diff options
| author | Neels Hofmeyr <nhofmeyr@sysmocom.de> | 2022-02-17 23:10:08 +0100 |
|---|---|---|
| committer | Neels Hofmeyr <nhofmeyr@sysmocom.de> | 2022-02-18 13:21:56 +0100 |
| commit | a0fb37906d60910909b288e29b9501eaf7213711 (patch) | |
| tree | 3ceee306ac261cb519c3b3dd38064f85e84ba146 /include | |
| parent | 3900aae7a3f2bcae146e77c3e7f4d1ae3320ff12 (diff) | |
rename RSL_ENC_ALG_A5 to ALG_A5_NR_TO_RSL, clarify
The naming confused me so that I wrote buggy code again. Hopefully this
clarifies which representations the code paths are using.
In the macro code, highlight the error case of n <= -1 explicitly.
Also add ALG_A5_NR_TO_PERM_ALG_BITS. I need the 1<<n case in an
upcoming patch.
Related: SYS#5839
Change-Id: I7557ae97764bba09c906748a18e9031dfb362611
Diffstat (limited to 'include')
| -rw-r--r-- | include/osmocom/bsc/gsm_data.h | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h index 910c3d33a..07d141da5 100644 --- a/include/osmocom/bsc/gsm_data.h +++ b/include/osmocom/bsc/gsm_data.h @@ -528,7 +528,24 @@ struct om2k_mo { #define A38_XOR_MIN_KEY_LEN 12 #define A38_XOR_MAX_KEY_LEN 16 #define A38_COMP128_KEY_LEN 16 -#define RSL_ENC_ALG_A5(x) (x+1) + +/* There are these representations of A5/n: + * + * - (uint8_t)(1<<n), either as a single bit, or combined as a list of + * permitted algorithms. + * A5/0 == 0x01, A5/3 == 0x08, none = 0 + * + * - n+1, used on the RSL wire. + * A5/0 == 1, A5/3 == 4, none = 0 + * + * - n, used for human interaction and returned by select_best_cipher(). + * A5/0 == 0, A5/3 == 3, none <= -1 + * + * These macros convert from n to the other representations: + */ +#define ALG_A5_NR_TO_RSL(A5_N) ((A5_N) >= 0 ? (A5_N)+1 : 0) +#define ALG_A5_NR_TO_PERM_ALG_BITS(A5_N) ((A5_N) >= 0 ? 1<<(A5_N) : 0) + /* Up to 16 SI2quater are multiplexed; each fits 3 EARFCNS, so the practical maximum is 3*16. * The real maximum that fits in a total of 16 SI2quater rest octets also depends on the bits left by other SI2quater * rest octets elements, so to really fit 48 EARFCNs most other SI2quater elements need to be omitted. */ |