input/csv: update TODO comments

[libsigrok.git] / src / input / csv.c

/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2013 Marc Schink <sigrok-dev@marcschink.de>
 * Copyright (C) 2019 Gerhard Sittig <gerhard.sittig@gmx.net>
 *
 * 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 "config.h"

#include <glib.h>
#include <stdlib.h>
#include <string.h>

#include <libsigrok/libsigrok.h>
#include "libsigrok-internal.h"
#include "scpi.h"	/* String un-quote for channel name from header line. */

#define LOG_PREFIX "input/csv"

#define CHUNK_SIZE	(4 * 1024 * 1024)

/*
 * The CSV input module has the following options:
 *
 * column_formats: Specifies the data formats and channel counts for the
 *     input file's text columns. Accepts a comma separated list of tuples
 *     with: an optional column repeat count ('*' as a wildcard meaning
 *     "all remaining columns", only applicable to the last field), a format
 *     specifying character ('x' hexadecimal, 'o' octal, 'b' binary, 'l'
 *     single-bit logic), and an optional bit count (translating to: logic
 *     channels communicated in that column). This "column_formats" option
 *     is most versatile, other forms of specifying the column layout only
 *     exist for backwards compatibility.
 *
 * single_column: Specifies the column number which contains the logic data
 *     for single-column mode. All logic data is taken from several bits
 *     which all are kept within that one column. Only exists for backwards
 *     compatibility, see "column_formats" for more flexibility.
 *
 * first_column: Specifies the number of the first column with logic data
 *     in simple multi-column mode. Only exists for backwards compatibility,
 *     see "column_formats" for more flexibility.
 *
 * logic_channels: Specifies the number of logic channels. Is required in
 *     simple single-column mode. Is optional in simple multi-column mode
 *     (and defaults to all remaining columns). Only exists for backwards
 *     compatibility, see "column_formats" for more flexibility.
 *
 * single_format: Specifies the format of the input text in simple single-
 *     column mode. Available formats are: 'bin' (default), 'hex' and 'oct'.
 *     Simple multi-column mode always uses single-bit data per column.
 *     Only exists for backwards compatibility, see "column_formats" for
 *     more flexibility.
 *
 * start_line: Specifies at which line to start processing the input file.
 *     Allows to skip leading lines which neither are header nor data lines.
 *     By default all of the input file gets processed.
 *
 * header: Boolean option, controls whether the first processed line is used
 *     to determine channel names. Off by default. Generic channel names are
 *     used in the absence of header line content.
 *
 * samplerate: Specifies the samplerate of the input data. Defaults to 0.
 *     User specs take precedence over data which optionally gets derived
 *     from input data.
 *
 * column_separator: Specifies the sequence which separates the text file
 *     columns. Cannot be empty. Defaults to comma.
 *
 * comment_leader: Specifies the sequence which starts comments that run
 *     up to the end of the current text line. Can be empty to disable
 *     comment support. Defaults to semicolon.
 *
 * Typical examples of using these options:
 * - ... -I csv:column_formats=*l ...
 *   All columns are single-bit logic data. Identical to the previous
 *   multi-column mode (the default when no options were given at all).
 * - ... -I csv:column_formats=3-,*l ...
 *   Ignore the first three columns, get single-bit logic data from all
 *   remaining lines (multi-column mode with first-column above 1).
 * - ... -I csv:column_formats=3-,4l,x8 ...
 *   Ignore the first three columns, get single-bit logic data from the
 *   next four columns, then eight-bit data in hex format from the next
 *   column. More columns may follow in the input text but won't get
 *   processed. (Mix of previous multi-column as well as single-column
 *   modes.)
 * - ... -I csv:column_formats=4x8,b16,5l ...
 *   Get eight-bit data in hex format from the first four columns, then
 *   sixteen-bit data in binary format, then five times single-bit data.
 * - ... -I csv:single_column=2:single_format=bin:logic_channels=8 ...
 *   Get eight logic bits in binary format from column 2. (Simple
 *   single-column mode, corresponds to the "-,b8" format.)
 * - ... -I csv:first_column=6:logic_channels=4 ...
 *   Get four single-bit logic channels from columns 6 to 9 respectively.
 *   (Simple multi-column mode, corresponds to the "5-,4b" format.)
 * - ... -I csv:start_line=20:header=yes:...
 *   Skip the first 19 text lines. Use line 20 to derive channel names.
 *   Data starts at line 21.
 */

/*
 * TODO
 *
 * - Add support for analog input data? (optional)
 *   - Extend the set of supported column types. Just grab a double
 *     value from floating point format input text.
 *   - Optionally get precision ('digits') from the column's format spec?
 *     From the position which is "bit count" for logic channels?
 * - Optionally get sample rate from timestamp column. Just best-effort
 *   approach, not necessarily reliable. Users can always specify rates.
 * - Add a test suite for input modules in general, and CSV in specific?
 *   Becomes more important with the multitude of options and their
 *   interaction. Could cover edge cases (BOM presence, line termination
 *   absence, etc) and auto-stuff as well (channel names, channel counts,
 *   samplerates, etc).
 */

