raspberrypi-pico: protocol.h cleanup

[libsigrok.git] / src / hardware / raspberrypi-pico / protocol.c

/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2022 Shawn Walker <ac0bi00@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/>.
 */
#define _GNU_SOURCE

#include <config.h>
#include <errno.h>
#include <glib.h>
#include <math.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <libsigrok/libsigrok.h>
#include "libsigrok-internal.h"
#include "protocol.h"

SR_PRIV int send_serial_str(struct sr_serial_dev_inst *serial, char *str)
{
	int len = strlen(str);
	if ((len > 15) || (len < 1)) {
		sr_err("ERROR:Serial string len %d invalid ", len);
		return SR_ERR;
	}
	/*100ms timeout. With USB CDC serial we can't define the timeout
	  based on link rate, so just pick something large as we shouldn't normally see them */
	if (serial_write_blocking(serial, str, len, 100) != len) {
		sr_err("ERROR:Serial str write failed");
		return SR_ERR;
	}

	return SR_OK;
}

SR_PRIV int send_serial_char(struct sr_serial_dev_inst *serial, char ch)
{
	char buf[1];
	buf[0] = ch;
	if (serial_write_blocking(serial, buf, 1, 100) != 1) {	/*100ms */
		sr_err("ERROR:Serial char write failed");
		return SR_ERR;
	}
	return SR_OK;
}

/* Issue a command that expects a string return that is less than 30 characters.
   returns the length of string */
int send_serial_w_resp(struct sr_serial_dev_inst *serial, char *str,
		       char *resp, size_t cnt)
{
	int num_read, i;
	send_serial_str(serial, str);
	/*Using the serial_read_blocking function when reading a response of unknown length requires 
	a long worst case timeout to always be taken.  So, instead loop waiting for a first byte, and
	then a final small delay for the rest.  */
	for (i = 0; i < 1000; i++) {	/* wait up to 1 second in ms increments */
		num_read = serial_read_blocking(serial, resp, cnt, 1);
		if (num_read > 0)
			break;
	}
	/* Since the serial port is usb CDC we can't calculate timeouts based on baud rate but
	even if the response is split between two USB transfers 10ms should be plenty. */
	num_read +=
	    serial_read_blocking(serial, &(resp[num_read]), cnt - num_read,
				 10);
	if ((num_read < 1) || (num_read > 30)) {
		sr_err("ERROR:Serial_w_resp failed (%d).", num_read);
		return -1;
	} else {
		return num_read;
	}
}

/*Issue a command that expects a single char ack  */
SR_PRIV int send_serial_w_ack(struct sr_serial_dev_inst *serial, char *str)
{
	char buf[2];
	int num_read;
	/*In case we have left over transfer from the device, drain them
	  These should not exist in normal operation */
	while ((num_read = serial_read_blocking(serial, buf, 2, 10))) {
		sr_dbg("swack drops 2 bytes %d %d",buf[0],buf[1]);
	}
	send_serial_str(serial, str);
	/*1000ms timeout */
	num_read = serial_read_blocking(serial, buf, 1, 1000);
	if ((num_read == 1) && (buf[0] == '*')) {
		return SR_OK;
	} else {
		sr_err("ERROR:Serial_w_ack %s failed (%d).", str,
		       num_read);
		if (num_read) {
			sr_err("ack resp char %c d %d\n\r", buf[0],
			       buf[0]);
		}
		return SR_ERR;
	}
}

