| /*! \file bitcomp.c |
| * Osmocom bit compression routines */ |
| /* |
| * (C) 2016 by sysmocom - s.f.m.c. GmbH |
| * Author: Max Suraev <msuraev@sysmocom.de> |
| * |
| * All Rights Reserved |
| * |
| * SPDX-License-Identifier: GPL-2.0+ |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License along |
| * with this program; if not, write to the Free Software Foundation, Inc., |
| * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| */ |
| |
| /*! \defgroup bitcomp Bit compression |
| * @{ |
| * \file bitcomp.c */ |
| |
| #include <stdint.h> |
| #include <stdbool.h> |
| #include <errno.h> |
| #include <string.h> |
| |
| #include <osmocom/core/bitvec.h> |
| #include <osmocom/core/bitcomp.h> |
| |
| /* |
| * 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_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[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 |
| } |
| }; |
| |
| /*! Make-up codes for a given length |
| * |
| * \return Return proper make-up code word for an uninterrupted |
| * sequence of b bits of length len according to modified ITU-T T.4 |
| * from TS 44.060 Table 9.1.10.2 */ |
| static inline int t4_rle(struct bitvec *bv, unsigned len, bool b) |
| { |
| if (len >= 960) { |
| bitvec_set_uint(bv, t4_make_up[b][14], t4_make_up_length[b][14]); |
| return bitvec_set_uint(bv, t4_term[b][len - 960], t4_term_length[b][len - 960]); |
| } |
| |
| if (len >= 896) { |
| bitvec_set_uint(bv, t4_make_up[b][13], t4_make_up_length[b][13]); |
| return bitvec_set_uint(bv, t4_term[b][len - 896], t4_term_length[b][len - 896]); |
| } |
| |
| if (len >= 832) { |
| bitvec_set_uint(bv, t4_make_up[b][12], t4_make_up_length[b][12]); |
| return bitvec_set_uint(bv, t4_term[b][len - 832], t4_term_length[b][len - 832]); |
| } |
| |
| if (len >= 768) { |
| bitvec_set_uint(bv, t4_make_up[b][11], t4_make_up_length[b][11]); |
| return bitvec_set_uint(bv, t4_term[b][len - 768], t4_term_length[b][len - 768]); |
| } |
| |
| if (len >= 704) { |
| bitvec_set_uint(bv, t4_make_up[b][10], t4_make_up_length[b][10]); |
| return bitvec_set_uint(bv, t4_term[b][len - 704], t4_term_length[b][len - 704]); |
| } |
| |
| if (len >= 640) { |
| bitvec_set_uint(bv, t4_make_up[b][9], t4_make_up_length[b][9]); |
| return bitvec_set_uint(bv, t4_term[b][len - 640], t4_term_length[b][len - 640]); |
| } |
| |
| if (len >= 576) { |
| bitvec_set_uint(bv, t4_make_up[b][8], t4_make_up_length[b][8]); |
| return bitvec_set_uint(bv, t4_term[b][len - 576], t4_term_length[b][len - 576]); |
| } |
| |
| if (len >= 512) { |
| bitvec_set_uint(bv, t4_make_up[b][7], t4_make_up_length[b][7]); |
| return bitvec_set_uint(bv, t4_term[b][len - 512], t4_term_length[b][len - 512]); |
| } |
| |
| if (len >= 448) { |
| bitvec_set_uint(bv, t4_make_up[b][6], t4_make_up_length[b][6]); |
| return bitvec_set_uint(bv, t4_term[b][len - 448], t4_term_length[b][len - 448]); |
| } |
| |
| if (len >= 384) { |
| bitvec_set_uint(bv, t4_make_up[b][5], t4_make_up_length[b][5]); |
| return bitvec_set_uint(bv, t4_term[b][len - 384], t4_term_length[b][len - 384]); |
| } |
| |
| if (len >= 320) { |
| bitvec_set_uint(bv, t4_make_up[b][4], t4_make_up_length[b][4]); |
| return bitvec_set_uint(bv, t4_term[b][len - 320], t4_term_length[b][len - 320]); |
| } |
| |
| if (len >= 256) { |
| bitvec_set_uint(bv, t4_make_up[b][3], t4_make_up_length[b][3]); |
| return bitvec_set_uint(bv, t4_term[b][len - 256], t4_term_length[b][len - 256]); |
| } |
| |
| if (len >= 192) { |
| bitvec_set_uint(bv, t4_make_up[b][2], t4_make_up_length[b][2]); |
| return bitvec_set_uint(bv, t4_term[b][len - 192], t4_term_length[b][len - 192]); |
| } |
| |
| if (len >= 128) { |
| bitvec_set_uint(bv, t4_make_up[b][1], t4_make_up_length[b][1]); |
| return bitvec_set_uint(bv, t4_term[b][len - 128], t4_term_length[b][len - 128]); |
| } |
| |
| if (len >= 64) { |
| bitvec_set_uint(bv, t4_make_up[b][0], t4_make_up_length[b][0]); |
| return bitvec_set_uint(bv, t4_term[b][len - 64], t4_term_length[b][len - 64]); |
| } |
| |
| return bitvec_set_uint(bv, t4_term[b][len], t4_term_length[b][len]); |
| } |
| |
| /*! encode bit vector in-place using T4 encoding |
| * Assumes MSB first encoding. |
| * \param[in] bv bit vector to be encoded |
| * \return color code (if the encoding started with 0 or 1) or -1 on |
| * failure (encoded is bigger than original) |
| */ |
| int osmo_t4_encode(struct bitvec *bv) |
| { |
| unsigned rl0 = bitvec_rl(bv, false), rl1 = bitvec_rl(bv, true); |
| int r = (rl0 > rl1) ? 0 : 1; |
| uint8_t orig[bv->data_len], tmp[bv->data_len * 2]; /* FIXME: better estimate max possible encoding overhead */ |
| struct bitvec comp, vec; |
| comp.data = tmp; |
| comp.data_len = bv->data_len * 2; |
| bitvec_zero(&comp); |
| vec.data = orig; |
| vec.data_len = bv->data_len; |
| bitvec_zero(&vec); |
| memcpy(vec.data, bv->data, bv->data_len); |
| vec.cur_bit = bv->cur_bit; |
| |
| while (vec.cur_bit > 0) { |
| if (rl0 > rl1) { |
| bitvec_shiftl(&vec, rl0); |
| t4_rle(&comp, rl0, false); |
| } else { |
| bitvec_shiftl(&vec, rl1); |
| t4_rle(&comp, rl1, true); |
| } |
| /* |
| TODO: implement backtracking for optimal encoding |
| printf(" -> [%d/%d]", comp.cur_bit + vec.cur_bit, bv->cur_bit); |
| */ |
| rl0 = bitvec_rl(&vec, false); |
| rl1 = bitvec_rl(&vec, true); |
| } |
| if (comp.cur_bit < bv->cur_bit) { |
| memcpy(bv->data, tmp, bv->data_len); |
| bv->cur_bit = comp.cur_bit; |
| return r; |
| } |
| return -1; |
| } |
| |
| |