/* Single column formats. */
enum single_col_format {
	FORMAT_NONE,	/* Ignore this column. */
	FORMAT_BIN,	/* Bin digits for a set of bits (or just one bit). */
	FORMAT_HEX,	/* Hex digits for a set of bits. */
	FORMAT_OCT,	/* Oct digits for a set of bits. */
};

static const char *col_format_text[] = {
	[FORMAT_NONE] = "unknown",
	[FORMAT_BIN] = "binary",
	[FORMAT_HEX] = "hexadecimal",
	[FORMAT_OCT] = "octal",
};

static const char col_format_char[] = {
	[FORMAT_NONE] = '?',
	[FORMAT_BIN] = 'b',
	[FORMAT_HEX] = 'x',
	[FORMAT_OCT] = 'o',
};

struct column_details {
	size_t col_nr;
	enum single_col_format text_format;
	size_t channel_offset;
	size_t channel_count;
};

struct context {
	gboolean started;

	/* Current selected samplerate. */
	uint64_t samplerate;
	gboolean samplerate_sent;

	/* Number of logic channels. */
	size_t logic_channels;

	/* Column delimiter (actually separator), comment leader, EOL sequence. */
	GString *delimiter;
	GString *comment;
	char *termination;

	/* Format specs for input columns, and processing state. */
	size_t column_seen_count;
	const char *column_formats;
	size_t column_want_count;
	struct column_details *column_details;

	/* Line number to start processing. */
	size_t start_line;

	/*
	 * Determines if the first line should be treated as header and used for
	 * channel names in multi column mode.
	 */
	gboolean use_header;
	gboolean header_seen;

	size_t sample_unit_size;	/**!< Byte count for a single sample. */
	uint8_t *sample_buffer;		/**!< Buffer for a single sample. */

	uint8_t *datafeed_buffer;	/**!< Queue for datafeed submission. */
	size_t datafeed_buf_size;
	size_t datafeed_buf_fill;

	/* Current line number. */
	size_t line_number;

	/* List of previously created sigrok channels. */
	GSList *prev_sr_channels;
};

/*
 * Primitive operations to handle sample sets:
 * - Keep a buffer for datafeed submission, capable of holding many
 *   samples (reduces call overhead, improves throughput).
 * - Have a "current sample set" pointer reference one position in that
 *   large samples buffer.
 * - Clear the current sample set before text line inspection, then set
 *   the bits which are found active in the current line of text input.
 *   Phrase the API such that call sites can be kept simple. Advance to
 *   the next sample set between lines, flush the larger buffer as needed
 *   (when it is full, or upon EOF).
 */

static void clear_logic_samples(struct context *inc)
{
	inc->sample_buffer = &inc->datafeed_buffer[inc->datafeed_buf_fill];
	memset(inc->sample_buffer, 0, inc->sample_unit_size);
}

static void set_logic_level(struct context *inc, size_t ch_idx, int on)
{
	size_t byte_idx, bit_idx;
	uint8_t bit_mask;

	if (ch_idx >= inc->logic_channels)
		return;
	if (!on)
		return;

	byte_idx = ch_idx / 8;
	bit_idx = ch_idx % 8;
	bit_mask = 1 << bit_idx;
	inc->sample_buffer[byte_idx] |= bit_mask;
}

static int flush_logic_samples(const struct sr_input *in)
{
	struct context *inc;
	struct sr_datafeed_packet packet;
	struct sr_datafeed_meta meta;
	struct sr_config *src;
	uint64_t samplerate;
	struct sr_datafeed_logic logic;
	int rc;

	inc = in->priv;
	if (!inc->datafeed_buf_fill)
		return SR_OK;

	if (inc->samplerate && !inc->samplerate_sent) {
		packet.type = SR_DF_META;
		packet.payload = &meta;
		samplerate = inc->samplerate;
		src = sr_config_new(SR_CONF_SAMPLERATE, g_variant_new_uint64(samplerate));
		meta.config = g_slist_append(NULL, src);
		sr_session_send(in->sdi, &packet);
		g_slist_free(meta.config);
		sr_config_free(src);
		inc->samplerate_sent = TRUE;
	}

	memset(&packet, 0, sizeof(packet));
	memset(&logic, 0, sizeof(logic));
	packet.type = SR_DF_LOGIC;
	packet.payload = &logic;
	logic.unitsize = inc->sample_unit_size;
	logic.length = inc->datafeed_buf_fill;
	logic.data = inc->datafeed_buffer;

	rc = sr_session_send(in->sdi, &packet);
	if (rc != SR_OK)
		return rc;

	inc->datafeed_buf_fill = 0;
	return SR_OK;
}

static int queue_logic_samples(const struct sr_input *in)
{
	struct context *inc;
	int rc;

	inc = in->priv;
	if (!inc->logic_channels)
		return SR_OK;

	inc->datafeed_buf_fill += inc->sample_unit_size;
	if (inc->datafeed_buf_fill == inc->datafeed_buf_size) {
		rc = flush_logic_samples(in);
		if (rc != SR_OK)
			return rc;
	}
	return SR_OK;
}

/* Helpers for "column processing". */

static int split_column_format(const char *spec,
	size_t *column_count, enum single_col_format *format, size_t *bit_count)
{
	size_t count;
	char *endp, format_char;
	enum single_col_format format_code;

	if (!spec || !*spec)
		return SR_ERR_ARG;

