SPNU118Y September   1995  – February 2020

 

  1.   Read This First
    1.     About This Manual
    2.     How to Use This Manual
    3.     Notational Conventions
    4.     Related Documentation From Texas Instruments
    5.     Trademarks
  2. 1 Introduction to the Software Development Tools
    1. 1.1 Software Development Tools Overview
    2. 1.2 Tools Descriptions
  3. 2 Introduction to Object Modules
    1. 2.1 Object File Format Specifications
    2. 2.2 Executable Object Files
    3. 2.3 Introduction to Sections
      1. 2.3.1 Special Section Names
    4. 2.4 How the Assembler Handles Sections
      1. 2.4.1 Uninitialized Sections
      2. 2.4.2 Initialized Sections
      3. 2.4.3 User-Named Sections
      4. 2.4.4 Current Section
      5. 2.4.5 Section Program Counters
      6. 2.4.6 Subsections
      7. 2.4.7 Using Sections Directives
    5. 2.5 How the Linker Handles Sections
      1. 2.5.1 Combining Input Sections
      2. 2.5.2 Placing Sections
    6. 2.6 Symbols
      1. 2.6.1 Global (External) Symbols
      2. 2.6.2 Local Symbols
      3. 2.6.3 Weak Symbols
      4. 2.6.4 The Symbol Table
    7. 2.7 Symbolic Relocations
      1.      Example 1. Code That Generates Relocation Entries
    8. 2.8 Loading a Program
  4. 3 Program Loading and Running
    1. 3.1 Loading
      1. 3.1.1 Load and Run Addresses
      2. 3.1.2 Bootstrap Loading
        1. 3.1.2.1 Boot, Load, and Run Addresses
        2. 3.1.2.2 Primary Bootloader
        3. 3.1.2.3 Secondary Bootloader
        4. 3.1.2.4 Boot Table
        5. 3.1.2.5 Bootloader Routine
          1.        Example 1. Sample Secondary Bootloader Routine
    2. 3.2 Entry Point
    3. 3.3 Run-Time Initialization
      1. 3.3.1 The _c_int00 Function
      2. 3.3.2 RAM Model vs. ROM Model
        1. 3.3.2.1 Autoinitializing Variables at Run Time (--rom_model)
        2. 3.3.2.2 Initializing Variables at Load Time (--ram_model)
        3. 3.3.2.3 The --rom_model and --ram_model Linker Options
      3. 3.3.3 About Linker-Generated Copy Tables
        1. 3.3.3.1 BINIT
        2. 3.3.3.2 CINIT
    4. 3.4 Arguments to main
    5. 3.5 Run-Time Relocation
    6. 3.6 Additional Information
  5. 4 Assembler Description
    1. 4.1  Assembler Overview
    2. 4.2  The Assembler's Role in the Software Development Flow
    3. 4.3  Invoking the Assembler
    4. 4.4  Controlling Application Binary Interface
    5. 4.5  Naming Alternate Directories for Assembler Input
      1. 4.5.1 Using the --include_path Assembler Option
      2. 4.5.2 Using the TI_ARM_A_DIR Environment Variable
    6. 4.6  Source Statement Format
      1. 4.6.1 Label Field
      2. 4.6.2 Mnemonic Field
      3. 4.6.3 Operand Field
        1. 4.6.3.1 Operand Syntaxes for Instructions
        2. 4.6.3.2 Immediate Values as Operands for Directives
      4. 4.6.4 Comment Field
    7. 4.7  Literal Constants
      1. 4.7.1 Integer Literals
        1. 4.7.1.1 Binary Integer Literals
        2. 4.7.1.2 Octal Integer Literals
        3. 4.7.1.3 Decimal Integer Literals
        4. 4.7.1.4 Hexadecimal Integer Literals
        5. 4.7.1.5 Character Literals
      2. 4.7.2 Character String Literals
      3. 4.7.3 Floating-Point Literals
    8. 4.8  Assembler Symbols
      1. 4.8.1 Identifiers
      2. 4.8.2 Labels
      3. 4.8.3 Local Labels
        1.       Example 1. Local Labels of the Form $n
      4. 4.8.4 Symbolic Constants
      5. 4.8.5 Defining Symbolic Constants (--asm_define Option)
      6.      Example 2. Using Symbolic Constants Defined on Command Line
      7. 4.8.6 Predefined Symbolic Constants
      8. 4.8.7 Registers
