noc - Bare metal subset of standard C library

noc project

This project is inspired by projects like newlib, picolib, AVR-libc

However, design goals are different:

• Focused on embedded software for platforms with constraint resources
• Specifically avoid any OS integration within library, but rather require very limited set of functions
• Permissive license compatible with everything (so rewritten from scratch)
• Minimized third party dependencies
• C11 as development language
• Limited support of compilers, primarily clang and gcc
• UTF-8 only support for multibyte locale (TBD)
• Limited floating point support (TBD)

Building

On x86_64 library includes platform adaptation for Linux which is used for testing. To run tests make test

Following variables are used:

• ARCH defines architecture class (x86_64, riscv32, aarch64, etc)
• TARGET defines target triple to build (e.g. riscv32-unknown-unknown-elf)
• CC defines compiler to use (e.g. /usr/bin/clang)
• CFLAGS define compilation flags for gcc and clang
• CFLAGS_CLANG defines compilation flags specific for clang
• CFLAGS_CLANG_LD defines compilation flags specific for clang for linking
• CFLAGS_GCC defines compilation flags specific for gcc
• CFLAGS_GCC_LD defines compilation flags specific for gcc for linking
• AR name of ar to use (e.g. /usr/bin/llvm-ar-15)
• OBJDUMP name of objdump to use (e.g. /usr/bin/llvm-objdump-15)
• OBJDUMP_FLAGS specific flags to OBJDUMP
• PLATFORM_SOURCES list of platform specific sources to build for tests
• LD_SCRIPT specifies platform specific linker script for tests

Currently only limited targets are configured as example: make ARCH=riscv32, make ARCH=aarch64 You can provide additional rules in Makefile.toolchain or call make with abovementioned variables configured for your target.

Integration Requirements

Platform shall provide following functions:

• sbrk() - allocate memory
• putnstr() - print buffer to console. can be implemented on top of putchar()

Compiler should provide:

• stddef.h
• stdalign.h
• stdint.h
• stdbool.h
• stdarg.h

Supported architectures

• x86_64 (Native and Linux hosted, for testing)
• RISC-V (both 32- and 64- bit)
• ARM (32- and 64- bit)

Supported compilers

• GNU C 10+
• Clang 11+