	/* Get the (optional, decimal, default 1) column count. Accept '*'. */
	endp = NULL;
	if (*spec == '*') {
		count = 0;
		endp = (char *)&spec[1];
	} else {
		count = strtoul(spec, &endp, 10);
	}
	if (!endp)
		return SR_ERR_ARG;
	if (endp == spec)
		count = 1;
	if (column_count)
		*column_count = count;
	spec = endp;

	/* Get the (mandatory, single letter) type spec (-/xob/l). */
	format_char = *spec++;
	switch (format_char) {
	case '-':	/* Might conflict with number-parsing. */
	case '/':
		format_char = '-';
		format_code = FORMAT_NONE;
		break;
	case 'x':
		format_code = FORMAT_HEX;
		break;
	case 'o':
		format_code = FORMAT_OCT;
		break;
	case 'b':
	case 'l':
		format_code = FORMAT_BIN;
		break;
	default:	/* includes NUL */
		return SR_ERR_ARG;
	}
	if (format)
		*format = format_code;

	/* Get the (optional, decimal, default 1) bit count. */
	endp = NULL;
	count = strtoul(spec, &endp, 10);
	if (!endp)
		return SR_ERR_ARG;
	if (endp == spec)
		count = 1;
	if (format_char == '-')
		count = 0;
	if (format_char == 'l')
		count = 1;
	if (bit_count)
		*bit_count = count;
	spec = endp;

	/* Input spec must have been exhausted. */
	if (*spec)
		return SR_ERR_ARG;

	return SR_OK;
}

static int make_column_details_from_format(struct context *inc,
	const char *column_format)
{
	char **formats, *format;
	size_t format_count, column_count, bit_count;
	size_t auto_column_count;
	size_t format_idx, c, b, column_idx, channel_idx;
	enum single_col_format f;
	struct column_details *detail;
	int ret;

	/* Split the input spec, count involved columns and bits. */
	formats = g_strsplit(column_format, ",", 0);
	if (!formats) {
		sr_err("Cannot parse columns format %s (comma split).", column_format);
		return SR_ERR_ARG;
	}
	format_count = g_strv_length(formats);
	if (!format_count) {
		sr_err("Cannot parse columns format %s (field count).", column_format);
		g_strfreev(formats);
		return SR_ERR_ARG;
	}
	column_count = bit_count = 0;
	auto_column_count = 0;
	for (format_idx = 0; format_idx < format_count; format_idx++) {
		format = formats[format_idx];
		ret = split_column_format(format, &c, &f, &b);
		sr_dbg("fmt %s -> %zu cols, %s fmt, %zu bits, rc %d", format, c, col_format_text[f], b, ret);
		if (ret != SR_OK) {
			sr_err("Cannot parse columns format %s (field split, %s).", column_format, format);
			g_strfreev(formats);
			return SR_ERR_ARG;
		}
		if (f && !c) {
			/* User requested "auto-count", must be last format. */
			if (formats[format_idx + 1]) {
				sr_err("Auto column count must be last format field.");
				g_strfreev(formats);
				return SR_ERR_ARG;
			}
			auto_column_count = inc->column_seen_count - column_count;
			c = auto_column_count;
		}
		column_count += c;
		bit_count += c * b;
	}
	sr_dbg("Column format %s -> %zu columns, %zu logic channels.",
		column_format, column_count, bit_count);

	/* Allocate and fill in "column processing" details. */
	inc->column_want_count = column_count;
	inc->column_details = g_malloc0_n(column_count, sizeof(inc->column_details[0]));
	column_idx = channel_idx = 0;
	for (format_idx = 0; format_idx < format_count; format_idx++) {
		format = formats[format_idx];
		(void)split_column_format(format, &c, &f, &b);
		if (f && !c)
			c = auto_column_count;
		while (c-- > 0) {
			detail = &inc->column_details[column_idx++];
			detail->col_nr = column_idx;
			detail->text_format = f;
			if (detail->text_format) {
				detail->channel_offset = channel_idx;
				detail->channel_count = b;
				channel_idx += b;
			}
			sr_dbg("detail -> col %zu, fmt %s, ch off/cnt %zu/%zu",
				detail->col_nr, col_format_text[detail->text_format],
				detail->channel_offset, detail->channel_count);
		}
	}
	inc->logic_channels = channel_idx;
	g_strfreev(formats);

	return SR_OK;
}

static const struct column_details *lookup_column_details(struct context *inc, size_t nr)
{
	if (!inc || !inc->column_details)
		return NULL;
	if (!nr || nr > inc->column_want_count)
		return NULL;
	return &inc->column_details[nr - 1];
}

/*
 * Primitive operations for text input: Strip comments off text lines.
 * Split text lines into columns. Process input text for individual
 * columns.
 */

static void strip_comment(char *buf, const GString *prefix)
{
	char *ptr;

	if (!prefix->len)
		return;

	if ((ptr = strstr(buf, prefix->str))) {
		*ptr = '\0';
		g_strstrip(buf);
	}
}

/**
 * @brief Splits a text line into a set of columns.
 *
 * @param[in] buf	The input text line to split.
 * @param[in] inc	The input module's context.
 *
 * @returns An array of strings, representing the columns' text.
 *
 * This routine splits a text line on previously determined separators.
 */
static char **split_line(char *buf, struct context *inc)
{
	return g_strsplit(buf, inc->delimiter->str, 0);
}

