input/csv: improve robustness of "use header for channel names"

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

/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2013 Marc Schink <sigrok-dev@marcschink.de>
 *
 * 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"

#define LOG_PREFIX "input/csv"

#define CHUNK_SIZE      (4 * 1024 * 1024)

/*
 * The CSV input module has the following options:
 *
 * single-column: Specifies the column number which stores the sample data for
 *                single column mode and enables single column mode. Multi
 *                column mode is used if this parameter is omitted.
 *
 * numchannels:   Specifies the number of channels to use. In multi column mode
 *                the number of channels are the number of columns and in single
 *                column mode the number of bits (LSB first) beginning at
 *                'first-channel'.
 *
 * delimiter:     Specifies the delimiter for columns. Must be at least one
 *                character. Comma is used as default delimiter.
 *
 * format:        Specifies the format of the sample data in single column mode.
 *                Available formats are: 'bin', 'hex' and 'oct'. The binary
 *                format is used by default. This option has no effect in multi
 *                column mode.
 *
 * comment:       Specifies the prefix character(s) for comments. No prefix
 *                characters are used by default which disables removing of
 *                comments.
 *
 * samplerate:    Samplerate which the sample data was captured with. Default
 *                value is 0.
 *
 * first-channel: Column number of the first channel in multi column mode and
 *                position of the bit for the first channel in single column mode.
 *                Default value is 0.
 *
 * header:        Determines if the first line should be treated as header
 *                and used for channel names in multi column mode. Empty header
 *                names will be replaced by the channel number. If enabled in
 *                single column mode the first line will be skipped. Usage of
 *                header is disabled by default.
 *
 * startline:     Line number to start processing sample data. Must be greater
 *                than 0. The default line number to start processing is 1.
 */

/*
 * TODO
 *
 * - Determine how the text line handling can get improved, regarding
 *   all of robustness and flexibility and correctness.
 *   - The current implementation splits on "any run of CR and LF". Which
 *     translates to: Line numbers are wrong in the presence of empty
 *     lines in the input stream. See below for an (expensive) fix.
 *   - Dropping support for CR style end-of-line markers could improve
 *     the situation a lot. Code could search for and split on LF, and
 *     trim optional trailing CR. This would result in proper support
 *     for CRLF (Windows) as well as LF (Unix), and allow for correct
 *     line number counts.
 *   - When support for CR-only line termination cannot get dropped,
 *     then the current implementation is inappropriate. Currently the
 *     input stream is scanned for the first occurance of either of the
 *     supported termination styles (which is good). For the remaining
 *     session a consistent encoding of the text lines is assumed (which
 *     is acceptable).
 *   - When line numbers need to be correct and reliable, _and_ the full
 *     set of previously supported line termination sequences are required,
 *     and potentially more are to get added for improved compatibility
 *     with more platforms or generators, then the current approach of
 *     splitting on runs of termination characters needs to get replaced,
 *     by the more expensive approach to scan for and count the initially
 *     determined termination sequence.
 *
 * - Add support for analog input data? (optional)
 *   - Needs a syntax first for user specs which channels (columns) are
 *     logic and which are analog. May need heuristics(?) to guess from
 *     input data in the absence of user provided specs.
 */

/* Single column formats. */
enum single_col_format {
        FORMAT_BIN,
        FORMAT_HEX,
        FORMAT_OCT,
};

struct context {
        gboolean started;

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

        /* Number of channels. */
        size_t num_channels;

        /* Column delimiter character(s). */
        GString *delimiter;

        /* Comment prefix character(s). */
        GString *comment;

        /* Termination character(s) used in current stream. */
        char *termination;

        /* Determines if sample data is stored in multiple columns. */
        gboolean multi_column_mode;

        /* Column number of the sample data in single column mode. */
        size_t single_column;

        /*
         * Number of the first column to parse. Equivalent to the number of the
         * first channel in multi column mode and the single column number in
         * single column mode.
         */
        size_t first_column;

        /*
         * Column number of the first channel in multi column mode and position of
         * the bit for the first channel in single column mode.
         */
        size_t first_channel;

        /* 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;

        /* Format sample data is stored in single column mode. */
        enum single_col_format format;

        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->num_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;

