xref: /OK3568_Linux_fs/kernel/tools/lib/traceevent/Documentation/libtraceevent-endian_read.txt (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593Smuzhiyunlibtraceevent(3)
2*4882a593Smuzhiyun================
3*4882a593Smuzhiyun
4*4882a593SmuzhiyunNAME
5*4882a593Smuzhiyun----
6*4882a593Smuzhiyuntep_read_number - Reads a number from raw data.
7*4882a593Smuzhiyun
8*4882a593SmuzhiyunSYNOPSIS
9*4882a593Smuzhiyun--------
10*4882a593Smuzhiyun[verse]
11*4882a593Smuzhiyun--
12*4882a593Smuzhiyun*#include <event-parse.h>*
13*4882a593Smuzhiyun
14*4882a593Smuzhiyununsigned long long *tep_read_number*(struct tep_handle pass:[*]_tep_, const void pass:[*]_ptr_, int _size_);
15*4882a593Smuzhiyun--
16*4882a593Smuzhiyun
17*4882a593SmuzhiyunDESCRIPTION
18*4882a593Smuzhiyun-----------
19*4882a593SmuzhiyunThe _tep_read_number()_ function reads an integer from raw data, taking into
20*4882a593Smuzhiyunaccount the endianness of the raw data and the current host. The _tep_ argument
21*4882a593Smuzhiyunis the trace event parser context. The _ptr_ is a pointer to the raw data, where
22*4882a593Smuzhiyunthe integer is, and the _size_ is the size of the integer.
23*4882a593Smuzhiyun
24*4882a593SmuzhiyunRETURN VALUE
25*4882a593Smuzhiyun------------
26*4882a593SmuzhiyunThe _tep_read_number()_ function returns the integer in the byte order of
27*4882a593Smuzhiyunthe current host. In case of an error, 0 is returned.
28*4882a593Smuzhiyun
29*4882a593SmuzhiyunEXAMPLE
30*4882a593Smuzhiyun-------
31*4882a593Smuzhiyun[source,c]
32*4882a593Smuzhiyun--
33*4882a593Smuzhiyun#include <event-parse.h>
34*4882a593Smuzhiyun...
35*4882a593Smuzhiyunstruct tep_handle *tep = tep_alloc();
36*4882a593Smuzhiyun...
37*4882a593Smuzhiyunvoid process_record(struct tep_record *record)
38*4882a593Smuzhiyun{
39*4882a593Smuzhiyun	int offset = 24;
40*4882a593Smuzhiyun	int data = tep_read_number(tep, record->data + offset, 4);
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun	/* Read the 4 bytes at the offset 24 of data as an integer */
43*4882a593Smuzhiyun}
44*4882a593Smuzhiyun...
45*4882a593Smuzhiyun--
46*4882a593Smuzhiyun
47*4882a593SmuzhiyunFILES
48*4882a593Smuzhiyun-----
49*4882a593Smuzhiyun[verse]
50*4882a593Smuzhiyun--
51*4882a593Smuzhiyun*event-parse.h*
52*4882a593Smuzhiyun	Header file to include in order to have access to the library APIs.
53*4882a593Smuzhiyun*-ltraceevent*
54*4882a593Smuzhiyun	Linker switch to add when building a program that uses the library.
55*4882a593Smuzhiyun--
56*4882a593Smuzhiyun
57*4882a593SmuzhiyunSEE ALSO
58*4882a593Smuzhiyun--------
59*4882a593Smuzhiyun_libtraceevent(3)_, _trace-cmd(1)_
60*4882a593Smuzhiyun
61*4882a593SmuzhiyunAUTHOR
62*4882a593Smuzhiyun------
63*4882a593Smuzhiyun[verse]
64*4882a593Smuzhiyun--
65*4882a593Smuzhiyun*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
66*4882a593Smuzhiyun*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
67*4882a593Smuzhiyun--
68*4882a593SmuzhiyunREPORTING BUGS
69*4882a593Smuzhiyun--------------
70*4882a593SmuzhiyunReport bugs to  <linux-trace-devel@vger.kernel.org>
71*4882a593Smuzhiyun
72*4882a593SmuzhiyunLICENSE
73*4882a593Smuzhiyun-------
74*4882a593Smuzhiyunlibtraceevent is Free Software licensed under the GNU LGPL 2.1
75*4882a593Smuzhiyun
76*4882a593SmuzhiyunRESOURCES
77*4882a593Smuzhiyun---------
78*4882a593Smuzhiyunhttps://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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