18863: boards/esp32s2-mini: add definition for ESP32 S2 Mini r=gschorcht a=benpicco
Co-authored-by: Benjamin Valentin <benjamin.valentin@bht-berlin.de>
Co-authored-by: Benjamin Valentin <benjamin.valentin@ml-pa.com>
19193: rust: Update dependencies, use riot-wrappers from git r=benpicco a=chrysn
### Contribution description
As riot-wrappers has advanced a bit since it was last released, Rust modules are switched to using it from git again. (This is a regular ping-pong between testing the latest release in RIOT master, and using released support crates when they're current).
This primarily updates riot-wrappers, which has accumulated several compatible changes. Several other crates receive updates as well.
### Testing procedure
* Green CI
### Issues/PRs references
Changes on the riot-wrappers side:
* https://github.com/RIOT-OS/rust-riot-wrappers/pull/17
* https://github.com/RIOT-OS/rust-riot-wrappers/pull/22
* https://github.com/RIOT-OS/rust-riot-wrappers/pull/29
* https://github.com/RIOT-OS/rust-riot-wrappers/pull/30
[edit: added:]
This also serves to help preparing a 0.8.1 release of riot-wrappers, which performs some deprecations so that a breaking 0.9 change can be done more effortlessly later on.
19214: cpu/gd32v: add periph_spi support r=benpicco a=gschorcht
### Contribution description
This PR provides the `periph_spi` support and is one of a bunch of PRs that complete the peripheral drivers for GD32VF103.
The driver is a modified version of the driver for STM32F1 with some changes that were necessary to get it working on GD32V.
### Testing procedure
`tests/periph_spi` as well as a test with any SPI sensor should work. `tests/driver_sdcard_spi` should work on `sipeed-longan-nano`.
### Issues/PRs references
Depeneds on PR #19216
Co-authored-by: chrysn <chrysn@fsfe.org>
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
16782: drivers/mfrc522: add new driver r=benpicco a=HendrikVE
### Contribution description
This PR adds support for the MFRC522. It is quite common in the Arduino world and it is quite cheap. The driver connects to the MFRC522 via SPI and is heavily based on the Arduino driver available [here](https://github.com/miguelbalboa/rfid). Basically it was ported, but with several improvements in readability and documentation.
### Testing procedure
The given (manual) test provides single commands for some driver functions.
19201: cpu/gd32v: add periph_i2c support r=benpicco a=gschorcht
### Contribution description
This PR provides the `periph_i2c` support and is one of a bunch of PRs that complete the peripheral drivers for GD32VF103.
The driver is a modified version of the driver for STM32F1 with some changes that were necessary to get it working on GD32V. As for STM32F1, the driver is using polling instead of interrupts for now. It will be implemented interrupt-driven later.
### Testing procedure
`tests/periph_i2c` as well as a test with any I2C sensor should work. The driver was tested with `tests/driver_l3gxxxx` and `tests/driver_bmp180`.
### Issues/PRs references
Co-authored-by: Hendrik van Essen <hendrik.ve@fu-berlin.de>
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
Testing the correct calculation of flash page indices without assuming the `periph_flashpage` feature and enabling the `periph_flashpage` module makes no sense. On ESP32x SoCs for example, the space in the flash is only reserved and `FLASHPAGE_NUMOF` is greater than 0 if `periph_flashpage` is used.
18472: drivers/mrf24j40: add support for IEEE 802.15.4 Radio HAL r=benpicco a=jia200x
19175: drivers/periph_common/flashpage: fix silent error r=benpicco a=Enoch247
### Contribution description
This patch removes a test that silently hides failed writes to NULL. Instead, assert is used to ensure that the address is not NULL.
### Testing procedure
I am not certain how to update the tests to catch asserts. If this is possible, I will add a test, if someone will point me to a good example to learn from.
### Issues/PRs references
- none
Co-authored-by: Jose Alamos <jose@alamos.cc>
Co-authored-by: Joshua DeWeese <jdeweese@primecontrols.com>
The way it's now it's easy to interpret that there was an error, when
really there was not. As seen in issue #19025 quite some time can be
spent following a wrong clue.
