fixup! gdb_packet: add no ack mode

blackmagic-debug · Jul 21, 2023 · e58436e · e58436e
1 parent c9c1389
commit e58436e
Showing 1 changed file with 15 additions and 41 deletions.
diff --git a/src/gdb_packet.c b/src/gdb_packet.c
@@ -37,6 +37,7 @@ typedef enum packet_state {
 	PACKET_GDB_ESCAPE,
 	PACKET_GDB_CHECKSUM_UPPER,
 	PACKET_GDB_CHECKSUM_LOWER,
+	PACKET_GDB_COMPLETE,
 } packet_state_e;
 
 static bool noackmode = false;
@@ -106,7 +107,7 @@ size_t gdb_getpacket(char *const packet, const size_t size)
 	uint8_t rx_checksum = 0, checksum = 0;
 
 	while (true) {
-		const char rx_char = gdb_if_getchar();
+		const char rx_char = state != PACKET_GDB_COMPLETE ? gdb_if_getchar() : '\0';
 		if (rx_char == '\x04') {
 			/* EOT (end of transmission) - connection was closed */
 			packet[0] = '\x04';
@@ -130,7 +131,7 @@ size_t gdb_getpacket(char *const packet, const size_t size)
 				 * returns PACKET_IDLE or PACKET_GDB_CAPTURE if it detects the start of a GDB packet
 				 */
 				state = consume_remote_packet(packet, size);
-				/* No need to handle csum or offset, everything happened in PACKET_IDLE state so nothing was modified */
+				/* No need to handle checksum or offset, everything happened in PACKET_IDLE state so nothing was modified */
 			}
 #endif
 			break;
@@ -139,35 +140,14 @@ size_t gdb_getpacket(char *const packet, const size_t size)
 			if (rx_char == GDB_PACKET_START) {
 				/* Restart GDB packet capture */
 				offset = 0;
-				csum = 0;
+				checksum = 0;
 				break;
 			}
 			if (rx_char == GDB_PACKET_END) {
 				/* End of GDB packet */
-				if (noackmode) {
-					/* We knowlingly ignore the checksum that follows the packet in no ack mode */
-
-					/* Null terminate packet */
-					packet[offset] = '\0';
-
-					/* Log packet for debugging */
-					DEBUG_GDB("%s: ", __func__);
-					for (size_t j = 0; j < offset; j++) {
-						const char value = packet[j];
-						if (value >= ' ' && value < '\x7f')
-							DEBUG_GDB("%c", value);
-						else
-							DEBUG_GDB("\\x%02X", value);
-					}
-					DEBUG_GDB("\n");
-
-					/* Return packet captured size */
-					return offset;
-				} else {
-					/* Move to checksum capture */
-					state = PACKET_GDB_CHECKSUM_UPPER;
-					break;
-				}
+				/* Move to checksum capture or knowlingly ignore the checksum that follows in no ack mode (as per spec) */
+				state = noackmode ? PACKET_GDB_COMPLETE : PACKET_GDB_CHECKSUM_UPPER;
+				break;
 			}
 
 			/* Not start or end of packet, add to checksum */
@@ -205,13 +185,12 @@ size_t gdb_getpacket(char *const packet, const size_t size)
 			state = PACKET_GDB_COMPLETE;
 			break;
 
-			/* Check checksum */
-			if (rx_csum == csum) {
-				/* Checksum matches our calculated checksum, captured valid packet */
-
-				/* Acknowledge packet */
-				gdb_if_putchar(GDB_PACKET_ACK, 1U);
+		case PACKET_GDB_COMPLETE:
+			if (!noackmode)
+				/* (N)Acknowledge packet */
+				gdb_if_putchar(rx_checksum == checksum ? GDB_PACKET_ACK : GDB_PACKET_NACK, 1U);
 
+			if (noackmode || rx_checksum == checksum) {
 				/* Null terminate packet */
 				packet[offset] = '\0';
 
@@ -228,15 +207,10 @@ size_t gdb_getpacket(char *const packet, const size_t size)
 
 				/* Return packet captured size */
 				return offset;
-			} else {
-				/* Checksum does not match our calculated checksum */
-
-				/* N-Acknowledge packet */
-				gdb_if_putchar(GDB_PACKET_NACK, 1U);
-
-				/* Restart packet capture */
-				state = PACKET_IDLE;
 			}
+
+			/* Restart packet capture */
+			state = PACKET_IDLE;
 			break;
 
 		default: