Add newlib-nano as companion lib

This allows building newlib-nano in addition to newlib and picolibc,
allowing users to select between C libraries within the same toolchain.

Signed-off-by: Keith Packard <keithp@keithp.com>

config/comp_libs/newlib-nano.in

@@ -0,0 +1,224 @@
+# newlib-nano options
+
+## depends on BARE_METAL
+
+## help Newlib-nano is a C library intended for use on embedded systems. It is a
+## help conglomeration of several library parts, all under free software
+## help licenses that make them easily usable on embedded products. Newlib-nano
+## help is only available in source form. It can be compiled for a wide
+## help array of processors, and will usually work on any architecture with
+## help the addition of a few low-level routines.
+
+# maybe older versions of newlib will support it too, but this
+# needs to be checked
+config NEWLIB_NANO_CXA_ATEXIT
+    def_bool y
+    depends on NEWLIB_NANO_2_0_or_later
+    select LIBC_PROVIDES_CXA_ATEXIT
+
+config NEWLIB_NANO_HAS_NANO_MALLOC
+    def_bool y
+    depends on NEWLIB_NANO_2_1_or_later
+
+config NEWLIB_NANO_HAS_NANO_FORMATTED_IO
+    def_bool y
+    depends on NEWLIB_NANO_2_2_or_later
+
+config LIBC_NEWLIB_NANO_TARGET_CFLAGS
+    string
+    prompt "Target CFLAGS for newlib"
+    default ""
+    help
+      Used to add specific options when compiling the target libraries
+      (eg. -ffunction-sections -fdata-sections), which can't be defined
+      in global TARGET_CFLAGS, because they shall be not used for the
+      gcc target libraries.
+      Note:  Both TARGET_CFLAGS and LIBC_NEWLIB_NANO_TARGET_CFLAGS are used
+             to compile the libraries.
+
+      Leave blank if you don't know better.
+
+config LIBC_NEWLIB_NANO_IO_C99FMT
+    bool
+    prompt "Enable IOs on C99 formats"
+    help
+      Enable support for IOs on C99 formats.
+
+config LIBC_NEWLIB_NANO_IO_LL
+    bool
+    prompt "Enable IOs on long long"
+    help
+      Enable support for IOs on long long integers.
+
+config LIBC_NEWLIB_NANO_IO_FLOAT
+    bool
+    prompt "Enable IOs on floats and doubles"
+    help
+      Enable support for IOs on floating point
+      values (float and double).
+
+config LIBC_NEWLIB_NANO_IO_LDBL
+    bool
+    prompt "Enable IOs on long doubles"
+    depends on LIBC_NEWLIB_NANO_IO_FLOAT
+    help
+      Enable support for IOs on long doubles.
+
+config LIBC_NEWLIB_NANO_IO_POS_ARGS
+    bool
+    prompt "Enable printf-family positional arg support"
+    help
+        Enable printf-family positional arg support.
+
+config LIBC_NEWLIB_NANO_FVWRITE_IN_STREAMIO
+    bool
+    prompt "Vector buffer mechanism to support stream IO buffering"
+    default y
+    help
+        NEWLIB implements the vector buffer mechanism to support stream IO
+        buffering required by C standard.  This feature is possibly
+        unnecessary for embedded systems which won't change file buffering
+        with functions like `setbuf' or `setvbuf'.  The buffering mechanism
+        still acts as default for STDIN/STDOUT/STDERR even if this option
+        is specified.
+
+config LIBC_NEWLIB_NANO_UNBUF_STREAM_OPT
+    bool
+    prompt "Optimize fprintf to unbuffered unix file"
+    help
+        NEWLIB does optimization when `fprintf to write only unbuffered unix
+        file'.  It creates a temorary buffer to do the optimization that
+        increases stack consumption by about `BUFSIZ' bytes. Disabling this option
+        disables the optimization and saves size of text and stack.
+
+config LIBC_NEWLIB_NANO_FSEEK_OPTIMIZATION
+    bool
+    prompt "Fseek optimisation"
+    help
+        Disabling fseek optimisation can decrease code size.
+
+config LIBC_NEWLIB_NANO_DISABLE_SUPPLIED_SYSCALLS
+    bool
+    prompt "Disable the syscalls supplied with newlib"
+    help
+      Disable the syscalls that come with newlib. You