19166: boards/seeedstudio-gd32: complete and improve board definition r=kaspar030 a=gschorcht
### Contribution description
This PR completes and improves the board definition for the Seeedstudio GD32 RISC-V Dev board. It
- adds the user LED and Button definitions to `board.h` (bef4209109)
- adds the SAUL support for user LED and Button definitions (7a5b2f1fb43f5e28eec4f65c8e7367510be6eb80)
- changes the OpenOCD configuration (32c0c4b1b5b9705ffcd2bb02a1d868ad35ca3bbc)
- to be usable with Upstream OpenOCD release version 0.12.0
- to allow different FTDI configuration and other adapters
- adds a documentation with flashing guide, feature list, support status, pinout, schematic reference (9dcc83b8ceb8a9ce526f0a03053a242e866ebf4a)
These changes is the first PR for a number of follow-up PR I will provide in next days to extend the GD32VF103 support. I have already working
- `periph_adc` support,
- `periph_spi` support,
- `tinyusb_device` support,
and almost finished
- `periph_i2c` support (implemented and working with some errors),
- `pm_layered` support (implemented but not working correctly yet), and
- `periph_usbdev` support (implemented by extending `usbdev_synopsys_dwc2 driver but bot working yet).
I will try to implement
- `periph_gpio_irq` support,
- `periph_rtc` support, and
- `periph_rtt` support.
Since I'm using the Sispeed Longan Nano board for testing, I will add the board definition for this board. I will then move some board definitions to a common folder.
### Testing procedure
Green CI.
Documentation should be generated correctly.
Flashing the `seeedstudio-gd32` should still work.
`tests/leds` should work.
### Issues/PRs references
19171: tests/gnrc_rpl: Disable CI test for native r=benpicco a=maribu
### Contribution description
This disables the `tests/grnc_rpl` test run for `native`. This test is too flaky to be included in the CI.
### Testing procedure
Not needed
### Issues/PRs references
None
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
19079: cpu/esp32: add periph_flashpage support r=kaspar030 a=gschorcht
### Contribution description
This PR provides the `periph_flashpage` support for ESP32x SoCs.
For byte-aligned read access to constant data in the flash, the MMU of all ESP32x SoCs allows to map a certain number of 64 kByte pages of the flash into the data address space of the CPU. This address space is called DROM. Normally the whole DROM address space is assigned to the section `.rodata`. The default flash layout used by all ESP32x SoCs is:
| Address in Flash | Content |
|:-----------------------|:-----------|
| `0x0000` or `0x1000` | bootloader |
| `0x8000` | parition table |
| `0x9000` | `nvs` parition with WiFi data |
| `0xf000` | `phy_init` partition with RF data |
| `0x10000` | `factory` partition with the app image |
The factory partition consists of a number of 64 kByte pages for the sections `.text`, `.rodata`, `.bss` and others. The `.text` and `rodata` sections are page-aligned and are simply mapped into the instruction address space (IROM) and the data address space (DROM), respectively. All other sections are loaded into RAM.
If the `periph_flashpage` module is used, the `periph_flashpage` driver
- decreases the size of the `.rodata` section in DROM address space by `CONFIG_ESP_FLASHPAGE_CAPACITY`,
- adds a section `.flashpage.writable` of size `CONFIG_ESP_FLASHPAGE_CAPACITY` at the end of DROM address space that is mapped into data address space of the CPU,
- reserves a region of size `CONFIG_ESP_FLASHPAGE_CAPACITY` starting from `0x10000` in front of the image partition `factory` and
- moves the image partition `factory` by `CONFIG_ESP_FLASHPAGE_CAPACITY` to address `0x10000 + CONFIG_ESP_FLASHPAGE_CAPACITY`.
The new flash layout is then:
| Address in Flash | Content |
|:-----------------------|:-----------|
| `0x0000` or `0x1000` | bootloader |
| `0x8000` | parition table |
| `0x9000` | `nvs` parition with WiFi data |
| `0xf000` | `phy_init` partition with RF data |
| `0x10000` | flashpage region |
| `0x10000 + CONFIG_ESP_FLASHPAGE_CAPACITY` | `factory` partition with the app image |
This guarantees that the flash pages are not overwritten if a new app image with changed size is flashed. `CONFIG_ESP_FLASHPAGE_CAPACITY` has to be a multiple of 64 kBytes.
