libsigrok/hardware/brymen-dmm/protocol.c

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/*
* This file is part of the libsigrok project.
*
* Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "protocol.h"
/* parser.c */
SR_PRIV int sr_brymen_parse(const uint8_t *buf, float *floatval,
struct sr_datafeed_analog *analog, void *info);
static void handle_packet(const uint8_t *buf, struct sr_dev_inst *sdi)
{
float floatval;
struct dev_context *devc;
struct sr_datafeed_packet packet;
struct sr_datafeed_analog analog;
devc = sdi->priv;
analog.num_samples = 1;
analog.mq = -1;
sr_brymen_parse(buf, &floatval, &analog, NULL);
analog.data = &floatval;
analog.probes = sdi->probes;
if (analog.mq != -1) {
/* Got a measurement. */
packet.type = SR_DF_ANALOG;
packet.payload = &analog;
sr_session_send(devc->cb_data, &packet);
devc->num_samples++;
}
}
static void handle_new_data(struct sr_dev_inst *sdi)
{
struct dev_context *devc;
int len, status, offset = 0;
struct sr_serial_dev_inst *serial;
devc = sdi->priv;
serial = sdi->conn;
/* Try to get as much data as the buffer can hold. */
len = DMM_BUFSIZE - devc->buflen;
len = serial_read(serial, devc->buf + devc->buflen, len);
if (len < 1) {
sr_err("Serial port read error: %d.", len);
return;
}
devc->buflen += len;
status = PACKET_INVALID_HEADER;
/* Now look for packets in that data. */
while (status != PACKET_NEED_MORE_DATA) {
/* We don't have a header, look for one. */
if (devc->next_packet_len == 0) {
len = devc->buflen - offset;
status = brymen_packet_length(devc->buf + offset, &len);
if (status == PACKET_HEADER_OK) {
/* We know how large the packet will be. */
devc->next_packet_len = len;
} else if (status == PACKET_NEED_MORE_DATA) {
/* We didn't yet receive the full header. */
devc->next_packet_len = 0;
break;
} else {
/* Invalid header. Move on. */
devc->next_packet_len = 0;
offset++;
continue;
}
}
/* We know how the packet size, but did we receive all of it? */
if (devc->buflen - offset < devc->next_packet_len)
break;
/* We should have a full packet here, so we can check it. */
if (brymen_packet_is_valid(devc->buf + offset)) {
handle_packet(devc->buf + offset, sdi);
offset += devc->next_packet_len;
} else {
offset++;
}
/* We are done with this packet. Look for a new one. */
devc->next_packet_len = 0;
}
/* If we have any data left, move it to the beginning of our buffer. */
memmove(devc->buf, devc->buf + offset, devc->buflen - offset);
devc->buflen -= offset;
}
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SR_PRIV int brymen_dmm_receive_data(int fd, int revents, void *cb_data)
{
struct sr_dev_inst *sdi;
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struct dev_context *devc;
struct sr_serial_dev_inst *serial;
int ret;
int64_t time;
(void)fd;
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if (!(sdi = cb_data))
return TRUE;
if (!(devc = sdi->priv))
return TRUE;
serial = sdi->conn;
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if (revents == G_IO_IN) {
/* Serial data arrived. */
handle_new_data(sdi);
} else {
/* Timeout, send another packet request. */
if ((ret = brymen_packet_request(serial)) < 0) {
sr_err("Failed to request packet: %d.", ret);
return FALSE;
}
}
if (devc->limit_samples && devc->num_samples >= devc->limit_samples) {
sr_info("Requested number of samples reached, stopping.");
sdi->driver->dev_acquisition_stop(sdi, cb_data);
return TRUE;
}
if (devc->limit_msec) {
time = (g_get_monotonic_time() - devc->starttime) / 1000;
if (time > (int64_t)devc->limit_msec) {
sr_info("Requested time limit reached, stopping.");
sdi->driver->dev_acquisition_stop(sdi, cb_data);
return TRUE;
}
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}
return TRUE;
}
/**
* Try to find a valid packet in a serial data stream.
*
* @param serial Previously initialized serial port structure.
* @param buf Buffer containing the bytes to write.
* @param buflen Size of the buffer.
* @param get_packet_size Callback that assesses the size of incoming packets.
* @param is_valid Callback that assesses whether the packet is valid or not.
* @param timeout_ms The timeout after which, if no packet is detected, to
* abort scanning.
* @param baudrate The baudrate of the serial port. This parameter is not
* critical, but it helps fine tune the serial port polling
* delay.
*
* @return SR_OK if a valid packet is found within the given timeout,
* SR_ERR upon failure.
*/
SR_PRIV int brymen_stream_detect(struct sr_serial_dev_inst *serial,
uint8_t *buf, size_t *buflen,
packet_length_t get_packet_size,
packet_valid_t is_valid,
uint64_t timeout_ms, int baudrate)
{
int64_t start, time, byte_delay_us;
size_t ibuf, i, maxlen;
int status, len, packet_len, stream_len;
maxlen = *buflen;
sr_dbg("Detecting packets on FD %d (timeout = %" PRIu64
"ms, baudrate = %d).", serial->fd, timeout_ms, baudrate);
/* Assume 8n1 transmission. That is 10 bits for every byte. */
byte_delay_us = 10 * (1000000 / baudrate);
start = g_get_monotonic_time();
packet_len = i = ibuf = len = 0;
while (ibuf < maxlen) {
len = serial_read(serial, &buf[ibuf], maxlen - ibuf);
if (len > 0) {
ibuf += len;
sr_spew("Read %d bytes.", len);
}
time = g_get_monotonic_time() - start;
time /= 1000;
stream_len = ibuf - i;
if (stream_len > 0 && packet_len == 0) {
/* How large of a packet are we expecting? */
packet_len = stream_len;
status = get_packet_size(&buf[i], &packet_len);
switch(status) {
case PACKET_HEADER_OK:
/* We know how much data we need to wait for. */
break;
case PACKET_NEED_MORE_DATA:
/* We did not receive the full header. */
packet_len = 0;
break;
case PACKET_INVALID_HEADER:
default:
/*
* We had enough data, but here was an error in
* parsing the header. Restart parsing from the
* next byte.
*/
packet_len = 0;
i++;
break;
}
}
if ((stream_len >= packet_len) && (packet_len != 0)) {
/* We have at least a packet's worth of data. */
if (is_valid(&buf[i])) {
sr_spew("Found valid %d-byte packet after "
"%" PRIu64 "ms.", packet_len, time);
*buflen = ibuf;
return SR_OK;
} else {
sr_spew("Got %d bytes, but not a valid "
"packet.", packet_len);
}
/* Not a valid packet. Continue searching. */
i++;
packet_len = 0;
}
if (time >= (int64_t)timeout_ms) {
/* Timeout */
sr_dbg("Detection timed out after %dms.", time);
break;
}
g_usleep(byte_delay_us);
}
*buflen = ibuf;
sr_err("Didn't find a valid packet (read %d bytes).", ibuf);
return SR_ERR;
}