2 * bits.h - extract binary data from message buffer
4 * These macros extract bytes, words, longwords, floats, doubles, or
5 * bitfields of arbitrary length and size from a message that contains
6 * these items in either MSB-first or LSB-first byte order.
8 * By defining the GET_ORIGIN and PUT_ORIGIN macros before including
9 * this header, it's possible to change the origin of the indexing.
12 * char is 8 bits, short is 16 bits, int is 32 bits, long long is 64 bits,
13 * float is 32 bits IEEE754, double is 64 bits IEEE754.
15 * The use of fixed-length types in the casts enforces these.
16 * Both 32- and 64-bit systems with gcc are OK with this set.
18 * This file is Copyright (c)2010 by the GPSD project
19 * BSD terms apply: see the file COPYING in the distribution root for details.
43 /* these are independent of byte order */
44 #define getsb(buf, off) ((int8_t)buf[(off)-(GET_ORIGIN)])
45 #define getub(buf, off) ((uint8_t)buf[(off)-(GET_ORIGIN)])
46 #define putbyte(buf,off,b) do {buf[(off)-(PUT_ORIGIN)] = (unsigned char)(b);} while (0)
48 /* little-endian access */
49 #define getlesw(buf, off) ((int16_t)(((uint16_t)getub((buf), (off)+1) << 8) | (uint16_t)getub((buf), (off))))
50 #define getleuw(buf, off) ((uint16_t)(((uint16_t)getub((buf), (off)+1) << 8) | (uint16_t)getub((buf), (off))))
51 #define getlesl(buf, off) ((int32_t)(((uint16_t)getleuw((buf), (off)+2) << 16) | (uint16_t)getleuw((buf), (off))))
52 #define getleul(buf, off) ((uint32_t)(((uint16_t)getleuw((buf),(off)+2) << 16) | (uint16_t)getleuw((buf), (off))))
54 #define putleword(buf, off, w) do {putbyte(buf, (off)+1, (uint)(w) >> 8); putbyte(buf, (off), (w));} while (0)
55 #define putlelong(buf, off, l) do {putleword(buf, (off)+2, (uint)(l) >> 16); putleword(buf, (off), (l));} while (0)
56 #define getlesL(buf, off) ((int64_t)(((uint64_t)getleul(buf, (off)+4) << 32) | getleul(buf, (off))))
57 #define getleuL(buf, off) ((uint64_t)(((uint64_t)getleul(buf, (off)+4) << 32) | getleul(buf, (off))))
59 #define getlef(buf, off) (i_f.i = getlesl(buf, off), i_f.f)
60 #define getled(buf, off) (l_d.l = getlesL(buf, off), l_d.d)
62 /* SiRF and most other GPS protocols use big-endian (network byte order) */
63 #define getbesw(buf, off) ((int16_t)(((uint16_t)getub(buf, (off)) << 8) | (uint16_t)getub(buf, (off)+1)))
64 #define getbeuw(buf, off) ((uint16_t)(((uint16_t)getub(buf, (off)) << 8) | (uint16_t)getub(buf, (off)+1)))
65 #define getbesl(buf, off) ((int32_t)(((uint16_t)getbeuw(buf, (off)) << 16) | getbeuw(buf, (off)+2)))
66 #define getbeul(buf, off) ((uint32_t)(((uint16_t)getbeuw(buf, (off)) << 16) | getbeuw(buf, (off)+2)))
67 #define getbesL(buf, off) ((int64_t)(((uint64_t)getbeul(buf, (off)) << 32) | getbeul(buf, (off)+4)))
68 #define getbeuL(buf, off) ((uint64_t)(((uint64_t)getbeul(buf, (off)) << 32) | getbeul(buf, (off)+4)))
70 #define putbeword(buf,off,w) do {putbyte(buf, (off) ,(w) >> 8); putbyte(buf, (off)+1, (w));} while (0)
71 #define putbelong(buf,off,l) do {putbeword(buf, (off) ,(l) >> 16); putbeword(buf, (off)+2, (l));} while (0)
73 #define getbef(buf, off) (i_f.i = getbesl(buf, off), i_f.f)
74 #define getbed(buf, off) (l_d.l = getbesL(buf, off), l_d.d)
77 /* Zodiac protocol description uses 1-origin indexing by little-endian word */
78 #define getwordz(buf, n) ( (buf[2*(n)-2]) \
79 | (buf[2*(n)-1] << 8))
80 #define getlongz(buf, n) ( (buf[2*(n)-2]) \
81 | (buf[2*(n)-1] << 8) \
82 | (buf[2*(n)+0] << 16) \
83 | (buf[2*(n)+1] << 24))
84 #define getstringz(to, from, s, e) \
85 (void)memcpy(to, from+2*(s)-2, 2*((e)-(s)+1))
87 /* bitfield extraction */
88 extern unsigned long long ubits(char buf[], unsigned int, unsigned int);
89 extern signed long long sbits(char buf[], unsigned int, unsigned int);
91 #endif /* _GPSD_BITS_H_ */