/*Process incoming data stream assuming it is optimized packing of 4 channels or less
Each byte is 4 channels of data and a 3 bit rle value, or a larger rle value, or a control signal.
This also checks for aborts and ends.
If an end is seen we stop processing but do not check the byte_cnt
The output is a set of samples fed to process group to perform sw triggering and sending of data to the session
as well as maintenance of the serial rx byte cnt.
Since we can get huge rle values we chop them up for processing into smaller groups
In this mode we can always consume all bytes because there are no cases where the processing of one 
byte requires the one after it.
*/
void process_D4(struct sr_dev_inst *sdi, struct dev_context *d)
{
	uint32_t j;
	uint8_t cbyte;
	uint8_t cval;
	uint32_t rlecnt = 0;
	while (d->ser_rdptr < d->bytes_avail) {
		cbyte = d->buffer[(d->ser_rdptr)];
		/*RLE only byte */
		if (cbyte >= 48 && cbyte <= 127) {
			rlecnt += (cbyte - 47) * 8;
			d->byte_cnt++;
		} else if (cbyte >= 0x80) {	/*sample with possible rle */
			rlecnt += (cbyte & 0x70) >> 4;
			if (rlecnt) {
			        /*On a value change, duplicate the previous values first.*/
				rle_memset(d, rlecnt);
				rlecnt = 0;
			}
			/*Finally add in the new values*/
			cval = cbyte & 0xF;
                        uint32_t didx=(d->cbuf_wrptr) * (d->dig_sample_bytes);
			d->d_data_buf[didx] = cval;
			/*pad in all other bytes since the sessions even wants disabled channels reported*/
			for (j = 1; j < d->dig_sample_bytes; j++) {
				d->d_data_buf[didx+j] = 0;
			}
			d->byte_cnt++;
			sr_spew
			    ("Dchan4 rdptr %d wrptr %d bytein 0x%X rle %d cval 0x%X didx %d\n",
			     (d->ser_rdptr) - 1, d->cbuf_wrptr, cbyte,
			     rlecnt, cval,didx);
                        d->cbuf_wrptr++;
			rlecnt = 0;
			d->d_last[0] = cval;
		}
		/*Any other character ends parsing - it could be a frame error or a start of the final byte cnt*/
		else {
			if (cbyte == '$') {
				sr_info
				    ("D4 Data stream stops with cbyte %d char %c rdidx %d cnt %llu",
				     cbyte, cbyte, d->ser_rdptr,
				     d->byte_cnt);
				d->rxstate = RX_STOPPED;
			} else {
				sr_err
				    ("D4 Data stream aborts with cbyte %d char %c rdidx %d cnt %llu",
				     cbyte, cbyte, d->ser_rdptr,
				     d->byte_cnt);
				d->rxstate = RX_ABORT;
			}
			break;	/* break from while loop*/
		}
		(d->ser_rdptr)++;
		/*To ensure we don't overflow the sample buffer, but still send it large chunks of data 
		(to make the packet sends to the session efficient) only call process group after
		a large number of samples have been seen.
                cbuf_wrptr counts slices, so shift right by 2 to create a worst case x4 multiple ratio of
                cbuf_wrptr value to the depth of the sample buffer.
		Likely we could use the max rle value of 640 but 1024 gives some extra room.
                Also do a simple check of rlecnt>2000 since that is a reasonable minimal value to send to the session */
		if ((rlecnt>=2000)
                     ||((rlecnt + ((d->cbuf_wrptr)<<2))) > (d->sample_buf_size - 1024)) {
                         sr_spew("D4 preoverflow wrptr %d bufsize %d rlecnt %d\n\r",d->cbuf_wrptr,d->sample_buf_size,rlecnt);
 			 rle_memset(d, rlecnt);
 			 process_group(sdi, d, d->cbuf_wrptr);
                         rlecnt=0;
		     }

	}/*while rdptr < wrptr*/
	sr_spew("D4 while done rdptr %d", d->ser_rdptr);
	/* If we reach the end of the serial input stream send any remaining values or rles to the session */
	if (rlecnt) {
		sr_spew("Residual D4 slice rlecnt %d", rlecnt);
		rle_memset(d, rlecnt);
	}
	if (d->cbuf_wrptr) {
		sr_spew("Residual D4 data wrptr %d", d->cbuf_wrptr);
		process_group(sdi, d, d->cbuf_wrptr);

