layer1: more comments about l1s data structure fields

also, change fn_offset from unsigned to signed.

diff --git a/src/target/firmware/include/layer1/sync.h b/src/target/firmware/include/layer1/sync.h
index 4bf7f2b..a30a1e2 100644 (file)
--- a/src/target/firmware/include/layer1/sync.h
+++ b/src/target/firmware/include/layer1/sync.h
@@ -6,11 +6,19 @@
 #include <layer1/tdma_sched.h>
 #include <l1a_l23_interface.h>
 
+/* structure representing L1 sync information about a cell */
 struct l1_cell_info {
+       /* on which ARFCN (+band) is the cell? */
        uint16_t        arfcn;
+       /* what's the BSIC of the cell (from SCH burst decoding) */
        uint32_t        bsic;
-       uint32_t        fn_offset;
+       /* whats the delta of the cells current GSM frame number
+        * compared to our current local frame number */
+       int32_t         fn_offset;
+       /* how much does the TPU need adjustment (delta) to synchronize
+        * with the cells burst */
        uint32_t        time_alignment;
+       /* FIXME: should we also store the AFC value? */
 };
 
 enum l1s_chan {
@@ -21,13 +29,16 @@ enum l1s_chan {
 
 
 struct l1s_state {
-       struct gsm_time current_time;   /* current time */
-       struct gsm_time next_time;      /* time at next TMDMA irq */
+       struct gsm_time current_time;   /* current GSM time */
+       struct gsm_time next_time;      /* GSM time at next TMDMA irq */
 
+       /* the cell on which we are camping right now */
        struct l1_cell_info serving_cell;
 
+       /* TDMA scheduler */
        struct tdma_scheduler tdma_sched;
 
+       /* The current TPU offset register */
        uint32_t        tpu_offset;
 
        /* Transmit queues of pending packets for main DCCH and ACCH */
@@ -36,6 +47,8 @@ struct l1s_state {
        /* bit-mask of multi-frame tasks that are currently active */
        uint32_t        mf_tasks;
 
+       /* Structures below are for L1-task specific parameters, used
+        * to communicate between l1-sync and l1-async (l23_api) */
        struct {
                /* power measurement l1 task */
                unsigned int mode;