| CMSIS-Core (Cortex-M) CMSIS-Core support for Cortex-M processor-based devices |

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CMSIS-Core Files

CMSIS-Core files can be differentiated in two main groups:

1. CMSIS-Core Standard Files are provided by Arm for supported CPU cores as part of the CMSIS-Core software component. These files typically do not require any modifications and are expected to be included via CMSIS-Core device files.
2. CMSIS-Core Device Files are specified in CMSIS-Core methodology, and are typically provided by CPU device vendors to correctly cover their specific functionalities. Some of them may expect additional application-specific changes.

The detailed file structure of the CMSIS-Core files is shown in the following picture.

CMSIS-Core File Structure

Delivery in CMSIS-Packs explains how CMSIS-Core Files can be distributed in CMSIS-Pack format.

# CMSIS-Core Standard Files

The CMSIS-Core Standard file implement all attributes specific to Arm processor cores and generally do not need any modifications.

The files are provided by Arm as CMSIS-Core software component that is part of the CMSIS Software pack. The CMSIS-Core standard files can be split into following categories explained below:

- CMSIS-Core Processor Files
- CMSIS-Core Compiler Files
- CMSIS-Core Architecture Feature Files

## CMSIS-Core Processor Files

The CMSIS-Core processor files define the core peripherals and provide helper functions for their access.

The files have naming convention `core_<cpu>.h`, with one file available for each supported processor `<cpu>` as listed in the table below.

Header File | Target Processor Core
--- | ---
📂 CMSIS/Core/Include | CMSIS-Core include folder (See on GitHub)
┣ 📄 core_cm0.h | Cortex-M0 processor
┣ 📄 core_cm0plus.h | Cortex-M0+ processor
┣ 📄 core_cm1.h | Cortex-M1 processor
┣ 📄 core_cm3.h | Cortex-M3 processor
┣ 📄 core_cm4.h | Cortex-M4 processor
┣ 📄 core_cm7.h | Cortex-M7 processor
┣ 📄 core_cm23.h | Cortex-M23 processor
┣ 📄 core_cm33.h | Cortex-M33 processor
┣ 📄 core_cm35p.h | Cortex-M35P processor
┣ 📄 core_cm52.h | Cortex-M52 processor
┣ 📄 core_cm55.h | Cortex-M55 processor
┣ 📄 core_cm85.h | Cortex-M85 processor
┣ 📄 core_starmc1.h | STAR-MC1 processor
┣ 📄 core_sc000.h | SC000 processor
┗ 📄 core_sc300.h | SC300 processor

The files also include the CMSIS-Core Compiler Files and depending on the features supported by the core also correponding CMSIS-Core Architecture Feature Files.

## CMSIS-Core Compiler Files

The CMSIS-Core compiler files provide consistent implementations of `#define` symbols that allow toolchain-agnostic usage of CMSIS-Core. CMSIS-Core Processor Files rely on such toolchain-agnostic abstractions by including `cmsis_compiler.h` file that then selects the target compiler-specific implementatation depending on the toolchain used in the project.

CMSIS-Core compiler files are provided in `CMSIS/Core/Include/` directory, and define the supported compilers as listed in Tested and Verified Toolchains. Compiler Control documents the functionalities provided by the CMSIS compliant toolchains.

Header File | Description
--- | ---
📂 CMSIS/Core/Include | CMSIS-Core include folder (See on GitHub)
┣ 📄 cmsis_compiler.h | Main CMSIS-Core compiler header file
┗ 📂 m-profile | Directory for M-Profile specific files
┣ 📄 cmsis_armclang_m.h | CMSIS-Core Arm Clang compiler file for Cortex-M
┣ 📄 cmsis_clang_m.h | CMSIS-Core Clang compiler file for Cortex-M
┣ 📄 cmsis_gcc_m.h | CMSIS-Core GCC compiler file for Cortex-M
┣ 📄 cmsis_iccarm_m.h | CMSIS-Core IAR compiler file for Cortex-M
┗ 📄 cmsis_tiarmclang_m.h | CMSIS-Core TI Clang compiler file

## CMSIS-Core Architecture Feature Files

Several architecture-specific features are implemented in separate header files that then gets included by CMSIS-Core Processor Files if corresponding feature is supported.

For Cortex-M cores following architecture feature files are provided in the `CMSIS/Core/Include/m-profile/` folder:

Header File | Feature
--- | ---
📂 CMSIS/Core/Include | CMSIS-Core include folder (See on GitHub)
┣ 📂 m-profile | Directory for M-Profile specific files
┣ 📄 armv7m_cache1.h | Cache Functions (Level-1)
┣ 📄 armv7m_mpu.h | MPU Functions for Armv6-M/v7-M
┣ 📄 armv8m_mpu.h | MPU Functions for Armv8-M
┣ 📄 armv8m_pmu.h | PMU Functions for Armv8.1-M
┗ 📄 armv81m_pac.h | PAC functions
┗ 📄 tz_context.h | API header file for RTOS Context Management

## CMSIS Version and Processor Information

__CM_CMSIS_VERSION is defined in the `cmsis_version.h` file and provides the version of the CMSIS-Core (Cortex-M). It is constructed as follows:

#define __CM_CMSIS_VERSION_MAIN ( 5U) /* [31:16] CMSIS Core(M) main version */
#define __CM_CMSIS_VERSION_SUB ( 7U) /* [15:0] CMSIS Core(M) sub version */
#define __CM_CMSIS_VERSION ((__CM_CMSIS_VERSION_MAIN << 16U) | \
__CM_CMSIS_VERSION_SUB ) /* CMSIS Core(M) version number */

The `cmsis_version.h` is included by each `cpu_<core>.h` so the CMSIS version defines are available via them already.

The `cpu_<core>.h` files use specific defines (such as __CORTEX_M) that provide identification of the target processor core.

These defines can be used in the Device Header File <Device.h> to verify a minimum CMSIS-Core version as well as the target processor. Read more at Version Control.