diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/bitcomp.c | 128 |
1 files changed, 0 insertions, 128 deletions
diff --git a/src/bitcomp.c b/src/bitcomp.c index 8b3090e6..9c01246b 100644 --- a/src/bitcomp.c +++ b/src/bitcomp.c @@ -180,19 +180,11 @@ static const unsigned t4_term_length[2][64] = { {8, 6, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8} }; -static const unsigned t4_min_term_length[] = {2, 4}; -static const unsigned t4_min_make_up_length[] = {10, 5}; - -static const unsigned t4_max_term_length[] = {12, 8}; -static const unsigned t4_max_make_up_length[] = {13, 9}; - static const unsigned t4_make_up_length[2][15] = { {10, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 13}, {5, 5, 6, 7, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9} }; -static const unsigned t4_make_up_ind[15] = {64, 128, 192, 256, 320, 384, 448, 512, 576, 640, 704, 768, 832, 896, 960}; - static const unsigned t4_make_up[2][15] = { { 0b0000001111, @@ -230,30 +222,6 @@ static const unsigned t4_make_up[2][15] = { } }; -/*! \brief Attempt to decode compressed bit vector - * - * \return length of RLE according to modified ITU-T T.4 from TS 44.060 - * Table 9.1.10.2 or -1 if no applicable RLE found N. B: we need - * explicit bit length to make decoding unambiguous -*/ -static inline int t4_rle_term(unsigned w, bool b, unsigned bits) -{ - unsigned i; - for (i = 0; i < 64; i++) - if (w == t4_term[b][i] && bits == t4_term_length[b][i]) - return i; - return -1; -} - -static inline int t4_rle_makeup(unsigned w, bool b, unsigned bits) -{ - unsigned i; - for (i = 0; i < 15; i++) - if (w == t4_make_up[b][i] && bits == t4_make_up_length[b][i]) - return t4_make_up_ind[i]; - return -1; -} - /*! \brief Make-up codes for a given length * * \return Return proper make-up code word for an uninterrupted @@ -339,102 +307,6 @@ static inline int t4_rle(struct bitvec *bv, unsigned len, bool b) return bitvec_set_uint(bv, t4_term[b][len], t4_term_length[b][len]); } -enum dec_state { - EXPECT_TERM, - TOO_LONG, - NEED_MORE_BITS, - CORRUPT, - OK -}; - -static inline enum dec_state _t4_step(struct bitvec *v, uint16_t w, bool b, unsigned bits, bool term_only) -{ - if (bits > t4_max_make_up_length[b]) - return TOO_LONG; - if (bits < t4_min_term_length[b]) - return NEED_MORE_BITS; - - if (term_only) { - if (bits > t4_max_term_length[b]) - return CORRUPT; - int t = t4_rle_term(w, b, bits); - if (-1 != t) { - bitvec_fill(v, t, b ? ONE : ZERO); - return OK; - } - return NEED_MORE_BITS; - } - - int m = t4_rle_makeup(w, b, bits); - if (-1 != m) { - bitvec_fill(v, m, b ? ONE : ZERO); - return EXPECT_TERM; - } - - m = t4_rle_term(w, b, bits); - if (-1 != m) { - bitvec_fill(v, m, b ? ONE : ZERO); - return OK; - } - - return NEED_MORE_BITS; -} - -/*! \brief decode T4-encoded bit vector - * Assumes MSB first encoding. - * \param[in] in bit vector with encoded data - * \param[in] cc color code (whether decoding should start with 1 or 0) - * \param[out] out the bit vector to store result into - * \return 0 on success, negative value otherwise - */ -int osmo_t4_decode(const struct bitvec *in, bool cc, struct bitvec *out) -{ - uint8_t orig[in->data_len]; - struct bitvec vec; - vec.data = orig; - vec.data_len = in->data_len; - bitvec_zero(&vec); - memcpy(vec.data, in->data, in->data_len); - vec.cur_bit = in->cur_bit; - - /* init decoder using known color code: */ - unsigned bits = t4_min_term_length[cc]; - enum dec_state d; - int16_t w = bitvec_get_int16_msb(&vec, bits); - bool b = cc; - bool term_only = false; - - while (vec.cur_bit > 0) { - d = _t4_step(out, w, b, bits, term_only); - - switch (d) { - case EXPECT_TERM: - bitvec_shiftl(&vec, bits); - bits = t4_min_term_length[b]; - w = bitvec_get_int16_msb(&vec, bits); - term_only = true; - break; - case OK: - bitvec_shiftl(&vec, bits); - bits = t4_min_term_length[!b]; - w = bitvec_get_int16_msb(&vec, bits); - b = !b; - term_only = false; - break; - case NEED_MORE_BITS: - bits++; - w = bitvec_get_int16_msb(&vec, bits); - break; - case TOO_LONG: - return -E2BIG; - case CORRUPT: - return -EINVAL; - } - } - - return 0; -} - /*! \brief encode bit vector in-place using T4 encoding * Assumes MSB first encoding. * \param[in] bv bit vector to be encoded |