source: ntrip/trunk/BNC/src/RTCM3/bits.h @ 9032

Last change on this file since 9032 was 9032, checked in by stuerze, 8 months ago

minor changes

File size: 3.1 KB
Line 
1// Part of BNC, a utility for retrieving decoding and
2// converting GNSS data streams from NTRIP broadcasters.
3//
4// Copyright (C) 2015
5// German Federal Agency for Cartography and Geodesy (BKG)
6// http://www.bkg.bund.de
7// Alberding GmbH
8// http://www.alberding.eu
9//
10// Email: euref-ip@bkg.bund.de
11//
12// This program is free software; you can redistribute it and/or
13// modify it under the terms of the GNU General Public License
14// as published by the Free Software Foundation, version 2.
15//
16// This program is distributed in the hope that it will be useful,
17// but WITHOUT ANY WARRANTY; without even the implied warranty of
18// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19// GNU General Public License for more details.
20//
21// You should have received a copy of the GNU General Public License
22// along with this program; if not, write to the Free Software
23// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
24
25#ifndef BITS_H
26#define BITS_H
27
28#define LOADBITS(a) { \
29  while((a) > numbits) { \
30    if(!size--) return false; \
31    bitfield = (bitfield<<8)|*(data++); \
32    numbits += 8; \
33  } \
34}
35
36/* extract bits from data stream
37   b = variable to store result, a = number of bits */
38#define GETBITS64(b, a) { \
39  if(((a) > 56) && ((a)-56) > numbits) { \
40    uint64_t x; \
41    GETBITS(x, 56) \
42    LOADBITS((a)-56) \
43    b = ((x<<((a)-56)) | (bitfield<<(sizeof(bitfield)*8-numbits)) \
44    >>(sizeof(bitfield)*8-((a)-56))); \
45    numbits -= ((a)-56); \
46  } \
47  else { \
48    GETBITS(b, a) \
49  } \
50}
51
52/* extract bits from data stream
53   b = variable to store result, a = number of bits */
54#define GETBITS(b, a) { \
55  LOADBITS(a) \
56  b = (bitfield<<(64-numbits))>>(64-(a)); \
57  numbits -= (a); \
58}
59
60/* extract bits from data stream
61   b = variable to store result, a = number of bits */
62#define GETBITSFACTOR(b, a, c) { \
63  LOADBITS(a) \
64  b = ((bitfield<<(sizeof(bitfield)*8-numbits))>>(sizeof(bitfield)*8-(a)))*(c); \
65  numbits -= (a); \
66}
67
68/* extract floating value from data stream
69   b = variable to store result, a = number of bits */
70#define GETFLOAT(b, a, c) { \
71  LOADBITS(a) \
72  b = ((double)((bitfield<<(64-numbits))>>(64-(a))))*(c); \
73  numbits -= (a); \
74}
75
76/* extract signed floating value from data stream
77   b = variable to store result, a = number of bits */
78#define GETFLOATSIGN(b, a, c) { \
79  LOADBITS(a) \
80  b = ((double)(((int64_t)(bitfield<<(64-numbits)))>>(64-(a))))*(c); \
81  numbits -= (a); \
82}
83
84/* extract bits from data stream
85   b = variable to store result, a = number of bits */
86#define GETBITSSIGN(b, a) { \
87  LOADBITS(a) \
88  b = ((int64_t)(bitfield<<(64-numbits)))>>(64-(a)); \
89  numbits -= (a); \
90}
91
92#define GETFLOATSIGNM(b, a, c) { \
93  int l; \
94  LOADBITS(a) \
95  l = (bitfield<<(64-numbits))>>(64-1); \
96  b = ((double)(((bitfield<<(64-(numbits-1))))>>(64-(a-1))))*(c); \
97  numbits -= (a); \
98  if(l) b *= -1.0; \
99}
100
101#define SKIPBITS(b) { LOADBITS(b) numbits -= (b); }
102
103/* extract byte-aligned byte from data stream,
104   b = variable to store size, s = variable to store string pointer */
105#define GETSTRING(b, s) { \
106  b = *(data++); \
107  s = (char *) data; \
108  data += b; \
109  size -= b+1; \
110}
111
112#endif /* BITS_H */
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