Using POSIX time related functions shows PTP time

One major different: The PTP time counts from 1990. POSIX function count from 1970.

The POSIX struct tm is
int tm_year
int tm_month
int tm_day
int tm_min
int tm_sec

Because I do not find function, I create the easy one to fill tm_xxx below.

/*
Copyright (C) 2016 YKLin

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
typedef struct _TIMESTAMP_S{
    uint16        epoch_number;
    uint32        seconds;
    uint32        nanoseconds;
} timestamp_t;
void _converttime(struct tm *mytime, uint64 epoch){
    int years=0, months=0,days=0,hours=0,minutes=0;
    if(!mytime){
        return;
    }
    if(epoch >= 31556926UL){
        years = epoch/31556926UL;
        epoch -= years*31556926UL;
    }
    if(epoch >= 2629743UL){
        months = epoch/2629743UL;
        epoch -= months*2629743UL;
    }
    if(epoch >= 86400UL){
        days = epoch/86400UL;
        epoch -= days*86400UL;
    }
    if(epoch >= 3600UL){
        hours = epoch/3600UL;
        epoch -= hours*3600UL;
    }
    if(epoch >= 60){
        minutes = epoch/60;
        epoch -= minutes*60;
    }
    mytime->tm_sec = (int)epoch;
    mytime->tm_year += years;
    mytime->tm_mon += months;
    mytime->tm_mday += days;
    mytime->tm_hour += hours;
    mytime->tm_min += minutes;
}
int _convertTimestapTotm(struct tm *mytime, timestamp_t *ts){
    if(!mytime || !ts){
        return FAILED;
    }
   _converttime(mytime, (uint64)ts->epoch_number<<32);
   _converttime(mytime, (uint64)ts->seconds);
    _converttime(mytime, (uint64)0x83aa7e80);
    return SUCCESS;
}

Modify binary file

It's been a while not writing anything because the my career changing to verify IC.
However, there is the little python script for modifying binary file byte by byte. The following code opens a file and seek to offset 0xAFF7 at the beginning. It writes 0xCC, 0xE2, 0x54, 0x7a into file.

import struct
magic = (0xCCE2, 0x547A)
with open("binary.bin", "r+b") as f:
    f.seek(0xAFF7)
    for m in magic:
        f.write(struct.pack('h', m))
    f.close()

select function does not stop

I use named FIFO and select function to do IPC programming. When program execute to "if(select(myfd+d, myfdSet, NULL, NULL, &waittime) > 0 && IS_SET(myfdSet))", it always fulfill condition even there is no any process wrote into named FIFO.
After I examin again, I find out that I open file as "O_RDONLY". Refer to Linux's man page, there is a section to discript it:

Under Linux, select() may report a socket file descriptor as "ready for reading", while nevertheless a subsequent read blocks.

Hence, I modify open statement from myfd = open("/tmp/a", O_RDONLY) to myfd = open("/tmp/a", O_RDWR|O_NONBLOCK). Everything is perfect right.

Convert Multicast IPv4 Address to MAC address

There is a mapping between Multicast IP address and MAC address. The first three bytes of Multicast MAC address are always 01:00:5e, the last three bytes are filled from Multicast IP-form.
We drop the highest nine bits of IP address and convert to MAC address. And this number will become Multicast MAC address.

For example, IP: 224.10.10.10 , its decimal is 375875314. After we drop the highest nine bits, it becomes 657930. So, the Multicast MAC address is: 01:00:5e:0a:0a:0a. Here is a example C source code (GPL) to show this:

/*
Copyright (C) 2010 YKLin

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
void cvtIP2MAC(unsigned long, unsigned char*);

int main(int argc, char **argv){
char ipaddress[255]="224.10.0.1";
unsigned char buf[6] = {0x01, 0x0, 0x5e, 0x0, 0x0, 0x0};
struct in_addr inputAddress;
int ret;
memset(&inputAddress, 0x0, sizeof(inputAddress));
if(argc > 1){
strcpy(ipaddress, argv[1]);
}

ret = inet_aton(ipaddress, &inputAddress);
if(!ret){
printf("Dest address(%s) is incorrect:%d\r\n", ipaddress, ret);
return -1;
}
printf("Conver IP(%s, %u) to MAC...\r\n", ipaddress, ntohl(inputAddress.s_addr));
MIPv42MAC(ntohl(inputAddress.s_addr), buf);
printf("MAC: %02x %02x %02x %02x %02x %02x\r\n", buf[0], buf[1], buf[2], buf[3], buf[4], buf[5]);
return 0;
}
void cvtIP2MAC(unsigned long ip, unsigned char *buf){
if(!buf){
return;
}
buf[5] = ip & 0xff;
buf[4] = (ip & 0xff00)>>8;
buf[3] = (ip & 0xff0000)>>16;
}

A coding convention of JAVA

I read a post about how to wirte JAVA in java-style. Here is a interesting item:

Use s == null, not null == s

It's true that I use null == s when I write c programming and it is really useful. The author explained why JAVA does not use null == s. In JAVA world, it will cause compile error when using statements below:
if( iNum = do_some_check()) {do_some_thing(iNum);} /*............Statement 1*/

We should use in JAVA world:
iNum = do_some_check();
if(iNum!=0){do_some_thing(iNum);} /*............Statement 2*/

