@micro-os-plus/semihosting/README.md

A source library xPack with the µOS++ portable semihosting definitions

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# A source library xPack with the µOS++ semihosting support

This project provides the **XXXX YYYY** source library as an xPack
dependency and includes support for semihosting.

It complements the newlib
implementation (arm/librdimon) with a more complete set of POSIX functions,
and also includes debugging support.

The project is hosted on GitHub as
[micro-os-plus/semihosting-xpack](https://github.com/micro-os-plus/semihosting-xpack).

## Maintainer info

This page is addressed to developers who plan to include this source
library into their own projects.

For maintainer info, please see the
[README-MAINTAINER](README-MAINTAINER.md) file.

## Install

As a source library xPack, the easiest way to add it to a project is via
**xpm**, but it can also be used as any Git project, for example as a submodule.

### Prerequisites

A recent [xpm](https://xpack.github.io/xpm/),
which is a portable [Node.js](https://nodejs.org/) command line application.

It is recommended to update to the latest version with:

```sh
npm install --global xpm@latest
```

For details please follow the instructions in the
[xPack install](https://xpack.github.io/install/) page.

### xpm

Note: the package will be available from npmjs.com at a later date.

For now, it can be installed from GitHub:

```sh
cd my-project
xpm init # Unless a package.json is already present

xpm install github:micro-os-plus/semihosting-xpack
```

When ready, this package will be available as
[`@micro-os-plus/semihosting`](https://www.npmjs.com/package/@micro-os-plus/semihosting)
from the `npmjs.com` registry:

```sh
cd my-project
xpm init # Unless a package.json is already present

xpm install @micro-os-plus/semihosting@latest

ls -l xpacks/micro-os-plus-semihosting
```

### Git submodule

If, for any reason, **xpm** is not available, the next recommended
solution is to link it as a Git submodule below an `xpacks` folder.

```sh
cd my-project
git init # Unless already a Git project
mkdir -p xpacks

git submodule add https://github.com/micro-os-plus/semihosting-xpack.git \
  xpacks/micro-os-plus-semihosting
```

## Branches

Apart from the unused `master` branch, there are two active branches:

- `xpack`, with the latest stable version (default)
- `xpack-develop`, with the current development version

All development is done in the `xpack-develop` branch, and contributions via
Pull Requests should be directed to this branch.

When new releases are published, the `xpack-develop` branch is merged
into `xpack`.

## Developer info

### Overview

This project provides several components, which can be enabled separately:

- the declarations for the basic semihosting calls
- implementations for the system calls
- implementations for the initialisations required during the startup
- implementations for the debug trace channels via semihosting

### Status

The **semihosting** source library is fully functional.

### C++ API

The C++ methods available to call semihosting functions are:

```c++
namespace micro_os_plus::semihosting
{
  response_t
  call_host (int reason, param_block_t* arg);
}
```

### C API

The same functionality is available from a similar C function,
defined in the architecture package:

```c
static micro_os_plus_semihosting_response_t
micro_os_plus_semihosting_call_host (
    int reason,
    micro_os_plus_semihosting_param_block_t* arg);
```

### Implementation

The architecture should provide a definition of the following function:

```c
  static inline __attribute__ ((always_inline)) int
  micro_os_plus_semihosting_call_host (int reason, void* arg);
```

### Build & integration info

The project is written in C++, and it is expected
to be used in C and C++ projects.

The source code was compiled with GCC 11, clang 12, clang 13
arm-none-eabi-gcc 11, riscv-none-elf-gcc 12, and should be warning free.

To ease the integration of this package into user projects, there
are already made CMake and meson configuration files (see below).

For other build systems, consider the following details:

#### Include folders

The following folders should be passed to the compiler during the build:

- `include`

The header files to be included in user projects are:

```c++
#include <micro-os-plus/semihosting.h>
```

#### Source files

The source files to be added to the build are:

- `src/semihosting-startup.cpp`
- `src/semihosting-syscalls.cpp`
- `src/semihosting-trace.cpp`

#### Preprocessor definitions

- `MICRO_OS_PLUS_INCLUDE_CONFIG_H` - to include `<micro-os-plus/config.h>`
- `MICRO_OS_PLUS_INCLUDE_SEMIHOSTING_SYSCALLS`
- `MICRO_OS_PLUS_INTEGER_SEMIHOSTING_MAX_OPEN_FILES` (20)
- `MICRO_OS_PLUS_DEBUG_SYSCALLS_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_CHDIR_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_CHMOD_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_CHOWN_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_CLOSEDIR_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_EXECVE_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_FCNTL_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_FORK_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_FSYNC_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_FTRUNCATE_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_IOCTL_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_KILL_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_LINK_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_OPENDIR_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_RAISE_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_READDIR_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_READLINK_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_REWINDDIR_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_RMDIR_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_SELECT_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_SYMLINK_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_SYNC_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_TRUNCATE_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_UTIME_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_WAIT_BRK`
- `MICRO_OS_PLUS_DEBUG_SYSCALL_WRITEV_BRK`
- `MICRO_OS_PLUS_INCLUDE_SEMIHOSTING_STARTUP`
- `MICRO_OS_PLUS_INTEGER_SEMIHOSTING_CMDLINE_ARRAY_SIZE` (80)
- `MICRO_OS_PLUS_INTEGER_SEMIHOSTING_ARGV_ARRAY_SIZE` (10)

#### Compiler options

- `-std=c++20` or higher for C++ sources
- `-std=c11` for C sources

#### C++ Namespaces

- `micro_os_plus::semihosting`

#### C++ Classes

- none

#### Dependencies

- the `@micro-os-plus/diag-trace` package, for the declarations of the
  debug trace channels

#### CMake

To integrate the semihosting source library into a CMake application,
add this folder to the build:

```cmake
add_subdirectory("xpacks/micro-os-plus-semihosting")`
```

The result is an interface library that can be added as an application
dependency with:

```cmake
target_link_libraries(your-target PRIVATE

  micro-os-plus::semihosting
)
```

#### meson

To integrate the semihosting source library into a meson application,
add this folder to the build:

```meson
subdir('xpacks/micro-os-plus-semihosting')
```

The result is a dependency object that can be added
to an application with:

```meson
exe = executable(
  your-target,
  link_with: [
    # Nothing, not static.
  ],
  dependencies: [
    micro_os_plus_semihosting_dependency,
  ]
)
```

### Examples

TBD

### Known problems

- none

### Tests

TBD

## Change log - incompatible changes

According to [semver](https://semver.org) rules:

> Major version X (X.y.z | X > 0) MUST be incremented if any
backwards incompatible changes are introduced to the public API.

The incompatible changes, in reverse chronological order, are:

- v7.x: get rid of the C++ posix:: namespace
- v6.x: rename source files
- v5.x: rename SYS_GETCMDLINE; use param_block_t
- v4.x: rename MICRO_OS_PLUS_DEBUG, MICRO_OS_PLUS_TRACE
- v3.x: rename the micro_os_plus namespace
- v2.x: update for new OpenOCD implementation; use the posix:: namespace
- v1.x: the code was extracted from the mono-repo µOS++ project

## License

The original content is released under the
[MIT License](https://opensource.org/licenses/MIT/),
with all rights reserved to
[Liviu Ionescu](https://github.com/ilg-ul/).