3 Newlib  chapter
6 `Newlib`_ is a complete C library implementation written for the embedded
14    the Newlib as a precompiled library.
17 library functions in the Newlib. These hook functions are implemented in
18 :file:`lib/libc/newlib/libc-hooks.c` and translate the library internal system
21 Types of Newlib
24 The Newlib included in the :ref:`toolchain_zephyr_sdk` comes in two versions:
27 Full Newlib  argument
30 The Newlib full variant (:file:`libc.a` and :file:`libm.a`) is the most capable
31 variant of the Newlib available in the Zephyr SDK, and supports almost all
41 Nano Newlib  argument
44 The Newlib nano variant (:file:`libc_nano.a` and :file:`libm_nano.a`) is the
45 size-optimized version of the Newlib, and supports all features that the full
55 Note that the Newlib nano variant is not available for all architectures. The
59 .. _`Newlib`: https://sourceware.org/newlib/  target
64 Newlib supports all standard C formatted input and output functions, including
67 The Newlib formatted input and output function implementation supports all
73 * C99 format specifiers are not supported in the Newlib nano variant (i.e.
80 Newlib implements an internal heap allocator to manage the memory blocks used
84 The internal heap allocator implemented by the Newlib may vary across the
85 different types of the Newlib used. For example, the heap allocator implemented
86 in the Full Newlib (:file:`libc.a` and :file:`libm.a`) of the Zephyr SDK
88 higher minimum memory requirement compared to that of the Nano Newlib
91 The only interface between the Newlib dynamic memory management functions and
93 Newlib to manage the size of the memory pool reserved for its internal heap
97 the memory pool size change requests from the Newlib and ensures that the
98 Newlib internal heap allocator memory pool size does not exceed the amount of
101 When userspace is enabled, the Newlib internal heap allocator memory pool is
105 The amount of memory space available for the Newlib heap depends on the system
109   memory space reserved for the Newlib heap is set by the size of the free
116   set to a non-zero value), the amount of memory space reserved for the Newlib
119 * Otherwise, the amount of memory space reserved for the Newlib heap is equal
123 Newlib are thread safe and may be simultaneously called by multiple threads.