gathdlc: Add support for detecting +++ escapes

diff --git a/gatchat/gathdlc.c b/gatchat/gathdlc.c
index 7c45454..00d9daf 100644 (file)
--- a/gatchat/gathdlc.c
+++ b/gatchat/gathdlc.c
@@ -50,6 +50,8 @@
 
 #define HDLC_FCS(fcs, c) crc_ccitt_byte(fcs, c)
 
+#define GUARD_TIMEOUT  1000    /* Pause time before and after '+++' sequence */
+
 struct _GAtHDLC {
        gint ref_count;
        GAtIO *io;
@@ -68,6 +70,11 @@ struct _GAtHDLC {
        gboolean in_read_handler;
        gboolean destroyed;
        gboolean no_carrier_detect;
+       GAtSuspendFunc suspend_func;
+       gpointer suspend_data;
+       guint suspend_source;
+       GTimer *timer;
+       guint num_plus;
 };
 
 static void hdlc_record(int fd, gboolean in, guint8 *data, guint16 length)
@@ -130,6 +137,86 @@ guint32 g_at_hdlc_get_recv_accm(GAtHDLC *hdlc)
        return hdlc->recv_accm;
 }
 
+void g_at_hdlc_set_suspend_function(GAtHDLC *hdlc, GAtSuspendFunc func,
+                                                       gpointer user_data)
+{
+       if (hdlc == NULL)
+               return;
+
+       if (func == NULL) {
+               if (hdlc->timer) {
+                       g_timer_destroy(hdlc->timer);
+                       hdlc->timer = NULL;
+               }
+
+               if (hdlc->suspend_source > 0) {
+                       g_source_remove(hdlc->suspend_source);
+                       hdlc->suspend_source = 0;
+               }
+       } else
+               hdlc->timer = g_timer_new();
+
+       hdlc->suspend_func = func;
+       hdlc->suspend_data = user_data;
+}
+
+static gboolean hdlc_suspend(gpointer user_data)
+{
+       GAtHDLC *hdlc = user_data;
+
+       g_at_io_drain_ring_buffer(hdlc->io, 3);
+
+       if (hdlc->suspend_func)
+               hdlc->suspend_func(hdlc->suspend_data);
+
+       hdlc->suspend_source = 0;
+
+       return FALSE;
+}
+
+static gboolean check_escape(GAtHDLC *hdlc, struct ring_buffer *rbuf)
+{
+       unsigned int len = ring_buffer_len(rbuf);
+       unsigned int wrap = ring_buffer_len_no_wrap(rbuf);
+       unsigned char *buf = ring_buffer_read_ptr(rbuf, 0);
+       unsigned int pos = 0;
+       unsigned int elapsed = g_timer_elapsed(hdlc->timer, NULL) * 1000;
+       unsigned int num_plus = 0;
+       gboolean guard_timeout = FALSE;
+
+       if (elapsed >= GUARD_TIMEOUT)
+               guard_timeout = TRUE;
+
+       while (pos < len && pos < 3) {
+               if (*buf != '+')
+                       break;
+
+               num_plus++;
+               buf++;
+               pos++;
+
+               if (pos == wrap)
+                       buf = ring_buffer_read_ptr(rbuf, pos);
+       }
+
+       if (num_plus != len)
+               return FALSE;
+
+       /* We got some escape chars, but no guard timeout first */
+       if (guard_timeout == FALSE && hdlc->num_plus == 0)
+               return FALSE;
+
+       if (num_plus != 3) {
+               hdlc->num_plus = num_plus;
+               return TRUE;
+       }
+
+       hdlc->num_plus = 0;
+       hdlc->suspend_source = g_timeout_add(GUARD_TIMEOUT, hdlc_suspend, hdlc);
+
+       return TRUE;
+}
+
 static void new_bytes(struct ring_buffer *rbuf, gpointer user_data)
 {
        GAtHDLC *hdlc = user_data;
@@ -142,6 +229,23 @@ static void new_bytes(struct ring_buffer *rbuf, gpointer user_data)
 
        hdlc->in_read_handler = TRUE;
 
+       /*
+        * We delete the the paused_timeout_cb or hdlc_suspend as soons as
+        * we read a data.
+        */
+       if (hdlc->suspend_source > 0) {
+               g_source_remove(hdlc->suspend_source);
+               hdlc->suspend_source = 0;
+               g_timer_start(hdlc->timer);
+       } else if (hdlc->timer) {
+               gboolean escaping = check_escape(hdlc, rbuf);
+
+               g_timer_start(hdlc->timer);
+
+               if (escaping)
+                       return;
+       }
+
        while (pos < len) {
                /*
                 * We try to detect NO CARRIER conditions here.  We
@@ -305,6 +409,9 @@ void g_at_hdlc_unref(GAtHDLC *hdlc)
        g_at_io_set_write_handler(hdlc->io, NULL, NULL);
        g_at_io_set_read_handler(hdlc->io, NULL, NULL);
 
+       if (hdlc->suspend_source > 0)
+               g_source_remove(hdlc->suspend_source);
+
        g_at_io_unref(hdlc->io);
        hdlc->io = NULL;
 

diff --git a/gatchat/gathdlc.h b/gatchat/gathdlc.h
index 95c389e..158f27f 100644 (file)
--- a/gatchat/gathdlc.h
+++ b/gatchat/gathdlc.h
@@ -57,6 +57,9 @@ GAtIO *g_at_hdlc_get_io(GAtHDLC *hdlc);
 
 void g_at_hdlc_set_no_carrier_detect(GAtHDLC *hdlc, gboolean detect);
 
+void g_at_hdlc_set_suspend_function(GAtHDLC *hdlc, GAtSuspendFunc func,
+                                                       gpointer user_data);
+
 #ifdef __cplusplus
 }
 #endif