SPRAC71B February   2019  – October 2023

 

  1.   1
  2. 1 Introduction
    1. 1.1  ABIs for the C28x
    2. 1.2  Scope
    3. 1.3  ABI Variants
    4. 1.4  Toolchains and Interoperability
    5. 1.5  Libraries
    6. 1.6  Types of Object Files
    7. 1.7  Segments
    8. 1.8  C28x Architecture Overview
    9. 1.9  C28x Memory Models
    10. 1.10 Reference Documents
    11. 1.11 Code Fragment Notation
  3. 2 Data Representation
    1. 2.1 Basic Types
    2. 2.2 Data in Registers
    3. 2.3 Data in Memory
    4. 2.4 Pointer Types
    5. 2.5 Complex Types
    6. 2.6 Structures and Unions
    7. 2.7 Arrays
    8. 2.8 Bit Fields
      1. 2.8.1 Volatile Bit Fields
    9. 2.9 Enumeration Types
  4. 3 Calling Conventions
    1. 3.1 Call and Return
      1. 3.1.1 Call Instructions
        1. 3.1.1.1 Indirect Calls
        2. 3.1.1.2 Direct Calls
      2. 3.1.2 Return Instruction
      3. 3.1.3 Pipeline Conventions
      4. 3.1.4 Weak Functions
    2. 3.2 Register Conventions
      1. 3.2.1 Argument Registers
      2. 3.2.2 Callee-Saved Registers
    3. 3.3 Argument Passing
      1. 3.3.1 Passing 16-Bit Arguments
      2. 3.3.2 Passing Longer Arguments
      3. 3.3.3 C++ Argument Passing
      4. 3.3.4 Passing Structs and Unions
      5. 3.3.5 Stack Layout of Arguments Not Passed in Registers
      6. 3.3.6 Frame Pointer
    4. 3.4 Return Values
    5. 3.5 Structures and Unions Passed and Returned by Reference
    6. 3.6 Conventions for Compiler Helper Functions
    7. 3.7 Prolog and Epilog Helper Functions
    8. 3.8 Scratch Registers for Functions Already Seen
    9. 3.9 Interrupt Functions
  5. 4 Data Allocation and Addressing
    1. 4.1 Data Sections and Segments
    2. 4.2 Data Blocking
    3. 4.3 Addressing Modes
    4. 4.4 Allocation and Addressing of Static Data
      1. 4.4.1 Addressing Methods for Static Data
      2. 4.4.2 Placement Conventions for Static Data
        1. 4.4.2.1 Abstract Conventions for Addressing
      3. 4.4.3 Initialization of Static Data
    5. 4.5 Automatic Variables
    6. 4.6 Frame Layout
      1. 4.6.1 Stack Alignment
      2. 4.6.2 Register Save Order
    7. 4.7 Heap-Allocated Objects
  6. 5 Code Allocation and Addressing
    1. 5.1 Computing the Address of a Code Label
    2. 5.2 Calls
      1. 5.2.1 Direct Call
      2. 5.2.2 Far Call Trampoline
      3. 5.2.3 Indirect Calls
  7. 6 Helper Function API
    1. 6.1 Floating-Point Behavior
    2. 6.2 C Helper Function API
    3. 6.3 Floating-Point Helper Functions for C99
  8. 7 Standard C Library API
    1. 7.1  About Standard C Libraries
    2. 7.2  Reserved Symbols
    3. 7.3  <assert.h> Implementation
    4. 7.4  <complex.h> Implementation
    5. 7.5  <ctype.h> Implementation
    6. 7.6  <errno.h> Implementation
    7. 7.7  <float.h> Implementation
    8. 7.8  <inttypes.h> Implementation
    9. 7.9  <iso646.h> Implementation
    10. 7.10 <limits.h> Implementation
    11. 7.11 <locale.h> Implementation
    12. 7.12 <math.h> Implementation
    13. 7.13 <setjmp.h> Implementation
    14. 7.14 <signal.h> Implementation
    15. 7.15 <stdarg.h> Implementation
    16. 7.16 <stdbool.h> Implementation
    17. 7.17 <stddef.h> Implementation
    18. 7.18 <stdint.h> Implementation
    19. 7.19 <stdio.h> Implementation
    20. 7.20 <stdlib.h> Implementation
    21. 7.21 <string.h> Implementation
    22. 7.22 <tgmath.h> Implementation
    23. 7.23 <time.h> Implementation