~The PR includes PR #19077 and PR #19078 for the moment to be compilable.~
### Testing procedure
The following tests should pass.
```
USEMODULE='esp_log_startup ps shell_cmds_default' BOARD=esp32-wroom-32 make -j8 -C tests/periph_flashpage flash term
```
```
USEMODULE='esp_log_startup ps shell_cmds_default' BOARD=esp32-wroom-32 make -j8 -C tests/mtd_flashpage flash term
```
### Issues/PRs references
Depends on PR #19077
Depends on PR #19078
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
If a board has fixed defines for `WS281X_PARAM_PIN` and `WS281X_PARAM_NUMOF`
the test will overwrite them.
This leads to the LEDs *not* working in with the test, which is very confusing.
17066: sys/irq: Add C++ wrapper using RAII r=maribu a=jenswet
### Contribution description
This adds a C++ wrapper around the `irq.h` API. The wrapper uses RAII to accomplish a convenient and bug resistent use.
A little background: I'm currently writing my master thesis on using C++ for embedded development, at the working group that `@maribu` is part of. For that I will try to add better C++ support to several parts of RIOT and then do some benchmarking and metrics to compare it with the C implementation. For example, I also plan to add a wrapper around i2c, a std::cout drop-in replacement and probably some more about networks or threads.
### Testing procedure
I've added a unit test to verify that the IRQ wrapper calls the original `irq` functions as expected. As C++ and wrapper testing isn't done much so far in this project, I've added two additional headers to ease testing:
1. #17076 - fake functions framework, already merged
2. As there is no framework for C++ unit tests yet, I've added something for this too. Unfortunately the existing frameworks like GoogleTest, CppUTest or CppUnit don't easily compile for embedded or are difficult to integrate in to the RIOT build process. That's why I wrote some (simple) helper functions and macros inspired by the above frameworks. That allows to create C++ tests based on a fixture class with set up and tear down methods. It also allows some simple assertions and is easily extendable for other use cases. It wraps some of the fff functionality too.
Both of this is obviously not required for the initial reason of this PR. But I'd like to provide unit tests for the features that I suggest to introduce where possible. So I'd appreciate some feedback on that too. If you'd prefer a PR without or different tests please let me know.
You can run the test `irq_cpp` locally or on the CI to test the implementation.
Please feel free to give feedback or suggest improvements!
Co-authored-by: Jens Wetterich <jens@wetterich-net.de>
17460: pkg/arduino_adafruit_sensor: add Adafruit Unified Sensor Driver as package r=benpicco a=gschorcht
### Contribution description
This PR provides the [Adafruit Unified Sensor Driver](https://github.com/adafruit/Adafruit_Sensor) as package.
There are a number of Adafruit sensor drivers which all use a common base class `Adafruit_Sensor` from the [Adafruit Unified Sensor Driver](https://github.com/adafruit/Adafruit_Sensor). To support such drivers, the Adafruit Unified Sensor Driver is provided as package.
Adafruit sensor driver for ST LSM9DS0 will be provided as separat PR as package for demonstration and testing.
PR #12518 will be rebased for testing to have an Adafruit sensor driver for a sensor for which there is a native driver in RIOT.
### Testing procedure
Use a board that provides the `arduino` feature and flash
```
BOARD=... make -C tests/pkg_arduino_adafruit_sensor flash test
```
PR #12518 can be used as a more complex test for using the package.
### Issues/PRs references
Prerequisite for PR #12518
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
18763: sys/tiny_strerror: add missing error codes r=benpicco a=maribu
### Contribution description
When double-checking the error codes provided by newlib by default (without magic defines, such as `__LINUX_ERRNO_EXTENSIONS__` or `__CYGWIN__`), some where still missing in `tiny_strerror()`. This adds the missing ones.
This in turn showed that three errno codes were missing in the avr-libc compat `errno.h`, which are added as well.
### Testing procedure
Murdock should double check that the added errno codes indeed are defined by default.
