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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

Definition of locale data blocks in the C library

1.9.3 Definition of locale data blocks in the C library

Locale data blocks let you customize your own locales.

The locale data blocks are defined using a set of assembly language macros provided in rt_locale.s. Therefore, the recommended way to define locale blocks is by writing an assembly language source file. The ARM® Compiler toolchain provides a set of macros for each type of locale data block. You define each locale block in the same way with a _begin macro, some data macros, and an _end macro.
LC_TYPE_begin prefix, name
Begins the definition of a locale block.
LC_TYPE_function
Specifies the data for a locale block.

Note

  • When specifying locale data, you must call the macro repeatedly for each respective function.
  • To specify the data for your locale block, call the macros for that locale type in the order specified for that particular locale type.
LC_TYPE_end
Ends the definition of a locale block.
Where:
TYPE
is one of the following:
  • CTYPE
  • COLLATE
  • MONETARY
  • NUMERIC
  • TIME
prefix
is the prefix for the assembler symbols defined within the locale data.
name
is the textual name for the locale data.
function
is a specific function, table(), full_wctype(), or multibyte(), related to your locale data.

Example of a fixed locale block

To write a fixed function that always returns the same locale, you can use the _start symbol name defined by the macros. The following shows how this is implemented for the CTYPE locale:
        GET rt_locale.s
        AREA my_locales, DATA, READONLY
        LC_CTYPE_begin my_ctype_locale, "MyLocale"
        ...                           ; include other LC_CTYPE_xxx macros here
        LC_CTYPE_end
        AREA my_locale_func, CODE, READONLY
    _get_lc_ctype FUNCTION
        LDR r0, =my_ctype_locale_start
        BX lr
        ENDFUNC

Example of multiple contiguous locale blocks

Contiguous locale blocks suitable for passing to the _findlocale() function must be declared in sequence. You must call the macro LC_index_end to end the sequence of locale blocks. The following shows how this is implemented for the CTYPE locale:
        GET rt_locale.s
        AREA my_locales, DATA, READONLY
    my_ctype_locales
        LC_CTYPE_begin my_first_ctype_locale, "MyLocale1"
        ...                           ; include other LC_CTYPE_xxx macros here
        LC_CTYPE_end
        LC_CTYPE_begin my_second_ctype_locale, "MyLocale2"
        ...                           ; include other LC_CTYPE_xxx macros here
        LC_CTYPE_end
        LC_index_end
        AREA my_locale_func, CODE, READONLY
        IMPORT _findlocale
    _get_lc_ctype FUNCTION
        LDR r0, =my_ctype_locales
        B _findlocale
        ENDFUNC
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