C programmers often use Statement 1 to save semantics, because it is totally legal to use "assign operater in "if" statement in C's world. If C programmer is "too tired", she/he will write incorrect semantic statement below to check iNum is equal to 99:
if(iNum = 99){do_some_thing(iNum)};/*............Statement 3*/

Hence, there is a common sense to check iNum is equal to 99 like this:
if( 99 == iNum){do_some_thing(iNum)};/*............Statement 4*/

However, we are free to this kind of fear in JAVA's world. We do not have to write JAVA like other languages.
FYI:
Speaking the Java language without an accent: http://www.ibm.com/developerworks/java/library/j-noaccent.html?ca=drs-

some gcc extensions in the linux kernel

Here are some gcc extensions syntax in the linux kernel.
1. typeof(VARIABLE): You can find this at list_head related macros
2.range extension
3.zero-length arrays. IEEE 1394.
4. __builtin_expect. Layer II entry point use likely() and unlikely()
5.__builtin_prefetch. You can find this at list_head related macros

More details, visit IBM developer works
FYI:
IBM GCC hacks in the linux kernel

doxygen addon- Moritz

If you need more template for output document of doxygen, try this open source-Moritz.

FYI:
http://sourceforge.net/projects/moritz

Change pipe to non-blocking mode

The default pipe(...) is one blocking fd. If you need non-blocking IO, you can refer fowling sample code:
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
int main(void) {
int fd[2], pipeAttr;
/*fd[0] for reader, fd[1] for writer*/
pipe(fd);
fnctl(fd[0], pipeAttr, F_GETFL);
pipeAttr |= O_NONBLOCK;
fnctl(fd[0], F_SETFL, pipeAttr);
do_something(fd);
close(fd[0]);
close(fd[1]);
}
viod do_something(int fd[]) {
/*......*/
}


Zombie while create child thread

I use pthread_create(...) to generate child thread. The child thread becomes zombie after I termite program. After some "google" pages, the answer comes out: join child thread at main process.

errno.h

If you want to use errno at c program, you must include errno.h not declare "extern int errno".

char *strerror(int) is used to display error text.

There are two related header files at kernel source directory:
include/$(ARCH)/errno.h
asm-generic/errno-base.h

jiffies comparison

If you want to compare time in kernel module, you can user flowing macro to avoid jiffies overflow :
/*in kernel/linux/include/linux/jiffies.h*/
time_after(a,b)
time_before(a,b)
time_after_eq(a,b)
time_before_eq(a,b)

If you compare jiffies directly, you will get wrong result sometimes.

Translate Decimal / IP dotted quad

Here are simple functions to translate decimal/ip dotted quad in python.
Usage:
>dot2dec("64.233.189.99")
1089060195L
>dec2dot(1089060195L)
'64.233.189.99'
>

import types
def dot2dec(ipForm, useHex = False):
 if type(ipForm) == types.StringType:
  ipf = ipForm.split(".")
 elif type(ipForm) in (types.ListType, types.TupleType):
  ipf = ipForm
 elif type(ipForm) in (types.LongType, types.IntType):
  return None
 return reduce(lambda a,b: long(a)*256 + long(b), ipf)

def dec2dot(numbericIP):
 if type(numbericIP) == types.StringType and not numbericIP.isdigit() :
  return None
 numIP = long(numbericIP)
 return "%d.%d.%d.%d" % ((numIP>>24)&0xFF, (numIP>>16)&0xFF, (numIP>>8)&0xFF, numIP&0xFF)

FYI:
python google group

Apache POI

Apache announce new release of POI. Current version is 3.01 beta. POI is java implementation of the OLE 2 compound document format.
FYI:
Apache POI project

C99

There are some features defined by C99:

1.set initial values when allocate new data structure variable
typedef struct humanInfo_s {
char *name;
int age;
}humanInfo_t;

humanInfo obj = {.name="YUNG"};
2. Variable Declarations does not limit on the top of the function body.

3. inline function.

There some many defines in C99 , but I do not list it.
FYI:
ISO/IEC JTC1/SSC22/WG14-C

iptables

If there are many tables must be update, you have to create new handel when table changes.

iptc_handle_t myhandle = NULL;
if (myhandle)
 iptc_free(&myhandle);
myhandle = create_handle(currentTable, "modprobe");
if (noflush == 0) {
 for_each_chain(flush_entries, verbose, 1, &myhandle);
 for_each_chain(delete_chain, verbose, 0, &myhandle) ;
}


FYI:
iptables-save.c
netfilter

jQuery

jQuery is a javascript tool. It can simplify the development processing of ajax.

FYI:
jQuery
IBM developerWorks about JQuery: Simplify Ajax development with jQuery

Write python more pythonic

There will be a simple way to archive your goal in python. Here you are:

http://shalabh.infogami.com/Be_Pythonic2
http://faassen.n--tree.net/blog/view/weblog/2005/08/06/0

JFrame.show()

JFrame.show() ==>Deprecated. As of JDK version 1.5, replaced by setVisible(boolean)

javax.swing.SpringLayout ==>add from 1.4. SpringLayout is a very flexible layout manager that can emulate many of the features of other layout managers.

URL:
How to Use SpringLayout