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"tiny" printf is derived from _vfprintf_r in libc/stdio/nano-vfprintf.c.
"tiny" puts has been implemented so that it just calls write, without
any other processing.
Support for buffering, reentrancy and streams has been removed from
these functions to achieve reduced code size.
This reduced code size implementation of printf and puts can be enabled
in an application by passing "--wrap printf" and "--wrap puts" to the
GNU linker. This will replace references to "printf" and "puts" in user
code with "__wrap_printf" and "__wrap_puts" respectively.
If there is no implementation of these __wrap* functions in user code,
these "tiny" printf and puts implementations will be linked into the
final executable.
The wrapping mechanism is supposed to be invisible to the user:
- A GCC wrapper option such as "-mtiny-printf" will be added to alias
these wrap commands.
- If the user is unaware of the "tiny" implementation, and chooses to
implement their own __wrap_printf and __wrap_puts, their own
implementation will be automatically chosen over the "tiny" printf and
puts from the library.
Newlib must be configured with --enable-newlib-nano-formatted-io for
the "tiny" printf and puts functions to be built into the library.
Code size reduction examples:
printf("Hello World\n")
baseline - msp430-elf-gcc gcc-8_3_0-release
text data bss
5638 214 26
"tiny" puts enabled
text data bss
714 90 20
printf("Hello %d\n", a)
baseline - msp430-elf-gcc gcc-8_3_0-release
text data bss
10916 614 28
"tiny" printf enabled
text data bss
4632 280 20
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.