+ printf("STA ID=%d time=%d\r\n",
+ beacon_id, status->ring[head].time);
+ }
+
+ if (beacon_id == TSOP_STA_BEACON_ID0) {
+ found |= 0x1;
+ data0 = (frame >> TSOP_STA_FRAME_DATA_SHIFT) & TSOP_STA_FRAME_DATA_MASK;
+ time0 = status->ring[head].time;
+ ref_time0 = status->ring[head].ref_time;
+ }
+ else if (beacon_id == TSOP_STA_BEACON_ID1) {
+ found |= 0x2;
+ data1 = (frame >> TSOP_STA_FRAME_DATA_SHIFT) & TSOP_STA_FRAME_DATA_MASK;
+ time1 = status->ring[head].time;
+ ref_time1 = status->ring[head].ref_time;
+ }
+
+ head = head_next;
+ }
+
+ /* if we didn't found beacon 0 and 1, return */
+ if (found != 0x3)
+ return;
+
+ /* update ring head */
+ status->head = head;
+
+ /* beacon 0 */
+ dist0 = data0;
+ dist0 /= 512.;
+ dist0 *= (MAX_DIST-MIN_DIST);
+ dist0 += MIN_DIST;
+
+ time0 = time0 - ref_time0;
+ angle0 = (double)time0 / (double)current_motor_period;
+ if (angle0 > 1.)
+ angle0 -= 1.;
+ if (angle0 > 1.)
+ return; /* fail */
+ angle0 *= (2 * M_PI);
+ if (angle0 > M_PI)
+ angle0 -= M_PI;
+
+ /* beacon 1 */
+ dist1 = data1;
+ dist1 /= 512.;
+ dist1 *= (MAX_DIST-MIN_DIST);
+ dist1 += MIN_DIST;
+
+ time1 = time1 - ref_time1;
+ angle1 = (double)time1 / (double)current_motor_period;
+ if (angle1 > 1.)
+ angle1 -= 1.;
+ if (angle1 > 1.)
+ return; /* fail */
+ angle1 *= (2 * M_PI);
+ if (angle0 > M_PI)
+ angle0 -= M_PI;
+
+ if (ad_to_posxya(&pos, &a, 0, &beacon0, &beacon1, angle0, dist0,
+ angle1, dist1) < 0)
+ return;
+
+ xmit_static((uint16_t)pos.x, (uint16_t)pos.y, (uint16_t)a);
+}
+
+/* process the received frame ring */
+static void process_opp_ring(struct frame_status *status)
+{
+ uint8_t head_next;
+ uint16_t frame;
+ uint8_t found = 0;
+ uint8_t beacon_id;
+ uint16_t data, time, ref_time;
+ double angle;
+ double dist;