/**
 * @brief Parse a multi-bit field into several logic channels.
 *
 * @param[in] column	The input text, a run of bin/hex/oct digits.
 * @param[in] inc	The input module's context.
 * @param[in] details	The column processing details.
 *
 * @retval SR_OK	Success.
 * @retval SR_ERR	Invalid input data (empty, or format error).
 *
 * This routine modifies the logic levels in the current sample set,
 * based on the text input and a user provided format spec.
 */
static int parse_logic(const char *column, struct context *inc,
	const struct column_details *details)
{
	size_t length, ch_rem, ch_idx, ch_inc;
	const char *rdptr;
	char c;
	gboolean valid;
	const char *type_text;
	uint8_t bits;

	/*
	 * Prepare to read the digits from the text end towards the start.
	 * A digit corresponds to a variable number of channels (depending
	 * on the value's radix). Prepare the mapping of text digits to
	 * (a number of) logic channels.
	 */
	length = strlen(column);
	if (!length) {
		sr_err("Column %zu in line %zu is empty.", details->col_nr,
			inc->line_number);
		return SR_ERR;
	}
	rdptr = &column[length];
	ch_idx = details->channel_offset;
	ch_rem = details->channel_count;

	/*
	 * Get another digit and derive up to four logic channels' state from
	 * it. Make sure to not process more bits than the column has channels
	 * associated with it.
	 */
	while (rdptr > column && ch_rem) {
		/* Check for valid digits according to the input radix. */
		c = *(--rdptr);
		switch (details->text_format) {
		case FORMAT_BIN:
			valid = g_ascii_isxdigit(c) && c < '2';
			ch_inc = 1;
			break;
		case FORMAT_OCT:
			valid = g_ascii_isxdigit(c) && c < '8';
			ch_inc = 3;
			break;
		case FORMAT_HEX:
			valid = g_ascii_isxdigit(c);
			ch_inc = 4;
			break;
		default:
			valid = FALSE;
			break;
		}
		if (!valid) {
			type_text = col_format_text[details->text_format];
			sr_err("Invalid text '%s' in %s type column %zu in line %zu.",
				column, type_text, details->col_nr, inc->line_number);
			return SR_ERR;
		}
		/* Use the digit's bits for logic channels' data. */
		bits = g_ascii_xdigit_value(c);
		switch (details->text_format) {
		case FORMAT_HEX:
			if (ch_rem >= 4) {
				ch_rem--;
				set_logic_level(inc, ch_idx + 3, bits & (1 << 3));
			}
			/* FALLTHROUGH */
		case FORMAT_OCT:
			if (ch_rem >= 3) {
				ch_rem--;
				set_logic_level(inc, ch_idx + 2, bits & (1 << 2));
			}
			if (ch_rem >= 2) {
				ch_rem--;
				set_logic_level(inc, ch_idx + 1, bits & (1 << 1));
			}
			/* FALLTHROUGH */
		case FORMAT_BIN:
			ch_rem--;
			set_logic_level(inc, ch_idx + 0, bits & (1 << 0));
			break;
		case FORMAT_NONE:
			/* ShouldNotHappen(TM), but silences compiler warning. */
			return SR_ERR;
		}
		ch_idx += ch_inc;
	}
	/*
	 * TODO Determine whether the availability of extra input data
	 * for unhandled logic channels is worth warning here. In this
	 * implementation users are in control, and can have the more
	 * significant bits ignored (which can be considered a feature
	 * and not really a limitation).
	 */

	return SR_OK;
}

/**
 * @brief Parse routine which ignores the input text.
 *
 * This routine exists to unify dispatch code paths, mapping input file
 * columns' data types to their respective parse routines.
 */
static int parse_ignore(const char *column, struct context *inc,
	const struct column_details *details)
{
	(void)column;
	(void)inc;
	(void)details;
	return SR_OK;
}

typedef int (*col_parse_cb)(const char *column, struct context *inc,
	const struct column_details *details);

static const col_parse_cb col_parse_funcs[] = {
	[FORMAT_NONE] = parse_ignore,
	[FORMAT_BIN] = parse_logic,
	[FORMAT_OCT] = parse_logic,
	[FORMAT_HEX] = parse_logic,
};

static int init(struct sr_input *in, GHashTable *options)
{
	struct context *inc;
	size_t single_column, first_column, logic_channels;
	const char *s;
	enum single_col_format format;
	char format_char;

	in->sdi = g_malloc0(sizeof(*in->sdi));
	in->priv = inc = g_malloc0(sizeof(*inc));

	single_column = g_variant_get_uint32(g_hash_table_lookup(options, "single_column"));

	logic_channels = g_variant_get_uint32(g_hash_table_lookup(options, "logic_channels"));

	inc->delimiter = g_string_new(g_variant_get_string(
			g_hash_table_lookup(options, "column_separator"), NULL));
	if (!inc->delimiter->len) {
		sr_err("Column separator cannot be empty.");
		return SR_ERR_ARG;
	}