### Issues/PRs references
None
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
19106: core/lib: Add macros/utils.h header r=aabadie a=maribu
### Contribution description
The macros CONCAT(), MIN(), and MAX() are defined over and over again in RIOT's code base. This de-duplicates the code by moving the macros to a common place.
### Testing procedure
Generated binaries don't change, as this only a de-duplication of macros that doesn't change their definition.
### Issues/PRs references
None
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
The macros CONCAT(), MIN(), and MAX() are defined over and over again in
RIOT's code base. This de-duplicates the code by moving the macros to a
common place.
18632: tests/thread_float: do not overload slow MCUs with IRQs r=kaspar030 a=maribu
### Contribution description
If the regular context switches are triggered too fast, slow MCUs will be able to spent little time on actually progressing in the test. This will scale the IRQ rate with the CPU clock as a crude way too keep load within limits.
### Testing procedure
The unit test should now pass on the Microduino CoreRF
```
$ make BOARD=microduino-corerf AVRDUDE_PROGRAMMER=dragon_jtag -C tests/thread_float flash test
make: Entering directory '/home/maribu/Repos/software/RIOT/tests/thread_float'
Building application "tests_thread_float" for "microduino-corerf" with MCU "atmega128rfa1".
[...]
text data bss dec hex filename
12834 520 3003 16357 3fe5 /home/maribu/Repos/software/RIOT/tests/thread_float/bin/microduino-corerf/tests_thread_float.elf
avrdude -c dragon_jtag -p m128rfa1 -U flash:w:/home/maribu/Repos/software/RIOT/tests/thread_float/bin/microduino-corerf/tests_thread_float.hex
[...]
Welcome to pyterm!
Type '/exit' to exit.
READY
s
START
main(): This is RIOT! (Version: 2022.10-devel-858-g18566-tests/thread_float)
THREADS CREATED
Context switch every 3125 µs
{ "threads": [{ "name": "idle", "stack_size": 192, "stack_used": 88 }]}
{ "threads": [{ "name": "main", "stack_size": 640, "stack_used": 220 }]}
THREAD t1 start
THREAD t2 start
THREAD t3 start
t1: 141.443770
t3: 141.466810
t1: 141.443770
t3: 141.466810
t1: 141.443770
t3: 141.466810
t1: 141.443770
t3: 141.466810
t1: 141.443770
t3: 141.466810
t1: 141.443770
t3: 141.466810
t1: 141.443770
make: Leaving directory '/home/maribu/Repos/software/RIOT/tests/thread_float'
```
(~~Note: The idle thread exiting is something that should never occur. I guess the culprit may be `cpu_switch_context_exit()` messing things up when the main thread exits. But that is not directly related to what this PR aims to fix. Adding a `thread_sleep()` at the end of `main()` does indeed prevent the idle thread from exiting.~~
Update: That's expected. The idle thread stats are printed on exit of the main thread, the idle thread does not actually exit.)
### Issues/PRs references
Fixes https://github.com/RIOT-OS/RIOT/issues/16908 maybe?
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
19030: tests/periph_timer_short_relative_set: improve test r=benpicco a=maribu
### Contribution description
Reduce the number lines to output by only testing for intervals 0..15 to speed up the test.
In addition, run each test case 128 repetitions (it is still faster than before) to give some confidence the short relative set actually succeeded.
### Testing procedure
The test application should consistently fail or succeed, rather than occasionally passing.
### Issues/PRs references
None
19085: makefiles/tests/tests.inc.mk: fix test/available target r=benpicco a=maribu
### Contribution description
`dist/tools/compile_and_test_for_board/compile_and_test_for_board.py` relies on `make test/available` to check if a test if available. However, this so far did not take `TEST_ON_CI_BLACKLIST` and `TEST_ON_CI_WHITELIST` into account, resulting in tests being executed for boards which they are not available. This should fix the issue.
### Testing procedure
#### Expected to fail
```
$ make BOARD=nrf52840dk -C tests/gcoap_fileserver test/available
$ make BOARD=microbit -C tests/log_color test/available
```
(On `master`, they succeed, but fail in this PR.)