        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;
}

/*
 * 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);
        }
}

/* TODO Move parse_line() here. */

/**
 * @brief Parse a text field into multiple bits, binary presentation.
 *
 * @param[in] str       The input text, a run of 0/1 digits.
 * @param[in] inc       The input module's context.
 *
 * @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 which consists of binary digits.
 */
static int parse_binstr(const char *str, struct context *inc)
{
        gsize i, j, length;
        char c;

        length = strlen(str);
        if (!length) {
                sr_err("Column %zu in line %zu is empty.", inc->single_column,
                        inc->line_number);
                return SR_ERR;
        }

        i = inc->first_channel;
        for (j = 0; i < length && j < inc->num_channels; i++, j++) {
                c = str[length - i - 1];
                if (c == '1') {
                        set_logic_level(inc, j, 1);
                } else if (c != '0') {
                        sr_err("Invalid text '%s' in binary column %zu in line %zu.",
                                str, inc->single_column, inc->line_number);
                        return SR_ERR;
                }
        }

        return SR_OK;
}

/**
 * @brief Parse a text field into multiple bits, hexadecimal presentation.
 *
 * @param[in] str       The input text, a run of hex digits.
 * @param[in] inc       The input module's context.
 *
 * @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 which consists of hexadecimal digits.
 */
static int parse_hexstr(const char *str, struct context *inc)
{
        gsize i, j, k, length;
        uint8_t value;
        char c;

        length = strlen(str);
        if (!length) {
                sr_err("Column %zu in line %zu is empty.", inc->single_column,
                        inc->line_number);
                return SR_ERR;
        }

        /* Calculate the position of the first hexadecimal digit. */
        i = inc->first_channel / 4;
        for (j = 0; i < length && j < inc->num_channels; i++) {
                c = str[length - i - 1];
                if (!g_ascii_isxdigit(c)) {
                        sr_err("Invalid text '%s' in hex column %zu in line %zu.",
                                str, inc->single_column, inc->line_number);
                        return SR_ERR;
                }

                value = g_ascii_xdigit_value(c);
                k = (inc->first_channel + j) % 4;
                for (; j < inc->num_channels && k < 4; j++, k++) {
                        set_logic_level(inc, j, value & (1 << k));
                }
        }

        return SR_OK;
}

/**
 * @brief Parse a text field into multiple bits, octal presentation.
 *
 * @param[in] str       The input text, a run of oct digits.
 * @param[in] inc       The input module's context.
 *
 * @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 which consists of octal digits.
 */
static int parse_octstr(const char *str, struct context *inc)
{
        gsize i, j, k, length;
        uint8_t value;
        char c;

        length = strlen(str);
        if (!length) {
                sr_err("Column %zu in line %zu is empty.", inc->single_column,
                        inc->line_number);
                return SR_ERR;
        }

        /* Calculate the position of the first octal digit. */
        i = inc->first_channel / 3;
        for (j = 0; i < length && j < inc->num_channels; i++) {
                c = str[length - i - 1];
                if (c < '0' || c > '7') {
                        sr_err("Invalid text '%s' in oct column %zu in line %zu.",
                                str, inc->single_column, inc->line_number);
                        return SR_ERR;
                }

                value = g_ascii_xdigit_value(c);
                k = (inc->first_channel + j) % 3;
                for (; j < inc->num_channels && k < 3; j++, k++) {
                        set_logic_level(inc, j, value & (1 << k));
                }
        }

        return SR_OK;
}

static int parse_single_column(const char *column, struct context *inc)
{
        switch (inc->format) {
        case FORMAT_BIN:
                return parse_binstr(column, inc);
        case FORMAT_HEX:
                return parse_hexstr(column, inc);
        case FORMAT_OCT:
                return parse_octstr(column, inc);
        }

        return SR_ERR;
}

/**
 * @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.
 * @param[in] max_cols  The maximum column count, negative to get all of them.
 *
 * @returns An array of strings, representing the columns' text.
 *
 * This routine splits a text line on previously determined separators.
 * A previously determined set of columns gets isolated (starting at a
 * first position and spanning a given number of columns). A negative
 * value for the maximum number of columns results in no restriction on
 * the result set's length (the first columns still get trimmed off).
 */
static char **parse_line(char *buf, struct context *inc, ssize_t max_cols)
{
        const char *str, *remainder;
        GSList *list, *l;
        char **columns;
        char *column;
        gsize seen, taken;

        seen = 0;
        taken = 0;
        list = NULL;

        remainder = buf;
        str = strstr(remainder, inc->delimiter->str);
        while (str && max_cols) {
                if (seen >= inc->first_column) {
                        column = g_strndup(remainder, str - remainder);
                        list = g_slist_prepend(list, g_strstrip(column));

