drivers: modem: Add support for commands that don't have a line ending

Some commands need to be processed before a "\r\n" is available and
there might also be commands that have "\r\n" as data but doesn't mean
the end of the command.

To solve this a MODEM_CMD_DIRECT has been added. cmd_handler_process()
will look for matching direct commands before checking if a whole line
is available for matching the normal commands.

A direct command can return either -EAGAIN, meaning that more data is
needed or it will return the number of bytes to skip forward, ie the
length of the command that was handled.

Signed-off-by: Tobias Svehagen <tobias.svehagen@gmail.com>

drivers/modem/modem_cmd_handler.c

@@ -70,6 +70,30 @@ static u16_t findcrlf(struct modem_cmd_handler_data *data,
 	return 0;
 }
 
+static bool starts_with(struct net_buf *buf, const char *str)
+{
+	int pos = 0;
+
+	while (buf && buf->len && *str) {
+		if (*(buf->data + pos) == *str) {
+			str++;
+			pos++;
+			if (pos >= buf->len) {
+				buf = buf->frags;
+				pos = 0;
+			}
+		} else {
+			return false;
+		}
+	}
+
+	if (*str == 0) {
+		return true;
+	}
+
+	return false;
+}
+
 /*
  * Cmd Handler Functions
  */
@@ -208,6 +232,29 @@ static struct modem_cmd *find_cmd_match(struct modem_cmd_handler_data *data)
 	return NULL;
 }
 
+static struct modem_cmd *find_cmd_direct_match(
+		struct modem_cmd_handler_data *data)
+{
+	int j, i;
+
+	for (j = 0; j < ARRAY_SIZE(data->cmds); j++) {
+		if (!data->cmds[j] || data->cmds_len[j] == 0U) {
+			continue;
+		}
+
+		for (i = 0; i < data->cmds_len[j]; i++) {
+			/* match start of cmd */
+			if (data->cmds[j][i].direct &&
+			    (data->cmds[j][i].cmd[0] == '\0' ||
+			     starts_with(data->rx_buf, data->cmds[j][i].cmd))) {
+				return &data->cmds[j][i];
+			}
+		}
+	}
+
+	return NULL;
+}
+
 static void cmd_handler_process(struct modem_cmd_handler *cmd_handler,
 				struct modem_iface *iface)
 {
@@ -263,6 +310,19 @@ static void cmd_handler_process(struct modem_cmd_handler *cmd_handler,
 			break;
 		}
 
+		cmd = find_cmd_direct_match(data);
+		if (cmd && cmd->func) {
+			ret = cmd->func(data, cmd->cmd_len, NULL, 0);
+			if (ret == -EAGAIN) {
+				/* Wait for more data */
+				break;
+			} else if (ret > 0) {
+				data->rx_buf = net_buf_skip(data->rx_buf, ret);
+			}
+
+			continue;
+		}
+
 		frag = NULL;
 		/* locate next CR/LF */
 		len = findcrlf(data, &frag, &offset);

drivers/modem/modem_cmd_handler.h

@@ -31,6 +31,18 @@ static int name_(struct modem_cmd_handler_data *data, u16_t len, \
 	.func = func_cb_, \
 	.arg_count = acount_, \
 	.delim = adelim_, \
+	.direct = false, \
+}
+
+#define MODEM_CMD_DIRECT_DEFINE(name_) MODEM_CMD_DEFINE(name_)
+
+#define MODEM_CMD_DIRECT(cmd_, func_cb_) { \
+	.cmd = cmd_, \
+	.cmd_len = (u16_t)sizeof(cmd_)-1, \
+	.func = func_cb_, \
+	.arg_count = 0, \
+	.delim = "", \
+	.direct = true, \
 }
 
 #define CMD_RESP	0
@@ -47,6 +59,7 @@ struct modem_cmd {
 	const char *delim;
 	u16_t cmd_len;
 	u16_t arg_count;
+	bool direct;
 };
 
 #define SETUP_CMD(cmd_send_, match_cmd_, func_cb_, num_param_, delim_) { \