#### Expected to succeed
```
$ make BOARD=native -C tests/gcoap_fileserver test/available
$ make BOARD=nrf52840dk -C tests/pkg_edhoc_c test/available
$ make BOARD=nrf52840dk -C tests/log_color test/available
```
(Succeed in both `master` and this PR.)
### Issues/PRs references
None
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
18950: tests/unittests: add unit tests for core_mbox r=benpicco a=maribu
### Contribution description
As the title says
### Testing procedure
The test cases are run on `native` by Murdock anyway.
### Issues/PRs references
Split out of https://github.com/RIOT-OS/RIOT/pull/18949
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
If the regular context switches are triggered too fast, slow MCUs
will be able to spent little time on actually progressing in the
test. This will scale the IRQ rate with the CPU clock as a crude way
too keep load within limits.
19037: sys/usb, pkg/tinyusb: move USB board reset from highlevel STDIO to CDC ACM r=dylad a=gschorcht
### Contribution description
The USB board reset function `usb_board_reset_coding_cb` can be used on any CDC-ACM interface, even if the CDC ACM interface is not used as high-level STDIO. Therefore, this PR provides the following changes:
- The call of the board reset function `usb_board_reset_coding_cb` from USBUS stack has been moved from the STDIO CDC ACM implementation to the CDC ACM implementation and is thus a feature of any USBUS CDC ACM interface which does not necessarily have to be used as highlevel STDIO.
- The call of the board reset function `usb_board_reset_coding_cb` from tinyUSB stack been moved from module `tinyusb_stdio_cdc_acm` to module `tinyusb_contrib` and is compiled in if the `tinyusb_class_cdc` module is used together the `tinyusb_device` module. Thus, it is now a feature of the tinyUSB CDC ACM interface, which does not necessarily have to be used as highlevel STDIO.
- The `usb_board_reset` module defines the `usb_board_reset_in_bootloader` function as a weak symbol to be used when reset in bootloader if no real implementation of this function is compiled in and the `riotboot_reset` module is not used. It only prints an error message that the reset in bootloader is not supported. This is necessary if the module `usb_board_reset` is used to be able to restart the board with an application via a USB CDC ACM interface, but the board's bootloader does not support the reset in bootloader feature.
- A test application has been added that either uses the highlevel STDIO `stdio_acm_cdc` or creates a CDC-ACM interface to enable board resets via USB. If the `usbus_dfu` module is used, it also initializes the DFU interface to be able to work together with the `riotboot_dfu` bootloader.
### Testing procedure
1. Use a board with a bootloader that supports the reset in bootloader via USB, but don't use the highlevel STDIO to check that it works with `usbus_cdc_acm`, for example:
```python
USEMODULE=stdio_uart BOARD=arduino-mkr1000 make -C tests/usb_board_reset flash
```
After reset in application with command
```python
stty -F /dev/ttyACM0 raw ispeed 600 ospeed 600 cs8 -cstopb ignpar eol 255 eof 255
```
command `dmesg` should give an output like the following with RIOT's test VID/PID:
```python
dmesg
[1745182.057403] usb 1-4.1.2: new full-speed USB device number 69 using xhci_hcd
[1745182.160386] usb 1-4.1.2: New USB device found, idVendor=1209, idProduct=7d01, bcdDevice= 1.00
[1745182.160390] usb 1-4.1.2: New USB device strings: Mfr=3, Product=2, SerialNumber=4
[1745182.160392] usb 1-4.1.2: Product: arduino-mkr1000
[1745182.160393] usb 1-4.1.2: Manufacturer: RIOT-os.org
[1745182.160395] usb 1-4.1.2: SerialNumber: 6B6C2CA5229020D8
[1745182.170982] cdc_acm 1-4.1.2:1.0: ttyACM0: USB ACM device
```
After reset in bootloader with command
```python