+      will have to implement your own _sbrk, _read,
+      _write... If you plan to port newlib to a new
+      platform/board, say Yes.
+
+config LIBC_NEWLIB_NANO_REGISTER_FINI
+    bool
+    prompt "Enable finalization function registration using atexit"
+    help
+        Enable finalization function registration using atexit.
+
+config LIBC_NEWLIB_NANO_ATEXIT_DYNAMIC_ALLOC
+    bool
+    prompt "Enable dynamic allocation of atexit entries"
+    default y
+    help
+        Enable dynamic allocation of atexit entries.
+
+config LIBC_NEWLIB_NANO_GLOBAL_ATEXIT
+    bool
+    prompt "Enable atexit data structure as global variable"
+    default y
+    help
+        Enable atexit data structure as global variable.  By doing so it is
+        move out of _reent structure, and can be garbage collected if atexit
+        is not referenced.
+
+config LIBC_NEWLIB_NANO_LITE_EXIT
+    bool
+    prompt "Enable lite exit"
+    default y
+    help
+        Enable lite exit, a size-reduced implementation of exit that doesn't
+        invoke clean-up functions such as _fini or global destructors.
+
+config LIBC_NEWLIB_NANO_REENT_SMALL
+    bool
+    prompt "Enable small reentrant struct support"
+    default y
+    help
+        Enable small reentrant struct support.
+
+config LIBC_NEWLIB_NANO_MULTITHREAD
+    bool
+    prompt "Enable support for multiple threads"
+    default y
+    help
+        Enable support for multiple threads.
+
+config LIBC_NEWLIB_NANO_RETARGETABLE_LOCKING
+    bool
+    prompt "Enable retargetable locking"
+    help
+        Enable retargetable locking to allow the operating system to override
+        the dummy lock functions defined within the newlib.
+
+config LIBC_NEWLIB_NANO_EXTRA_SECTIONS
+    bool
+    prompt "Place each function & data element in their own section"
+    help
+        Place each function & data symbol in their own section. This allows
+        the linker to garbage collect unused symbols at link time.
+
+config LIBC_NEWLIB_NANO_WIDE_ORIENT
+    bool
+    prompt "Allow wide C99 stream orientation"
+    default n
+    help
+        C99 states that each stream has an orientation, wide or byte.  This
+        feature is possibly unnecessary for embedded systems which only do
+        byte input/output operations on stream. Disabling this feature can
+        decrease code size.
+
+config LIBC_NEWLIB_NANO_ENABLE_TARGET_OPTSPACE
+    bool
+    prompt "Optimize newlib for size"
+    default y
+    help
+      Pass --enable-target-optspace to newlib configure.
+
+      This will compile newlib with -Os.
+
+config LIBC_NEWLIB_NANO_LTO
+    bool
+    prompt "Enable Link Time Optimization"
+    depends on CC_GCC_USE_LTO
+    help
+      Builds the libraries with -flto to enable more aggressive link time
+      optimization. You will need to add -flto-partition=one to your
+      application's link line to keep the RETURN assembler macro together
+      with it's consumers.
+
+config LIBC_NEWLIB_NANO_NANO_MALLOC
+    bool
+    prompt "Enable Nano Malloc"
+    default y
+    depends on NEWLIB_NANO_HAS_NANO_MALLOC
+    help
+      NEWLIB has two implementations of malloc family's functions, one in
+      `mallocr.c' and the other one in `nano-mallocr.c'.  This options
+      enables the nano-malloc implementation, which is for small systems
+      with very limited memory.  Note that this implementation does not
+      support `--enable-malloc-debugging' any more.
+
+config LIBC_NEWLIB_NANO_NANO_FORMATTED_IO
+    bool
+    prompt "Enable Nano Formatted I/O"
+    default y
+    depends on NEWLIB_NANO_HAS_NANO_FORMATTED_IO
+    help
+      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.
+
+config LIBC_NEWLIB_NANO_EXTRA_CONFIG_ARRAY
+    string
+    prompt "Extra config for newlib"
+    default ""
+    help
+      Extra flags to pass onto ./configure when configuring the newlib.

