Why I failed to read from my hid device, while I can write to it?
Why I failed to read from my hid device, while I can write to it?
- Subject: Why I failed to read from my hid device, while I can write to it?
- From: "Carlyang" <email@hidden>
- Date: Thu, 27 Feb 2003 17:29:07 +0800
Hi,
I have a Hid device. When I write a report it, it behave correctly(do what I want it to do), though the return value is NOT equal to kIOReturnSucess(the return value is -536854447). when I try to read from it, I can get nothing from it. All datas I preset in the buffer do not been changed. The return value is -536854449.
What do the both return values mean?
My system is Max OS 10.2.4. the following is my codes:
bool HidObj_Mac::readResult(char* resultBuf, int &len)
{
IOReturn ioRet = kIOReturnSuccess;
memset(resultBuf, 0 , len);
ioReturn = (*m_hidDeviceInterface)->open(m_hidDeviceInterface,0);
if (!kIOReturnSuccess != ioRet)
return false;
ioRet = (*m_hidDeviceInterface)->getReport(m_hidDeviceInterface,
kIOHIDReportTypeInput,
0,
resultBuf,
len,
NULL, NULL, NULL);
//here ioRet is allways equal to -536854449
(*m_hidDevieInterface)->close(m_hidDeviceInterface);
return (kIOReturnSuccess == ioRet);
}
Thanks for your attention
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