| 1 | // Part of BNC, a utility for retrieving decoding and
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| 2 | // converting GNSS data streams from NTRIP broadcasters.
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| 3 | //
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| 4 | // Copyright (C) 2015
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| 5 | // German Federal Agency for Cartography and Geodesy (BKG)
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| 6 | // http://www.bkg.bund.de
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| 7 | // Alberding GmbH
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| 8 | // http://www.alberding.eu
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| 9 | //
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| 10 | // Email: euref-ip@bkg.bund.de
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| 11 | //
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| 12 | // This program is free software; you can redistribute it and/or
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| 13 | // modify it under the terms of the GNU General Public License
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| 14 | // as published by the Free Software Foundation, version 2.
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| 15 | //
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| 16 | // This program is distributed in the hope that it will be useful,
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| 17 | // but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 18 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 19 | // GNU General Public License for more details.
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| 20 | //
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| 21 | // You should have received a copy of the GNU General Public License
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| 22 | // along with this program; if not, write to the Free Software
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| 23 | // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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| 24 |
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| 25 | #ifndef BITS_H
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| 26 | #define BITS_H
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| 27 |
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| 28 | #define LOADBITS(a) { \
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| 29 | while((a) > numbits) { \
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| 30 | if(!size--) return false; \
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| 31 | bitfield = (bitfield<<8)|*(data++); \
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| 32 | numbits += 8; \
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| 33 | } \
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| 34 | }
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| 35 |
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| 36 | /* extract bits from data stream
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| 37 | b = variable to store result, a = number of bits */
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| 38 | #define GETBITS64(b, a) { \
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| 39 | if(((a) > 56) && ((a)-56) > numbits) { \
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| 40 | uint64_t x; \
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| 41 | GETBITS(x, 56) \
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| 42 | LOADBITS((a)-56) \
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| 43 | b = ((x<<((a)-56)) | (bitfield<<(sizeof(bitfield)*8-numbits)) \
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| 44 | >>(sizeof(bitfield)*8-((a)-56))); \
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| 45 | numbits -= ((a)-56); \
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| 46 | } \
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| 47 | else { \
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| 48 | GETBITS(b, a) \
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| 49 | } \
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| 50 | }
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| 51 |
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| 52 | /* extract bits from data stream
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| 53 | b = variable to store result, a = number of bits */
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| 54 | #define GETBITS(b, a) { \
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| 55 | LOADBITS(a) \
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| 56 | b = (bitfield<<(64-numbits))>>(64-(a)); \
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| 57 | numbits -= (a); \
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| 58 | }
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| 59 |
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| 60 | /* extract bits from data stream
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| 61 | b = variable to store result, a = number of bits */
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| 62 | #define GETBITSFACTOR(b, a, c) { \
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| 63 | LOADBITS(a) \
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| 64 | b = ((bitfield<<(sizeof(bitfield)*8-numbits))>>(sizeof(bitfield)*8-(a)))*(c); \
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| 65 | numbits -= (a); \
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| 66 | }
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| 67 |
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| 68 | /* extract floating value from data stream
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| 69 | b = variable to store result, a = number of bits */
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| 70 | #define GETFLOAT(b, a, c) { \
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| 71 | LOADBITS(a) \
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| 72 | b = ((double)((bitfield<<(64-numbits))>>(64-(a))))*(c); \
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| 73 | numbits -= (a); \
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| 74 | }
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| 75 |
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| 76 | /* extract signed floating value from data stream
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| 77 | b = variable to store result, a = number of bits */
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| 78 | #define GETFLOATSIGN(b, a, c) { \
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| 79 | LOADBITS(a) \
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| 80 | b = ((double)(((int64_t)(bitfield<<(64-numbits)))>>(64-(a))))*(c); \
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| 81 | numbits -= (a); \
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| 82 | }
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| 83 |
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| 84 | /* extract bits from data stream
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| 85 | b = variable to store result, a = number of bits */
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| 86 | #define GETBITSSIGN(b, a) { \
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| 87 | LOADBITS(a) \
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| 88 | b = ((int64_t)(bitfield<<(64-numbits)))>>(64-(a)); \
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| 89 | numbits -= (a); \
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| 90 | }
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| 91 |
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| 92 | #define GETFLOATSIGNM(b, a, c) { \
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| 93 | int l; \
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| 94 | LOADBITS(a) \
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| 95 | l = (bitfield<<(64-numbits))>>(64-1); \
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| 96 | b = ((double)(((bitfield<<(64-(numbits-1))))>>(64-(a-1))))*(c); \
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| 97 | numbits -= (a); \
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| 98 | if(l) b *= -1.0; \
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| 99 | }
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| 100 |
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| 101 | #define SKIPBITS(b) { LOADBITS(b) numbits -= (b); }
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| 102 |
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| 103 | /* extract byte-aligned byte from data stream,
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| 104 | b = variable to store size, s = variable to store string pointer */
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| 105 | #define GETSTRING(b, s) { \
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| 106 | b = *(data++); \
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| 107 | s = (char *) data; \
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| 108 | data += b; \
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| 109 | size -= b+1; \
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| 110 | }
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| 111 |
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| 112 | #endif /* BITS_H */
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