2014-07-04 Bin Cheng <bin.cheng@arm.com>

        * README (--enable-newlib-nano-formatted-io): Describe.
        * acconfig.h (_NANO_FORMATTED_IO): Undef.
        * newlib.hin (_NANO_FORMATTED_IO): Undef.
        * configure.in (--enable-newlib-nano-formatted-io): New option.
        * configure: Regenerated.
        * libc/configure.in (--enable-newlib-nano-formatted-io): New option.
        * libc/configure: Regenerated.
        * libc/stdio/Makefile.am (NEWLIB_NANO_FORMATTED_IO): Support new
        configuration option.
        * libc/stdio/Makefile.in: Regenerated.
        * libc/stdio/asnprintf.c (_asniprintf_r, asniprintf): Use
        _NANO_FORMATTED_IO to declare alias prototypes.
        * libc/stdio/asprintf.c (_asiprintf_r, asiprintf): Ditto.
        * libc/stdio/dprintf.c (_diprintf_r, diprintf): Ditto.
        * libc/stdio/fprintf.c (_fiprintf_r, fiprintf): Ditto.
        * libc/stdio/fscanf.c (fiscanf, _fiscanf_r): Ditto.
        * libc/stdio/printf.c (_iprintf_r, iprintf): Ditto.
        * libc/stdio/scanf.c (iscanf, _iscanf_r): Ditto.
        * libc/stdio/snprintf.c (_sniprintf_r, sniprintf): Ditto.
        * libc/stdio/sprintf.c (_siprintf_r, siprintf): Ditto.
        * libc/stdio/sscanf.c (siscanf, _siscanf_r): Ditto.
        * libc/stdio/vasnprintf.c (_vasniprintf_r, vasniprintf): Ditto.
        * libc/stdio/vasprintf.c (vasiprintf, _vasiprintf_r): Ditto.
        * libc/stdio/vdprintf.c (_vdiprintf_r, vdiprintf): Ditto.
        * libc/stdio/vprintf.c (viprintf, _viprintf_r): Ditto.
        * libc/stdio/vscanf.c (viscanf, _viscanf_r): Ditto.
        * libc/stdio/vsnprintf.c (vsniprintf, _vsniprintf_r): Ditto.
        * libc/stdio/vsprintf.c (vsiprintf, _vsiprintf_r): Ditto.
        * libc/stdio/vsscanf.c (vsiscanf, _vsiscanf_r): Ditto.
        * libc/stdio/nano-vfprintf.c: New file.
        * libc/stdio/nano-vfprintf_float.c: New file.
        * libc/stdio/nano-vfprintf_i.c: New file.
        * libc/stdio/nano-vfprintf_local.h: New file.
        * libc/stdio/nano-vfscanf.c: New file.
        * libc/stdio/nano-vfscanf_float.c: New file.
        * libc/stdio/nano-vfscanf_i.c: New file.
        * libc/stdio/nano-vfscanf_local.h: New file.

1 files changed, 67 insertions, 0 deletions

diff --git a/newlib/README b/newlib/README
index adad87111..a3d915dda 100644
--- a/newlib/README
+++ b/newlib/README
@@ -372,6 +372,73 @@ One feature can be enabled by specifying `--enable-FEATURE=yes' or
      invoke clean-up functions such as _fini or global destructors.
      Disabled by default.
 
+`--enable-newlib-nano-formatted-io'
+     This builds NEWLIB with a special implementation of formatted I/O
+     functions, designed to lower the size of application on small systems
+     with size constraint issues.  This option does not affect wide-char
+     formatted I/O functions.  Some notes about the feature:
+      1) The non-wide-char formatted I/O functions only support the C89
+	 standard.  The only exception is the configuration option provides
+	 limited support for long double.  Internally, the nano formatted I/O
+	 functions use double so accuracy is only guaranteed to double
+	 precision.
+      2) Floating-point support is split out of the formatted I/O code into
+	 weak functions which are not linked by default.  Programs that need
+	 floating-point I/O support must explicitly request linking of one or
+	 both of the floating-point functions: _printf_float or _scanf_float.
+	 This can be done at link time using the -u option which can be passed
+	 to either gcc or ld.  The -u option forces the link to resolve those
+	 function references.  Floating-point format specifiers are recognized
+	 by default, but if the floating-point functions are not explicitly
+	 linked in, this may result in undefined behavior for programs that
+	 need floating-point I/O support.
+      3) Integer-only versions of the formatted I/O functions (the iprintf/
+	 iscanf family) simply alias their regular counter-parts.
+	 The affected functions are:
+
+	  diprintf vdiprintf
+
+	  siprintf fiprintf iprintf sniprintf asiprintf asniprintf
+
+	  siscanf fiscanf iscanf
+
+	  viprintf vfiprintf vsiprintf vsniprintf vasiprintf vasniprintf
+
+	  viscanf vfiscanf vsiscanf
+
+	  _diprintf_r _vdiprintf_r
+
+	  _siprintf_r _fiprintf_r _iprintf_r _sniprintf_r _asiprintf_r
+	  _asniprintf_r
+
+	  _siscanf_r _fiscanf_r _iscanf_r
+
+	  _viprintf_r _vfiprintf_r _vsiprintf_r _asniprintf_r _vasiprintf_r
+	  _vasniprintf_r
+
+	  _viscanf_r _vfiscanf_r _vsiscanf_r
+
+      4) As mentioned, the option does not affect wide-char formatted I/O.
+	 The following configuration options are ignored for non-wide-char
+	 formatted I/O functions, and can be thought of as disabled.
+
+	  enable-newlib-io-pos-args
+	  enable-newlib-io-c99-formats
+	  enable-newlib-io-long-long
+	  enable-newlib-io-long-double
+	  enable-newlib-mb
+
+	 Additionally, "enable/disable-newlib-io-float" is supported in
+	 this specific implementation, one can use "disable-newlib-io-float"
+	 to further reduce code size.  In this case, the floating-point
+	 specifiers will not be recognized or handled, and the -u option
+	 will not work either.
+
+      5) As a rule, no features from outside of C89 standard will be
+	 considered in this implementation.
+
+     Disabled by default.
+
 Running the Testsuite
 =====================