drivers: modem: cmd_handler: rework reading from interface
So far a dedicated buffer was used for data read from modem
interface. New net_bufs were allocated and filled later, which means
that data was lost when no more net_bufs were available in the pool.
Prevent data loss by allocating net_buf before attempting any read on
modem interface. Process incoming data in a loop as long as reading from
interface results in new data. Also remove dedicated buffer
(data->read_buf) and directly fill net_buf content instead. As a side
effect there are less memory copy operations and RAM usage is reduced.
Pre-allocated net_buf is now always appended to data->rx_buf. When there
was no (more) data read from interface to such net_buf, then this empty
net_buf will be on the end of data->rx_buf fragment list. Update
skipcrlf() and findcrlf() implementations to explicitly check for each
net_buf length, instead of blindly assuming them to have at least single
byte.
Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
6 files changed
