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RealView Libraries and Floating Point Support Guide

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RealView Libraries and Floating Point Support Guide

Preface
Introduction
The C and C++ Libraries
About the C and C++ libraries
Features of the C and C++ libraries
Namespaces
Writing reentrant and thread‑safe code
Introduction to reentrancy and thread‑safety
Use of static data in the C libraries
The __user_libspace static data area
Managing locks in multithreaded applications
Using the ARM C libraries with a multithreaded app
Thread‑safety in the ARM C libraries
Thread‑safety in the ARM C++ libraries
Building an application with the C library
Using the libraries with an application
Building an application for a semihosted environme
Building an application for a non semihosting envi
Building an application without the C library
Integer and FP helper functions
Bare machine integer C
Bare machine C with floating‑point
Exploiting the C library
The standalone C library functions
Tailoring the C library to a new execution environ
How C and C++ programs use the library functions
__rt_entry
Exiting from the program
__rt_exit()
__rt_lib_init()
__rt_lib_shutdown()
Tailoring static data access
Tailoring locale and CTYPE using assembler macros
Selecting locale at link time
Selecting locale at runtime
Defining a locale block
LC_CTYPE data block
LC_COLLATE data block
LC_MONETARY data block
LC_NUMERIC data block
LC_TIME data block
_get_lconv()
localeconv()
setlocale()
_findlocale()
The lconv structure
Tailoring locale and CTYPE using C macros
Selecting locale at link time
Selecting locale at runtime
Macros and utility functions
_get_lc_ctype()
_get_lc_collate()
_get_lc_monetary()
_get_lc_numeric()
_get_lc_time()
_get_lconv()
localeconv()
setlocale()
_findlocale()
__LC_CTYPE_DEF
__LC_COLLATE_DEF
__LC_TIME_DEF
__LC_NUMERIC_DEF
__LC_MONETARY_DEF
__LC_INDEX_END
The lconv structure
Tailoring error signaling, error handling, and pro
_sys_exit()
errno
__rt_errno_addr()
__raise()
__rt_raise()
__default_signal_handler()
_ttywrch()
__rt_fp_status_addr()
Tailoring storage management
Avoiding the ARM‑supplied heap and heap‑using
Support for malloc
Tailoring the runtime memory model
The memory models
Controlling the runtime memory model
Writing your own memory model
__user_initial_stackheap()
__user_setup_stackheap()
__user_heap_extend()
__user_heap_extent()
__user_stack_cleanup_space()
__rt_heap_extend()
__rt_stack_postlongjmp()
Tailoring the input/output functions
Dependencies on low‑level functions
Target‑dependent input/output support functions
_sys_open()
_sys_close()
_sys_read()
_sys_write()
_sys_ensure()
_sys_flen()
_sys_seek()
_sys_istty()
_sys_tmpnam()
_sys_command_string()
#pragma import(_main_redirection)
Tailoring other C library functions
clock()
_clock_init()
time()
remove()
rename()
system()
getenv()
_getenv_init()
Selecting real‑time division
ISO implementation definition
ISO C library implementation definition
Standard C++ library implementation definition
C library extensions
atoll()
strtoll()
strtoull()
printf()
snprintf()
vsnprintf()
lldiv()
llabs()
wcstombs()
alloca()
strlcpy()
strlcat()
_fisatty()
__heapstats()
__heapvalid()
Library naming conventions
Placing ARM libraries
Helper libraries
Identifying library variants
The C Micro-library
Floating‑point Support

errno

2.9.2. errno

The C library errno variable is defined in the implicit static data area of the library. This area is identified by __user_libspace(). It occupies part of initial stack space used by the functions that established the runtime stack. The definition of errno is:

(*(volatile int *) __rt_errno_addr())

You can define __rt_errno_addr() if you want to place errno at a user‑defined location instead of the default location identified by __user_libspace(). Also, see The __user_libspace static data area.

Return

The default implementation is a veneer on __user_libspace() that returns the address of the status word. A suitable default definition is given in the C library standard headers.

Copyright © 2007 ARM Limited. All rights reserved.ARM DUI 0378A