	}

} /* Process_D4 */

/*Process incoming data stream and forward to trigger processing with process_group
The final value of ser_rdptr indicates how many bytes were processed.
This version handles all other enabled channel configurations that Process_D4 doesn't */
void process_slice(struct sr_dev_inst *sdi, struct dev_context *devc)
{
	int32_t i;
	uint32_t tmp32;
	uint8_t cbyte;
	uint32_t cword;
	uint32_t slice_bytes;	/*number of bytes that have legal slice values including RLE
	/*Only process legal data values for this mode which are 0x32-0x7F for RLE and 0x80 to 0xFF for data*/
	for (slice_bytes = 1; (slice_bytes < devc->bytes_avail)
	     && (devc->buffer[slice_bytes - 1] >= 0x30); slice_bytes++);
	if (slice_bytes != devc->bytes_avail) {
		cbyte = devc->buffer[slice_bytes - 1];
		slice_bytes--;	/* Don't process the ending character */
		if (cbyte == '$') {
			sr_info
			    ("Data stream stops with cbyte %d char %c rdidx %d sbytes %d cnt %llu",
			     cbyte, cbyte, devc->ser_rdptr, slice_bytes,
			     devc->byte_cnt);
			devc->rxstate = RX_STOPPED;
		} else {
			sr_err
			    ("Data stream aborts with cbyte %d char %c rdidx %d sbytes %d cnt %llu",
			     cbyte, cbyte, devc->ser_rdptr, slice_bytes,
			     devc->byte_cnt);
			devc->rxstate = RX_ABORT;
		}
	}
	/* If the wrptr is non-zero due to a residual from the previous serial transfer don't double count it towards byte_cnt*/
	devc->byte_cnt += slice_bytes - (devc->wrptr);
	sr_spew("process slice avail %d rdptr %d sb %d byte_cnt %" PRIu64 "",
		devc->bytes_avail, devc->ser_rdptr, slice_bytes,
		devc->byte_cnt);
	/*Must have a full slice or one rle byte*/
        while (((devc->ser_rdptr + devc->bytes_per_slice) <= slice_bytes) 
               ||((devc->ser_rdptr  < slice_bytes)&&(devc->buffer[devc->ser_rdptr] < 0x80))) { 

          if(devc->buffer[devc->ser_rdptr] < 0x80){
	     int16_t rlecnt;
	     if(devc->buffer[devc->ser_rdptr]<=79){
                rlecnt=devc->buffer[devc->ser_rdptr]-47;
             }else{ 
	       rlecnt=(devc->buffer[devc->ser_rdptr]-78)*32;
	     }
             sr_info("RLEcnt of %d in %d",rlecnt,devc->buffer[devc->ser_rdptr]);
             if((rlecnt < 1)||(rlecnt>1568)){
                sr_err("Bad rlecnt val %d in %d",rlecnt,devc->buffer[devc->ser_rdptr]);
             }else{
                rle_memset(devc,rlecnt);
             }
             devc->ser_rdptr++;

          }else{
		cword = 0;
		/* build up a word 7 bits at a time, using only enabled channels */
		for (i = 0; i < devc->num_d_channels; i += 7) {
			if (((devc->d_chan_mask) >> i) & 0x7F) {
				cword |=
				    ((devc->buffer[devc->ser_rdptr]) &
				     0x7F) << i;
				(devc->ser_rdptr)++;
			}
		}
		/*and then distribute 8 bits at a time to all possible channels
		  but first save of cword for rle */
                devc->d_last[0]=cword&0xFF;
                devc->d_last[1]=(cword>>8)&0xFF;
                devc->d_last[2]=(cword>>16)&0xFF;
                devc->d_last[3]=(cword>>24)&0xFF;
		for (i = 0; i < devc->num_d_channels; i += 8) {
			uint32_t idx =
			    ((devc->cbuf_wrptr) * devc->dig_sample_bytes) +
			    (i >> 3);
			devc->d_data_buf[idx] = cword & 0xFF;
			sr_spew
			    ("Dchan i %d wrptr %d idx %d char 0x%X cword 0x%X",
			     i, devc->cbuf_wrptr, idx,
			     devc->d_data_buf[idx], cword);
			cword >>= 8;
		}

		/*Each analog value is one or more 7 bit values */
		for (i = 0; i < devc->num_a_channels; i++) {
			if ((devc->a_chan_mask >> i) & 1) {

				tmp32 =
				    devc->buffer[devc->ser_rdptr] - 0x80;
				for(int a=1;a<devc->a_size;a++){
                                    tmp32+=(devc->buffer[(devc->ser_rdptr)+a] - 0x80)<<(7*a);
                                }
				devc->a_data_bufs[i][devc->cbuf_wrptr] =
				    ((float) tmp32 * devc->a_scale[i]) +
				    devc->a_offset[i];
				devc->a_last[i] =
				    devc->a_data_bufs[i][devc->cbuf_wrptr];
				sr_spew
				    ("AChan %d t32 %d value %f wrptr %d rdptr %d sc %f off %f",
				     i, tmp32,
				     devc->
				     a_data_bufs[i][devc->cbuf_wrptr],
				     devc->cbuf_wrptr, devc->ser_rdptr,
				     devc->a_scale[i], devc->a_offset[i]);
				devc->ser_rdptr+=devc->a_size;
			}	/*if channel enabled*/
		}		/*for num_a_channels*/
		devc->cbuf_wrptr++;
	  }/*Not an RLE */
           /*RLEs can create a large number of samples relative to the incoming serial buffer
           To prevent overflow of the sample data buffer we call process_group.
           cbuf_wrptr and sample_buf_size are both in terms of slices
           2048 is more than needed for a max rle of 1640 on the next incoming character */
           if((devc->cbuf_wrptr +2048) >  devc->sample_buf_size){
              sr_spew("Drain large buff %d %d\n\r",devc->cbuf_wrptr,devc->sample_buf_size);
              process_group(sdi, devc, devc->cbuf_wrptr);

