 , int src2 );USAXdst , src1 , src2Exchange halfwords of src2, subtract the top halfwords and add the bottom halfwords
int dst _uxtab(int src1 , int src2 , int rotamt );UXTABdst , src1 , src2 , ROR #rotamtExtracts an optionally rotated 8-bit value from src2 and zero extends it to 32 bits, then adds the value to src1. The rotation amount can be 0, 8, 16, or 24.
int dst _uxtab16(int src1 , int src2 , int rotamt );UXTAB16 dst , src1 , src2 , ROR #rotamtExtracts two optionally rotated 8-bit values from src2 and zero extends them to 16 bits each, then adds the values to the two 16-bit values in src1. The rotation amount should be 0, 8, 16, or 24.
int dst _uxtah(int src1 , int src2 , int rotamt );UXTAHdst , src1 , src2 , ROR #rotamtExtracts an optionally rotated 16-bit value from src2 and zero extends it to 32 bits, then adds the result to src1. The rotation amount can be 0, 8, 16, or 32.
int dst _uxtb(int src1 , int rotamt );UXTBdst , src1 , ROR #rotamtExtracts an optionally rotated 8-bit value from src2 and zero extends it to 32 bits. The rotation amount can be 0, 8, 16, or 24.
int dst _uxtb16(int src1 , int rotamt );UXTB16dst , src1 , ROR #rotamtExtracts two optionally rotated 8-bit values from src1 and zero extends them to 16-bits. The rotation amount can be 0, 8, 16, or 24.
int dst _uxth(int src1 , int rotamt );UXTHdst , src1 , ROR #rotamtExtracts an optionally rotated 16-bit value from src2 and zero extends it to 32 bits. The rotation amount can be 0, 8, 16, or 24.
void _ _wfe( void );WFEWait for event. Save power by waiting for an exception or event..
void _ _wfi( void );WFIWait for interrupt. Enter standby, dormant or shutdown mode, where an interrupt is required to wake-up the processor.

In addition, the compiler supports many of the intrinsics described in the ARM C Language Extensions (ACLE) specification. These intrinsics are applicable for the Cortex-M and Cortex-R processor variants. The ACLE intrinsics are implemented in order to support the development of source code that can be compiled using ACLE-compliant compilers from multiple vendors for a variety of ARM processors. A number of the intrinsics are duplicates of intrinsics listed in the previous table but with slightly different names (such as one vs. two leading underscores).

The compiler does not support all of the ACLE intrinsics listed in the ACLE specification. For example, the __cls, __clsl, and __clsll ACLE intrinsics are not supported, because the CLS instruction is not available on the Cortex-M or Cortex-R architectures.

In order to use the ACLE intrinsics, your code must include the provided arm_acle.h header file. For details about the ACLE intrinsics, see the ACLE specification. For information about which ACLE intrinsics are supported, see the arm_acle.h file. Where applicable, the declarations of ACLE intrinsics that are not supported are enclosed in comments in that header file along with a brief explanation of why the intrinsic is not supported and a reference to the appropriate section in the ACLE specification where the intrinsic is described.