diff options
Diffstat (limited to 'src/egprs_rlc_compression.cpp')
| -rw-r--r-- | src/egprs_rlc_compression.cpp | 334 |
1 files changed, 332 insertions, 2 deletions
diff --git a/src/egprs_rlc_compression.cpp b/src/egprs_rlc_compression.cpp index f4e6bdee..82605ff2 100644 --- a/src/egprs_rlc_compression.cpp +++ b/src/egprs_rlc_compression.cpp @@ -84,8 +84,203 @@ void egprs_compress::build_codewords(egprs_compress_node *root, const char *cdwd } } -/* The code words for one run length and zero run length are described in - * table 9.1.10.1 of 3gpp 44.060 +/* + * Terminating codes for uninterrupted sequences of 0 and 1 up to 64 bit length + * according to TS 44.060 9.1.10 + */ +static const unsigned t4_term[2][64] = { + { + 0b0000110111, + 0b10, + 0b11, + 0b010, + 0b011, + 0b0011, + 0b0010, + 0b00011, + 0b000101, + 0b000100, + 0b0000100, + 0b0000101, + 0b0000111, + 0b00000100, + 0b00000111, + 0b000011000, + 0b0000010111, + 0b0000011000, + 0b0000001000, + 0b00001100111, + 0b00001101000, + 0b00001101100, + 0b00000110111, + 0b00000101000, + 0b00000010111, + 0b00000011000, + 0b000011001010, + 0b000011001011, + 0b000011001100, + 0b000011001101, + 0b000001101000, + 0b000001101001, + 0b000001101010, + 0b000001101011, + 0b000011010010, + 0b000011010011, + 0b000011010100, + 0b000011010101, + 0b000011010110, + 0b000011010111, + 0b000001101100, + 0b000001101101, + 0b000011011010, + 0b000011011011, + 0b000001010100, + 0b000001010101, + 0b000001010110, + 0b000001010111, + 0b000001100100, + 0b000001100101, + 0b000001010010, + 0b000001010011, + 0b000000100100, + 0b000000110111, + 0b000000111000, + 0b000000100111, + 0b000000101000, + 0b000001011000, + 0b000001011001, + 0b000000101011, + 0b000000101100, + 0b000001011010, + 0b000001100110, + 0b000001100111 + + }, + { + 0b00110101, + 0b000111, + 0b0111, + 0b1000, + 0b1011, + 0b1100, + 0b1110, + 0b1111, + 0b10011, + 0b10100, + 0b00111, + 0b01000, + 0b001000, + 0b000011, + 0b110100, + 0b110101, + 0b101010, + 0b101011, + 0b0100111, + 0b0001100, + 0b0001000, + 0b0010111, + 0b0000011, + 0b0000100, + 0b0101000, + 0b0101011, + 0b0010011, + 0b0100100, + 0b0011000, + 0b00000010, + 0b00000011, + 0b00011010, + 0b00011011, + 0b00010010, + 0b00010011, + 0b00010100, + 0b00010101, + 0b00010110, + 0b00010111, + 0b00101000, + 0b00101001, + 0b00101010, + 0b00101011, + 0b00101100, + 0b00101101, + 0b00000100, + 0b00000101, + 0b00001010, + 0b00001011, + 0b01010010, + 0b01010011, + 0b01010100, + 0b01010101, + 0b00100100, + 0b00100101, + 0b01011000, + 0b01011001, + 0b01011010, + 0b01011011, + 0b01001010, + 0b01001011, + 0b00110010, + 0b00110011, + 0b00110100 + } +}; +static const unsigned t4_term_length[2][64] = { + {10, 2, 2, 3, 3, 4, 4, 5, 6, 6, 7, 7, 7, 8, 8, 9, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12}, + {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, + 0b000011001000, + 0b000011001001, + 0b000001011011, + 0b000000110011, + 0b000000110100, + 0b000000110101, + 0b0000001101100, + 0b0000001101101, + 0b0000001001010, + 0b0000001001011, + 0b0000001001100, + 0b0000001001101, + 0b0000001110010, + 0b0000001110011 + }, + { + 0b11011, + 0b10010, + 0b010111, + 0b0110111, + 0b00110110, + 0b00110111, + 0b01100100, + 0b01100101, + 0b01101000, + 0b01100111, + 0b011001100, + 0b011001101, + 0b011010010, + 0b011010011, + 0b011010100 + } +}; + +/* The code words for one run length and zero + * run length are described in table 9.1.10.1 + * of 3gpp 44.060 */ const char *one_run_len_code_list[EGPRS_CODEWORDS] = { "00110101", @@ -359,3 +554,138 @@ egprs_compress::egprs_compress() decode_tree_init(); } +/* Compress received block bitmap + * \param run_len_cnt[in] Count of number of 1's and 0's + * \param codewrd_bitmap[in] Code word for coresponding