Nano雞排

2018年1月28日星期日

dtc - Device Tree Compiler

從dtc manpage可以簡略瞭解一下DTC(Device Tree Compiler)功能, 就是將device-tree的format轉成另一種format, 其input格式有三種,

dts - device tree source text
dtb - device tree blob
fs - /proc/device-tree style directory

而output格式也有三種,

dts - device tree source text
dtb - device tree blob
asm - assembler source

而dtc支援的phandle可支援三種

legacy - "linux,phandle" properties only
epapr - "phandle" properties only
both - Both "linux,phandle" and "phandle" properties

根據Device Tree Mysteries,

what is the reason for having a phandle? 
It is really just a hack to get around the fact that device tree does 
not have a pointer data type. 
It is a way to reference 
"that node over there that is related to this node for some reason".

簡單來說, phandler就是pointer data type, 用個例子說明

pic@10000000 {
    phandle = < 1 >;
};

A phandle value of 1 is defined. 
Another device node could reference the pic node with a
phandle value of 1:

uart@20000000 {
    interrupt-parent = > 1 >;
};

"phandle = < 1 >"的"1"是一個隨意的unit32數值, 只要不衝突即可, 但是這並不是很好記, 所以DTC貼心的可以用lable來建立phandle,如下範例

PIC_3: pic@10000000 {
    interrupt-controller;
};

uart@20000000 {
    interrupt-parent = < &PIC_3 >;
};

這裡的"&"是告訴DTC後面接一個字串, 是個phandle參考到某個lable, 然後DTC就會幫user建立unit32的數值, 建立出phandle. 除此之外也可以使用full path來取代lable, 如下範例

/{
    soc {
        PIC_3: pic@10000000 {
            interrupt-controller;
        };
    };

    uart@20000000 {
        interrupt-parent = < &PIC_3 >;
    };

    uart@30000000 {
        interrupt-parent = < &{/soc/pic@10000000} >;
    };
};

下面再用一個例子同時說明DTC與phandle

brook@vista:~/dts$ cat test_phandle.dts
/dts-v1/;
/{
    soc {
        PIC_3: pic@10000000 {
           interrupt-controller;
        };
    };

    uart@20000000 {
        interrupt-parent = < &PIC_3 >;
    };

    uart@30000000 {
        interrupt-parent = < &{/soc/pic@10000000} >;
    };
};
brook@vista:~/dts$ dtc -O dtb -I dts test_phandle.dts > test_phandle.dtb
brook@vista:~/dts$ dtc -O dts -I dtb test_phandle.dtb
/dts-v1/;

/ {

        soc {

                pic@10000000 {
                        interrupt-controller;
                        linux,phandle = <0x1>;
                        phandle = <0x1>;
                };
        };

        uart@20000000 {
                interrupt-parent = <0x1>;
        };

        uart@30000000 {
                interrupt-parent = <0x1>;
        };
};

這篇文章主要簡單講解利用dtc來轉換dtb與dts, 順帶說明一下phandle是一種pointer data type, 與其基本原理

2018年1月7日星期日

note for "The Art of Readable Code" - CH6 Making Comments Precise and Compact

CH6, Making Comments Precise and Compact

Comments should have a high information-to-space ratio.當你準備寫註解時, 請盡可能的精簡, 因為註解會佔版面, 而且需要時間了解

// CategoryType -> (score, weight)
typedef hash_map<int, pair<float, float> > ScoreMap;
會比下面例子精簡
// The int is the CategoryType.
// The first float in the inner pair is the 'score',
// the second is the 'weight'.
typedef hash_map<int, pair<float, float> > ScoreMap;

// Return the number of lines in this file.
int CountLines(string filename) { ... }
這段註解不精確, 因為一行有很多種定義, 下面例子會相對精準
// Count how many newline bytes ('\n') are in the file.
int CountLines(string filename) { ... }

Use Input/Output Examples That Illustrate Corner Cases有時候用範例當註解可以更容易讓人理解,比如

// Rearrange 'v' so that elements < pivot come before those >= pivot;
// Then return the largest 'i' for which v[i] < pivot (or -1 if none are < pivot)
// Example: Partition([8 5 9 8 2], 8) might result in [5 2 | 8 9 8] and return 1
int Partition(vector<int>* v, int pivot);

"Named Function Parameter” Comments即在function參數上加上註解

Connect(/* timeout_ms = */ 10, /* use_encryption = */ false);

The Art of Readable Code

2018年1月1日星期一

note for "The Art of Readable Code" - CH5 Knowing What to Comment

CH5, Knowing What to Comment

The purpose of commenting is to help the reader know as much as the writer did.千萬別為了註解而註解, 因為凌亂的畫面, 不會讓人對程式碼更清晰

無意義的註解範例

// The class definition for Account
    class Account {
      public:
        // Constructor
Account();
        // Set the profit member to a new value
        void SetProfit(double profit);
        // Return the profit from this Account
        double GetProfit();
    };

不要註解不好的名稱, 直接修正名稱

// Enforce limits on the Reply as stated in the Request,
// such as the number of items returned, or total byte size, etc. 
void CleanReply(Request request, Reply reply);
直接修改上述function name從CleanReply()改為EnforceLimitsFromRequest()會比註解一堆來得有意義,
// Make sure 'reply' meets the count/byte/etc. limits from the 'request' 
void EnforceLimitsFromRequest(Request request, Reply reply);

Recording Your Thoughts / directory commentary,註解重要的紀錄,比如以下幾個註解

// This heuristic might miss a few words. That's OK; solving this 100% is hard.
...
// This class is getting messy. Maybe we should create a 'ResourceNode' subclass to
// help organize things.
...

Comment the Flaws in Your Code,程式會不斷的被修改, 不要害怕記錄這些需要改進的地方, 以下是常用的標記

TODO:	Stuff I haven’t gotten around to yet
FIXME:	Known-broken code here
HACK:	Admittedly inelegant solution to a problem
XXX:	Danger! major problem here

// TODO: move this into sched_fork()
...
// FIXME: do we need to worry about rq being invalidated by the
...

Summary Comments,對一些code給予一些comment, 比如

# Find all the items that customers purchased for themselves.
    for customer_id in all_customers:
        for sale in all_sales[customer_id].sales:
            if sale.recipient == customer_id:
                ...

def GenerateUserReport():
    # Acquire a lock for this user
    ...

    # Read user's info from the database
    ...

    # Write info to a file
    ...

    # Release the lock for this user
    ...

The Art of Readable Code

2017年12月23日星期六

note for "The Art of Readable Code" - CH3 & CH4

CH3, Names That Can’t Be Misconstrued

Actively scrutinize your names by asking yourself, “What other meanings could someone interpret from this name?”

