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Libraries and Floating Point Support Guide

Preface The ARM C and C++ Libraries Mandatory linkage with the C library C and C++ runtime libraries Summary of the C and C++ runtime libraries Compliance with the Application Binary Interface ( Increasing portability of object files to other CL ARM C and C++ library directory structure Selection of ARM C and C++ library variants based Thumb C libraries C and C++ library features C++ and C libraries and the std namespace Multithreaded support in ARM C libraries ARM C libraries and multithreading ARM C libraries and reentrant functions ARM C libraries and thread-safe functions Use of static data in the C libraries Use of the __user_libspace static data area by the C library functions to access subsections of the _ Re-implementation of legacy function __user_libspa Management of locks in multithreaded applications How to ensure re-implemented mutex functions are c Using the ARM C library in a multithreaded environ Thread safety in the ARM C library Thread safety in the ARM C++ library The floating-point status word in a multithreaded Support for building an application with the C lib Using the C library with an application Using the C and C++ libraries with an application Using $Sub$$ to mix semihosted and nonsemihosted I Using the libraries in a nonsemihosting environmen C++ exceptions in a non-semihosting environment Direct semihosting C library function dependencies Indirect semihosting C library function dependenci C library API definitions for targeting a differen Support for building an application without the C Building an application without the C library Creating an application as bare machine C without Integer and floating-point compiler functions and Bare machine integer C Bare machine C with floating-point processing Customized C library startup code and access to C Using low-level functions when exploiting the C li Using high-level functions when exploiting the C l Using malloc() when exploiting the C library Tailoring the C library to a new execution environ Initialization of the execution environment and ex C++ initialization, construction and destruction Exceptions system initialization Emergency buffer memory for exceptions Library functions called from main() Program exit and the assert macro Assembler macros that tailor locale functions in t Link time selection of the locale subsystem in the Runtime selection of the locale subsystem in the C Definition of locale data blocks in the C library LC_CTYPE data block LC_COLLATE data block LC_MONETARY data block LC_NUMERIC data block LC_TIME data block Modification of C library functions for error sign Stack and heap memory allocation and the ARM C and Library heap usage requirements of the ARM C and C Choosing a heap implementation for memory allocati Stack pointer initialization and heap bounds Legacy support for __user_initial_stackheap() Avoiding the heap and heap-using library functions Tailoring input/output functions in the C and C++ Target dependencies on low-level functions in the The C library printf family of functions The C library scanf family of functions Redefining low-level library functions to enable d The C library functions fread(), fgets() and gets( Re-implementing __backspace() in the C library Re-implementing __backspacewc() in the C library Redefining target-dependent system I/O functions i Tailoring non-input/output C library functions Real-time integer division in the ARM libraries ISO C library implementation definition How the ARM C library fulfills ISO C specification mathlib error handling ISO-compliant implementation of signals supported ISO-compliant C library input/output characteristi Standard C++ library implementation definition C library functions and extensions Compiler generated and library-resident helper fun C and C++ library naming conventions Using macro__ARM_WCHAR_NO_IO to disable FILE decla Using library functions with execute-only memory The ARM C Micro-library Floating-point Support The C and C++ Library Functions reference Floating-point Support Functions Reference

Program exit and the assert macro

1.8.6 Program exit and the assert macro

A program can exit normally at the end of main() or it can exit prematurely because of an error. The behavior of the assert macro depends on a number of conditions:

  1. If the NDEBUG macro is defined (on the command line or as part of a source file), the assert macro has no effect.
  2. If the NDEBUG macro is not defined, the assert expression (the expression given to the assert macro) is evaluated. If the result is TRUE, that is != 0, the assert macro has no more effect.
  3. If the assert expression evaluates to FALSE, the assert macro calls the __aeabi_assert() function if any of the following are true:
    • You are compiling with --strict.
    • You are using -O0 or -O1.
    • __OPT_SMALL_ASSERT is defined.
    • __ASSERT_MSG is defined.
    • _AEABI_PORTABILITY_LEVEL is defined and not 0.
  4. If the assert expression evaluates to FALSE and the conditions specified in point 3 do not apply, the assert macro calls abort(). Then:
    1. abort() calls __rt_raise().
    2. If __rt_raise() returns, abort() tries to finalize the library.
If you are creating an application that does not use the library, __aeabi_assert() works if you re-implement abort() and the stdio functions.
Another solution for retargeting is to re-implement the __aeabi_assert() function itself. The function prototype is:
void __aeabi_assert(const char *expr, const char *file, int line);
  • expr points to the string representation of the expression that was not TRUE.
  • file and line identify the source location of the assertion.
The behavior for __aeabi_assert() supplied in the ARM C library is to print a message on stderr and call abort().
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