static int scpi_usbtmc_libusb_read_data(void *priv, char *buf, int maxlen)
{
struct scpi_usbtmc_libusb *uscpi = priv;
int read_length;
if (uscpi->response_bytes_read >= uscpi->response_length) {
if (uscpi->remaining_length > 0) {
if (scpi_usbtmc_bulkin_continue(uscpi, uscpi->buffer,
sizeof(uscpi->buffer)) <= 0)
return SR_ERR;
} else {
if (uscpi->bulkin_attributes & EOM)
return SR_ERR;
if (scpi_usbtmc_libusb_read_begin(uscpi) < 0)
return SR_ERR;
}
}
read_length = MIN(uscpi->response_length - uscpi->response_bytes_read, maxlen);
memcpy(buf, uscpi->buffer + uscpi->response_bytes_read, read_length);
uscpi->response_bytes_read += read_length;
return read_length;
}
QByteArray USBTMC::read_answer() {
assert(uscpi.usb.devhdl);
int ret;
QByteArray response;
if (scpi_usbtmc_libusb_read_begin(&uscpi) != SR_OK) {
return {};
//SR_ERR;
}
auto timeout_until = std::chrono::high_resolution_clock::now() + this->timeout;
while (!scpi_usbtmc_libusb_read_complete(&uscpi)) {
/* Read another chunk of the response. */
ret = sr_scpi_read_response(response, timeout_until);
if (ret < 0) {
return {};
}
if (ret > 0) {
timeout_until = std::chrono::high_resolution_clock::now() + this->timeout;
}
}
return response;
}