5. Nuclei C Runtime Library

• 5.1. About Nuclei C Runtime Library
• 5.2. Nuclei C Runtime Library for Nuclei Toolchain
  • 5.2.1. Usage
  • 5.2.2. zicfilp landing pad usage
  • 5.2.3. Big-endian usage
  • 5.2.4. Varieties
• 5.3. Quick start
  • 5.3.1. exit()
  • 5.3.2. Basic UART I/O functions (-lfileops_uart)
  • 5.3.3. Using Semihosting (-lfileops_semi)
  • 5.3.4. Using RTT (-lfileops_rtt)
  • 5.3.5. Thread-local storage
  • 5.3.6. Heap
• 5.4. Runtime support
  • 5.4.1. Getting to main() and then exit()
  • 5.4.2. Multithreaded protection for the heap
• 5.5. Using customized fileops
• 5.6. C library API
  • 5.6.1. <assert.h>
  • 5.6.2. <complex.h>
  • 5.6.3. <ctype.h>
  • 5.6.4. <errno.h>
  • 5.6.5. <fcntl.h>
  • 5.6.6. <fenv.h>
  • 5.6.7. <float.h>
  • 5.6.8. <iso646.h>
  • 5.6.9. <limits.h>
  • 5.6.10. <locale.h>
  • 5.6.11. <malloc.h>
  • 5.6.12. <math.h>
  • 5.6.13. <setjmp.h>
  • 5.6.14. <stdalign.h>
  • 5.6.15. <stdbool.h>
  • 5.6.16. <stddef.h>
  • 5.6.17. <stdint.h>
  • 5.6.18. <stdio.h>
  • 5.6.19. <stdlib.h>
  • 5.6.20. <string.h>
  • 5.6.21. <time.h>
  • 5.6.22. <unistd.h>
  • 5.6.23. <wchar.h>
  • 5.6.24. <wctype.h>
  • 5.6.25. <xlocale.h>
• 5.7. Compiler support API
  • 5.7.1. GNU library API
• 5.8. External function interface
  • 5.8.1. I/O functions
  • 5.8.2. Heap protection functions
  • 5.8.3. Error and assertion functions
  • 5.8.4. RTC functions
  • 5.8.5. Locale functions
• 5.9. Changelog
  • 5.9.1. Version 2026.10
  • 5.9.2. Version 2025.02
  • 5.9.3. Version 2024.06
  • 5.9.4. Version 2023.10
• 5.10. Known Issues
  • 5.10.1. Version 2026.10
  • 5.10.2. Version 2025.02
  • 5.10.3. Version 2024.06