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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

C and C++ library naming conventions

1.26 C and C++ library naming conventions

The library filename identifies how the variant was built.


The library naming convention described in this documentation applies to the current release of the ARM compilation tools. Do not rely on C and C++ library names. They might change in future releases.
Normally, you do not have to list any of the C and C++ libraries explicitly on the linker command line. The ARM linker automatically selects the correct C or C++ libraries to use, and it might use several, based on the accumulation of the object attributes.
The values for the fields of the filename, and the relevant build options are:
ARM C library.
C++ library for ARM.
ISO C and C++ basic runtime support.
Rogue Wave C++ library.
ARM C++ runtime libraries.
IEEE-compliant library with a fixed rounding mode (round to nearest) and no inexact exceptions.
IEEE-compliant library with a fixed rounding mode (round to nearest) and no exceptions.
--fpmode=fast or --fpmode=std.
Behaves like the fj library, but additionally flushes denormals and infinities to zero.
This library behaves like the ARM VFP in Fast mode. This is the default.
IEEE-compliant library with configurable rounding mode and all IEEE exceptions.
Compiler support (helper function) library.
Transcendental math functions.
Non ISO C-compliant ISO C micro-library basic runtime support.
Non IEEE 754 floating-point compliant micro-library support.
An ARM only library for use with ARMv4.
An ARM/Thumb interworking library for use with ARMv4T.
An ARM/Thumb interworking library for use with ARMv5T and later.
A Thumb only library for use with ARMv6-M.
A Thumb only library for use with ARMv7-M.
A combined ARM and Thumb library for use with Cortex-R series processors. You can prevent this library being selected using the linker option --no_thumb2_library.
A variant of the library for processors that have single-precision hardware floating-point only, such as Cortex-M4.
Uses VFP instruction set.
Soft VFP.


If none of v, m, or s are present in a library name, the library provides no floating-point support.
Position-independent access to static data.
FPIC addressing is enabled.


If neither e nor f is present in a library name, the library either:
  • Uses position-dependent access to static data. This is the case for the main C libraries with prefixes c or mc.
  • Does not access static data, or does so only with the help of the main C library. This is the case for fplib and mathlib libraries with prefixes fz, fj, f, g, mf, or m.
Compatible with the compiler option, --enum_is_int.
Indicates the size of wchar_t.When present, the library is compatible with the compiler option, --wchar32. Otherwise, it is compatible with --wchar16.
For example:


Not all variant/name combinations are valid. See the armlib and cpplib directories for the libraries that are supplied with the ARM Compiler.
The linker command-line option --info libraries provides information on every library that is automatically selected for the link stage.
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