比如results = Database.all_objects.filter("year <= 2011")的結果是<= 2011還是過濾了<= 2011的結果？如果用select()或exclude()會更為明確

對於含有邊界意思的, 可以使用"min_"與"max_"加以辨識.

對於閉區間使用first與end, 而半開放區間使用begin與end, 因為這些已經在C++中成為慣例了.

關於bool則可以加上is, has, can, should等意思會更明確, 如

bool user_is_authed = true
會比下面這行更容易被明確
bool read_password = true

get*()(開頭的function), 通常指直接回傳內部成員, 如果還需要計算, 最好改用compute*()或count*(),

CH4, Aesthetics

這個章節是在講述, 好的排版會讓人更容易看懂code, 以下是我摘要的幾個範例

給予參數一些註解

public class PerformanceTester {
   // TcpConnectionSimulator(throughput, latency, jitter, packet_loss)
   //                            [Kbps]   [ms]     [ms]    [percent]
   public static final TcpConnectionSimulator wifi =
       new TcpConnectionSimulator(500,     80,     200,     1);
   public static final TcpConnectionSimulator t3_fiber =
       new TcpConnectionSimulator(45000,   10,       0,     0);
   public static final TcpConnectionSimulator cell =
       new TcpConnectionSimulator(100,    400,     250,     5);
}

讓參數對齊

CheckFullName("Doug Adams"  , "Mr. Douglas Adams" , "");
CheckFullName(" Jake Brown ", "Mr. Jake Brown III", "");
CheckFullName("No Such Guy" , ""                  , "no match found");
CheckFullName("John"        , ""                  , "more than one result");

段落分明

def suggest_new_friends(user, email_password):
  # Get the user's friends' email addresses.
  friends = user.friends()
  friend_emails = set(f.email for f in friends)

  # Import all email addresses from this user's email account.
  contacts = import_contacts(user.email, email_password)
  contact_emails = set(c.email for c in contacts)

  # Find matching users that they aren't already friends with.
  non_friend_emails = contact_emails - friend_emails
  suggested_friends = User.objects.select(email__in=non_friend_emails)

Consistent style is more important than the “right” style. 無論你是用什麼coding style, 一致性會比你用“對”的style更重要.

The Art of Readable Code

note for "The Art of Readable Code" - CH1 & CH2

CH1, Code Should Be Easy to Understand

Code should be written to minimize the time it would take for someone else to understand it.

越容易理解的code是越好的, 雖然減少程式碼數量是很好的目標, 但是縮短理解的時間是更為重要的, 甚至於超越效能, 比如

bucket = FindBucket(key);
if (bucket != NULL) assert(!bucket->IsOccupied());
會比下面這行更容易被理解
assert((!(bucket = FindBucket(key))) || !bucket->IsOccupied());

CH2, Pack information into your names

提高可讀性可以從"好的名稱", "好的註解", "簡潔的編排方式"著手, 比如, 將資訊放入名稱中

void download_page(url);
或
void fetch_page(url);
會比下面這行更容易被理解
void get_page(url);

名稱選擇上也需要注意, 比如open(), begin(), create(), launch()會比start()來的明確, 盡量用明確的命名, 比如tmp_file會比tmp更明確, 比如

var start = (new Date()).getTime();
...
var elasped = (new Date()).getTime();
..
會比下面這行更容易被明確
var ms_start = (new Date()).getTime();
...
var ms_elasped = (new Date()).getTime();
..

排除不必要的詞彙, 比如

ToString();
會比下面這行更簡潔
ConveterToString();

ServerLoop();
會比下面這行更簡潔
DoServerLoop();

我也習慣在static function,使用"_"開頭, 比如

static void _sleep();
void sleep();

Pack information into your names的幾個重點

• Use specific words—for example, instead of Get, words like Fetch or Download might be
better, depending on the context.
• Avoid generic names like tmp and retval, unless there’s a specific reason to use them.
• Use concrete names that describe things in more detail—the name ServerCanStart() is
vague compared to CanListenOnPort().
• Attach important details to variable names—for example, append _ms to a variable
whose value is in milliseconds or prepend raw_ to an unprocessed variable that needs
escaping.
• Use longer names for larger scopes—don’t use cryptic one- or two-letter names for
variables that span multiple screens; shorter names are better for variables that span only
a few lines.
• Use capitalization, underscores, and so on in a meaningful way—for example, you
can append “_” to class members to distinguish them from local variables.

The Art of Readable Code

2017年12月9日星期六

Note for Yocto Project Reference Manual v2.4 - ch8.141 update-alternatives.bbclass

當有多個recipes提供相同的命令時, update-alternatives.bbclass可以幫你做替代("alternative"), 例如，可以從busybox，binutils和elfutils中使用ar命令。 update-alternatives.bbclass會幫你重新命名，以便安裝多個package而不會發生衝突。無論安裝或隨後刪除哪些package，ar命令仍然有效。
要使用update-alternatives.bbclass，你需要為這個package定義一些變量：
ALTERNATIVE_ = "name1 name2 name3 ..."
列出所有這個package的alternatives指令

設定name這個命令的link的路徑
ALTERNATIVE_LINK_NAME[name] = "target"

設定該package的預設priority，數值越大，priority越高
ALTERNATIVE_PRIORITY

針對特定命令另外設定priority，數值越大，priority越高
ALTERNATIVE_PRIORITY[name] = "20"

範例

brook這個package的檔案結構

brook@vista:~/oe-core/meta/recipes-devtools/brook$ tree
.
|-- brook-1.0.0
|   |-- brookbox
|   |-- copyright
|   `-- insmod
`-- brook_1.0.0.bb

1 directory, 4 files

brookbox類似busybox，後面會有多個檔案link到該檔案，而insmod是一個獨立檔案

brook_1.0.0.bb

SUMMARY = "Brook demo update-alternatives"
DESCRIPTION = "This package is used for Brook to demo update-alternatives"
LICENSE = "GPLv2+"
LIC_FILES_CHKSUM = "file://${WORKDIR}/copyright;md5=afcc69d729fbf1d0a2af28ce44a23991 \
"
SRC_URI = "file://insmod \
        file://copyright \
        file://brookbox \
"
inherit update-alternatives

ALTERNATIVE_${PN} = "insmod route reboot shutdown poweroff"
ALTERNATIVE_PRIORITY = "100"

ALTERNATIVE_LINK_NAME[insmod] = "${base_sbindir}/insmod"
ALTERNATIVE_PRIORITY[insmod] = "50"

ALTERNATIVE_LINK_NAME[route] = "${base_sbindir}/route"
ALTERNATIVE_PRIORITY[route] = "50"

ALTERNATIVE_LINK_NAME[reboot] = "${base_sbindir}/reboot"