	s = g_variant_get_string(g_hash_table_lookup(options, "single_format"), NULL);
	if (g_ascii_strncasecmp(s, "bin", 3) == 0) {
		format = FORMAT_BIN;
	} else if (g_ascii_strncasecmp(s, "hex", 3) == 0) {
		format = FORMAT_HEX;
	} else if (g_ascii_strncasecmp(s, "oct", 3) == 0) {
		format = FORMAT_OCT;
	} else {
		sr_err("Invalid single-column format: '%s'", s);
		return SR_ERR_ARG;
	}

	inc->comment = g_string_new(g_variant_get_string(
			g_hash_table_lookup(options, "comment_leader"), NULL));
	if (g_string_equal(inc->comment, inc->delimiter)) {
		/*
		 * Using the same sequence as comment leader and column
		 * separator won't work. The user probably specified ';'
		 * as the column separator but did not adjust the comment
		 * leader. Try DWIM, drop comment strippin support here.
		 */
		sr_warn("Comment leader and column separator conflict, disabling comment support.");
		g_string_truncate(inc->comment, 0);
	}

	inc->samplerate = g_variant_get_uint64(g_hash_table_lookup(options, "samplerate"));

	first_column = g_variant_get_uint32(g_hash_table_lookup(options, "first_column"));

	inc->use_header = g_variant_get_boolean(g_hash_table_lookup(options, "header"));

	inc->start_line = g_variant_get_uint32(g_hash_table_lookup(options, "start_line"));
	if (inc->start_line < 1) {
		sr_err("Invalid start line %zu.", inc->start_line);
		return SR_ERR_ARG;
	}

	/*
	 * Scan flexible, to get prefered format specs which describe
	 * the input file's data formats. As well as some simple specs
	 * for backwards compatibility and user convenience.
	 *
	 * This logic ends up with a copy of the format string, either
	 * user provided or internally derived. Actual creation of the
	 * column processing details gets deferred until the first line
	 * of input data was seen. To support automatic determination of
	 * e.g. channel counts from column counts.
	 */
	s = g_variant_get_string(g_hash_table_lookup(options, "column_formats"), NULL);
	if (s && *s) {
		inc->column_formats = g_strdup(s);
		sr_dbg("User specified column_formats: %s.", s);
	} else if (single_column && logic_channels) {
		format_char = col_format_char[format];
		if (single_column == 1) {
			inc->column_formats = g_strdup_printf("%c%zu",
				format_char, logic_channels);
		} else {
			inc->column_formats = g_strdup_printf("%zu-,%c%zu",
				single_column - 1,
				format_char, logic_channels);
		}
		sr_dbg("Backwards compat single_column, col %zu, fmt %s, bits %zu -> %s.",
			single_column, col_format_text[format], logic_channels,
			inc->column_formats);
	} else if (!single_column) {
		if (first_column > 1) {
			inc->column_formats = g_strdup_printf("%zu-,%zul",
				first_column - 1, logic_channels);
		} else {
			inc->column_formats = g_strdup_printf("%zul",
				logic_channels);
		}
		sr_dbg("Backwards compat multi-column, col %zu, chans %zu -> %s.",
			first_column, logic_channels,
			inc->column_formats);
	} else {
		sr_warn("Unknown or unsupported columns layout spec, assuming simple multi-column mode.");
		inc->column_formats = g_strdup("*l");
	}

	return SR_OK;
}

/*
 * Check the channel list for consistency across file re-import. See
 * the VCD input module for more details and motivation.
 */

static void keep_header_for_reread(const struct sr_input *in)
{
	struct context *inc;

	inc = in->priv;
	g_slist_free_full(inc->prev_sr_channels, sr_channel_free_cb);
	inc->prev_sr_channels = in->sdi->channels;
	in->sdi->channels = NULL;
}

static int check_header_in_reread(const struct sr_input *in)
{
	struct context *inc;

	if (!in)
		return FALSE;
	inc = in->priv;
	if (!inc)
		return FALSE;
	if (!inc->prev_sr_channels)
		return TRUE;

	if (sr_channel_lists_differ(inc->prev_sr_channels, in->sdi->channels)) {
		sr_err("Channel list change not supported for file re-read.");
		return FALSE;
	}
	g_slist_free_full(in->sdi->channels, sr_channel_free_cb);
	in->sdi->channels = inc->prev_sr_channels;
	inc->prev_sr_channels = NULL;

	return TRUE;
}

static const char *delim_set = "\r\n";

static const char *get_line_termination(GString *buf)
{
	const char *term;

	term = NULL;
	if (g_strstr_len(buf->str, buf->len, "\r\n"))
		term = "\r\n";
	else if (memchr(buf->str, '\n', buf->len))
		term = "\n";
	else if (memchr(buf->str, '\r', buf->len))
		term = "\r";

	return term;
}

static int initial_parse(const struct sr_input *in, GString *buf)
{
	struct context *inc;
	GString *channel_name;
	size_t num_columns, ch_idx, ch_name_idx, col_idx, col_nr;
	size_t line_number, line_idx;
	int ret;
	char **lines, *line, **columns, *column;
	const char *col_caption;
	gboolean got_caption;
	const struct column_details *detail;

	ret = SR_OK;
	inc = in->priv;
	columns = NULL;

	line_number = 0;
	if (inc->termination)
		lines = g_strsplit(buf->str, inc->termination, 0);
	else
		lines = g_strsplit_set(buf->str, delim_set, 0);
	for (line_idx = 0; (line = lines[line_idx]); line_idx++) {
		line_number++;
		if (inc->start_line > line_number) {
			sr_spew("Line %zu skipped (before start).", line_number);
			continue;
		}
		if (line[0] == '\0') {
			sr_spew("Blank line %zu skipped.", line_number);
			continue;
		}
		strip_comment(line, inc->comment);
		if (line[0] == '\0') {
			sr_spew("Comment-only line %zu skipped.", line_number);
			continue;
		}

