On Mon, Jan 16, 2017 at 2:46PM, Eric Schott <eric@xxxxxxxxxxxxxx> wrote
The two additional changes (below) make for a better solution.
> The file ftdi.hpp contains
> enum Direction
> {
> Input,
> Output
> };
>
> The file ftdi.cpp contains
> int Context::flush(int mask)
> {
> int ret = 1;
>
> if (mask & Input)
> ret &= ftdi_usb_purge_rx_buffer(d->ftdi);
> if (mask & Output)
> ret &= ftdi_usb_purge_tx_buffer(d->ftdi);
>
> return ret;
> }
The "&=" is inappropriate as a failure with the rx flush would be
masked if the tx flush was successful. A better fix is to use the
additional purge function in libftdi.c like:
int Context::flush(int mask)
{
switch (mask)
{
case Input:
return ftdi_usb_purge_rx_buffer(d->ftdi);
case Output:
return ftdi_usb_purge_tx_buffer(d->ftdi);
case Input | Output:
return ftdi_usb_purge_buffers(d->ftdi);
case 0:
return 0;
default:
d->ftdi->error_str = "Wrong arguments";
return -101;
}
}
> Since the enumeration assigns the value "0" to Input, the input queue is
> never flushed.
> The enumeration should be something like
>
> The file ftdi.hpp contains
> enum Direction
> {
> Input = 0x1,
> Output = 0x2
> };
To allow previously compiled programs to work with a corrected shared
library, the enumeration should be
enum Direction
{
Input = 0x2,
Output = 0x1
};
Old API New API
---------------- -----------------
Arg as coded Val Behavior Val Behavior
-------------- --- ----------- --- ------------
<zero> 0x0 No action 0x0 No action
Input 0x0 No action 0x2 Rx Flushed
Output 0x1 Out Flushed 0x1 Tx Flushed
Input | Output 0x1 Out Flushed 0x3 Both Flushed
--
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