ALTERNATIVE_LINK_NAME[shutdown] = "${base_sbindir}/shutdown"
ALTERNATIVE_PRIORITY[shutdown] = "10"

ALTERNATIVE_LINK_NAME[poweroff] = "${base_sbindir}/poweroff"
ALTERNATIVE_PRIORITY[poweroff] = "500"

do_install () {
        install -d                              ${D}${base_sbindir}
        install -m 0755    ${WORKDIR}/insmod    ${D}${base_sbindir}/insmod
        install -m 0755    ${WORKDIR}/brookbox  ${D}${base_sbindir}/brook
        ln -s ${base_sbindir}/brook ${D}${base_sbindir}/route
        ln -s ${base_sbindir}/brook ${D}${base_sbindir}/reboot
        ln -s ${base_sbindir}/brook ${D}${base_sbindir}/shutdown
        ln -s ${base_sbindir}/brook ${D}${base_sbindir}/poweroff
}

sysvinit也同時註冊了reboot，shutdown與poweroff，其priority都是200，而這裡的priority分別為100，10，500，所以最後結果如下

brook@vista:~/oe-core/build/tmp-glibc/work/oe-linux-gnueabi/image/1.0-r0/rootfs$ ls -al sbin/|grep brook
-rwxr-xr-x  1 jenkins jenkins      6 Dec  9 22:17 brook
lrwxrwxrwx  1 jenkins jenkins     18 Dec  9 22:17 insmod -> /sbin/insmod.brook
-rwxr-xr-x  1 jenkins jenkins      6 Dec  9 22:17 insmod.brook
lrwxrwxrwx  1 jenkins jenkins     20 Dec  9 22:17 poweroff -> /sbin/poweroff.brook
lrwxrwxrwx  1 jenkins jenkins     11 Dec  9 22:17 poweroff.brook -> /sbin/brook
lrwxrwxrwx  1 jenkins jenkins     11 Dec  9 22:17 reboot.brook -> /sbin/brook
lrwxrwxrwx  1 jenkins jenkins     17 Dec  9 22:17 route -> /sbin/route.brook
lrwxrwxrwx  1 jenkins jenkins     11 Dec  9 22:17 route.brook -> /sbin/brook
lrwxrwxrwx  1 jenkins jenkins     11 Dec  9 22:17 shutdown.brook -> /sbin/brook

reboot與shutdown都小於sysvinit，所以不適用brook，poweroff高於sysvinit，所以使用brook這個package提供的命令

Yocto Project Reference Manual 2.4

2017年11月25日星期六

An Sample Code for Syslogd - A log pattern with categorize, level and format

寫程式常常需要有log system用於debug，大程式常常會有很多thread或是模組，我們想根據模組分類，並且給予log特定等級，如ERR/INFO/DEBUG等等，也會希望多打印一些資訊，如function name，TPID等等，這裡就是要提供這些功能的sample code，此外，根據syslog_r for Linux?說的According to the POSIX specification, the syslog function is already thread-safe, and so implemented in Linux. So syslog_r is unnecessary - use syslog if you need a reentrant logger function.

brook-log.h

#ifndef _LOG_H_
#define _LOG_H_
#include <syslog.h>
#include <unistd.h>
#include <sys/syscall.h>

/*************************************************
 * TYPE
 *************************************************/
enum log_type {
/* 這裡我先設定有三個類別，分別為AT，CORE與DB，之後請自行新增刪減修改 */
       LOG_TYPE_AT,
       LOG_TYPE_CORE,
       LOG_TYPE_DB,
       LOG_TYPE_MAX
};

/***** internal function for MACRO used *****/
void _log_type_toggle(enum log_type type);
void _log_type_clr(enum log_type type);
void _log_type_set(enum log_type type);

/***** public function to enable/disable log on certain type *****/
#define log_type_toggle(type) _log_type_toggle(LOG_TYPE_##type)
#define log_type_clr(type) _log_type_clr(LOG_TYPE_##type)
#define log_type_set(type) _log_type_set(LOG_TYPE_##type)

char *get_log_type_status(void);


/*************************************************
 * Format
 *************************************************/
enum log_fmt {
 LOG_FMT_FUNC_AND_LINE,
 LOG_FMT_TID, ///< thread ID.
 LOG_FMT_LOG_TYPE,
 LOG_FMT_LOG_LEVEL,
 LOG_FMT_MAX,
};

/***** internal function for MACRO used *****/
void _log_fmt_toggle(enum log_fmt fmt);
void _log_fmt_set(enum log_fmt fmt);
void _log_fmt_clr(enum log_fmt fmt);
int _log_fmt_is_set(enum log_fmt fmt);

/***** public function to enable/disable certain format type *****/
#define log_fmt_toggle(fmt) _log_fmt_toggle(LOG_FMT_##fmt)
#define log_fmt_set(fmt) _log_fmt_set(LOG_FMT_##fmt)
#define log_fmt_clr(fmt) _log_fmt_clr(LOG_FMT_##fmt)
#define log_fmt_is_set(fmt) _log_fmt_is_set(LOG_FMT_##fmt)


/*************************************************
 * Level
 *************************************************/
/***** internal function for MACRO used *****/
int _log_type_level_is(enum log_type type, int *level);
int _log_type_level_set(enum log_type type, int level);

/***** public function to set debug level. the level is leveraged from syslog *****/
#define log_type_level_is(type, level) _log_type_level_is(LOG_TYPE_##type, level)
#define log_type_level_set(type, level) _log_type_level_set(LOG_TYPE_##type, LOG_##level)

void log_pr(enum log_type type, int level, char const * const fmt, ...);

#define _log_pr(type, level, fmt, ...)                 \
do {                                                    \
        unsigned char func[36] = {}, tid[16] = {}, tp[16] = {}, lv[16] = {};\
        if (log_fmt_is_set(FUNC_AND_LINE)) {    \
                snprintf(func, sizeof(func) - 1, "%s(#%d), ", __FUNCTION__, __LINE__);   \
        }                                               \
                                                        \
        if (log_fmt_is_set(TID)) {              \
                snprintf(tid, sizeof(tid) - 1, "TID:%ld, ", syscall(__NR_gettid));       \
        }                                               \
                                                        \
        if (log_fmt_is_set(LOG_TYPE)) {         \
                snprintf(tp, sizeof(tp) - 1, "%s, ", #type);     \
        }                                               \
        if (log_fmt_is_set(LOG_TYPE)) {         \
                snprintf(tp, sizeof(lv) - 1, "%s, ", #level);     \
        }                                               \
        log_pr(LOG_TYPE_##type, LOG_##level, "%s%s%s%s"fmt, func, tid, tp, lv, ##__VA_ARGS__);     \
} while(0)