                        max_cols--;
                        taken++;
                }

                remainder = str + inc->delimiter->len;
                str = strstr(remainder, inc->delimiter->str);
                seen++;
        }

        if (buf[0] && max_cols && seen >= inc->first_column) {
                column = g_strdup(remainder);
                list = g_slist_prepend(list, g_strstrip(column));
                taken++;
        }

        if (!(columns = g_try_new(char *, taken + 1)))
                return NULL;
        columns[taken--] = NULL;
        for (l = list; l; l = l->next)
                columns[taken--] = l->data;

        g_slist_free(list);

        return columns;
}

/**
 * @brief Picks logic levels from multiple binary colomns, one channel per column.
 *
 * @param[in] columns   The text fields which are kept in the columns.
 * @param[in] inc       The input module's context.
 *
 * @retval SR_OK        Success.
 * @retval SR_ERR       Insufficient input, or syntax errors.
 *
 * This routine exclusively handles binary input where one logic channel
 * occupies one column each. All channels are expected to reside in one
 * consequtive run of columns.
 */
static int parse_multi_columns(char **columns, struct context *inc)
{
        gsize i;
        char *column;

        for (i = 0; i < inc->num_channels; i++) {
                column = columns[i];
                if (strcmp(column, "1") == 0) {
                        set_logic_level(inc, i, 1);
                } else if (!strlen(column)) {
                        sr_err("Column %zu in line %zu is empty.",
                                inc->first_channel + i, inc->line_number);
                        return SR_ERR;
                } else if (strcmp(column, "0") != 0) {
                        sr_err("Invalid text '%s' in bit column %zu in line %zu.",
                                column, inc->first_channel + i,
                                inc->line_number);
                        return SR_ERR;
                }
        }

        return SR_OK;
}

static int init(struct sr_input *in, GHashTable *options)
{
        struct context *inc;
        const char *s;

        in->sdi = g_malloc0(sizeof(struct sr_dev_inst));
        in->priv = inc = g_malloc0(sizeof(struct context));

        inc->single_column = g_variant_get_uint32(g_hash_table_lookup(options, "single-column"));
        inc->multi_column_mode = inc->single_column == 0;

        inc->num_channels = g_variant_get_uint32(g_hash_table_lookup(options, "numchannels"));

        inc->delimiter = g_string_new(g_variant_get_string(
                        g_hash_table_lookup(options, "delimiter"), NULL));
        if (inc->delimiter->len == 0) {
                sr_err("Delimiter must be at least one character.");
                return SR_ERR_ARG;
        }

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

        inc->comment = g_string_new(g_variant_get_string(
                        g_hash_table_lookup(options, "comment"), NULL));
        if (g_string_equal(inc->comment, inc->delimiter)) {
                /* That's never going to work. Likely the result of the user
                 * setting the delimiter to ; -- the default comment. Clearing
                 * the comment setting will work in that case. */
                g_string_truncate(inc->comment, 0);
        }

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

        inc->first_channel = g_variant_get_uint32(g_hash_table_lookup(options, "first-channel"));

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

        if (inc->multi_column_mode)
                inc->first_column = inc->first_channel;
        else
                inc->first_column = inc->single_column;

        if (!inc->multi_column_mode && !inc->num_channels) {
                sr_err("Number of channels needs to be specified in single column mode.");
                return SR_ERR_ARG;
        }

        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, i;
        size_t line_number, l;
        int ret;
        char **lines, *line, **columns, *column;

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

        line_number = 0;
        lines = g_strsplit_set(buf->str, delim_set, 0);
        for (l = 0; lines[l]; l++) {
                line_number++;
                line = lines[l];
                if (inc->start_line > line_number) {
                        sr_spew("Line %zu skipped.", 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 (!lines[l]) {
                /* Not enough data for a proper line yet. */
                ret = SR_ERR_NA;
                goto out;
        }

        /*
         * In order to determine the number of columns parse the current line
         * without limiting the number of columns.
         */
        columns = parse_line(line, inc, -1);
        if (!columns) {
                sr_err("Error while parsing line %zu.", line_number);
                ret = SR_ERR;
                goto out;
        }
        num_columns = g_strv_length(columns);

        /* Ensure that the first column is not out of bounds. */
        if (!num_columns) {
                sr_err("Column %zu in line %zu is out of bounds.",
                        inc->first_column, line_number);
                ret = SR_ERR;
                goto out;
        }

        if (inc->multi_column_mode) {
                /*
                 * Detect the number of channels in multi column mode
                 * automatically if not specified.
                 */
                if (!inc->num_channels) {
                        inc->num_channels = num_columns;
                        sr_dbg("Number of auto-detected channels: %zu.",
                                inc->num_channels);
                }

