am7xxx: rename am7xxx_header.unknown0 to am7xxx_header.direction

This field should indicate the direction of the communication, according to
the USB dumps it is 0 for outgoing packets and 1 for incoming packets.

diff --git a/src/am7xxx.c b/src/am7xxx.c
index aaab4f4..e5427ca 100644 (file)
--- a/src/am7xxx.c
+++ b/src/am7xxx.c
@@ -156,9 +156,13 @@ struct am7xxx_power_header {
  * 04 00 00 00 00 0c ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  */
 
+/* Direction of the communication from the host point of view */
+#define AM7XXX_DIRECTION_OUT 0 /* host -> device */
+#define AM7XXX_DIRECTION_IN  1 /* host <- device */
+
 struct am7xxx_header {
        uint32_t packet_type;
-       uint8_t unknown0;
+       uint8_t direction;
        uint8_t header_data_len;
        uint8_t unknown2;
        uint8_t unknown3;
@@ -214,7 +218,7 @@ static void debug_dump_header(am7xxx_context *ctx, struct am7xxx_header *h)
 
        debug(ctx, "BEGIN\n");
        debug(ctx, "packet_type:     0x%08x (%u)\n", h->packet_type, h->packet_type);
-       debug(ctx, "unknown0:        0x%02hhx (%hhu)\n", h->unknown0, h->unknown0);
+       debug(ctx, "direction:       0x%02hhx (%hhu)\n", h->direction, h->direction);
        debug(ctx, "header_data_len: 0x%02hhx (%hhu)\n", h->header_data_len, h->header_data_len);
        debug(ctx, "unknown2:        0x%02hhx (%hhu)\n", h->unknown2, h->unknown2);
        debug(ctx, "unknown3:        0x%02hhx (%hhu)\n", h->unknown3, h->unknown3);
@@ -319,7 +323,7 @@ static void serialize_header(struct am7xxx_header *h, uint8_t *buffer)
        uint8_t **buffer_iterator = &buffer;
 
        put_le32(h->packet_type, buffer_iterator);
-       put_8(h->unknown0, buffer_iterator);
+       put_8(h->direction, buffer_iterator);
        put_8(h->header_data_len, buffer_iterator);
        put_8(h->unknown2, buffer_iterator);
        put_8(h->unknown3, buffer_iterator);
@@ -334,7 +338,7 @@ static void unserialize_header(uint8_t *buffer, struct am7xxx_header *h)
        uint8_t **buffer_iterator = &buffer;
 
        h->packet_type = get_le32(buffer_iterator);
-       h->unknown0 = get_8(buffer_iterator);
+       h->direction = get_8(buffer_iterator);
        h->header_data_len = get_8(buffer_iterator);
        h->unknown2 = get_8(buffer_iterator);
        h->unknown3 = get_8(buffer_iterator);
@@ -356,7 +360,13 @@ static int read_header(am7xxx_device *dev, struct am7xxx_header *h)
 
        debug_dump_header(dev->ctx, h);
 
-       ret = 0;
+       if (h->direction == AM7XXX_DIRECTION_IN) {
+               ret = 0;
+       } else {
+               error(dev->ctx,
+                     "Received a packet with direction AM7XXX_DIRECTION_OUT, weird!\n");
+               ret = -EINVAL;
+       }
 
 out:
        return ret;
@@ -685,7 +695,7 @@ AM7XXX_PUBLIC int am7xxx_get_device_info(am7xxx_device *dev,
        int ret;
        struct am7xxx_header h = {
                .packet_type     = AM7XXX_PACKET_TYPE_DEVINFO,
-               .unknown0        = 0x00,
+               .direction       = AM7XXX_DIRECTION_OUT,
                .header_data_len = 0x00,
                .unknown2        = 0x3e,
                .unknown3        = 0x10,
@@ -790,7 +800,7 @@ AM7XXX_PUBLIC int am7xxx_send_image(am7xxx_device *dev,
        int ret;
        struct am7xxx_header h = {
                .packet_type     = AM7XXX_PACKET_TYPE_IMAGE,
-               .unknown0        = 0x00,
+               .direction       = AM7XXX_DIRECTION_OUT,
                .header_data_len = sizeof(struct am7xxx_image_header),
                .unknown2        = 0x3e,
                .unknown3        = 0x10,
@@ -821,7 +831,7 @@ AM7XXX_PUBLIC int am7xxx_set_power_mode(am7xxx_device *dev, am7xxx_power_mode mo
        int ret;
        struct am7xxx_header h = {
                .packet_type     = AM7XXX_PACKET_TYPE_POWER,
-               .unknown0        = 0x00,
+               .direction       = AM7XXX_DIRECTION_OUT,
                .header_data_len = sizeof(struct am7xxx_power_header),
                .unknown2        = 0x3e,
                .unknown3        = 0x10,