/***** public function *****/
/* 請呼叫下面MACRO來印log */
#define pr_emerg(type, fmt, ...)  _log_pr(type, EMERG, fmt, ##__VA_ARGS__)
#define pr_alert(type, fmt, ...)  _log_pr(type, ALERT, fmt, ##__VA_ARGS__)
#define pr_crit(type, fmt, ...)   _log_pr(type, CRIT, fmt, ##__VA_ARGS__)
#define pr_err(type, fmt, ...)    _log_pr(type, ERR, fmt, ##__VA_ARGS__)
#define pr_warn(type, fmt, ...)   _log_pr(type, WARNING, fmt, ##__VA_ARGS__)
#define pr_notice(type, fmt, ...) _log_pr(type, NOTICE, fmt, ##__VA_ARGS__)
#define pr_info(type, fmt, ...)   _log_pr(type, INFO, fmt, ##__VA_ARGS__)
#define pr_dbg(type, fmt, ...)    _log_pr(type, DEBUG, fmt, ##__VA_ARGS__)

#endif

brook-log.c

#include <stdio.h>
#include <stdarg.h>
#include <syslog.h>
#include "brook-log.h"

#define DEFAULT_LOG_TYPE ((1 << LOG_TYPE_AT) | \
   (1 << LOG_TYPE_CORE) | \
   (1 << LOG_TYPE_DB))

#define DEFAULT_LOG_FMT ((1 << LOG_FMT_FUNC_AND_LINE) | \
   (1 << LOG_FMT_TID) | \
   (1 << LOG_FMT_LOG_TYPE))

static unsigned int _log_types = DEFAULT_LOG_TYPE;
static unsigned int _log_fmts = DEFAULT_LOG_FMT;

#define DEFAULT_LOG_OPTION (LOG_CONS | LOG_NDELAY)
#define DEFAULT_LOG_FACILITY LOG_LOCAL0
#define DEFAULT_LOG_LEVEL LOG_INFO

char const * const level_str[] = {
 [LOG_EMERG] = "EMERG",
 [LOG_ALERT] = "ALERT",
 [LOG_CRIT] = "CRIT",
 [LOG_ERR] = "ERR",
 [LOG_WARNING] = "WARN",
 [LOG_NOTICE] = "NOTICE",
 [LOG_INFO] = "INFO",
 [LOG_DEBUG] = "DEBUG",
};

char const * const level_fmt_str[] = {
 [LOG_FMT_FUNC_AND_LINE] = "FUNC_AND_LINE",
 [LOG_FMT_TID] = "TID",
 [LOG_FMT_LOG_TYPE] = "LOG_TYPE",
};

#define AR_SZ(a) (sizeof(a)/sizeof(a[0]))

#define BIT_SET(_v, _b) \
do {   \
 (_v) |= (1 << (_b));\
} while(0)

#define BIT_CLR(_v, _b) \
do {   \
 (_v) &= ~(1 << (_b));\
} while(0)

#define BIT_TOGGLE(_v, _b)  \
do {    \
 (_v) ^= (1 <<(_b)); \
} while(0)

int _log_fmt_is_set(enum log_fmt fmt)
{
 if (_log_fmts & (1 << fmt)) {
  return 1;
 }
 return 0;
}

void _log_fmt_set(enum log_fmt fmt)
{
 BIT_SET(_log_fmts, fmt);
}

void _log_fmt_clr(enum log_fmt fmt)
{
 BIT_CLR(_log_fmts, fmt);
}

void _log_fmt_toggle(enum log_fmt fmt)
{
 BIT_TOGGLE(_log_fmts, fmt);
}

struct log_type_str_and_level {
 char const * const name;
 int level;
} log_type_str_and_level [] = {
/* TYPE有增減，請更新這個ARRAY */
 [LOG_TYPE_AT] = { "AT", DEFAULT_LOG_LEVEL},
 [LOG_TYPE_CORE] = { "CORE", DEFAULT_LOG_LEVEL},
 [LOG_TYPE_DB] = { "DB", DEFAULT_LOG_LEVEL},
 [LOG_TYPE_MAX] = { "MAX", DEFAULT_LOG_LEVEL},
};

int _log_type_level_is(enum log_type type, int *level)
{
 if (type >= 0 && type < AR_SZ(log_type_str_and_level)) {
  *level = log_type_str_and_level[type].level;
  return 0;
 }
 return -1;
}

int _log_type_level_set(enum log_type type, int level)
{
 if (type >= 0 && type < AR_SZ(log_type_str_and_level) && level >= 0 && level <= LOG_DEBUG) {
  log_type_str_and_level[type].level = level;
  return 0;
 }
 return -1;
}

int log_type_is_set(enum log_type type)
{
 if (_log_types & (1 << type)) {
  return 1;
 }
 return 0;
}

void _log_type_set(enum log_type type)
{
 BIT_SET(_log_types, type);
}

void _log_type_clr(enum log_type type)
{
 BIT_CLR(_log_types, type);
}

void _log_type_toggle(enum log_type type)
{
 BIT_TOGGLE(_log_types, type);
}

void log_pr(enum log_type type, int level, char const * const fmt, ...)
{
 va_list ap;
 if ((_log_types & (1 << type)) && (log_type_str_and_level[type].level >= level)) {
  va_start(ap, fmt);
  vsyslog(LOG_MAKEPRI(LOG_LOCAL0, level), fmt, ap);
  va_end(ap);
 }
}

char *get_log_type_status_str(void)
{
 int i = 0, re_sz;
 static char buf[1024], *p;

 p = buf;
 re_sz = sizeof(buf);
 p += snprintf(p, re_sz, "%2s %-16s %-10s %-12s\r\n", "id", "type", "status", "level");

 for (i = 0; i < AR_SZ(log_type_str_and_level); i++) {
  re_sz = sizeof(buf) - (p - buf);
  if (re_sz < 1) {
   break;
  }
  p += snprintf(p, re_sz, "%2d %-16s %-10s %-12s\r\n", i, log_type_str_and_level[i].name,
   log_type_is_set((enum log_type)i) ? "enabled" : "disabled",
   level_str[log_type_str_and_level[i].level]);
 }
 return buf;
}

char *get_log_fmt_status_str(void)
{
 int i = 0, re_sz;
 static char buf[256], *p;

 p = buf;
 re_sz = sizeof(buf);
 p += snprintf(p, re_sz, "%2s %-16s %-12s\r\n", "id", "fmt", "status");