      9. 4.8.8 Substitution Symbols
    9. 4.9  Expressions
      1. 4.9.1 Mathematical and Logical Operators
      2. 4.9.2 Relational Operators and Conditional Expressions
      3. 4.9.3 Well-Defined Expressions
      4. 4.9.4 Relocatable Symbols and Legal Expressions
      5. 4.9.5 Expression Examples
    10. 4.10 Built-in Functions and Operators
      1. 4.10.1 Built-In Math and Trigonometric Functions
    11. 4.11 Unified Assembly Language Syntax Support
    12. 4.12 Source Listings
    13. 4.13 Debugging Assembly Source
      1.      Example 3. Viewing Assembly Variables as C Types C Program
      2.      Example 4. Assembly Program for
    14. 4.14 Cross-Reference Listings
      1.      Example 5. An Assembler Cross-Reference Listing
  6. 5 Assembler Directives
    1. 5.1  Directives Summary
    2. 5.2  Directives that Define Sections
      1.      Example 1. Sections Directives
    3. 5.3  Directives that Change the Instruction Type
    4. 5.4  Directives that Initialize Values
    5. 5.5  Directives that Perform Alignment and Reserve Space
    6. 5.6  Directives that Format the Output Listings
    7. 5.7  Directives that Reference Other Files
    8. 5.8  Directives that Enable Conditional Assembly
    9. 5.9  Directives that Define Union or Structure Types
    10. 5.10 Directives that Define Enumerated Types
    11. 5.11 Directives that Define Symbols at Assembly Time
    12. 5.12 Miscellaneous Directives
    13. 5.13 Directives Reference
  7. 6 Macro Language Description
    1. 6.1  Using Macros
    2. 6.2  Defining Macros
      1.      Example 1. Macro Definition, Call, and Expansion
    3. 6.3  Macro Parameters/Substitution Symbols
      1.      Example 2. Calling a Macro With Varying Numbers of Arguments
      2. 6.3.1 Directives That Define Substitution Symbols
        1.       Example 3. The .asg Directive
        2.       Example 4. The .eval Directive
      3. 6.3.2 Built-In Substitution Symbol Functions
      4.      Example 5. Using Built-In Substitution Symbol Functions
      5. 6.3.3 Recursive Substitution Symbols
      6.      Example 6. Recursive Substitution
      7. 6.3.4 Forced Substitution
        1.       Example 7. Using the Forced Substitution Operator
      8. 6.3.5 Accessing Individual Characters of Subscripted Substitution Symbols
      9.      Example 8. Using Subscripted Substitution Symbols to Redefine an Instruction
      10.      Example 9. Using Subscripted Substitution Symbols to Find Substrings
      11. 6.3.6 Substitution Symbols as Local Variables in Macros
    4. 6.4  Macro Libraries
    5. 6.5  Using Conditional Assembly in Macros
      1.      Example 10. The .loop/.break/.endloop Directives
      2.      Example 11. Nested Conditional Assembly Directives
      3.      Example 12. Built-In Substitution Symbol Functions in a Conditional Assembly Code Block
    6. 6.6  Using Labels in Macros
      1.      Example 13. Unique Labels in a Macro
    7. 6.7  Producing Messages in Macros
      1.      Example 14. Producing Messages in a Macro
    8. 6.8  Using Directives to Format the Output Listing
    9. 6.9  Using Recursive and Nested Macros
      1.      Example 15. Using Nested Macros
      2.      Example 16. Using Recursive Macros
    10. 6.10 Macro Directives Summary
  8. 7 Archiver Description
    1. 7.1 Archiver Overview
    2. 7.2 The Archiver's Role in the Software Development Flow
    3. 7.3 Invoking the Archiver
    4. 7.4 Archiver Examples
      1.      Example 1. Archiver Command File
    5. 7.5 Library Information Archiver Description
      1. 7.5.1 Invoking the Library Information Archiver
      2. 7.5.2 Library Information Archiver Example
      3. 7.5.3 Listing the Contents of an Index Library
      4. 7.5.4 Requirements
  9. 8 Linker Description
    1. 8.1  Linker Overview
    2. 8.2  The Linker's Role in the Software Development Flow
    3. 8.3  Invoking the Linker
    4. 8.4  Linker Options
      1. 8.4.1  Wildcards in File, Section, and Symbol Patterns
      2. 8.4.2  Specifying C/C++ Symbols with Linker Options
      3. 8.4.3  Relocation Capabilities (--absolute_exe and --relocatable Options)
        1. 8.4.3.1 Producing an Absolute Output Module (--absolute_exe option)
        2. 8.4.3.2 Producing a Relocatable Output Module (--relocatable option)
        3. 8.4.3.3 Producing an Executable, Relocatable Output Module (-ar Option)
      4. 8.4.4  Allocate Memory for Use by the Loader to Pass Arguments (--arg_size Option)
      5. 8.4.5  Changing Encoding of Big-Endian Instructions
      6. 8.4.6  Compression (--cinit_compression and --copy_compression Option)
      7. 8.4.7  Compress DWARF Information (--compress_dwarf Option)
      8. 8.4.8  Control Linker Diagnostics
      9. 8.4.9  Automatic Library Selection (--disable_auto_rts Option)
      10. 8.4.10 Do Not Remove Unused Sections (--unused_section_elimination Option)
      11. 8.4.11 Linker Command File Preprocessing (--disable_pp, --define and --undefine Options)
      12. 8.4.12 Error Correcting Code Testing (--ecc Options)
      13. 8.4.13 Define an Entry Point (--entry_point Option)
      14. 8.4.14 Set Default Fill Value (--fill_value Option)
      15. 8.4.15 Generate List of Dead Functions (--generate_dead_funcs_list Option)
      16. 8.4.16 Define Heap Size (--heap_size Option)
      17. 8.4.17 Hiding Symbols
      18. 8.4.18 Alter the Library Search Algorithm (--library, --search_path, and TI_ARM_C_DIR )
        1. 8.4.18.1 Name an Alternate Library Directory (--search_path Option)
        2. 8.4.18.2 Name an Alternate Library Directory (TI_ARM_C_DIR Environment Variable)
        3. 8.4.18.3 Exhaustively Read and Search Libraries (--reread_libs and --priority Options)
      19. 8.4.19 Change Symbol Localization
        1. 8.4.19.1 Make All Global Symbols Static (--make_static Option)
      20. 8.4.20 Create a Map File (--map_file Option)
      21. 8.4.21 Managing Map File Contents (--mapfile_contents Option)
      22. 8.4.22 Disable Name Demangling (--no_demangle)
      23. 8.4.23 Disable Merging of Symbolic Debugging Information (--no_sym_merge Option)
      24. 8.4.24 Strip Symbolic Information (--no_symtable Option)
      25. 8.4.25 Name an Output Module (--output_file Option)
      26. 8.4.26 Prioritizing Function Placement (--preferred_order Option)
      27. 8.4.27 C Language Options (--ram_model and --rom_model Options)
      28. 8.4.28 Retain Discarded Sections (--retain Option)
      29. 8.4.29 Create an Absolute Listing File (--run_abs Option)
      30. 8.4.30 Scan All Libraries for Duplicate Symbol Definitions (--scan_libraries)
      31. 8.4.31 Define Stack Size (--stack_size Option)
      32. 8.4.32 Enforce Strict Compatibility (--strict_compatibility Option)
      33. 8.4.33 Mapping of Symbols (--symbol_map Option)
      34. 8.4.34 Generate Far Call Trampolines (--trampolines Option)
        1. 8.4.34.1 Advantages and Disadvantages of Using Trampolines
        2. 8.4.34.2 Minimizing the Number of Trampolines Required (--minimize_trampolines Option)
        3. 8.4.34.3 Making Trampoline Reservations Adjacent (--trampoline_min_spacing Option)
        4. 8.4.34.4 Carrying Trampolines From Load Space to Run Space
      35. 8.4.35 Introduce an Unresolved Symbol (--undef_sym Option)
      36. 8.4.36 Display a Message When an Undefined Output Section Is Created (--warn_sections)
      37. 8.4.37 Generate XML Link Information File (--xml_link_info Option)
      38. 8.4.38 Zero Initialization (--zero_init Option)
    5. 8.5  Linker Command Files
      1.      Example 1. Linker Command File
      2.      Example 2. Command File With Linker Directives
      3. 8.5.1  Reserved Names in Linker Command Files
      4. 8.5.2  Constants in Linker Command Files
      5. 8.5.3  Accessing Files and Libraries from a Linker Command File
      6. 8.5.4  The MEMORY Directive
        1. 8.5.4.1 Default Memory Model
        2. 8.5.4.2 MEMORY Directive Syntax
          1.        Example 3. The MEMORY Directive
        3. 8.5.4.3 Expressions and Address Operators
          1.        Example 4. Origin and Length as Expressions
        4. 8.5.4.4 The ALIAS Statement
      7. 8.5.5  The SECTIONS Directive
        1. 8.5.5.1 SECTIONS Directive Syntax
          1.        Example 5. The SECTIONS Directive
        2. 8.5.5.2 Section Allocation and Placement
          1. 8.5.5.2.1 Example: Placing Functions in RAM
          2. 8.5.5.2.2 Binding
          3. 8.5.5.2.3 Named Memory
          4. 8.5.5.2.4 Controlling Placement Using The HIGH Location Specifier
            1.         Example 6. Linker Placement With the HIGH Specifier
            2.         Example 7. Linker Placement Without HIGH Specifier
          5. 8.5.5.2.5 Alignment and Blocking
          6. 8.5.5.2.6 Alignment With Padding
        3. 8.5.5.3 Specifying Input Sections
          1.        Example 8. The Most Common Method of Specifying Section Contents
        4. 8.5.5.4 Using Multi-Level Subsections
        5. 8.5.5.5 Specifying Library or Archive Members as Input to Output Sections
          1.        Example 9. Archive Members to Output Sections
        6. 8.5.5.6 Allocation Using Multiple Memory Ranges
        7. 8.5.5.7 Automatic Splitting of Output Sections Among Non-Contiguous Memory Ranges
      8. 8.5.6  Placing a Section at Different Load and Run Addresses
        1. 8.5.6.1 Specifying Load and Run Addresses
        2. 8.5.6.2 Referring to the Load Address by Using the .label Directive
          1.        Example 10. Moving a Function from Slow to Fast Memory at Run Time
          2.        Example 11. Linker Command File for
      9. 8.5.7  Using GROUP and UNION Statements
        1. 8.5.7.1 Grouping Output Sections Together
          1.        Example 12. Allocate Sections Together
        2. 8.5.7.2 Overlaying Sections With the UNION Statement
          1.        Example 13. The UNION Statement
          2.        Example 14. Separate Load Addresses for UNION Sections
        3. 8.5.7.3 Using Memory for Multiple Purposes
        4. 8.5.7.4 Nesting UNIONs and GROUPs
          1.        Example 15. Nesting GROUP and UNION Statements
        5. 8.5.7.5 Checking the Consistency of Allocators
        6. 8.5.7.6 Naming UNIONs and GROUPs
      10. 8.5.8  Special Section Types (DSECT, COPY, NOLOAD, and NOINIT)
      11. 8.5.9  Configuring Error Correcting Code (ECC) with the Linker
        1. 8.5.9.1 Using the ECC Specifier in the Memory Map
        2. 8.5.9.2 Using the ECC Directive
        3. 8.5.9.3 Using the VFILL Specifier in the Memory Map
      12. 8.5.10 Assigning Symbols at Link Time
        1. 8.5.10.1 Syntax of Assignment Statements
        2. 8.5.10.2 Assigning the SPC to a Symbol
        3. 8.5.10.3 Assignment Expressions
        4. 8.5.10.4 Symbols Automatically Defined by the Linker