           }
	}/* While another slice or RLE available */
	if (devc->cbuf_wrptr){
		process_group(sdi, devc, devc->cbuf_wrptr);
	}

}

/* Send the processed analog values to the session */
int send_analog(struct sr_dev_inst *sdi, struct dev_context *devc,
		uint32_t num_samples, uint32_t offset)
{
	struct sr_datafeed_packet packet;
	struct sr_datafeed_analog analog;
	struct sr_analog_encoding encoding;
	struct sr_analog_meaning meaning;
	struct sr_analog_spec spec;
	struct sr_channel *ch;
	uint32_t i;
	float *fptr;

	sr_analog_init(&analog, &encoding, &meaning, &spec, ANALOG_DIGITS);
	for (i = 0; i < devc->num_a_channels; i++) {
		if ((devc->a_chan_mask >> i) & 1) {
			ch = devc->analog_groups[i]->channels->data;
			analog.meaning->channels =
			    g_slist_append(NULL, ch);
			analog.num_samples = num_samples;
			analog.data = (devc->a_data_bufs[i]) + offset;
			fptr = analog.data;
			sr_spew
			    ("send analog num %d offset %d first %f 2 %f",
			     num_samples, offset, *(devc->a_data_bufs[i]),
			     *fptr);
			analog.meaning->mq = SR_MQ_VOLTAGE;
			analog.meaning->unit = SR_UNIT_VOLT;
			analog.meaning->mqflags = 0;
			packet.type = SR_DF_ANALOG;
			packet.payload = &analog;
			sr_session_send(sdi, &packet);
			g_slist_free(analog.meaning->channels);
		}/* if enabled */
	}/* for channels */
	return 0;

}

/*Send the ring buffer of pre-trigger analog samples.
  The entire buffer is sent (as long as it filled once), but need send two payloads split at the 
  the writeptr  */
int send_analog_ring(struct sr_dev_inst *sdi, struct dev_context *devc,
		     uint32_t num_samples)
{
	struct sr_datafeed_packet packet;
	struct sr_datafeed_analog analog;
	struct sr_analog_encoding encoding;
	struct sr_analog_meaning meaning;
	struct sr_analog_spec spec;
	struct sr_channel *ch;
	int i;
	uint32_t num_pre, start_pre;
	uint32_t num_post, start_post;
	num_pre =
	    (num_samples >=
	     devc->pretrig_wr_ptr) ? devc->pretrig_wr_ptr : num_samples;
	start_pre = devc->pretrig_wr_ptr - num_pre;
	num_post = num_samples - num_pre;
	start_post = devc->pretrig_entries - num_post;
	sr_spew
	    ("send_analog ring wrptr %u ns %d npre %u spre %u npost %u spost %u",
	     devc->pretrig_wr_ptr, num_samples, num_pre, start_pre,
	     num_post, start_post);
	float *fptr;
	sr_analog_init(&analog, &encoding, &meaning, &spec, ANALOG_DIGITS);
	for (i = 0; i < devc->num_a_channels; i++) {
		if ((devc->a_chan_mask >> i) & 1) {
			ch = devc->analog_groups[i]->channels->data;
			analog.meaning->channels =
			    g_slist_append(NULL, ch);
			analog.meaning->mq = SR_MQ_VOLTAGE;
			analog.meaning->unit = SR_UNIT_VOLT;
			analog.meaning->mqflags = 0;
			packet.type = SR_DF_ANALOG;
			packet.payload = &analog;
			/*First send what is after the write pointer because it is oldest */
			if (num_post) {
				analog.num_samples = num_post;
				analog.data =
				    (devc->a_pretrig_bufs[i]) + start_post;
				for (uint32_t j = 0;
				     j < analog.num_samples; j++) {
					fptr =
					    analog.data +
					    (j * sizeof(float));
				}
				sr_session_send(sdi, &packet);
			}
			if (num_pre) {
				analog.num_samples = num_pre;
				analog.data =
				    (devc->a_pretrig_bufs[i]) + start_pre;
				sr_dbg("Sending A%d ring buffer newest ",
				       i);
				for (uint32_t j = 0;
				     j < analog.num_samples; j++) {
					fptr =
					    analog.data +
					    (j * sizeof(float));
					sr_spew("RNGDCW%d j %d %f %p", i,
						j, *fptr, (void *) fptr);
				}
				sr_session_send(sdi, &packet);
			}
			g_slist_free(analog.meaning->channels);
			sr_dbg("Sending A%d ring buffer done ", i);
		}/*if enabled */
	}/* for channels */
	return 0;