 for (i = 0; i < AR_SZ(level_fmt_str); i++) {
  re_sz = sizeof(buf) - (p - buf);
  if (re_sz < 1) {
   break;
  }
  p += snprintf(p, re_sz, "%2d %-16s %-12s\r\n", i, level_fmt_str[i],
   _log_fmt_is_set((enum log_fmt)i) ? "enabled" : "disabled");
 }
 return buf;
}

void init_brook_log(void)
{
 openlog(NULL, DEFAULT_LOG_OPTION, DEFAULT_LOG_FACILITY);
}

void exit_brook_log(void)
{
 closelog();
}

void init_brook_log() __attribute__ ((constructor (101)));
void exit_brook_log() __attribute__ ((destructor (101)));

main.c

#include <stdio.h>
#include "brook-log.h"

int main(int argc, char *argv[])
{
 pr_info(AT, "AT=%d", 0);

 log_type_clr(AT);
 pr_info(AT, "AT=%d", 1);

 log_type_set(AT);
 pr_info(AT, "AT=%d", 2);


 log_fmt_toggle(FUNC_AND_LINE);
 pr_info(AT, "AT=%d", 3);

 log_fmt_clr(TID);
 pr_info(AT, "AT=%d", 4);

 log_type_level_set(AT, ERR);
 pr_info(AT, "AT=%d", 5);

 return 0;
}

結果

brook@vista:~/sample/syslog$ gcc main.c brook-log.c -o brook-log
brook@vista:~/sample/syslog$ brook-log
brook@vista:~/sample/syslog$ tail /var/log/local.log
Nov 26 09:51:26 vista brook-log: main(#6), TID:21765, INFO, AT=0
Nov 26 09:51:26 vista brook-log: main(#12), TID:21765, INFO, AT=2
Nov 26 09:51:26 vista brook-log: TID:21765, INFO, AT=3
Nov 26 09:51:26 vista brook-log: INFO, AT=4

MQTT sample code using libmosquitto

Sample code for publisher

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <mosquitto.h>

// Server connection parameters
#define MQTT_HOSTNAME "localhost"
#define MQTT_PORT 1883
#define MQTT_TOPIC "/brook"

struct brook_obj {
 unsigned long long published;
 unsigned long long connected;
 unsigned long long disconnected;
 unsigned long long loged;
};

/*
 mosq the mosquitto instance making the callback.
 obj the user data provided in mosquitto_new
 rc the return code of the connection response, one of:
*/
static void connect_cb(struct mosquitto *mosq, void *obj, int rc)
{
 struct brook_obj *bobj = (struct brook_obj*) obj;
 bobj->connected++;
        printf("%s(), connect:%llu, published:%llu, loged:%llu, rc:%d\n",
  __FUNCTION__, bobj->connected, bobj->published, bobj->loged, rc);
}

static void publish_cb(struct mosquitto *mosq, void *obj, int mid)
{
 struct brook_obj *bobj = (struct brook_obj*) obj;
 bobj->published++;
        printf("%s(), connect:%llu, published:%llu, loged:%llu, mid:%d\n",
  __FUNCTION__, bobj->connected, bobj->published, bobj->loged, mid);
}

static void log_cb(struct mosquitto *mosq, void *obj, int level, const char *str)
{
 struct brook_obj *bobj = (struct brook_obj*) obj;
 bobj->loged++;
        printf("%s(), connect:%llu, published:%llu, loged:%llu, level:%d,\n\tstr:%s\n",
  __FUNCTION__, bobj->connected, bobj->published, bobj->loged, level, str);
}

static void disconnect_cb(struct mosquitto *mosq, void *obj, int rc)
{
 struct brook_obj *bobj = (struct brook_obj*) obj;
 bobj->disconnected++;
        printf("%s(), connect:%llu, published:%llu, loged:%llu, disconnected:%llu\n",
  __FUNCTION__, bobj->connected, bobj->published, bobj->loged, bobj->disconnected);
}

/*
 * Start here
 */
int main (int argc, char **argv)
{
 char clientid[24], text[20];
 struct mosquitto *mosq = NULL;
 unsigned long long i;
 int rc, major, minor, rev;
 struct brook_obj brook_obj = {};

 /* Must be called before any other mosquitto functions.
    This function is not thread safe. */
  mosquitto_lib_init();

  rc = mosquitto_lib_version(&major, &minor, &rev);
  fprintf(stdout, "rc:%d, major:%d, minor:%d, rev:%d\n",
  rc, major, minor, rev);

  memset(clientid, 0, sizeof(clientid));
  snprintf(clientid, sizeof(clientid) - 1, "cid-pub-%d", getpid());
  mosq = mosquitto_new(clientid, true, &brook_obj);
 if (!mosq) {
  fprintf (stderr, "new mosq failed \n");
  exit(-1);
 }

  rc = mosquitto_tls_opts_set(mosq, 1, "tlsv1", NULL);
 if (rc) {
  fprintf (stderr, "set tls failed %d\n", rc);
  exit (-1);
 }

  rc = mosquitto_tls_set(mosq, "ca/client/ca.crt", NULL, "ca/client/client.crt", "ca/client/client.key", NULL);
  if (rc) {
  fprintf (stderr, "set tls failed %d\n", rc);
  exit (-1);
  }

   rc = mosquitto_tls_insecure_set(mosq, true);
  if (rc) {
  fprintf (stderr, "set insecure failed %d\n", rc);
  exit (-1);
  }

 // Set callback function
  mosquitto_connect_callback_set(mosq, connect_cb);
  mosquitto_publish_callback_set(mosq, publish_cb);
  mosquitto_log_callback_set(mosq, log_cb);
  mosquitto_disconnect_callback_set(mosq, disconnect_cb);

  rc = mosquitto_connect(mosq, MQTT_HOSTNAME, MQTT_PORT, 60);
  if (rc) {
   fprintf (stderr, "Can't connect to Mosquitto server. %d\n", rc);
   exit (-1);
  }

  for (i = 0; i < 10 ;i++) {
   sprintf(text, "%llu", i);
   printf("send %d, %s\n", (int)strlen(text), text);
   // Publish the message to the topic
  rc = mosquitto_publish(mosq, NULL, MQTT_TOPIC, strlen(text), text, 2, false);
  if (rc) {
   fprintf (stderr, "Can't publish to Mosquitto server\n");
   exit (-1);
  }
  if (!(i % 3)) {
   do {
    rc = mosquitto_loop(mosq, 3, 1);
    fprintf (stdout, "mosquitto_loop %d, published:%llu, i:%llu\n",
      rc, brook_obj.published, i);
   } while(rc == 0 && brook_obj.published < i);
  }
 }

 do {
  rc = mosquitto_loop(mosq, 3, 1);
  fprintf (stdout, "mosquitto_loop %d, published:%llu, i:%llu\n",
    rc, brook_obj.published, i);
 } while(rc == 0 && brook_obj.published != i);

