[PATCH 2/3] hdlc: handle wrapped buffers

[Kristen Carlson Accardi]

---
 gatchat/gathdlc.c |   75 ++++++++++++++++++++++++++++------------------------
 1 files changed, 40 insertions(+), 35 deletions(-)

diff --git a/gatchat/gathdlc.c b/gatchat/gathdlc.c
index c5c02cf..13e15a1 100644
--- a/gatchat/gathdlc.c
+++ b/gatchat/gathdlc.c
@@ -59,11 +59,12 @@ static void new_bytes(GAtHDLC *hdlc)
 {
 	unsigned int len = ring_buffer_len(hdlc->read_buffer);
 	unsigned char *buf = ring_buffer_read_ptr(hdlc->read_buffer, 0);
+	unsigned int wrap = ring_buffer_len_no_wrap(hdlc->read_buffer);
 	unsigned char val;
 	unsigned int pos = 0;
 
 	while (pos < len) {
-		if (buf[pos] == 0x7e) {
+		if (*buf == 0x7e) {
 			if (hdlc->receive_func && hdlc->decode_offset > 2 &&
 						hdlc->decode_fcs == 0xf0b8) {
 				hdlc->receive_func(hdlc->decode_buffer,
@@ -74,29 +75,44 @@ static void new_bytes(GAtHDLC *hdlc)
 			hdlc->decode_fcs = 0xffff;
 			hdlc->decode_offset = 0;
 			pos++;
+			buf++;
+			if (pos == wrap)
+				buf = ring_buffer_read_ptr(hdlc->read_buffer,
+								pos);
 			continue;
 		}
 
 		if (hdlc->recv_escape_func &&
 				hdlc->recv_escape_func(hdlc->recv_escape_data,
-				buf[pos])) {
+				*buf)) {
 			pos++;
+			buf++;
+			if (pos == wrap)
+				buf = ring_buffer_read_ptr(hdlc->read_buffer,
+								pos);
 			continue;
 		}
 
-		if (buf[pos] == 0x7d) {
+		if (*buf == 0x7d) {
 			if (pos + 2 > len)
 				break;
 			pos++;
-			val = buf[pos] ^ 0x20;
+			buf++;
+			if (pos == wrap)
+				buf = ring_buffer_read_ptr(hdlc->read_buffer,
+								pos);
+			val = *buf ^ 0x20;
 		} else
-			val = buf[pos];
+			val = *buf;
 
 		hdlc->decode_buffer[hdlc->decode_offset] = val;
 		hdlc->decode_fcs = crc_ccitt_byte(hdlc->decode_fcs, val);
 
 		hdlc->decode_offset++;
 		pos++;
+		buf++;
+		if (pos == wrap)
+			buf = ring_buffer_read_ptr(hdlc->read_buffer, pos);
 	}
 
 	ring_buffer_drain(hdlc->read_buffer, pos);
@@ -344,55 +360,44 @@ static void wakeup_write(GAtHDLC *hdlc)
 				can_write_data, hdlc, write_watch_destroy);
 }
 
-static inline void hdlc_put(GAtHDLC *hdlc, guint8 *buf, gsize *pos, guint8 c,
-				gboolean scan_result)
+static inline void hdlc_buffer_put_char(struct ring_buffer *buffer,
+					const char val)
 {
-	gsize i = *pos;
+	ring_buffer_write(buffer, &val, 1);
+}
 
+static inline void hdlc_put(GAtHDLC *hdlc, guint8 c, gboolean scan_result)
+{
 	if ((hdlc->send_escape_func &&
 				hdlc->send_escape_func(hdlc->send_escape_data,
 							c, scan_result))
 			|| c == 0x7e || c == 0x7d) {
-		buf[i++] = 0x7d;
-		buf[i++] = c ^ 0x20;
+		hdlc_buffer_put_char(hdlc->write_buffer, 0x7d);
+		hdlc_buffer_put_char(hdlc->write_buffer, c ^ 0x20);
 	} else
-		buf[i++] = c;
-
-	*pos = i;
+		hdlc_buffer_put_char(hdlc->write_buffer, c);
 }
 
 gboolean g_at_hdlc_send(GAtHDLC *hdlc, const unsigned char *data, gsize size)
 {
-	unsigned char *buf;
-	unsigned int space, i = 0;
 	guint16 fcs = 0xffff;
-	gsize pos;
 	gboolean scan_result = FALSE;
+	unsigned int i = 0;
 
 	if (hdlc->scan_func)
 		scan_result = hdlc->scan_func(hdlc->scan_data, data);
 
-	do {
-		space = ring_buffer_avail_no_wrap(hdlc->write_buffer);
-		if (space == 0)
-			break;
+	hdlc_buffer_put_char(hdlc->write_buffer, 0x7e);
 
-		buf = ring_buffer_write_ptr(hdlc->write_buffer);
-		pos = 0;
-
-		while (size--) {
-			fcs = crc_ccitt_byte(fcs, data[i]);
-			hdlc_put(hdlc, buf, &pos, data[i++], scan_result);
-		}
-
-		fcs ^= 0xffff;
-		hdlc_put(hdlc, buf, &pos, fcs & 0xff, scan_result);
-		hdlc_put(hdlc, buf, &pos, fcs >> 8, scan_result);
-
-		buf[pos++] = 0x7e;
+	while (size--) {
+		fcs = crc_ccitt_byte(fcs, data[i]);
+		hdlc_put(hdlc, data[i++], scan_result);
+	}
 
-		ring_buffer_write_advance(hdlc->write_buffer, pos);
-	} while (0);
+	fcs ^= 0xffff;
+	hdlc_put(hdlc, fcs & 0xff, scan_result);
+	hdlc_put(hdlc, fcs >> 8, scan_result);
+	hdlc_buffer_put_char(hdlc->write_buffer, 0x7e);
 
 	wakeup_write(hdlc);
 
-- 
1.6.6.1