                /*
                 * Ensure that the number of channels does not exceed the number
                 * of columns in multi column mode.
                 */
                if (num_columns < inc->num_channels) {
                        sr_err("Not enough columns for desired number of channels in line %zu.",
                                line_number);
                        ret = SR_ERR;
                        goto out;
                }
        }

        channel_name = g_string_sized_new(64);
        for (i = 0; i < inc->num_channels; i++) {
                column = columns[i];
                if (inc->use_header && inc->multi_column_mode && column[0] != '\0')
                        g_string_assign(channel_name, column);
                else
                        g_string_printf(channel_name, "%zu", i);
                sr_channel_new(in->sdi, i, 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->num_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 max_columns, l;
        int ret;
        char *p, **lines, *line, **columns;

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

        /* Limit the number of columns to parse. */
        if (inc->multi_column_mode)
                max_columns = inc->num_channels;
        else
                max_columns = 1;

        /*
         * 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_set(in->buf->str, delim_set, 0);
        for (l = 0; lines[l]; l++) {
                inc->line_number++;
                line = lines[l];
                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;
                }

                columns = parse_line(line, inc, max_columns);
                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) {
                        sr_err("Column %zu in line %zu is out of bounds.",
                                inc->first_column, inc->line_number);
                        g_strfreev(columns);
                        g_strfreev(lines);
                        return SR_ERR;
                }
                /*
                 * Ensure that the number of channels does not exceed the number
                 * of columns in multi column mode.
                 */
                if (inc->multi_column_mode && num_columns < inc->num_channels) {
                        sr_err("Not enough columns for desired number of channels in line %zu.",
                                inc->line_number);
                        g_strfreev(columns);
                        g_strfreev(lines);
                        return SR_ERR;
                }

                clear_logic_samples(inc);

                if (inc->multi_column_mode)
                        ret = parse_multi_columns(columns, inc);
                else
                        ret = parse_single_column(columns[0], inc);
                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->termination) {
                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_SINGLE_COL,
        OPT_NUM_LOGIC,
        OPT_DELIM,
        OPT_FORMAT,
        OPT_COMMENT,
        OPT_RATE,
        OPT_FIRST_LOGIC,
        OPT_HEADER,
        OPT_START,
        OPT_MAX,
};

static struct sr_option options[] = {
        [OPT_SINGLE_COL] = { "single-column", "Single column", "Enable single-column mode, using the specified column (>= 1); 0: multi-col. mode", NULL, NULL },
        [OPT_NUM_LOGIC] = { "numchannels", "Number of logic channels", "The number of (logic) channels (single-col. mode: number of bits beginning at 'first channel', LSB-first)", NULL, NULL },
        [OPT_DELIM] = { "delimiter", "Column delimiter", "The column delimiter (>= 1 characters)", NULL, NULL },
        [OPT_FORMAT] = { "format", "Data format (single-col. mode)", "The numeric format of the data (single-col. mode): bin, hex, oct", NULL, NULL },
        [OPT_COMMENT] = { "comment", "Comment character(s)", "The comment prefix character(s)", NULL, NULL },
        [OPT_RATE] = { "samplerate", "Samplerate (Hz)", "The sample rate (used during capture) in Hz", NULL, NULL },
        [OPT_FIRST_LOGIC] = { "first-channel", "First channel", "The column number of the first channel (multi-col. mode); bit position for the first channel (single-col. mode)", NULL, NULL },
        [OPT_HEADER] = { "header", "Interpret first line as header (multi-col. mode)", "Treat the first line as header with channel names (multi-col. mode)", NULL, NULL },
        [OPT_START] = { "startline", "Start line", "The line number at which to start processing samples (>= 1)", NULL, NULL },
        [OPT_MAX] = ALL_ZERO,
};

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

        if (!options[0].def) {
                options[OPT_SINGLE_COL].def = g_variant_ref_sink(g_variant_new_int32(0));
                options[OPT_NUM_LOGIC].def = g_variant_ref_sink(g_variant_new_int32(0));
                options[OPT_DELIM].def = g_variant_ref_sink(g_variant_new_string(","));
                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_COMMENT].def = g_variant_ref_sink(g_variant_new_string(";"));
                options[OPT_RATE].def = g_variant_ref_sink(g_variant_new_uint64(0));
                options[OPT_FIRST_LOGIC].def = g_variant_ref_sink(g_variant_new_int32(0));
                options[OPT_HEADER].def = g_variant_ref_sink(g_variant_new_boolean(FALSE));
                options[OPT_START].def = g_variant_ref_sink(g_variant_new_int32(1));
        }

        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,
};