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Libraries and Floating Point Support Guide

Conventions and feedback The ARM C and C++ libraries Mandatory linkage with the C library C and C++ runtime libraries C and C++ library features Library heap usage requirements of the ARM C and C 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 libraries and the std namespace 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 Using the C library with an application Using the C and C++ libraries with an application Using $Sub$$ to mix semihosted and nonsemihosted I Using the libraries in a nonsemihosting environmen C++ exceptions in a non-semihosting environment Direct semihosting C library function dependencies Indirect semihosting C library function dependenci C library API definitions for targeting a differen Building an application without the C library Creating an application as bare machine C without Integer and floating-point compiler functions and Bare machine integer C Bare machine C with floating-point processing Customized C library startup code and access to C Program design when exploiting the C library Using low-level functions when exploiting the C li Using high-level functions when exploiting the C l Using malloc() when exploiting the C library Tailoring the C library to a new execution environ How C and C++ programs use the library functions Initialization of the execution environment and ex C++ initialization, construction and destruction Legacy support for C$$pi_ctorvec instead of .init_ 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 ISO8859-1 implementation Shift-JIS and UTF-8 implementation 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 Modification of memory management functions in the Avoiding the heap and heap-using library functions C library support for memory allocation functions Heap1, standard heap implementation Heap2, alternative heap implementation Using a heap implementation from bare machine C Stack pointer initialization and heap bounds Defining __initial_sp, __heap_base and __heap_limi Extending heap size at runtime Legacy support for __user_initial_stackheap() 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 Selecting real-time division in the ARM libraries 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 Persistence of C and C++ library names across rele Link time selection of C and C++ libraries Managing projects that have explicit C or C++ libr Compiler generated and library-resident helper fun C and C++ library naming conventions Using macro__ARM_WCHAR_NO_IO to disable FILE decla The ARM C micro-library Floating-point support

Libraries and Floating Point Support Guide

Definition of locale data blocks in the C library

Definition of locale data blocks in the C library

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, for example LC_CTYPE, LC_COLLATE, LC_MONETARY, LC_NUMERIC, and LC_TIME. You define each locale block in the same way with a _begin macro, some data macros, and an _end macro.

Show/hideBeginning the definition of a locale block

To begin defining your locale block, call the _begin macro. This macro takes two arguments, a prefix and the textual name, as follows:

LC_TYPE_begin prefix, name

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.

Show/hideSpecifying the data for a locale block

To specify the data for your locale block, call the macros for that locale type in the order specified for that particular locale type. The syntax is as follows:

LC_TYPE_function

Where:

TYPE

is one of the following:

  • CTYPE

  • COLLATE

  • MONETARY

  • NUMERIC

  • TIME.

function

is a specific function, table(), full_wctype(), or multibyte(), related to your locale data.

When specifying locale data, you must call the macro repeatedly for each respective function.

Show/hideEnding the definition of a locale block

To complete the definition of your locale data block, you call the _end macro. This macro takes no arguments, as follows:

LC_TYPE_end

where:

TYPE

is one of the following:

  • CTYPE

  • COLLATE

  • MONETARY

  • NUMERIC

  • TIME.

Show/hideExample 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:

Example 2. Fixed 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

Show/hideExample 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:

Example 3. Multiple locales

        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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