}

/* Given a chunk of slices forward to trigger check or session as appropriate and update state
   these could be real slices or those generated by rles */
int process_group(struct sr_dev_inst *sdi, struct dev_context *devc,
		  uint32_t num_slices)
{
	int trigger_offset;
	int pre_trigger_samples;
	/*  These are samples sent to session and are less than num_slices if we reach limit_samples */
	size_t num_samples;
	struct sr_datafeed_logic logic;
	struct sr_datafeed_packet packet;
	int i;
	size_t cbuf_wrptr_cpy;
	cbuf_wrptr_cpy = devc->cbuf_wrptr;
	/*regardless of whether we forward samples on or not (because we aren't triggered), always reset the 
	  pointer into the device data buffers  */
	devc->cbuf_wrptr = 0;
	if (devc->trigger_fired) {	/*send directly to session */
		if (devc->limit_samples &&
		    num_slices >
		    devc->limit_samples - devc->sent_samples) {
			num_samples =
			    devc->limit_samples - devc->sent_samples;
		} else {
			num_samples = num_slices;
		}
		if (num_samples > 0) {
			sr_spew
			    ("Process_group sending %d post trig samples dsb %d",
			     num_samples, devc->dig_sample_bytes);
			if (devc->num_d_channels) {
				packet.type = SR_DF_LOGIC;
				packet.payload = &logic;
				/*Size the number of bytes required to fit all of the channels */
				logic.unitsize = devc->dig_sample_bytes;
				/*The total length of the array sent */
				logic.length =
				    num_samples * logic.unitsize;
				logic.data = devc->d_data_buf;
				sr_session_send(sdi, &packet);
			}
			send_analog(sdi, devc, num_samples, 0);
		}/*num_samples >0 */
		devc->sent_samples += num_samples;
		return 0;
	}/* trigger_fired */
	else {
		size_t num_ring_samples;
		size_t sptr;
		size_t eptr;
		size_t numtail;
		size_t numwrap;
		size_t srcptr;
		/*The trigger_offset is -1 if no trigger is found, but if a trigger is found
		then trigger_offset is the offset into the data buffer sent to it.
		The pre_trigger_samples is the total number of samples before the trigger, but limited to
		the size of the ring buffer set by the capture_ratio. So the pre_trigger_samples can include both the new samples
		and the ring buffer, but trigger_offset is only in relation to the new samples */
		trigger_offset = soft_trigger_logic_check(devc->stl,
							  devc->d_data_buf,
							  num_slices *
							  devc->dig_sample_bytes,
							  &pre_trigger_samples);
		/*A trigger offset >=0 indicates a trigger was seen.  The stl will isue the trigger to the session
		and will forward all pre trigger logic samples, but we must send any post trigger logic 
		and all pre and post trigger analog signals */
		if (trigger_offset > -1) {
			devc->trigger_fired = TRUE;
			devc->sent_samples += pre_trigger_samples;
			packet.type = SR_DF_LOGIC;
			packet.payload = &logic;
			num_samples = num_slices - trigger_offset;
/*Since we are in continuous mode for SW triggers it is possible to get more samples than limit_samples, so
once the trigger fires make sure we don't get beyond limit samples. At this point sent_samples should
be equal to pre_trigger_samples (just added above) because without being triggered we'd never increment
sent_samples.
This number is the number of post trigger logic samples to send to the session, the number of floats
is larger because of the analog ring buffer we track. */
			if (devc->limit_samples &&
			    num_samples >
			    devc->limit_samples - devc->sent_samples)
				num_samples =
				    devc->limit_samples -
				    devc->sent_samples;
			/*The soft trigger logic issues the trigger and sends packest for all logic data that was pretrigger
			  so only send what is left */
			if (num_samples > 0) {
				sr_dbg
				    ("Sending post trigger logical remainder of %d",
				     num_samples);
				logic.length =
				    num_samples * devc->dig_sample_bytes;
				logic.unitsize = devc->dig_sample_bytes;
				logic.data =
				    devc->d_data_buf +
				    (trigger_offset *
				     devc->dig_sample_bytes);
				devc->sent_samples += num_samples;
				sr_session_send(sdi, &packet);
			}
			size_t new_start, new_end, new_samples,
			    ring_samples;
			/*Figure out the analog data to send.
			We might need to send:
			-some or all of incoming data
			-all of incoming data and some of ring buffer
			-all of incoming data and all of ring buffer (and still might be short)
			We don't need to compare to limit_samples because pretrig_entries can never be more than limit_samples
			trigger offset indicatese where in the new samples the trigger was, but we need to go back pretrig_entries before it    */         
			new_start =
			    (trigger_offset >
			     (int) devc->pretrig_entries) ? trigger_offset
			    - devc->pretrig_entries : 0;
			/*Note that we might not have gotten all the pre triggerstore data we were looking for. In such a case the sw trigger
			logic seems to fill up to the limit_samples and thus the ratio is off, but we get the full number of samples
			The number of entries in the ring buffer is pre_trigger_samples-trigger_offset so subtract that from limit samples
			as a threshold */
			new_end =
			    MIN(num_slices - 1,
				devc->limit_samples -
				(pre_trigger_samples - trigger_offset) -
				1);
			/*This includes pre and post trigger storage.*/
			new_samples = new_end - new_start + 1;
			/* pre_trigger_samples can never be greater than trigger_offset by more than the ring buffer depth (pretrig entries)  */
			ring_samples =
			    (pre_trigger_samples >
			     trigger_offset) ? pre_trigger_samples -
			    trigger_offset : 0;
			sr_spew
			    ("SW trigger float info newstart %zu new_end %zu new_samp %zu ring_samp %zu",
			     new_start, new_end, new_samples,
			     ring_samples);
			if (ring_samples > 0) {
				send_analog_ring(sdi, devc, ring_samples);
			}
			if (new_samples) {
				send_analog(sdi, devc, new_samples,
					    new_start);
			}