stty -F /dev/ttyACM0 raw ispeed 1200 ospeed 1200 cs8 -cstopb ignpar eol 255 eof 255
```
command `dmesg` should give an output like the following with vendor VID/PID:
```python
[1746220.443792] usb 1-4.1.2: new full-speed USB device number 70 using xhci_hcd
[1746220.544705] usb 1-4.1.2: New USB device found, idVendor=2341, idProduct=024e, bcdDevice= 2.00
[1746220.544708] usb 1-4.1.2: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[1746220.553471] cdc_acm 1-4.1.2:1.0: ttyACM0: USB ACM device
```
2. Test the same as in 1., but this time use the highlevel STDIO to check that there is no regression and it still works with `stdio_cdc_acm`, for example:
```python
BOARD=arduino-mkr1000 make -C tests/usb_board_reset flash
```
3. Use a board that supports `riotboot_dfu` but doesn't use the highlevel STDIO and flash the `riotboot_dfu` bootloader, for example:
```python
BOARD=stm32f429i-disc1 make -C bootloaders/riotboot_dfu flash term
```
Once the bootloader is flashed, command `dfu-util --list` should give something like the following:
```python
Found DFU: [1209:7d02] ver=0100, devnum=14, cfg=1, intf=0, path="1-2", alt=1, name="RIOT-OS Slot 1", serial="6591620BCB270283"
Found DFU: [1209:7d02] ver=0100, devnum=14, cfg=1, intf=0, path="1-2", alt=0, name="RIOT-OS Slot 0", serial="6591620BCB270283"
```
If the output gives only
```python
Found Runtime: [1209:7d00] ver=0100, devnum=123, cfg=1, intf=0, path="1-2", alt=0, name="RIOT-OS bootloader", serial="6591620BCB270283"
```
an application is already running in DFU Runtime mode. Use `dfu-util -e` to restart it in bootloader DFU mode.
Then flash the test application, for example:
```python
FEATURES_REQUIRED=riotboot USEMODULE='usbus_dfu riotboot_reset' \
BOARD=stm32f429i-disc1 make -C tests/usbus_board_reset PROGRAMMER=dfu-util riotboot/flash-slot0
```
Once the test application is flashed, command `dfu-util --list` should give:
```python
Found Runtime: [1209:7d00] ver=0100, devnum=123, cfg=1, intf=0, path="1-2", alt=0, name="RIOT-OS bootloader", serial="6591620BCB270283"
```
Now, use command
```python
stty -F /dev/ttyACM1 raw ispeed 600 ospeed 600 cs8 -cstopb ignpar eol 255 eof 255
```
to restart the board in application. Command `dfu-util --list` should give again the following:
```python
Found Runtime: [1209:7d00] ver=0100, devnum=123, cfg=1, intf=0, path="1-2", alt=0, name="RIOT-OS bootloader", serial="6591620BCB270283"
```
That is, the application is running in DFU Runtime mode. Then use command
```python
stty -F /dev/ttyACM1 raw ispeed 1200 ospeed 1200 cs8 -cstopb ignpar eol 255 eof 255
```
to restart the board in bootloader DFU mode. Command `dfu-util --list` should now give the following:
```python
Found DFU: [1209:7d02] ver=0100, devnum=50, cfg=1, intf=0, path="1-2", alt=1, name="RIOT-OS Slot 1", serial="7D156425A950A8EB"
Found DFU: [1209:7d02] ver=0100, devnum=50, cfg=1, intf=0, path="1-2", alt=0, name="RIOT-OS Slot 0", serial="7D156425A950A8EB"
```
That is, the bootloader is in DFU mode and another application can be flash.
4. After a hard reset of the board under 3., try the commands `reboot` and `bootloader`.
5. To check the same for tinyUSB, use the existing tinyUSB application with a CDC ACM interface and add module `usb_board_reset`, for example:
```python
USEMODULE=usb_board_reset BOARD=stm32f429i-disc1 make -C tests/pkg_tinyusb_cdc_msc flash term
```
After flashing, it should be possible to restart the application with command:
```python
stty -F /dev/ttyACM1 raw ispeed 600 ospeed 600 cs8 -cstopb ignpar eol 255 eof 255
```
When using command
```python
stty -F /dev/ttyACM1 raw ispeed 1200 ospeed 1200 cs8 -cstopb ignpar eol 255 eof 255
```
the following error message should be shown in terminal
```python
[cdc-acm] reset in bootloader is not supported
```
### Issues/PRs references
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
