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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 SupportBare machine integer C
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If you are writing a program in C that does not use the library and is to run without any environment initialization, you must:
Re‑implement
__rt_raise(), because this error‑handling function can be called from numerous places within the compiled code.Not define
main()to avoid linking in the library initialization code.Write an assembly language veneer that establishes the register state required to run C. This veneer must branch to the entry function in your application.
Provide your own RW/ZI initialization code.
Ensure that your initialization veneer is executed by, for example, placing it in your reset handler.
Build your application using
‑‑fpu=noneand link it normally. The linker uses the appropriate C library variant to find any required compiler helper functions.
Many library facilities require __user_libspace for static data. Even without the initialization code activated by having a main() function, __user_libspace is created automatically and uses 96 bytes in the ZI segment. See The __user_libspace static data area for a description of the __user_libspace area.
| Copyright © 2007 ARM Limited. All rights reserved. | ARM DUI 0378A |
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