SLAU646F September   2015  – June 2020

 

  1.   Read This First
    1.     How to Use This User's Guide
    2.     Related Documentation
    3.     If You Need Assistance
    4.     Trademarks
  2. 1Introduction
  3. 2Installing MSP430 GCC Toolchain
    1. 2.1 Installing MSP430 GCC in CCS Releases Before v7.2
    2. 2.2 Installing MSP430 GCC as Stand-Alone Package
  4. 3Using MSP430 GCC Within CCS
    1. 3.1 Create New Project
    2. 3.2 Debug Using MSP-FET, MSPFET430UIF, eZ-FET, eZ430
    3. 3.3 Build Options for MSP430 GCC
      1. 3.3.1  GNU Compiler
      2. 3.3.2  GNU Compiler: Runtime
      3. 3.3.3  GNU Compiler: Symbols
      4. 3.3.4  GNU Compiler: Directories
      5. 3.3.5  GNU Compiler: Optimization
      6. 3.3.6  GNU Compiler: Preprocessor
      7. 3.3.7  GNU Compiler: Assembler
      8. 3.3.8  GNU Compiler: Debugging
      9. 3.3.9  GNU Compiler: Diagnostic Options
      10. 3.3.10 GNU Compiler: Miscellaneous
      11. 3.3.11 GNU Linker
      12. 3.3.12 GNU Linker: Basic
      13. 3.3.13 GNU Linker: Libraries
      14. 3.3.14 GNU Linker: Symbols
      15. 3.3.15 GNU Linker: Miscellaneous
      16. 3.3.16 GNU Objcopy Utility
    4. 3.4 CCS Compared to MSP430 GCC
  5. 4MSP430 GCC Stand-Alone Package
    1. 4.1 MSP430 GCC Stand-Alone Package Folder Structure
    2. 4.2 Package Content
    3. 4.3 MSP430 GCC Options
    4. 4.4 MSP430 Built-in Functions
    5. 4.5 Using MSP430 GCC Support Files
    6. 4.6 Quick Start: Blink the LED
      1. 4.6.1 Building with a Makefile
      2. 4.6.2 Building Manually with gcc
      3. 4.6.3 Debugging
        1. 4.6.3.1 Starting GDB Agent
          1. 4.6.3.1.1 Using the GUI
          2. 4.6.3.1.2 Using the Command Line
        2. 4.6.3.2 Debugging With GDB
          1. 4.6.3.2.1 Running a Program in the Debugger
          2. 4.6.3.2.2 Setting a Breakpoint
          3. 4.6.3.2.3 Single Stepping
          4. 4.6.3.2.4 Stopping or Interrupting a Running Program
      4. 4.6.4 Creating a New Project
    7. 4.7 GDB Settings
      1. 4.7.1 Console Application
      2. 4.7.2 Optional Parameters for msp430.dat
      3. 4.7.3 GUI Application
      4. 4.7.4 Attaching the Debugger
      5. 4.7.5 Configuring the Target Voltage
      6. 4.7.6 Resetting the Target
      7. 4.7.7 Halting the Target
  6. 5MSP430 GCC Features
    1. 5.1 C/C++ Attributes
      1. 5.1.1 GCC Function Attribute Support
      2. 5.1.2 GCC Data Attribute Support
      3. 5.1.3 GCC Section Attribute Support
    2. 5.2 Hints for Reducing the Size of MSP430 GCC Programs
      1. 5.2.1 The -mtiny-printf Option
      2. 5.2.2 The -ffunction-sections and -fdata-sections Options
      3. 5.2.3 Making Large Programs Fit Across Upper and Lower Memory
      4. 5.2.4 NOP Instructions Surrounding Interrupt State Changes
    3. 5.3 C Runtime Library (CRT) Startup Behavior
    4. 5.4 Using printf with MSP430 GCC
    5. 5.5 Link-time Optimization (LTO)
    6. 5.6 The __int20 Type and Pointers in the Large Memory Model
  7. 6Building MSP430 GCC From Sources
    1. 6.1 Required Tools
    2. 6.2 Building MSP430 GCC (Mitto Systems Limited)
      1. 6.2.1 Building a Native MSP430 GCC Toolchain
      2. 6.2.2 Building the MSP430 GCC Toolchain for Windows
    3. 6.3 Building MSP430 GCC Stand-Alone Full Package
  8. 7MSP430 GCC and MSPGCC
    1. 7.1 Calling Convention
    2. 7.2 Other Portions of the ABI
  9. 8Appendix
    1. 8.1 GCC Intrinsic Support
    2. 8.2 NOP Instructions Required Between Interrupt State Changes
  10. 9References
  11.   Revision History

5.2.4 NOP Instructions Surrounding Interrupt State Changes

To prevent incorrect behavior when two adjacent instructions both change the global interrupt enable state (see Section 8.2), the C macros for modifying the interrupt state contain NOP instructions. The following macros are affected and are defined in in430.h, which is part of the msp430-gcc-support-files package:

  • _set_interrupt_state
  • _enable_interrupts
  • _disable_interrupts
  • _bis_SR_register
  • _bic_SR_register

Macros that modify the status register (SR) might be used for purposes other than changing the interrupt state, so NOP instructions in these macros may not be needed. If code size is important, you can examine places your source code uses the _bic_SR_register and _bis_SR_register macros. If NOPs inserted by macros are not needed in some places, you can define your own macros that omit NOPs and use them where appropriate.