    24. 7.24 <wchar.h> Implementation
    25. 7.25 <wctype.h> Implementation
  9. 8 C++ ABI
    1. 8.1  Limits (GC++ABI 1.2)
    2. 8.2  Export Template (GC++ABI 1.4.2)
    3. 8.3  Data Layout (GC++ABI Chapter 2)
    4. 8.4  Initialization Guard Variables (GC++ABI 2.8)
    5. 8.5  Constructor Return Value (GC++ABI 3.1.5)
    6. 8.6  One-Time Construction API (GC++ABI 3.3.2)
    7. 8.7  Controlling Object Construction Order (GC++ ABI 3.3.4)
    8. 8.8  Demangler API (GC++ABI 3.4)
    9. 8.9  Static Data (GC++ ABI 5.2.2)
    10. 8.10 Virtual Tables and the Key function (GC++ABI 5.2.3)
    11. 8.11 Unwind Table Location (GC++ABI 5.3)
  10. 9 Exception Handling
    1. 9.1  Overview
    2. 9.2  PREL31 Encoding
    3. 9.3  The Exception Index Table (EXIDX)
      1. 9.3.1 Pointer to Out-of-Line EXTAB Entry
      2. 9.3.2 EXIDX_CANTUNWIND
      3. 9.3.3 Inlined EXTAB Entry
    4. 9.4  The Exception Handling Instruction Table (EXTAB)
      1. 9.4.1 EXTAB Generic Model
      2. 9.4.2 EXTAB Compact Model
      3. 9.4.3 Personality Routines
    5. 9.5  Unwinding Instructions
      1. 9.5.1 Common Sequence
      2. 9.5.2 Byte-Encoded Unwinding Instructions
    6. 9.6  Descriptors
      1. 9.6.1 Encoding of Type Identifiers
      2. 9.6.2 Scope
      3. 9.6.3 Cleanup Descriptor
      4. 9.6.4 Catch Descriptor
      5. 9.6.5 Function Exception Specification (FESPEC) Descriptor
    7. 9.7  Special Sections
    8. 9.8  Interaction With Non-C++ Code
      1. 9.8.1 Automatic EXIDX Entry Generation
      2. 9.8.2 Hand-Coded Assembly Functions
    9. 9.9  Interaction With System Features
      1. 9.9.1 Shared Libraries
      2. 9.9.2 Overlays
      3. 9.9.3 Interrupts
    10. 9.10 Assembly Language Operators in the TI Toolchain
  11. 10DWARF
    1. 10.1 DWARF Register Names
    2. 10.2 Call Frame Information
    3. 10.3 Vendor Names
    4. 10.4 Vendor Extensions
  12. 11ELF Object Files (Processor Supplement)
    1. 11.1 Registered Vendor Names
    2. 11.2 ELF Header
    3. 11.3 Sections
      1. 11.3.1 Section Indexes
      2. 11.3.2 Section Types
      3. 11.3.3 Extended Section Header Attributes
      4. 11.3.4 Subsections
      5. 11.3.5 Special Sections
      6. 11.3.6 Section Alignment
    4. 11.4 Symbol Table
      1. 11.4.1 Symbol Types
      2. 11.4.2 Common Block Symbols
      3. 11.4.3 Symbol Names
      4. 11.4.4 Reserved Symbol Names
      5. 11.4.5 Mapping Symbols
    5. 11.5 Relocation
      1. 11.5.1 Relocation Types
        1. 11.5.1.1 Absolute Relocations
        2. 11.5.1.2 PC-Relative Relocations
        3. 11.5.1.3 Relocations in Data Sections
        4. 11.5.1.4 Relocations for C28x Instructions
        5. 11.5.1.5 Other Relocation Types
      2. 11.5.2 Relocation Operations
      3. 11.5.3 Relocation of Unresolved Weak References
  13. 12ELF Program Loading and Linking (Processor Supplement)
    1. 12.1 Program Header
      1. 12.1.1 Base Address
      2. 12.1.2 Segment Contents
      3. 12.1.3 Thread-Local Storage
    2. 12.2 Program Loading
  14. 13Build Attributes
    1. 13.1 About Build Attributes
    2. 13.2 C28x ABI Build Attribute Subsection
    3. 13.3 Build Attribute Tags
  15. 14Copy Tables and Variable Initialization
    1. 14.1 About Copy Tables
    2. 14.2 Copy Table Format
    3. 14.3 Compressed Data Formats
      1. 14.3.1 RLE
      2. 14.3.2 LZSS Format
    4. 14.4 Variable Initialization
  16. 15Revision History
    1.     188