run length. + * \param crbb_vec[out] compressed bitvector. + */ +static void compress_bitmap( + uint16_t *run_len_cnt, /* cnt: run length count */ + uint16_t *codewrd_bitmap, /* code word */ + int16_t *codewrd_len, /* number of bits in the code word */ + bitvec *crbb_vec, /* bitmap buffer to put code word in */ + bool start) +{ + int i = 0; + unsigned writeIndex = crbb_vec->cur_bit; + *codewrd_bitmap = 0; + *codewrd_len = 0; + if (*run_len_cnt >= 64) { + for (i = 0; i < 15; i++) { + if (t4_make_up_ind[i] == *run_len_cnt) { + *codewrd_bitmap = t4_make_up[start][i]; + *codewrd_len = t4_make_up_length[start][i]; + } + } + } else { + *codewrd_bitmap = t4_term[start][*run_len_cnt]; + *codewrd_len = t4_term_length[start][*run_len_cnt]; + } + bitvec_write_field(crbb_vec, writeIndex, *codewrd_bitmap, *codewrd_len); +} + +/* Compress received block bitmap */ +int egprs_compress::osmo_t4_compress(struct bitvec *bv) +{ + uint8_t crbb_len = 0; + uint8_t uclen_crbb = 0; + uint8_t crbb_bitmap[127] = {'\0'}; + bool start = (bv->data[0] & 0x80)>>7; + struct bitvec crbb_vec; + + crbb_vec.data = crbb_bitmap; + crbb_vec.cur_bit = 0; + crbb_vec.data_len = 127; + bv->data_len = bv->cur_bit; + bv->cur_bit = 0; + if (egprs_compress::compress_rbb(bv, &crbb_vec, &uclen_crbb, 23*8)) { + memcpy(bv->data, crbb_bitmap, (crbb_len+7)/8); + bv->cur_bit = crbb_len; + bv->data_len = (crbb_len+7)/8; + return start; + } + else + printf("Encode failed\n"); + return -1; +} + +/*! \brief compression algorithm using T4 encoding + * the compressed bitmap's are copied in crbb_bitmap + * \param[in] rbb_vec bit vector to be encoded + * \return 1 if compression is success or 0 for failure + */ +int egprs_compress::compress_rbb( + struct bitvec *urbb_vec, + struct bitvec *crbb_vec, + uint8_t *uclen_crbb, /* Uncompressed bitmap len in CRBB */ + uint8_t max_bits) /* max remaining bits */ +{ + bool run_len_bit; + int buflen = urbb_vec->cur_bit; + int total_bits = urbb_vec->cur_bit; + uint16_t rlen; + uint16_t temprl = 0; + uint16_t cbmap = 0; /* Compressed code word */ + int16_t nbits; /* Length of code word */ + uint16_t uclen = 0; + int16_t clen = 0; + bool start; /* Starting color code see 9.1.10, 3GPP 44.060 */ + urbb_vec->cur_bit = 0; + run_len_bit = (urbb_vec->data[0] & 0x80)>>7; + while (buflen > 0) { + temprl = 0; + /* Find Run length */ + if (run_len_bit == 1) + rlen = bitvec_rl_curbit(urbb_vec, true, total_bits); + else + rlen = bitvec_rl_curbit(urbb_vec, false, total_bits); + buflen = buflen - rlen; + /* if rlen > 64 need Makeup code word */ + /*Compress the bits */ + if (run_len_bit == 0) { + start = 0; + if (rlen >= 64) { + temprl = (rlen/64)*64; + compress_bitmap(&temprl, &cbmap, &nbits, + crbb_vec, start); + clen = clen + nbits; + } + temprl = MOD64(rlen); + compress_bitmap(&temprl, &cbmap, &nbits, + crbb_vec, start); + /* next time the run length will be Ones */ + run_len_bit = 1; + } else { + start = 1; + if (rlen >= 64) { + temprl = (rlen/64)*64; + compress_bitmap(&temprl, &cbmap, &nbits, + crbb_vec, start); + clen = clen + nbits; + } + temprl = MOD64(rlen); + compress_bitmap(&temprl, &cbmap, &nbits, + crbb_vec, start); + + /* next time the run length will be Zeros */ + run_len_bit = 0; + } + uclen = uclen + rlen; + clen = clen + nbits; + /*compressed bitmap exceeds the buffer space */ + if (clen > max_bits) { + uclen = uclen - rlen; + clen = clen - nbits; + break; + } + } + crbb_vec->cur_bit = clen; + *uclen_crbb = uclen; + if (clen >= uclen) + /* No Gain is observed, So no need to compress */ + return 0; + else + LOGP(DRLCMACUL, LOGL_DEBUG, "CRBB bitmap = %s\n", osmo_hexdump(crbb_vec->data, (crbb_vec->cur_bit+7)/8)); + /* Add compressed bitmap to final buffer */ + return 1; +} |