        5. 8.5.10.5 Assigning Exact Start, End, and Size Values of a Section to a Symbol
        6. 8.5.10.6 Why the Dot Operator Does Not Always Work
        7. 8.5.10.7 Address and Dimension Operators
          1. 8.5.10.7.1 Input Items
          2. 8.5.10.7.2 Output Section
          3. 8.5.10.7.3 GROUPs
          4. 8.5.10.7.4 UNIONs
        8. 8.5.10.8 LAST Operator
      13. 8.5.11 Creating and Filling Holes
        1. 8.5.11.1 Initialized and Uninitialized Sections
        2. 8.5.11.2 Creating Holes
        3. 8.5.11.3 Filling Holes
        4. 8.5.11.4 Explicit Initialization of Uninitialized Sections
    6. 8.6  Linker Symbols
      1. 8.6.1 Using Linker Symbols in C/C++ Applications
      2. 8.6.2 Declaring Weak Symbols
      3. 8.6.3 Resolving Symbols with Object Libraries
    7. 8.7  Default Placement Algorithm
      1.      Example 16. Default Allocation for ARM Devices
      2. 8.7.1 How the Allocation Algorithm Creates Output Sections
      3. 8.7.2 Reducing Memory Fragmentation
    8. 8.8  Using Linker-Generated Copy Tables
      1. 8.8.1 Using Copy Tables for Boot Loading
      2. 8.8.2 Using Built-in Link Operators in Copy Tables
      3. 8.8.3 Overlay Management Example
        1.       Example 17. Using a UNION for Memory Overlay
      4. 8.8.4 Generating Copy Tables With the table() Operator
        1.       Example 18. Produce Address for Linker Generated Copy Table
        2. 8.8.4.1 The table() Operator
        3. 8.8.4.2 Boot-Time Copy Tables
        4. 8.8.4.3 Using the table() Operator to Manage Object Components
          1.        Example 19. Linker Command File to Manage Object Components
        5. 8.8.4.4 Linker-Generated Copy Table Sections and Symbols
          1.        Example 20. Controlling the Placement of the Linker-Generated Copy Table Sections
        6. 8.8.4.5 Splitting Object Components and Overlay Management
          1.        Example 21. Creating a Copy Table to Access a Split Object Component
          2.        Example 22. Split Object Component Driver
      5. 8.8.5 Compression
        1. 8.8.5.1 Compressed Copy Table Format
        2. 8.8.5.2 Compressed Section Representation in the Object File
        3. 8.8.5.3 Compressed Data Layout
        4. 8.8.5.4 Run-Time Decompression
        5. 8.8.5.5 Compression Algorithms
      6. 8.8.6 Copy Table Contents
        1.       Example 23. ARM cpy_tbl.h File
      7. 8.8.7 General Purpose Copy Routine
        1.       Example 24. Run-Time-Support cpy_tbl.c File
    9. 8.9  Linker-Generated CRC Tables
      1. 8.9.1 The crc_table() Operator
      2. 8.9.2 Restrictions
      3. 8.9.3 Examples
        1.       Example 25. Using crc_table() Operator to Compute the CRC Value for .text Data
        2.       Example 26. Specifying an Algorithm in the crc_table() Operator
        3.       Example 27. Using a Single Table for Multiple Sections
        4.       Example 28. Applying the crc_table() Operator to a GROUP or UNION
      4. 8.9.4 Interface
        1.       Example 29. The CRC Table Header, crc_tbl.h
        2.       Example 30. General Purpose CRC Check Routine
      5. 8.9.5 A Note on the TMS570_CRC64_ISO Algorithm
    10. 8.10 Partial (Incremental) Linking
    11. 8.11 Linking C/C++ Code
      1. 8.11.1 Run-Time Initialization
      2. 8.11.2 Object Libraries and Run-Time Support
      3. 8.11.3 Setting the Size of the Stack and Heap Sections
      4. 8.11.4 Initializing and AutoInitialzing Variables at Run Time
      5. 8.11.5 Initialization of Cinit and Watchdog Timer Hold
    12. 8.12 Linker Example
      1.      Example 31. Linker Command File, demo.cmd