		}		/* if trigger_offset */
		else {		/* We didn't trigger but need to copy to ring buffer */
			if ((devc->a_chan_mask) && (devc->pretrig_entries)) {
			        /*The incoming data buffer could be much larger than the ring buffer, so never copy more than 
				  the size of the ring buffer */
				num_ring_samples =
				    num_slices >
				    devc->
				    pretrig_entries ? devc->pretrig_entries
				    : num_slices;
				sptr = devc->pretrig_wr_ptr;	/*starting pointer to copy to */
				/*endptr can't go past the end */
				eptr =
				    (sptr + num_ring_samples) >=
				    devc->
				    pretrig_entries ? devc->pretrig_entries
				    - 1 : sptr + num_ring_samples - 1;
				numtail = (eptr - sptr) + 1;	/*number of samples to copy to the tail of ring buffer without wrapping */
				numwrap =
				    (num_ring_samples >
				     numtail) ? num_ring_samples -
				    numtail : 0;
				/* cbuf_wrptr points to where the next write should go, not the actual write data */
				srcptr = cbuf_wrptr_cpy - num_ring_samples;
				sr_spew("RNG num %zu sptr %zu eptr %zu ",
					num_ring_samples, sptr, eptr);
				for (i = 0; i < devc->num_a_channels; i++) {
					if ((devc->a_chan_mask >> i) & 1) {
					        /* copy tail */
						for (uint32_t j = 0;
						     j < numtail; j++) {
							devc->a_pretrig_bufs
							    [i][sptr + j] =
							    devc->a_data_bufs
							    [i]
							    [srcptr + j];
						}      
					}	
				}	
				/* Copy wrap */
				srcptr += numtail;
				for (i = 0; i < devc->num_a_channels; i++) {
					if ((devc->a_chan_mask >> i) & 1) {
						for (uint32_t j = 0;
						     j < numwrap; j++) {
							devc->a_pretrig_bufs
							    [i][j] =
							    devc->a_data_bufs
							    [i]
							    [srcptr + j];
						}	
					}	
				}	
				devc->pretrig_wr_ptr =
				    (numwrap) ? numwrap : (eptr +
							   1) %
				    devc->pretrig_entries;
			}	/*if any analog channel enabled and pretrig_entries */
		}		/*else (trigger not detected) */
	}			/*trigger not set on function entry */
	return 0;
}				/*  process_group */


/*Duplicate previous sample values
  This function relies on the caller to ensure d_data_buf has samples to handle the full value of the rle */
void rle_memset(struct dev_context *devc, uint32_t num_slices)
{
	uint32_t j, k,didx;
	sr_spew("rle_memset vals 0x%X, 0x%X, 0x%X slices %d dsb %d\n", devc->d_last[0],devc->d_last[1],devc->d_last[2],
		num_slices, devc->dig_sample_bytes);
	/* Even if a channel is disabled, PV expects the same location and size for the enabled
	   channels as if the channel were enabled. */
	for (j = 0; j < num_slices; j++) {
                didx=devc->cbuf_wrptr*devc->dig_sample_bytes;
		for (k = 0; k < devc->dig_sample_bytes; k++) {
			devc->d_data_buf[didx + k] =  devc->d_last[k];
		}
		/* cbuf_wrptr always counts slices/samples (and not the bytes in the buffer)
		   regardless of mode */
                devc->cbuf_wrptr++;
	}
        
}

/* This callback function is mapped from api.c with serial_source_add and is created after a capture
has been setup and is responsible for querying the device trigger status, downloading data
and forwarding packets */
SR_PRIV int raspberrypi_pico_receive(int fd, int revents, void *cb_data)
{
	struct sr_dev_inst *sdi;
	struct dev_context *devc;
	struct sr_serial_dev_inst *serial;
	uint32_t i;
	int len;
	uint32_t bytes_rem;
	uint32_t residual_bytes;
	(void) fd;

	if (!(sdi = cb_data))
		return TRUE;

	if (!(devc = sdi->priv))
		return TRUE;
	if (devc->rxstate != RX_ACTIVE) {
	        /*This condition is normal operation and expected to happen 
		  but printed as information */
		sr_dbg("Reached non active state in receive %d",
		       devc->rxstate);
		/*don't return - we may be waiting for a final bytecnt*/
	}
	if (devc->rxstate == RX_IDLE) {
	        /*This is the normal end condition where we do one more receive
		  to make sure we get the full byte_cnt */
		sr_dbg("Reached idle state in receive %d", devc->rxstate);
		return FALSE;
	}

	serial = sdi->conn;
	/*return true if it is some kind of event we don't handle */
	if (!(revents == G_IO_IN || revents == 0))
		return TRUE;
	/*Fill the buffer, note the end may have partial slices */
	bytes_rem = devc->serial_buffer_size - devc->wrptr;
	/*Read one byte less so that we can null it and print as a string
	  Do a small 10ms timeout, if we get nothing, we'll always come back again*/
	len =
	    serial_read_blocking(serial, &(devc->buffer[devc->wrptr]),
				 bytes_rem - 1, 10);
	sr_spew("Entry wrptr %u bytes_rem %u len %d", devc->wrptr,
		bytes_rem, len);

	if (len > 0) {
		devc->buffer[devc->wrptr + len] = 0;
		/*Add the "#" so that spaces in the string are clearly seen */
		sr_dbg("rx string %s#", devc->buffer);
		devc->bytes_avail = (devc->wrptr + len);
		sr_spew
		    ("rx len %d bytes_avail %ul sent_samples %ul wrptr %u",
		     len, devc->bytes_avail, devc->sent_samples,
		     devc->wrptr);
	} else if (len == 0) {
		return TRUE;
	} else {
		sr_err("ERROR:Negative serial read code %d", len);
		sdi->driver->dev_acquisition_stop(sdi);
		return FALSE;
	}/* if len>0 */

