diff options
| author | Vadim Yanitskiy <vyanitskiy@sysmocom.de> | 2020-06-17 03:55:46 +0700 |
|---|---|---|
| committer | laforge <laforge@osmocom.org> | 2020-06-17 21:09:51 +0000 |
| commit | ed0445b38b0c0beb5fa602a79fbf22fcbd94e1ad (patch) | |
| tree | 3b6a01e8149fd6bf66392b77f79411b139bb4471 | |
| parent | 30856ca5cba3cc398809e1d1a78953694acc3410 (diff) | |
gsm0502: add TDMA frame number constants and modular arithmetic
These TDMA constatns and modular arithmetic operations are used in
a number of osmo-* projects, so it makes sense to have them all
in a single header file, with minimalistic documentation.
Change-Id: Ic291fd3644f34964374227a191c7045d79d77e0d
| -rw-r--r-- | include/osmocom/gsm/gsm0502.h | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/include/osmocom/gsm/gsm0502.h b/include/osmocom/gsm/gsm0502.h index cb993dce..1be2cc39 100644 --- a/include/osmocom/gsm/gsm0502.h +++ b/include/osmocom/gsm/gsm0502.h @@ -7,6 +7,30 @@ #include <osmocom/gsm/protocol/gsm_04_08.h> #include <osmocom/gsm/protocol/gsm_08_58.h> +/* 4.3.3 TDMA frame number : constants and modular arithmetic */ +#define GSM_TDMA_FN_DURATION_nS 4615384 /* in 1e−9 seconds (approx) */ +#define GSM_TDMA_FN_DURATION_uS 4615 /* in 1e-6 seconds (approx) */ + +#define GSM_TDMA_SUPERFRAME (26 * 51) +#define GSM_TDMA_HYPERFRAME (2048 * GSM_TDMA_SUPERFRAME) + +/*! Return the sum of two specified TDMA frame numbers (summation) */ +#define GSM_TDMA_FN_SUM(a, b) \ + ((a + b) % GSM_TDMA_HYPERFRAME) +/*! Return the difference of two specified TDMA frame numbers (subtraction) */ +#define GSM_TDMA_FN_SUB(a, b) \ + ((a + GSM_TDMA_HYPERFRAME - b) % GSM_TDMA_HYPERFRAME) +/*! Return the *minimum* difference of two specified TDMA frame numbers (distance) */ +#define GSM_TDMA_FN_DIFF(a, b) \ + OSMO_MIN(GSM_TDMA_FN_SUB(a, b), GSM_TDMA_FN_SUB(b, a)) + +/*! Increment the given TDMA frame number by 1 and return the result (like ++fn) */ +#define GSM_TDMA_FN_INC(fn) \ + ((fn) = GSM_TDMA_FN_SUM((fn), 1)) +/*! Decrement the given TDMA frame number by 1 and return the result (like --fn) */ +#define GSM_TDMA_FN_DEC(fn) \ + ((fn) = GSM_TDMA_FN_SUB((fn), 1)) + /* Table 5 Clause 7 TS 05.02 */ static inline unsigned int gsm0502_get_n_pag_blocks(struct gsm48_control_channel_descr *chan_desc) |