      2.      Example 32. Output Map File, demo.map
  10. 9 Absolute Lister Description
    1. 9.1 Producing an Absolute Listing
    2. 9.2 Invoking the Absolute Lister
    3. 9.3 Absolute Lister Example
      1.      Example 1. module1.lst
      2.      Example 2. module2.lst
  11. 10Cross-Reference Lister Description
    1. 10.1 Producing a Cross-Reference Listing
    2. 10.2 Invoking the Cross-Reference Lister
    3. 10.3 Cross-Reference Listing Example
      1.      Example 1. Cross-Reference Listing
  12. 11Object File Utilities
    1. 11.1 Invoking the Object File Display Utility
    2. 11.2 Invoking the Disassembler
      1.      Example 1. Object File memcpy32.asm
      2.      Example 2. Disassembly From memcpy32.asm
      3.      Example 3. Partial Copy Record Output With Different Load and Run Address
    3. 11.3 Invoking the Name Utility
    4. 11.4 Invoking the Strip Utility
  13. 12Hex Conversion Utility Description
    1. 12.1  The Hex Conversion Utility's Role in the Software Development Flow
    2. 12.2  Invoking the Hex Conversion Utility
      1. 12.2.1 Invoking the Hex Conversion Utility From the Command Line
      2. 12.2.2 Invoking the Hex Conversion Utility With a Command File
    3. 12.3  Understanding Memory Widths
      1. 12.3.1 Target Width
      2. 12.3.2 Specifying the Memory Width
      3. 12.3.3 Partitioning Data Into Output Files
    4. 12.4  The ROMS Directive
      1. 12.4.1 When to Use the ROMS Directive
      2. 12.4.2 An Example of the ROMS Directive
        1.       Example 1. A ROMS Directive Example
        2.       Example 2. Map File Output From Showing Memory Ranges
    5. 12.5  The SECTIONS Directive
    6. 12.6  The Load Image Format (--load_image Option)
      1. 12.6.1 Load Image Section Formation
      2. 12.6.2 Load Image Characteristics
    7. 12.7  Excluding a Specified Section
    8. 12.8  Assigning Output Filenames
    9. 12.9  Image Mode and the --fill Option
      1. 12.9.1 Generating a Memory Image
      2. 12.9.2 Specifying a Fill Value
      3. 12.9.3 Steps to Follow in Using Image Mode
    10. 12.10 Array Output Format
    11. 12.11 Building a Table for an On-Chip Boot Loader
      1. 12.11.1 Description of the Boot Table
      2. 12.11.2 The Boot Table Format
      3. 12.11.3 How to Build the Boot Table
        1. 12.11.3.1 Building the Boot Table
        2. 12.11.3.2 Leaving Room for the Boot Table
      4. 12.11.4 Booting From a Device Peripheral
      5. 12.11.5 Setting the Entry Point for the Boot Table
      6. 12.11.6 Using the ARM Boot Loader
        1.       Example 3. Sample Command File for Booting From 8-Bit SPI Boot
        2.       Example 4. Sample Command File for ARM 16-Bit Parallel Boot GP I/O
    12. 12.12 Using Secure Flash Boot on TMS320F2838x Devices
    13. 12.13 Controlling the ROM Device Address
    14. 12.14 Control Hex Conversion Utility Diagnostics
    15. 12.15 Description of the Object Formats
      1. 12.15.1 ASCII-Hex Object Format (--ascii Option)
      2. 12.15.2 Intel MCS-86 Object Format (--intel Option)
      3. 12.15.3 Motorola Exorciser Object Format (--motorola Option)
      4. 12.15.4 Extended Tektronix Object Format (--tektronix Option)
      5. 12.15.5 Texas Instruments SDSMAC (TI-Tagged) Object Format (--ti_tagged Option)
      6. 12.15.6 TI-TXT Hex Format (--ti_txt Option)
        1.       Example 5. TI-TXT Object Format
  14. 13Sharing C/C++ Header Files With Assembly Source
    1. 13.1 Overview of the .cdecls Directive
    2. 13.2 Notes on C/C++ Conversions
      1. 13.2.1  Comments
      2. 13.2.2  Conditional Compilation (#if/#else/#ifdef/etc.)
      3. 13.2.3  Pragmas
      4. 13.2.4  The #error and #warning Directives
      5. 13.2.5  Predefined symbol __ASM_HEADER__
      6. 13.2.6  Usage Within C/C++ asm( ) Statements
      7. 13.2.7  The #include Directive
      8. 13.2.8  Conversion of #define Macros
      9. 13.2.9  The #undef Directive
      10. 13.2.10 Enumerations
      11. 13.2.11 C Strings
      12. 13.2.12 C/C++ Built-In Functions
      13. 13.2.13 Structures and Unions
      14. 13.2.14 Function/Variable Prototypes
      15. 13.2.15 C Constant Suffixes
      16. 13.2.16 Basic C/C++ Types
    3. 13.3 Notes on C++ Specific Conversions
      1. 13.3.1 Name Mangling
      2. 13.3.2 Derived Classes
      3. 13.3.3 Templates
      4. 13.3.4 Virtual Functions
    4. 13.4 Special Assembler Support
      1. 13.4.1 Enumerations (.enum/.emember/.endenum)
      2. 13.4.2 The .define Directive
      3. 13.4.3 The .undefine/.unasg Directives
      4. 13.4.4 The $$defined( ) Built-In Function
      5. 13.4.5 The $$sizeof Built-In Function
      6. 13.4.6 Structure/Union Alignment and $$alignof( )
      7. 13.4.7 The .cstring Directive
  15.   A Symbolic Debugging Directives
    1.     A.1 DWARF Debugging Format
    2.     A.2 Debug Directive Syntax
  16.   B XML Link Information File Description
    1.     B.1 XML Information File Element Types
    2.     B.2 Document Elements
      1.      B.2.1 Header Elements
        1.       Example 1. Header Element for the hi.out Output File
      2.      B.2.2 Input File List
        1.       Example 2. Input File List for the hi.out Output File
      3.      B.2.3 Object Component List
        1.       Example 3. Object Component List for the fl-4 Input File
      4.      B.2.4 Logical Group List
        1.       Example 4. Logical Group List for the fl-4 Input File
      5.      B.2.5 Placement Map
        1.       Example 5. Placement Map for the fl-4 Input File
      6.      B.2.6 Far Call Trampoline List
        1.       Example 6. Fall Call Trampoline List for the fl-4 Input File
      7.      B.2.7 Symbol Table
        1.       Example 7. Symbol Table for the fl-4 Input File
  17.   C Hex Conversion Utility Examples
    1.     C.1 Scenario 1 -- Building a Hex Conversion Command File for a Single 8-Bit EPROM
      1.      Example 1. Linker Command File and Link Map for Scenario 1
      2.      Example 2. Hex Conversion Command File for Scenario 1
      3.      Example 3. Contents of Hex Map File example1.mxp
    2.     C.2 Scenario 2 -- Building a Hex Conversion Command File for 16-BIS Code
      1.      Example 4. Linker Command File for Scenario 2
      2.      Example 5. Hex Conversion Command File for Scenario 2
      3.      Example 6. Contents of Hex Map File example2.mxp
    3.     C.3 Scenario 3 -- Building a Hex Conversion Command File for Two 8-Bit EPROMs
      1.      Example 7. Linker Command File for Scenario 3
      2.      Example 8. Hex Conversion Command File for Scenario 3
      3.      Example 9. Contents of Hex Map File example3.mxp
  18.   D Glossary
    1.     D.1 Terminology
  19.   E Revision History
    1.     E.1 Recent Revisions

Example 13. The UNION Statement

SECTIONS { .text: load = SLOW_MEM UNION: run = FAST_MEM { .bss:part1: { file1.c.obj(.bss) } .bss:part2: { file2.c.obj(.bss) } } .bss:part3: run = FAST_MEM { globals.c.obj(.bss) } }

Allocation of a section as part of a union affects only its run address. Under no circumstances can sections be overlaid for loading. If an initialized section is a union member (an initialized section, such as .text, has raw data), its load allocation must be separately specified. See Example 14. (There is an exception to this rule when combining an initialized section with uninitialized sections; see Section 8.5.7.3.)