 // Tidy up
 mosquitto_disconnect(mosq);
 mosquitto_destroy(mosq);
 mosquitto_lib_cleanup();

 return 0;
}

Sample code subscriber

#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>

#include <sys/types.h>
#include <unistd.h>

#include <mosquitto.h>

#define MQTT_HOSTNAME "localhost" 
#define MQTT_PORT 1883 
#define MQTT_TOPIC "/brook/#"

struct brook_obj {
 unsigned long long msgs;
 unsigned long long connected;
 unsigned long long disconnected;
 unsigned long long loged;
 unsigned long long subscribed;
 unsigned long long unsubscribed;
};

/*
 mosq the mosquitto instance making the callback.
 obj the user data provided in mosquitto_new
 rc the return code of the connection response, one of:
*/
static void connect_cb(struct mosquitto *mosq, void *obj, int rc)
{
 struct brook_obj *bobj = (struct brook_obj*) obj;
 bobj->connected++;
 printf("%s(), connect:%llu, msgs:%llu, loged:%llu, rc:%d\n",
  __FUNCTION__, bobj->connected, bobj->msgs, bobj->loged, rc);
}

static void log_cb(struct mosquitto *mosq, void *obj, int level, const char *str)
{
 struct brook_obj *bobj = (struct brook_obj*) obj;
 bobj->loged++;
 printf("%s(), connect:%llu, msgs:%llu, loged:%llu, level:%d,\n\tstr:%s\n",
  __FUNCTION__, bobj->connected, bobj->msgs, bobj->loged, level, str);
}

static void disconnect_cb(struct mosquitto *mosq, void *obj, int rc)
{
 struct brook_obj *bobj = (struct brook_obj*) obj;
 bobj->disconnected++;
 printf("%s(), connect:%llu, msgs:%llu, loged:%llu, disconnected:%llu\n",
  __FUNCTION__, bobj->connected, bobj->msgs, bobj->loged, bobj->disconnected);
}

static void message_cb(struct mosquitto *mosq, void *obj, const struct mosquitto_message *message)
{
 struct brook_obj *bobj = (struct brook_obj*) obj;
 bobj->msgs++;
 bool match = 0;
 static unsigned long long i = 0, j = 0;

 printf("%s(), connect:%llu, msgs:%llu, loged:%llu, disconnected:%llu\n",
  __FUNCTION__, bobj->connected, bobj->msgs, bobj->loged, bobj->disconnected);
 printf("%s(), got message mid:%d, '%.*s' for topic '%s'\n",
  __FUNCTION__, message->mid, message->payloadlen, (char*) message->payload, message->topic);

 mosquitto_topic_matches_sub(MQTT_TOPIC, message->topic, &match);
 if (match) {
  printf("got matched topic to %s\n", MQTT_TOPIC);
 }
}

static void unsubscribe_cb(struct mosquitto *mosq, void *obj, int mid)
{
 struct brook_obj *bobj = (struct brook_obj*) obj;
 bobj->unsubscribed++;
 printf("%s(), connect:%llu, msgs:%llu, loged:%llu, disconnected:%llu, unsubscribed:%llu\n",
  __FUNCTION__, bobj->connected, bobj->msgs, bobj->loged, bobj->disconnected,
  bobj->unsubscribed);
}

static void subscribe_cb(struct mosquitto *mosq, void *obj, int mid, int qos_count, const int *granted_qos)
{
 int i;
 struct brook_obj *bobj = (struct brook_obj*) obj;
 bobj->subscribed++;
 printf("%s(), mid:%d, qos_count:%d\n",
  __FUNCTION__, mid, qos_count);
 for (i = 0; i < qos_count; i++) {
  printf("\tQ[%d]:%d\n", i, granted_qos[i]);
 }
 printf("%s(), connect:%llu, msgs:%llu, loged:%llu, disconnected:%llu, subscribed:%llu\n",
  __FUNCTION__, bobj->connected, bobj->msgs, bobj->loged, bobj->disconnected,
  bobj->subscribed);
}

int main(int argc, char *argv[])
{
 char clientid[24];
 struct mosquitto *mosq;
 int rc = 0;
 struct brook_obj brook_obj = {};

 mosquitto_lib_init();

 memset(clientid, 0, sizeof(clientid));
 snprintf(clientid, sizeof(clientid) - 1, "cid-sub-%d", getpid());
 mosq = mosquitto_new(clientid, true, &brook_obj);
 if (!mosq) {
  fprintf (stderr, "new mosq failed\n");
  exit(-1);
 }

 rc = mosquitto_tls_opts_set(mosq, 1, "tlsv1", NULL);
 if (rc) {
  fprintf (stderr, "set tls opt failed %d\n", rc);
  exit(-1);
 }

 rc = mosquitto_tls_insecure_set(mosq, true);
 if (rc) {
  fprintf (stderr, "set insecure failed %d\n", rc);
  exit(-1);
 }

 rc = mosquitto_tls_set(mosq, "ca/client/ca.crt", NULL, "ca/client/client.crt", "ca/client/client.key", NULL);
 if (rc) {
  fprintf (stderr, "set tls failed %d\n", rc);
  exit(-1);
 }

 mosquitto_connect_callback_set(mosq, connect_cb);
 mosquitto_log_callback_set(mosq, log_cb);
 mosquitto_subscribe_callback_set(mosq, subscribe_cb);
 mosquitto_unsubscribe_callback_set(mosq, unsubscribe_cb);
 mosquitto_message_callback_set(mosq, message_cb);
 mosquitto_disconnect_callback_set(mosq, disconnect_cb);

 rc = mosquitto_connect(mosq, MQTT_HOSTNAME, MQTT_PORT, 60);
 if (rc) {
  fprintf(stderr, "mosquitto_connect failed. %d\n", rc);
  exit(-1);
 }

 mosquitto_subscribe(mosq, NULL, MQTT_TOPIC, 1);

 do {
  rc = mosquitto_loop(mosq, 3000, 1);
  fprintf(stdout, "mosquitto_loop %d, msgs%llu\n",
   rc, brook_obj.msgs);
 } while(rc == 0 && brook_obj.msgs < 5);

 mosquitto_disconnect(mosq);
 mosquitto_destroy(mosq);
 mosquitto_lib_cleanup();

 return rc;
}

2017年11月5日星期日

MQTT

MQ Telemetry Transport (MQTT)網路文章已經很多，也很完善，大家可以參考本文章後面的reference，這裡快速帶過幾個重點：
MQTT是一個輕量級的基於broker的Publish/Subscribe messaging protocol，旨在實現開放，簡單，輕量級和易於實現。
協議的特點包括：