6.2 C Helper Function API

The compiler generates calls to helper functions to perform operations that need to be supported by the compiler, but are not supported directly by the architecture, such as floating-point operations on devices that lack dedicated hardware. These helper functions must be implemented in the RTS library of any toolchain that conforms to the ABI.

Helper functions are named using the prefix _ _C28x_. Any identifier with this prefix is reserved for the ABI.

The helper functions adhere to the standard calling conventions.

The following tables specify the helper functions using C notation and syntax. The types in the table correspond to the generic data types specified in Section 2.1.

The functions in Table 6-1 perform various mathematical, logical, and comparison operations.

Table 6-1 TMS320C28x EABI Functions
SignatureDescription
__c28xabi_absllReturn the absolute value of a long long int.
__c28xabi_adddAdd two double-precision floating numbers.
__c28xabi_addfAdd two single-precision floating numbers.
__c28xabi_andllBitwise AND for two long long integer values.
__c28xabi_cmpdCompare two double-precision floating numbers.
__c28xabi_cmpfCompare two single-precision floating numbers.
__c28xabi_cmpllCompare two signed long long int values.
__c28xabi_cmpullCompare two unsigned long long int values.
__c28xabi_divdDivide two double-precision floating numbers.
__c28xabi_divfDivide two single-precision floating numbers.
__c28xabi_diviDivide two signed 16-bit integers.
__c28xabi_divlDivide two signed 32-bit integers.
__c28xabi_divllDivide two signed 64-bit long long integers.
__c28xabi_divuDivide two unsigned 16-bit integers.
__c28xabi_divulDivide two unsigned 32-bit integers.
__c28xabi_divullDivide two unsigned 64-bit long long integers.
__c28xabi_dtofConvert a double-precision floating number to a single-precision floating number.
__c28xabi_dtoiConvert a double-precision floating number to a signed 16-bit integer.
__c28xabi_dtolConvert a double-precision floating number to a signed 32-bit integer.
__c28xabi_dtollConvert a double-precision floating number to a signed 64-bit long long integer.
__c28xabi_dtouConvert a double-precision floating number to an unsigned 16-bit integer.
__c28xabi_dtoulConvert a double-precision floating number to an unsigned 32-bit integer.
__c28xabi_dtoullConvert a double-precision floating number to an unsigned 64-bit long long integer.
__c28xabi_ftodConvert a single-precision floating number to a double-precision floating number.
__c28xabi_ftoiConvert a single-precision floating number to a signed 16-bit integer.
__c28xabi_ftolConvert a single-precision floating number to a signed 32-bit integer.
__c28xabi_ftollConvert a single-precision floating number to a signed 64-bit long long integer.
__c28xabi_ftouConvert a single-precision floating number to an unsigned 16-bit integer.
__c28xabi_ftoulConvert a single-precision floating number to an unsigned 32-bit integer.
__c28xabi_ftoullConvert a single-precision floating number to an unsigned 64-bit long long integer.
__c28xabi_itodConvert a signed 16-bit integer to a double-precision floating number.
__c28xabi_itofConvert a signed 16-bit integer to a single-precision floating number.
__c28xabi_lltodConvert a signed 64-bit integer to a double-precision floating number.
__c28xabi_lltofConvert a signed 64-bit integer to a single-precision floating number.
__c28xabi_ltodConvert a signed 32-bit integer to a double-precision floating number.
__c28xabi_ltofConvert a signed 32-bit integer to a single-precision floating number.
__c28xabi_modiCompute the remainder of signed 16-bit division.
__c28xabi_modlCompute the remainder of signed 32-bit division.
__c28xabi_modllCompute the remainder of signed 64-bit long long integer division.
__c28xabi_moduCompute the remainder of unsigned 16-bit division.
__c28xabi_modulCompute the remainder of unsigned 32-bit division.
__c28xabi_modullCompute the remainder of unsigned 64-bit long long integer division.
__c28xabi_mpydMultiply two double-precision floating numbers.
__c28xabi_mpyfMultiply two single-precision floating numbers.
__c28xabi_mpyllMultiply two signed 64-bit long long integer.s
__c28xabi_negdNegate a double-precision floating number.
__c28xabi_negfNegate a single-precision floating number.
__c28xabi_orllBitwise OR for two long long integer values.
__c28xabi_subdSubtract one double-precision floating number from another.
__c28xabi_subfSubtract one single-precision floating number from another.
__c28xabi_ulltodConvert an unsigned 64-bit long long integer to a double-precision floating number.
__c28xabi_ulltofConvert an unsigned 64-bit long long integer to a single-precision floating number.
__c28xabi_ultodConvert an unsigned 32-bit integer to a double-precision floating number.
__c28xabi_ultofConvert an unsigned 32-bit integer to a single-precision floating number.
__c28xabi_utodConvert an unsigned 16-bit integer to a double-precision floating number.
__c28xabi_utofConvert an unsigned 16-bit integer to a single-precision floating number.
__c28xabi_xorllBitwise XOR for two long long integer values.