blob: 08034361d4a897841d66d24f4a1766aba1d9fd37 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
#ifndef WORDACCESS_H_INCLUDED
#define WORDACCESS_H_INCLUDED
/* These are facilities for accessing data in C programs in ways that
exploit the way the machine defines words in order to squeeze out
speed and CPU efficiency.
In particular, routines in this file exploit the endianness of the
machine and use explicit machine instructions to access C
variables.
A word is the amount of data that fits in a register; the amount of
data that a single machine instruction can process. For example,
on IA32, a word is 32 bits because a single load or store
instruction moves that many bits and a single add instruction
operates on that many bits.
These facilities revolve around two data types: wordInt and
wordIntBytes.
wordint is an unsigned integer with precision (size) of one word.
It is just the number -- nothing is implied about how it is
represented in memory.
wordintBytes is an array of bytes that represent a word-sized
unsigned integer. x[0] is the high order 8 digits of the binary
coding of the integer, x[1] the next highest 8 digits, etc.
Note that it has big-endian form, regardless of what endianness the
underlying machine uses.
The actual size of word differs by machine. Usually it is 32 or 64
bits. Logically it can be as small as one byte. Fixed bit sequences
in each program impose a lower limit of word width. For example, the
longest bit sequence in pbmtog3 has 13 bits, so an 8-bit word won't
work with that.
We also assume that a char is 8 bits.
*/
#include "pm_config.h"
#if (!defined(WORDACCESS_GENERIC) \
&& defined(__GNUC__) && defined(__GLIBC__) \
&& (__GNUC__ * 100 + __GNUC_MINOR__ >= 304) )
#if BYTE_ORDER==BIG_ENDIAN /* defined by GCC */
#include "wordaccess_gcc3_be.h"
#elif defined(__ia64__) || defined(__amd64__) || defined(__x86_64__)
/* all these macros are defined by GCC */
#include "wordaccess_64_le.h"
#else
#include "wordaccess_gcc3_le.h"
#endif
#else
#include "wordaccess_generic.h"
#endif
#endif
|
