GPIOPin.getValue() runs into Exceptions for an input pin

[Jeff Prestes]

Hi Peter,

looks great! I face same issue and I believe your fix can solve it.

Thanks for helping the project. Hopefully some commiters can submit a
pullrequest soon.

Cheers!

-Jeff

On Thu, Oct 29, 2015 at 4:41 AM, Peter Saitz <peter.saitz at savien.at> wrote:

> Hi
>
> I would suggest the following code change in gpio.c (line 814 to 822) for
> better compatibility to various Linux GPIO implementations:
>
>     if(48 == inBuffer[0]) { // char "0" is FALSE
>         *value = JAVACALL_FALSE;
>     } else if((49 <= inBuffer[0]) && (57 >= inBuffer[0])) { // accept char
> "1" to "9" as TRUE
>         *value = JAVACALL_TRUE;
>     } else { // treat all other none numeric chars as failure
>         JAVACALL_REPORT_WARN3(JC_DIO, "Error values from value GPIO pin %d
> file was read: %d %d", handle->number, inBuffer[0], inBuffer[1]);
>         return JAVACALL_DIO_FAIL;
>     }
>     return JAVACALL_DIO_OK;
>
> Greetings to everyone
> Peter Saitz
>
> _________________________
>
> Peter Saitz
> Software Developer
>
> Savien Technologies GmbH.
> Bierhäuselberggasse 31
> A-1140 Wien
>
> mailto: peter.saitz at savien.at
> phone: +43 699 19650224
>
> Am 29.10.2015 um 12:27 schrieb Peter Saitz:
>
>>
>> Hi
>>
>> This could be the reason for my problem I have reported on October 23,
>> 2015:
>>
>> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/drivers/gpio/gpio-generic.c?id=25b35da7f4cce82271859f1b6eabd9f3bd41a2bb
>>
>> Some Linux implementations of /sys/class/gpio/gpioNN/value return 0 for
>> low generic GPIO, and something != 0 for high GPIO.
>>
>> In gpio.c line 814 to 821 only "0" (decimal 48) and "1" (decmal 49) will
>> be accepted. All other values result in JAVACALL_DIO_FAIL (line 820). On my
>> Ubuntu Linux, I receive a "2" (decimal 50).
>>
>> The BufferUnderflowException in
>> com.oracle.dio.impl.EventQueueManager.handleEvent() (line 98) seems to be
>> an additional failure, which occurres when read_value_from_pin() returns
>> JAVACALL_DIO_FAIL. Perhaps I'm the first who came into this situation.
>>
>> With kind regards from Vienna/Austria
>> Peter Saitz
>>
>> _________________________
>>
>> Peter Saitz
>> Software Developer
>>
>> Savien Technologies GmbH.
>> Bierhäuselberggasse 31
>> A-1140 Wien
>>
>> mailto: peter.saitz at savien.at
>> phone: +43 699 19650224
>>
>>
>> On October 23, 2015 at 09:53 PM Peter Saitz wrote:
>>
>>>
>>> Hi
>>>
>>> As I have mentioned in my last mail (October 21, 2015), I have ported
>>> OpenJDK Digital I/O to an embedded board with a Freescale i.MX6 Quad
>>> processor, running Ubunto Linux, built dio.jar and libdio.s on the board.
>>>
>>> When I configure a GPIO pin for output, *GPIOPin.getValue()* crashes
>>> with the following appearance:
>>>
>>>    From: src/share/linux/native/com/oracle/dio/gpio/gpio.c, line 819
>>>    Error values from value GPIO pin 124 file was readed: 50 54
>>>    From: src/share/linux/native/com/oracle/dio/gpio/gpio.c, line 819
>>>    Error values from value GPIO pin 124 file was readed: 50 54
>>>
>>>    java.io.IOException
>>>             at com.oracle.dio.gpio.impl.GPIOPinImpl.readPin0(Native
>>> Method)
>>>             at
>>> com.oracle.dio.gpio.impl.GPIOPinImpl.getValue(GPIOPinImpl.java:118)
>>>             .....
>>>    ===== Uncaught exception catched =====
>>>    java.nio.BufferUnderflowException
>>>             at java.nio.Buffer.nextGetIndex(Buffer.java:500)
>>>             at
>>> java.nio.ByteBufferAsIntBufferB.get(ByteBufferAsIntBufferB.java:111)
>>>             at
>>> com.oracle.dio.impl.EventQueueManager.handleEvent(EventQueueManager.java:98)
>>>
>>>             at
>>> com.oracle.dio.impl.EventQueue.dispatch(EventQueue.java:161)
>>>             at
>>> com.oracle.dio.impl.EventQueue.access$500(EventQueue.java:38)
>>>             at
>>> com.oracle.dio.impl.EventQueue$EventDispatchThread.run(EventQueue.java:116)
>>>             at java.lang.Thread.run(Thread.java:745)
>>>
>>>
>>> Note: It's not a copy/paste problem, the first 2 lines from gpio.c came
>>> realy 2 times.
>>>
>>> Here the relevant code from my sources:
>>>
>>>    GPIOPinConfig pinConfig = new GPIOPinConfig.Builder()
>>>             .setControllerNumber(0)
>>>             .setPinNumber(124)
>>>             .setDirection(GPIOPinConfig.DIR_INPUT_ONLY)
>>>             .setTrigger(GPIOPinConfig.TRIGGER_BOTH_EDGES)
>>>             .setDriveMode(GPIOPinConfig.MODE_INPUT_PULL_DOWN)
>>>             .setInitValue(true)
>>>             .build();
>>>    GPIOPin pin = (GPIOPin)DeviceManager.open(GPIOPin.class, pinConfig);
>>>
>>>    ...... in another method ......
>>>    boolean value = pin.getValue();
>>>
>>>
>>> Who can help or fix this bug?
>>>
>>> Note:
>>> I'm using the latest release from http://hg.openjdk.java.net/dio/dev
>>>
>>> With kind regards
>>> Peter Saitz
>>>
>>>
>>
>