	/* Process the serial read data */
	devc->ser_rdptr = 0;
	if (devc->rxstate == RX_ACTIVE) {
		if ((devc->a_chan_mask == 0)
		    && ((devc->d_chan_mask & 0xFFFFFFF0) == 0)) {
			process_D4(sdi, devc);
		} else {
			process_slice(sdi, devc);
		}
	}
	/*process_slice/process_D4 increment ser_rdptr as bytes of the serial buffer are used
	But they may not use all of it, and thus the residual unused bytes are shifted to the start of the buffer
	for the next call. */
	residual_bytes = devc->bytes_avail - devc->ser_rdptr;
	if (residual_bytes) {
		for (i = 0; i < residual_bytes; i++) {
			devc->buffer[i] =
			    devc->buffer[i + devc->ser_rdptr];
		}
		devc->ser_rdptr = 0;
		devc->wrptr = residual_bytes;
		sr_spew("Residual shift rdptr %u wrptr %u",
			devc->ser_rdptr, devc->wrptr);
	} else {
	        /* If there are no residuals shifted then zero the wrptr since all data is used */
		devc->wrptr = 0;
	}
	/*ABORT ends immediately */
	if (devc->rxstate == RX_ABORT) {
		sr_err("Ending receive on abort");
		sdi->driver->dev_acquisition_stop(sdi);
		return FALSE;	
	}
	/*if stopped, look for final '+' indicating the full byte_cnt is received */
	if (devc->rxstate == RX_STOPPED) {
		sr_dbg("Stopped, checking byte_cnt");
		if (devc->buffer[0] != '$') {
		        /*If this happens it means that we got a set of data that was not processed as
			  whole groups of slice bytes. So either we lost data or are not parsing it correctly. */
			sr_err("ERROR: Stop marker should be byte zero");
			devc->rxstate = RX_ABORT;
			sdi->driver->dev_acquisition_stop(sdi);
			return FALSE;
		}
		for (i = 1; i < devc->wrptr; i++) {
			if (devc->buffer[i] == '+') {
				devc->buffer[i] = 0;
				uint64_t rxbytecnt;
				rxbytecnt = atol((char *)&(devc->buffer[1]));
				sr_dbg
				    ("Byte_cnt check device cnt %llu host cnt %llu",
				     rxbytecnt, devc->byte_cnt);
				if (rxbytecnt != devc->byte_cnt) {
					sr_err
					    ("ERROR: received %llu and counted %llu bytecnts don't match, data may be lost",
					     rxbytecnt, devc->byte_cnt);
				}
				/* Since we got the bytecnt we know the device is done sending data */
				devc->rxstate = RX_IDLE;
				/* We must always call acquisition_stop on all completed runs */
				sdi->driver->dev_acquisition_stop(sdi);
				return TRUE;
			}
		}
		/*It's possible we need one more serial transfer to get the byte_cnt, so print that here */
		sr_dbg("Haven't seen byte_cnt + yet");
	} /*if RX_STOPPED*/
	/*If at the sample limit, send a "+" in case we are in continuous mode and need
	to stop the device.  Not that even in non continous mode there might be cases where get an extra
	sample or two... */

	if ((devc->sent_samples >= devc->limit_samples)
	    && (devc->rxstate == RX_ACTIVE)) {
		sr_dbg
		    ("Ending: sent %u of limit %llu samples byte_cnt %llu",
		     devc->sent_samples, devc->limit_samples,
		     devc->byte_cnt);
		send_serial_char(serial, '+');

	}
	sr_spew
	    ("Receive function done: sent %u limit %llu wrptr %u len %d",
	     devc->sent_samples, devc->limit_samples, devc->wrptr, len);
	return TRUE;
}/* raspberrypi_pico_receive */

/* Read device specific information from the device */
SR_PRIV int raspberrypi_pico_get_dev_cfg(const struct sr_dev_inst *sdi)
{
	struct dev_context *devc;
	struct sr_serial_dev_inst *serial;
	char *cmd, response[20];
	gchar **tokens;
	unsigned int i;
	int ret, num_tokens;

	devc = sdi->priv;
	sr_dbg("At get_dev_cfg");
	serial = sdi->conn;
	for (i = 0; i < devc->num_a_channels; i++) {
		cmd = g_strdup_printf("a%d\n", i);
		ret = send_serial_w_resp(serial, cmd, response, 20);
		if (ret <= 0) {
			sr_err
			    ("ERROR:No response from device for analog channel query");
			return SR_ERR;
		}
		response[ret] = 0;
		tokens = NULL;
		tokens = g_strsplit(response, "x", 0);
		num_tokens = g_strv_length(tokens);
		if (num_tokens == 2) {
			devc->a_scale[i] =
			    ((float) atoi(tokens[0])) / 1000000.0;
			devc->a_offset[i] =
			    ((float) atoi(tokens[1])) / 1000000.0;
			sr_dbg
			    ("A%d scale %f offset %f response #%s# tokens #%s# #%s#\n",
			     i, devc->a_scale[i], devc->a_offset[i],
			     response, tokens[0], tokens[1]);
		} else {
			sr_err
			    ("ERROR:Ascale read c%d got unparseable response %s tokens %d",
			     i, response, num_tokens);
			/*force a legal fixed value assuming a 3.3V scale */
			devc->a_scale[i] = 0.0257;
			devc->a_offset[i] = 0.0;
		}
		g_strfreev(tokens);
		g_free(cmd);
	}
	return SR_OK;
}