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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__user_setup_stackheap()
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| Home > The C and C++ Libraries > Tailoring the runtime memory model > __user_setup_stackheap() | |||
__user_setup_stackheap() returns the locations of the initial stack and heap in the same way as __user_initial_stackheap() (see __user_initial_stackheap()). You can re‑implement either one of these functions as necessary.
__user_setup_stackheap() returns the:
heap base in
r0stack base in
spheap limit in
r2stack limit in
r3.
Unlike __user_initial_stackheap(), __user_setup_stackheap() works with systems where the application starts with a value of sp (r13) that is already correct, for example, Cortex‑M3. To make use of sp, implement __user_setup_stackheap() to set up r0, r2, and r3 (for a two‑region model) and return. For a one‑region model, set only r0.
When __user_setup_stackheap() is called, sp has the same value it had on entry to the application. If this value is not valid then __user_setup_stackheap() must change the value of sp before using any stack.
Using __user_setup_stackheap() rather than __user_initial_stackheap() improves code size because there is no requirement for a temporary stack.
Note
__user_setup_stackheap() must be re‑implemented in assembler.
| Copyright © 2007 ARM Limited. All rights reserved. | ARM DUI 0378A |
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