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

11.2 ELF Header

The ELF header provides a number of fields that guide interpretation of the file. Most of these are specified in the System V ELF specification. This section augments the base standard with specific details for the C28x.

e_indent

The 16-byte ELF identification field identifies the file as an object file and provides machine-independent data with which to decode and interpret the file's contents. Table 11-2 specifies the values to be used for C28x object files.

Table 11-2 ELF Identification Fields
IndexSymbolic ValueNumeric ValueComments
EI_MAG00x7fPer System V ABI
EI_MAG1EPer System V ABI
EI_MAG2LPer System V ABI
EI_MAG3FPer System V ABI
EI_CLASSELFCLASS32132-bit ELF
EI_DATAELFDATA2LSB1Little-endian
EI_VERSIONEV_CURRENT1
EI_ABIVERSION0

The EI_OSABI field shall be ELFOSABI_NONE unless overridden by the conventions of a specific platform. No platforms for the C28x family override the default setting of the EI_OSABI field; its value is always ELFOSABI_NONE.

e_type

There are currently no C28x-specific object file types. All values between ET_LOPROC and ET_HIPROC are reserved to future revisions of this specification.

e_machine

An object file conforming to this specification must have the value EM_TI_C2000 (141, 0x8D).

e_entry

The base ELF specification requires this field to be zero if an application does not have an entry point. Nonetheless, some applications may require an entry point of zero (for example, via the reset vector).

A platform standard may specify that an executable file always has an entry point, in which case e_entry specifies that entry point, even if zero.

e_flags

This member holds processor-specific flags associated with the file. There are no C28x-specific flags for e_flags field.