packages/newlib-nano/3.3.0

@@ -0,0 +1 @@
+../newlib/3.3.0/

packages/newlib-nano/package.desc

@@ -0,0 +1,10 @@
+origin='RedHat'
+repository='git git://sourceware.org/git/newlib-cygwin.git'
+# Do not use "$(CT_Mirrors sourceware newlib)" here: the mirrors (kernel.org
+# and gnu.org) only store some older releases of newlib (2.0.0 and before).
+mirrors='ftp://sourceware.org/pub/newlib'
+milestones='2.0 2.1 2.2'
+relevantpattern='*.*|.*. *.*|.'
+archive_filename='newlib-@{version}'
+archive_dirname='newlib-@{version}'
+archive_formats='.tar.gz'

samples/arm-unknown-eabi/crosstool.config

@@ -8,3 +8,4 @@ CT_LIBC_NEWLIB_DISABLE_SUPPLIED_SYSCALLS=y
 CT_CC_LANG_CXX=y
 CT_COMP_LIBS_PICOLIBC=y
 CT_TARGET_CFLAGS="-ftls-model=local-exec"
+CT_COMP_LIBS_NEWLIB_NANO=y

scripts/build/companion_libs/350-newlib_nano.sh

@@ -0,0 +1,128 @@
+# This file adds functions to build the Newlib library using the 'nano' configuration
+# Copyright © 2021 Keith Packard
+# Licensed under the GPL v2 or later. See COPYING in the root of this package
+#
+# Edited by Keith Packard <keithp@keithp.com>
+#
+
+do_newlib_nano_get() { :; }
+do_newlib_nano_extract() { :; }
+do_newlib_nano_for_build() { :; }
+do_newlib_nano_for_host() { :; }
+do_newlib_nano_for_target() { :; }
+
+if [ "${CT_COMP_LIBS_NEWLIB_NANO}" = "y" ]; then
+
+# Download newlib_nano
+do_newlib_nano_get() {
+    CT_Fetch NEWLIB_NANO
+}
+
+do_newlib_nano_extract() {
+    CT_ExtractPatch NEWLIB_NANO
+}
+
+do_newlib_nano_for_target() {
+    local -a newlib_nano_opts
+    local cflags_for_target
+
+    CT_DoStep INFO "Installing Newlib Nano library"
+
+    CT_mkdir_pushd "${CT_BUILD_DIR}/build-newlib_nano-build-${CT_BUILD}"
+
+    CT_DoLog EXTRA "Configuring Newlib Nano library"
+
+    # Multilib is the default, so if it is not enabled, disable it.
+    if [ "${CT_MULTILIB}" != "y" ]; then
+        newlib_nano_opts+=("-Dmultilib=false")
+    fi
+
+    if [ "${CT_LIBC_NEWLIB_NANO_IO_FLOAT}" = "y" ]; then
+        newlib_opts+=( "--enable-newlib-io-float" )
+        if [ "${CT_LIBC_NEWLIB_NANO_IO_LDBL}" = "y" ]; then
+            newlib_opts+=( "--enable-newlib-io-long-double" )
+        else
+            newlib_opts+=( "--disable-newlib-io-long-double" )
+        fi
+    else
+        newlib_opts+=( "--disable-newlib-io-float" )
+        newlib_opts+=( "--disable-newlib-io-long-double" )
+    fi
+
+    if [ "${CT_LIBC_NEWLIB_NANO_DISABLE_SUPPLIED_SYSCALLS}" = "y" ]; then
+        newlib_opts+=( "--disable-newlib-supplied-syscalls" )
+    else
+        newlib_opts+=( "--enable-newlib-supplied-syscalls" )
+    fi
+
+    yn_args="IO_POS_ARGS:newlib-io-pos-args
+IO_C99FMT:newlib-io-c99-formats
+IO_LL:newlib-io-long-long