提供一對多的訊息發布
三種QoS
"At most once" - message丟失或重複可能發生。
"At least once" - 確保message到達，但可能會發生重複。
"Exactly once" - 確保message只送達一次。

MQTT Architecture(Publish/Subscribe with broker)

MQTT有三種主要的組成元件，分別為Publisher、Subscriber以及Broker。 Publisher為訊息的來源，它會將訊息(Topic)發送給Broker，而Subscriber向Broker註冊，表示他們想要接收某Topic訊息；因此當有某個Publisher對Broker發送Topic訊息時，只要是有對此Topic註冊的Subscriber，都會收到此則訊息。

Topic wildcards

Topic為UTF-8編碼字串，最長長度為32,767字元，Topic支援階層式命名方式，如："住家/客廳/溫度"，階層的分隔符號為"/"，所以前面這個Topic有三層架構，Topic可以透過萬用字元一次訂閱多個主題。但是這些萬用字元只能放在最後一層
"#"為Multi-level wildcard，可以包含零個以上的階層，如有人送出"a/b/c/d"，那以下訂閱都可以被match "a/b/c/d"，"#"，"a/#"，"a/b/#"，"a/b/c/#"，"+/b/c/#"，
"+"為Single-level wildcard，只能包含該層的Topic，如有人送出"a/b/c/d"，那以下訂閱都可以被match “a/b/c/d"，"+/b/c/d"，"a/+/c/d"，"a/+/+/d"，"+/+/+/+"，而以下這些事不能match的"a/b/c"，"b/+/c/d"，"+/+/+"

Deom the MQTT - mosquitto

請用apt-get install mosquitto mosquitto-clients安裝mosquitto套件
run the broker

brook@vista:~$ mosquitto -v
1511094611: mosquitto version 1.4.8 (build date Mon, 26 Jun 2017 09:31:02 +0100) starting
1511094611: Using default config.
1511094611: Opening ipv4 listen socket on port 1883.
1511094611: Opening ipv6 listen socket on port 1883.
1511094635: New connection from 127.0.0.1 on port 1883.
1511094635: New client connected from 127.0.0.1 as mosqsub/16408-jpr-Verit (c1, k60). 有人連上就會顯示
1511094635: Sending CONNACK to mosqsub/16408-jpr-Verit (0, 0)
1511094635: Received SUBSCRIBE from mosqsub/16408-jpr-Verit
1511094635:     /brook/L1 (QoS 0)
1511094635: mosqsub/16408-jpr-Verit 0 /brook/L1
1511094635: Sending SUBACK to mosqsub/16408-jpr-Verit
1511094659: New connection from 127.0.0.1 on port 1883.
1511094659: New client connected from 127.0.0.1 as mosqpub/16687-jpr-Verit (c1, k60).
1511094659: Sending CONNACK to mosqpub/16687-jpr-Verit (0, 0)
1511094659: Received PUBLISH from mosqpub/16687-jpr-Verit (d0, q0, r0, m0, '/brook/L1', ... (11 bytes))
1511094659: Sending PUBLISH to mosqsub/16408-jpr-Verit (d0, q0, r0, m0, '/brook/L1', ... (11 bytes))
1511094659: Received DISCONNECT from mosqpub/16687-jpr-Verit
1511094659: Client mosqpub/16687-jpr-Verit disconnected.

向Broker註冊topic "/brook/L1"

brook@vista:~$ mosquitto_sub -h localhost -t '/brook/L1'
test for L1有人向Broker推送/brook/L1訊息就會顯示

向Broker推送topic "/brook/L1"的訊息

brook@vista:~$ mosquitto_pub -h localhost -t '/brook/L1' -m 'test for L1'

mosquitto - Broker log notes

brook@vista:~$ mosquitto -v
1511094635: New client connected from 127.0.0.1 as mosqsub/16408-jpr-Verit (c1, k60). 

mosquitto-1.4.8/src/read_handle_server.c
521 if(context->username){
522   _mosquitto_log_printf(NULL, MOSQ_LOG_NOTICE, 
                           "New client connected from %s as %s (c%d, k%d, u'%s').",
                            context->address, client_id, clean_session, 
                            context->keepalive, context->username);
523 }else{
524   _mosquitto_log_printf(NULL, MOSQ_LOG_NOTICE,
                           "New client connected from %s as %s (c%d, k%d).", 
                           context->address, client_id, clean_session,
                           context->keepalive);
525 }

1511094635: Sending CONNACK to mosqsub/16408-jpr-Verit (0, 0)
1511094635: Received SUBSCRIBE from mosqsub/16408-jpr-Verit
1511094635:     /brook/L1 (QoS 0)

man mqtt
QUALITY OF SERVICE
  MQTT defines three levels of Quality of Service (QoS). The QoS defines how hard the 
  broker/client will try to ensure that a message is received. Messages may be sent 
  at any QoS level, and clients may attempt to subscribe to topics at any QoS level.
  This means that the client chooses the maximum QoS it will receive. For example, 
  if a message is published at QoS 2 and a client is subscribed with QoS 0, the 
  message will be delivered to that client with QoS 0. If a second client is also 
  subscribed to the same topic, but with QoS 2, then it will receive the same message 
  but with QoS 2. For a second example, if a client is subscribed with QoS 2 and a 
  message is published on QoS 0, the client will receive it on QoS 0.

  Higher levels of QoS are more reliable, but involve higher latency and have higher bandwidth requirements.
    o 0: The broker/client will deliver the message once, with no confirmation.
    o 1: The broker/client will deliver the message at least once, with confirmation required.
    o 2: The broker/client will deliver the message exactly once by using a four step handshake.

1511094635: mosqsub/16408-jpr-Verit 0 /brook/L1
1511094635: Sending SUBACK to mosqsub/16408-jpr-Verit
1511094659: New connection from 127.0.0.1 on port 1883.
1511094659: New client connected from 127.0.0.1 as mosqpub/16687-jpr-Verit (c1, k60).
1511094659: Sending CONNACK to mosqpub/16687-jpr-Verit (0, 0)
1511094659: Received PUBLISH from mosqpub/16687-jpr-Verit (d0, q0, r0, m0, '/brook/L1', ... (11 bytes))

mosquitto-1.4.8/src/read_handle.c
217 _mosquitto_log_printf(NULL, MOSQ_LOG_DEBUG, 
                          "Received PUBLISH from %s (d%d, q%d, r%d, m%d, '%s', ... (%ld bytes))",
                          context->id, dup, qos, retain, mid, topic, (long)payloadlen);

1511094659: Sending PUBLISH to mosqsub/16408-jpr-Verit (d0, q0, r0, m0, '/brook/L1', ... (11 bytes))

mosquitto-1.4.8/lib/send_mosq.c
156 _mosquitto_log_printf(NULL, MOSQ_LOG_DEBUG, 
                          "Sending PUBLISH to %s (d%d, q%d, r%d, m%d, '%s', ... (%ld bytes))",
                          mosq->id, dup, qos, retain, mid, mapped_topic, (long)payloadlen);

1511094659: Received DISCONNECT from mosqpub/16687-jpr-Verit
1511094659: Client mosqpub/16687-jpr-Verit disconnected.

