diff options
author | Harald Welte <laforge@osmocom.org> | 2020-02-13 10:55:25 +0100 |
---|---|---|
committer | laforge <laforge@osmocom.org> | 2023-02-27 13:34:43 +0000 |
commit | 6345333fb101d5fc3ebe70e87c90673ac40cae3f (patch) | |
tree | 0e1c2121af29be9a8cde16fc86f6b53a2220e0f3 /src | |
parent | 94e0af0a6d1e080e8debb06e56e4278c262c74c1 (diff) |
Interleaving for CSD
This patch adds the [de]interleaving for CSD (circuit switched data),
nominally for TCH/F 9.6, but the same is also used for TCH/F 4.8,
TCH/H 4.8, TCH/F 2.4 and TCH/F 14.4.
Related: OS#4396, OS#1572
Change-Id: I6b16c2d0d7febf3883da662b2c7fec543335de12
Diffstat (limited to 'src')
-rw-r--r-- | src/coding/gsm0503_interleaving.c | 52 | ||||
-rw-r--r-- | src/coding/libosmocoding.map | 2 |
2 files changed, 54 insertions, 0 deletions
diff --git a/src/coding/gsm0503_interleaving.c b/src/coding/gsm0503_interleaving.c index 7809e832..cd2f2356 100644 --- a/src/coding/gsm0503_interleaving.c +++ b/src/coding/gsm0503_interleaving.c @@ -678,4 +678,56 @@ void gsm0503_tch_hr_interleave(const ubit_t *cB, ubit_t *iB) } } +/* 3GPP TS 45.003 Section 3.3.4 + * The coded bits are reordered and interleaved according to the following rule: + * i(B,j) = c(n,k) for k = 0,1,...,455 + * n = 0,1,...,N,N + 1,... + * B = B0 +4n + (k mod 19) + (k div 114) + * j = (k mod 19) + 19 (k mod 6) + * + * The result of the interleaving is a distribution of the reordered 114 + * bit of a given data block, n = N, over 19 blocks, 6 bits equally + * distributed in each block, in a diagonal way over consecutive blocks. + * + * Or in other words the interleaving is a distribution of the encoded, + * reordered 456 bits from four given input data blocks, which taken + * together give n = N, over 22 bursts, 6 bits equally distributed in + * the first and 22 nd bursts, 12 bits distributed in the second and 21 + * st bursts, 18 bits distributed in the third and 20 th bursts and 24 + * bits distributed in the other 16 bursts. + * + * The block of coded data is interleaved "diagonal", where a new block + * of coded data starts with every fourth burst and is distributed over + * 22 bursts. + * + * Also used for TCH/F4.8, TCH/H4.8, TCH/F2.4 and TCH/H2.4 and TCH/F14.4 */ +void gsm0503_tch_f96_interleave(const ubit_t *cB, ubit_t *iB) +{ + int j, k, B; + + for (k = 0; k < 456; k++) { + /* upper bound for B: 4*n + 18 + 4 = 4*n + 22 */ + B = /* B0 + 4n + */ (k % 19) + (k / 114); + /* upper bound for j: 18 + 19*5 = 113 */ + j = (k % 19) + 19 * (k % 6); + /* upper iB index: 4*n+23*114-1 */ + iB[B * 114 + j] = cB[k]; + } +} + +void gsm0503_tch_f96_deinterleave(sbit_t *cB, const sbit_t *iB) +{ + int j, k, B; + + for (k = 0; k < 456; k++) { + /* upper bound for B: 4*n + 18 + 4 = 4*n + 22 */ + B = /* B0 + 4n + */ (k % 19) + (k / 114); + /* upper bound for j: 18 + 19*5 = 113 */ + j = (k % 19) + 19 * (k % 6); + /* upper iB index: 4*n+23*114-1 */ + cB[k] = iB[B * 114 + j]; + } +} + + /*! @} */ diff --git a/src/coding/libosmocoding.map b/src/coding/libosmocoding.map index b083564a..ff6ea802 100644 --- a/src/coding/libosmocoding.map +++ b/src/coding/libosmocoding.map @@ -76,6 +76,8 @@ gsm0503_xcch_deinterleave; gsm0503_xcch_interleave; gsm0503_tch_fr_deinterleave; gsm0503_tch_fr_interleave; +gsm0503_tch_f96_deinterleave; +gsm0503_tch_f96_interleave; gsm0503_tch_hr_deinterleave; gsm0503_tch_hr_interleave; gsm0503_mcs1_ul_deinterleave; |