+REGISTER_FINI:newlib-register-fini
+NANO_MALLOC:newlib-nano-malloc
+NANO_FORMATTED_IO:newlib-nano-formatted-io
+ATEXIT_DYNAMIC_ALLOC:newlib-atexit-dynamic-alloc
+GLOBAL_ATEXIT:newlib-global-atexit
+LITE_EXIT:lite-exit
+REENT_SMALL:newlib-reent-small
+MULTITHREAD:newlib-multithread
+RETARGETABLE_LOCKING:newlib-retargetable-locking
+WIDE_ORIENT:newlib-wide-orient
+FSEEK_OPTIMIZATION:newlib-fseek-optimization
+FVWRITE_IN_STREAMIO:newlib-fvwrite-in-streamio
+UNBUF_STREAM_OPT:newlib-unbuf-stream-opt
+ENABLE_TARGET_OPTSPACE:target-optspace
+    "
+
+    for ynarg in $yn_args; do
+        var="CT_LIBC_NEWLIB_NANO_${ynarg%:*}"
+        eval var=\$${var}
+        argument=${ynarg#*:}
+
+
+        if [ "${var}" = "y" ]; then
+            newlib_opts+=( "--enable-$argument" )
+        else
+            newlib_opts+=( "--disable-$argument" )
+        fi
+    done
+
+    [ "${CT_LIBC_NEWLIB_NANO_EXTRA_SECTIONS}" = "y" ] && \
+        CT_LIBC_NEWLIB_NANO_TARGET_CFLAGS="${CT_LIBC_NEWLIB_NANO_TARGET_CFLAGS} -ffunction-sections -fdata-sections"
+
+    [ "${CT_LIBC_NEWLIB_NANO_LTO}" = "y" ] && \
+        CT_LIBC_NEWLIB_NANO_TARGET_CFLAGS="${CT_LIBC_NEWLIB_NANO_TARGET_CFLAGS} -flto"
+
+    cflags_for_target="${CT_ALL_TARGET_CFLAGS} ${CT_LIBC_NEWLIB_NANO_TARGET_CFLAGS}"
+
+    # Note: newlib handles the build/host/target a little bit differently
+    # than one would expect:
+    #   build  : not used
+    #   host   : the machine building newlib
+    #   target : the machine newlib runs on
+    CT_DoExecLog CFG                                               \
+    CC_FOR_BUILD="${CT_BUILD}-gcc"                                 \
+    CFLAGS_FOR_TARGET="${cflags_for_target}"                       \
+    AR_FOR_TARGET="`which ${CT_TARGET}-gcc-ar`"                    \
+    RANLIB_FOR_TARGET="`which ${CT_TARGET}-gcc-ranlib`"            \
+    ${CONFIG_SHELL}                                                \
+    "${CT_SRC_DIR}/newlib-nano/configure"                          \
+        --host=${CT_BUILD}                                         \
+        --target=${CT_TARGET}                                      \
+        --prefix=${CT_PREFIX_DIR}                                  \
+	--exec-prefix=${CT_PREFIX_DIR}/newlib-nano                 \
+	--libdir=${CT_PREFIX_DIR}/newlib-nano/${CT_TARGET}/lib     \
+        "${newlib_opts[@]}"                                        \
+        "${CT_LIBC_NEWLIB_NANO_EXTRA_CONFIG_ARRAY[@]}"
+
+    CT_DoLog EXTRA "Building Newlib Nano C library"
+    CT_DoExecLog ALL make ${CT_JOBSFLAGS}
+
+    CT_DoLog EXTRA "Installing Newlib Nano C library"
+    CT_DoExecLog ALL make install
+
+    CT_Popd
+    CT_EndStep
+}
+
+fi