		/* Reached first proper line. */
		break;
	}
	if (!line) {
		/* Not enough data for a proper line yet. */
		ret = SR_ERR_NA;
		goto out;
	}

	/* See how many columns the current line has. */
	columns = split_line(line, inc);
	if (!columns) {
		sr_err("Error while parsing line %zu.", line_number);
		ret = SR_ERR;
		goto out;
	}
	num_columns = g_strv_length(columns);
	if (!num_columns) {
		sr_err("Error while parsing line %zu.", line_number);
		ret = SR_ERR;
		goto out;
	}
	sr_dbg("DIAG Got %zu columns in text line: %s.", num_columns, line);

	/*
	 * Track the observed number of columns in the input file. Do
	 * process the previously gathered columns format spec now that
	 * automatic channel count can be dealt with.
	 */
	inc->column_seen_count = num_columns;
	ret = make_column_details_from_format(inc, inc->column_formats);
	if (ret != SR_OK) {
		sr_err("Cannot parse columns format using line %zu.", line_number);
		goto out;
	}

	/*
	 * Assume all lines have equal length (column count). Bail out
	 * early on suspicious or insufficient input data (check input
	 * which became available here against previous user specs or
	 * auto-determined properties, regardless of layout variant).
	 */
	if (num_columns < inc->column_want_count) {
		sr_err("Insufficient input text width for desired data amount, got %zu but want %zu columns.",
			num_columns, inc->column_want_count);
		ret = SR_ERR;
		goto out;
	}

	/*
	 * Determine channel names. Optionally use text from a header
	 * line (when requested by the user, and only works in multi
	 * column mode). In the absence of header text, or in single
	 * column mode, channels are assigned rather generic names.
	 *
	 * Manipulation of the column's caption is acceptable here, the
	 * header line will never get processed another time.
	 */
	channel_name = g_string_sized_new(64);
	for (col_idx = 0; col_idx < inc->column_want_count; col_idx++) {

		col_nr = col_idx + 1;
		detail = lookup_column_details(inc, col_nr);
		if (detail->text_format == FORMAT_NONE)
			continue;
		column = columns[col_idx];
		col_caption = sr_scpi_unquote_string(column);
		got_caption = inc->use_header && *col_caption;
		sr_dbg("DIAG col %zu, ch count %zu, text %s.",
			col_nr, detail->channel_count, col_caption);
		for (ch_idx = 0; ch_idx < detail->channel_count; ch_idx++) {
			ch_name_idx = detail->channel_offset + ch_idx;
			if (got_caption && detail->channel_count == 1)
				g_string_assign(channel_name, col_caption);
			else if (got_caption)
				g_string_printf(channel_name, "%s[%zu]",
					col_caption, ch_idx);
			else
				g_string_printf(channel_name, "%zu", ch_name_idx);
			sr_dbg("DIAG ch idx %zu, name %s.", ch_name_idx, channel_name->str);
			sr_channel_new(in->sdi, ch_name_idx, SR_CHANNEL_LOGIC, TRUE,
				channel_name->str);
		}
	}
	g_string_free(channel_name, TRUE);
	if (!check_header_in_reread(in)) {
		ret = SR_ERR_DATA;
		goto out;
	}

	/*
	 * Calculate the minimum buffer size to store the set of samples
	 * of all channels (unit size). Determine a larger buffer size
	 * for datafeed submission that is a multiple of the unit size.
	 * Allocate the larger buffer, the "sample buffer" will point
	 * to a location within that large buffer later.
	 */
	inc->sample_unit_size = (inc->logic_channels + 7) / 8;
	inc->datafeed_buf_size = CHUNK_SIZE;
	inc->datafeed_buf_size *= inc->sample_unit_size;
	inc->datafeed_buffer = g_malloc(inc->datafeed_buf_size);
	inc->datafeed_buf_fill = 0;

out:
	if (columns)
		g_strfreev(columns);
	g_strfreev(lines);

	return ret;
}

/*
 * Gets called from initial_receive(), which runs until the end-of-line
 * encoding of the input stream could get determined. Assumes that this
 * routine receives enough buffered initial input data to either see the
 * BOM when there is one, or that no BOM will follow when a text line
 * termination sequence was seen. Silently drops the UTF-8 BOM sequence
 * from the input buffer if one was seen. Does not care to protect
 * against multiple execution or dropping the BOM multiple times --
 * there should be at most one in the input stream.
 */
static void initial_bom_check(const struct sr_input *in)
{
	static const char *utf8_bom = "\xef\xbb\xbf";

