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>comedi_dio_bitfield2</H1
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><H2
>Name</H2
>comedi_dio_bitfield2 -- read/write multiple digital channels</DIV
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>Synopsis</H2
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><PRE
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>#include <comedilib.h></PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int comedi_dio_bitfield2</CODE
>(comedi_t * device, unsigned int subdevice, unsigned int write_mask, unsigned int * bits, unsigned int base_channel);</CODE
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> Description
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><P
>The function comedi_dio_bitfield2() allows multiple channels to
be read or written together on a digital input, output,
or configurable digital I/O device.
The parameter <CODE
CLASS="PARAMETER"
>write_mask</CODE
>
and the value pointed to by <CODE
CLASS="PARAMETER"
>bits</CODE
>
are interpreted as bit fields, with the least significant bit
representing channel <CODE
CLASS="PARAMETER"
>base_channel</CODE
>.
For each bit in <CODE
CLASS="PARAMETER"
>write_mask</CODE
> that is
set to 1, the cooresponding bit in <CODE
CLASS="PARAMETER"
>*bits</CODE
>
is written to the digital
output channel. After writing all the output channels, each
channel is read, and the result placed in the approprate bits in
<CODE
CLASS="PARAMETER"
>*bits</CODE
>. The result of
reading an output channel is the last
value written to the output channel.</P
><P
>All the channels may not be read or written at the exact same time.
For example, the driver may need to sequentially write to
several ports in order to set all the digital channels specified
by the <CODE
CLASS="PARAMETER"
>write_mask</CODE
>.</P
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