Re: Re: write and read functions in asyn

[Mark Rivers via Tech-talk <tech-talk@aps.anl.gov>]

• Does the (* write) function in asynInt32.h inherit from the writeIt function in drvAsynSerialPort.c (when accessing a serial port)?

No, the drvAsynSerialPort driver does not implement the asynInt32 interface.

It implements the asynCommon inteface here.  All drivers must implement asynCommon:

https://github.com/epics-modules/asyn/blob/413a3b834b3b3cfd01b1098a023fb01fd9396a59/asyn/drvAsynSerial/drvAsynSerialPort.c#L1096

It implements the asynOption interface here:

https://github.com/epics-modules/asyn/blob/413a3b834b3b3cfd01b1098a023fb01fd9396a59/asyn/drvAsynSerial/drvAsynSerialPort.c#L1099

It implements the asynOctet interface here:

https://github.com/epics-modules/asyn/blob/413a3b834b3b3cfd01b1098a023fb01fd9396a59/asyn/drvAsynSerial/drvAsynSerialPort.c#L1123

Those are the only interfaces that it implements.

This is a simple example driver that implements the asynInt32 interface:

https://github.com/epics-modules/asyn/blob/master/testEpicsApp/src/int32Driver.c

Many drivers now use the asynPortDriver base class.  It greatly simplifies the code required to register and implement asyn interfaces.  This is the code:

https://github.com/epics-modules/asyn/tree/master/asyn/asynPortDriver

This is the documentation:

https://epics-modules.github.io/asyn/asynPortDriver.html

This is a real driver for a simple device that implements the asynInt32 interface using asynPortDriver.

https://github.com/epics-modules/dac128V/blob/master/dac128VApp/src/drvDac128V.cpp

Mark

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From: 高振华 <gaozh@ihep.ac.cn>
Sent: Saturday, April 12, 2025 6:39 AM
To: Mark Rivers <rivers@cars.uchicago.edu>
Cc: tech-talk@aps.anl.gov <tech-talk@aps.anl.gov>
Subject: Re: Re: write and read functions in asyn

 

Hi Mark,

Thanks,

Does the (* write) function in asynInt32.h inherit from the writeIt function in drvAsynSerialPort.c (when accessing a serial port)?

static asynStatus writeIt(void *drvPvt, asynUser *pasynUser, const char *data, size_t numchars,size_t *nbytesTransfered)

{
    ttyController_t *tty = (ttyController_t *)drvPvt;

    int thisWrite;

    int nleft = numchars;

    int timerStarted = 0;

    asynStatus status = asynSuccess;

    assert(tty);

    ...

Gao Zhenhua

-----原始邮件-----
发件人: "Mark Rivers" <rivers@cars.uchicago.edu>
发送时间: 2025-04-11 11:23:41 (星期五)
收件人: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>, 高振华 <gaozh@ihep.ac.cn>
主题: Re: write and read functions in asyn

Those functions are implemented by the asyn driver.  asynInt32.h defines the interface, but the implementation is done in each driver.

They are analogous to C++ pure virtual functions that each derived class must implement.

Mark

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From: Tech-talk <tech-talk-bounces@aps.anl.gov> on behalf of 高振华 via Tech-talk <tech-talk@aps.anl.gov>
Sent: Thursday, April 10, 2025 8:46 PM
To: tech-talk@aps.anl.gov <tech-talk@aps.anl.gov>
Subject: write and read functions in asyn

 

Hi all,

I saw the prototype declarations for the write and read functions in this. h file(asyn/asyn/interfaces/asynInt32.h),

But I couldn't find the bodies of the write and read functions,

Does anyone know where it is?

typedef struct asynInt32 {

    asynStatus (*write)(void *drvPvt, asynUser *pasynUser, epicsInt32 value);

    asynStatus (*read)(void *drvPvt, asynUser *pasynUser, epicsInt32 *value);

    asynStatus (*getBounds)(void *drvPvt, asynUser *pasynUser,

                           epicsInt32 *low, epicsInt32 *high);

    asynStatus (*registerInterruptUser)(void *drvPvt,asynUser *pasynUser,

                           interruptCallbackInt32 callback, void *userPvt,

                           void **registrarPvt);

    asynStatus (*cancelInterruptUser)(void *drvPvt, asynUser *pasynUser,

                           void *registrarPvt);

} asynInt32;

Thanks,

Gao Zhenhua

--

BSRF

Email:gaozh@ihep.ac.cn

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祝好！

高振华

电话：010-88235426

Email:gaozh@ihep.ac.cn