	if (in->buf->len < strlen(utf8_bom))
		return;
	if (strncmp(in->buf->str, utf8_bom, strlen(utf8_bom)) != 0)
		return;
	g_string_erase(in->buf, 0, strlen(utf8_bom));
}

static int initial_receive(const struct sr_input *in)
{
	struct context *inc;
	GString *new_buf;
	int len, ret;
	char *p;
	const char *termination;

	initial_bom_check(in);

	inc = in->priv;

	termination = get_line_termination(in->buf);
	if (!termination)
		/* Don't have a full line yet. */
		return SR_ERR_NA;

	p = g_strrstr_len(in->buf->str, in->buf->len, termination);
	if (!p)
		/* Don't have a full line yet. */
		return SR_ERR_NA;
	len = p - in->buf->str - 1;
	new_buf = g_string_new_len(in->buf->str, len);
	g_string_append_c(new_buf, '\0');

	inc->termination = g_strdup(termination);

	if (in->buf->str[0] != '\0')
		ret = initial_parse(in, new_buf);
	else
		ret = SR_OK;

	g_string_free(new_buf, TRUE);

	return ret;
}

static int process_buffer(struct sr_input *in, gboolean is_eof)
{
	struct context *inc;
	gsize num_columns;
	size_t line_idx, col_idx, col_nr;
	const struct column_details *details;
	col_parse_cb parse_func;
	int ret;
	char *p, **lines, *line, **columns, *column;

	inc = in->priv;
	if (!inc->started) {
		std_session_send_df_header(in->sdi);
		inc->started = TRUE;
	}

	/*
	 * Consider empty input non-fatal. Keep accumulating input until
	 * at least one full text line has become available. Grab the
	 * maximum amount of accumulated data that consists of full text
	 * lines, and process what has been received so far, leaving not
	 * yet complete lines for the next invocation.
	 *
	 * Enforce that all previously buffered data gets processed in
	 * the "EOF" condition. Do not insist in the presence of the
	 * termination sequence for the last line (may often be missing
	 * on Windows). A present termination sequence will just result
	 * in the "execution of an empty line", and does not harm.
	 */
	if (!in->buf->len)
		return SR_OK;
	if (is_eof) {
		p = in->buf->str + in->buf->len;
	} else {
		p = g_strrstr_len(in->buf->str, in->buf->len, inc->termination);
		if (!p)
			return SR_ERR;
		*p = '\0';
		p += strlen(inc->termination);
	}
	g_strstrip(in->buf->str);

	ret = SR_OK;
	lines = g_strsplit(in->buf->str, inc->termination, 0);
	for (line_idx = 0; (line = lines[line_idx]); line_idx++) {
		inc->line_number++;
		if (inc->line_number < inc->start_line) {
			sr_spew("Line %zu skipped (before start).", inc->line_number);
			continue;
		}
		if (line[0] == '\0') {
			sr_spew("Blank line %zu skipped.", inc->line_number);
			continue;
		}

		/* Remove trailing comment. */
		strip_comment(line, inc->comment);
		if (line[0] == '\0') {
			sr_spew("Comment-only line %zu skipped.", inc->line_number);
			continue;
		}

		/* Skip the header line, its content was used as the channel names. */
		if (inc->use_header && !inc->header_seen) {
			sr_spew("Header line %zu skipped.", inc->line_number);
			inc->header_seen = TRUE;
			continue;
		}

		/* Split the line into columns, check for minimum length. */
		columns = split_line(line, inc);
		if (!columns) {
			sr_err("Error while parsing line %zu.", inc->line_number);
			g_strfreev(lines);
			return SR_ERR;
		}
		num_columns = g_strv_length(columns);
		if (num_columns < inc->column_want_count) {
			sr_err("Insufficient column count %zu in line %zu.",
				num_columns, inc->line_number);
			g_strfreev(columns);
			g_strfreev(lines);
			return SR_ERR;
		}

		/* Have the columns of the current text line processed. */
		clear_logic_samples(inc);
		for (col_idx = 0; col_idx < inc->column_want_count; col_idx++) {
			column = columns[col_idx];
			col_nr = col_idx + 1;
			details = lookup_column_details(inc, col_nr);
			if (!details || !details->text_format)
				continue;
			parse_func = col_parse_funcs[details->text_format];
			if (!parse_func)
				continue;
			ret = parse_func(column, inc, details);
			if (ret != SR_OK) {
				g_strfreev(columns);
				g_strfreev(lines);
				return SR_ERR;
			}
		}

		/* Send sample data to the session bus (buffered). */
		ret = queue_logic_samples(in);
		if (ret != SR_OK) {
			sr_err("Sending samples failed.");
			g_strfreev(columns);
			g_strfreev(lines);
			return SR_ERR;
		}

		g_strfreev(columns);
	}
	g_strfreev(lines);
	g_string_erase(in->buf, 0, p - in->buf->str);

	return ret;
}

static int receive(struct sr_input *in, GString *buf)
{
	struct context *inc;
	int ret;

	g_string_append_len(in->buf, buf->str, buf->len);

	inc = in->priv;
	if (!inc->column_seen_count) {
		ret = initial_receive(in);
		if (ret == SR_ERR_NA)
			/* Not enough data yet. */
			return SR_OK;
		else if (ret != SR_OK)
			return SR_ERR;

		/* sdi is ready, notify frontend. */
		in->sdi_ready = TRUE;
		return SR_OK;
	}

	ret = process_buffer(in, FALSE);

	return ret;
}

static int end(struct sr_input *in)
{
	struct context *inc;
	int ret;

	if (in->sdi_ready)
		ret = process_buffer(in, TRUE);
	else
		ret = SR_OK;
	if (ret != SR_OK)
		return ret;

	ret = flush_logic_samples(in);
	if (ret != SR_OK)
		return ret;

	inc = in->priv;
	if (inc->started)
		std_session_send_df_end(in->sdi);

	return ret;
}

static void cleanup(struct sr_input *in)
{
	struct context *inc;

	keep_header_for_reread(in);

	inc = in->priv;

	g_free(inc->termination);
	inc->termination = NULL;
	g_free(inc->datafeed_buffer);
	inc->datafeed_buffer = NULL;
}

static int reset(struct sr_input *in)
{
	struct context *inc = in->priv;

	cleanup(in);
	inc->started = FALSE;
	g_string_truncate(in->buf, 0);

	return SR_OK;
}

enum option_index {
	OPT_COL_FMTS,
	OPT_SINGLE_COL,
	OPT_FIRST_COL,
	OPT_NUM_LOGIC,
	OPT_FORMAT,
	OPT_START,
	OPT_HEADER,
	OPT_RATE,
	OPT_DELIM,
	OPT_COMMENT,
	OPT_MAX,
};

static struct sr_option options[] = {
	[OPT_COL_FMTS] = {
		"column_formats", "Column format specs",
		"Specifies text columns data types: comma separated list of [<cols>]<fmt>[<bits>], with -/x/o/b/l format specifiers.",
		NULL, NULL,
	},
	[OPT_SINGLE_COL] = {
		"single_column", "Single column",
		"Enable single-column mode, exclusively use text from the specified column (number starting at 1).",
		NULL, NULL,
	},
	[OPT_FIRST_COL] = {
		"first_column", "First column",
		"Number of the first column with logic data in simple multi-column mode (number starting at 1, default 1).",
		NULL, NULL,
	},
	[OPT_NUM_LOGIC] = {
		"logic_channels", "Number of logic channels",
		"Logic channel count, required in simple single-column mode, defaults to \"all remaining columns\" in simple multi-column mode. Obsoleted by 'column_formats'.",
		NULL, NULL,
	},
	[OPT_FORMAT] = {
		"single_format", "Data format for simple single-column mode.",
		"The number format of single-column mode input data: bin, hex, oct.",
		NULL, NULL,
	},
	[OPT_START] = {
		"start_line", "Start line",
		"The line number at which to start processing input text (default: 1).",
		NULL, NULL,
	},
	[OPT_HEADER] = {
		"header", "Get channel names from first line.",
		"Use the first processed line's column captions (when available) as channel names.",
		NULL, NULL,
	},
	[OPT_RATE] = {
		"samplerate", "Samplerate (Hz)",
		"The input data's sample rate in Hz.",
		NULL, NULL,
	},
	[OPT_DELIM] = {
		"column_separator", "Column separator",
		"The sequence which separates text columns. Non-empty text, comma by default.",
		NULL, NULL,
	},
	[OPT_COMMENT] = {
		"comment_leader", "Comment leader character",
		"The text which starts comments at the end of text lines.",
		NULL, NULL,
	},
	[OPT_MAX] = ALL_ZERO,
};

static const struct sr_option *get_options(void)
{
	GSList *l;

	if (!options[0].def) {
		options[OPT_COL_FMTS].def = g_variant_ref_sink(g_variant_new_string(""));
		options[OPT_SINGLE_COL].def = g_variant_ref_sink(g_variant_new_uint32(0));
		options[OPT_FIRST_COL].def = g_variant_ref_sink(g_variant_new_uint32(1));
		options[OPT_NUM_LOGIC].def = g_variant_ref_sink(g_variant_new_uint32(0));
		options[OPT_FORMAT].def = g_variant_ref_sink(g_variant_new_string("bin"));
		l = NULL;
		l = g_slist_append(l, g_variant_ref_sink(g_variant_new_string("bin")));
		l = g_slist_append(l, g_variant_ref_sink(g_variant_new_string("hex")));
		l = g_slist_append(l, g_variant_ref_sink(g_variant_new_string("oct")));
		options[OPT_FORMAT].values = l;
		options[OPT_START].def = g_variant_ref_sink(g_variant_new_uint32(1));
		options[OPT_HEADER].def = g_variant_ref_sink(g_variant_new_boolean(FALSE));
		options[OPT_RATE].def = g_variant_ref_sink(g_variant_new_uint64(0));
		options[OPT_DELIM].def = g_variant_ref_sink(g_variant_new_string(","));
		options[OPT_COMMENT].def = g_variant_ref_sink(g_variant_new_string(";"));
	}

	return options;
}

SR_PRIV struct sr_input_module input_csv = {
	.id = "csv",
	.name = "CSV",
	.desc = "Comma-separated values",
	.exts = (const char*[]){"csv", NULL},
	.options = get_options,
	.init = init,
	.receive = receive,
	.end = end,
	.cleanup = cleanup,
	.reset = reset,
};