2017年7月29日星期六

A pattern for state machine

State machine是很常見的應用/Pattern，這章節會根據下面的圖來實作State machine pattern

enum state {
 STATE_INITIAL = 0,
 STATE_1,
 STATE_2,
 STATE_3,
 STATE_4,
};

enum event {
 E1 = 1,
 E2,
 E3,
 E4,
};

先定義State Machine狀態與Event

struct instance_data {
 enum event evt;
 int data;
};

struct instance {
 enum state cur_state;
 struct instance_data data;
};

定義一個struct來儲存"現在狀態"，Event與data

typedef enum state state_func_t(struct instance_data *data);

state_func_t* const state_table[] = {
 [STATE_INITIAL] = in_init,
 [STATE_1] = in_state_1,
 [STATE_2] = in_state_2,
 [STATE_3] = in_state_3,
 [STATE_4] = in_state_4,
};

void run_state(struct instance *inst)
{
 inst->cur_state = state_table[inst->cur_state](&(inst->data));
};

建立一個Table，將每一個state對應的function填入，run_state()會根據目前的State處理該event/data，並回傳下一個狀態

enum state in_state_1(struct instance_data *data)
{
 printf("%s(#%d): got EVT:%d\n", __FUNCTION__, __LINE__, data->evt);
 switch (data->evt) {
 case E1:
  printf("change to S2\n");
  return do_s2();
 case E2:
  printf("change to S3\n");
  return do_s3();
 default:
  printf("keep the same STATE && do nothing\n");
  return STATE_1;
 }
}

enum state in_state_2(struct instance_data *data)
{
 printf("%s(#%d): got EVT:%d\n", __FUNCTION__, __LINE__, data->evt);
 switch (data->evt) {
 case E3:
  printf("change to S3\n");
  return do_s3();
 default:
  printf("keep the same STATE && do s2 again\n");
  return do_s2(); // do s2 again
 }
}

enum state in_state_3(struct instance_data *data)
{
 printf("%s(#%d): got EVT:%d\n", __FUNCTION__, __LINE__, data->evt);
 switch (data->evt) {
 case E2:
  printf("change to S4\n");
  return do_s4();
 default:
  printf("keep the same STATE && do nothing\n");
  return STATE_3;
 }
}

enum state in_state_4(struct instance_data *data)
{
 printf("%s(#%d): got EVT:%d\n", __FUNCTION__, __LINE__, data->evt);
 switch (data->evt) {
 case E1:
  printf("change to S2\n");
  return do_s2();
 case E3:
  printf("change to S1\n");
  return do_s1();
 default:
  printf("keep the same STATE && do again\n");
  return do_s4();
 }
}

定義每一個狀態中的行為

enum state do_s1(void)
{
 printf("%s(#%d)\n", __FUNCTION__, __LINE__);
 return STATE_1;
}

enum state do_s2(void)
{
 printf("%s(#%d)\n", __FUNCTION__, __LINE__);
 return STATE_2;
}

enum state do_s3(void)
{
 printf("%s(#%d)\n", __FUNCTION__, __LINE__);
 return STATE_3;
}

enum state do_s4(void)
{
 printf("%s(#%d)\n", __FUNCTION__, __LINE__);
 return STATE_4;
}

enum state in_init(struct instance_data *data)
{
 printf("%s(#%d): do some init. E:%d\n", __FUNCTION__, __LINE__, data->evt);
 printf("change to S1\n");
 return STATE_1;
}

定義進入每一個狀態要執行的動作

int main( void ) {
 int ch;
 struct instance inst = {STATE_INITIAL, 0};
 while ( 1 ) {
  run_state(&inst);
  // do other program logic, run other state machines, etc
  printf("MENU: E1/E2/E3/E4\n");
  while(((ch = getc(stdin)) == '\n') || (ch <= '0') || (ch > '4'));
  inst.data.evt = ch - '0';
 }
}

main function模擬State Machine收到不同event(1~4)

以下是收到event 1, 2, 3, 4的執行結果

2017年7月8日星期六

How to send a html email with the bash command "mail"/“sendmail”?

有時我們會需要透過Linux發送一些report mail，這時候我們就可以用mail這個指令

brook@vista:~/kernel$ ls | txt2html| mail --debug-level=7 -s 'show kernel floder' rene3210@gmail.com
mail: sendmail (/usr/sbin/sendmailn
mail: Getting auth info for UID 1003
mail: source=system, name=brook, passwd=x, uid=1003, gid=1000, gecos=,,,, dir=/home/brook, shell=/bin/bash, mailbox=/var/mail/brook, quota=0, change_uid=1
mail: Getting auth info for UID 1003
mail: source=system, name=brook, passwd=x, uid=1003, gid=1000, gecos=,,,, dir=/home/brook, shell=/bin/bash, mailbox=/var/mail/brook, quota=0, change_uid=1
mail: mu_mailer_send_message(): using From: brook@vista
mail: Sending headers...
mail: Sending body...
mail: /usr/sbin/sendmail exited with: 0
mail:

上面這個指令會送出raw data，mail看到的也是顯示一些HTML內容，如

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<meta name="generator" content="HTML::TextToHTML v2.51"/>
</head>
<body>
<p>AndroidKernel.mk<br/>
<strong>COPYING</strong><br/>
<strong>CREDITS</strong><br/>
Documentation<br/>
Kbuild<br/>
Kconfig<br/>
<strong>MAINTAINERS</strong><br/>
Makefile<br/>
<strong>README</strong><br/>
<strong>REPORTING-BUGS</strong><br/>
android<br/>
arch<br/>
block<br/>
crypto<br/>
drivers<br/>
firmware<br/>
fs<br/>
include<br/>
init<br/>
ipc<br/>
kernel<br/>
lib<br/>
linaro<br/>
mm<br/>
net<br/>
samples<br/>
scripts<br/>
security<br/>
sound<br/>
tools<br/>
usr<br/>
virt</p>

</body>
</html>

如果我們要支援"Multipurpose Internet Mail Extensions (MIME)"只要在subject後面接上"\nContent-Type: text/html"即可

brook@vista:~/kernel$ ls | txt2html| mail --debug-level=7 -s "$(echo -e "show kernel floder\nContent-Type: text/html")" rene3210@gmail.com

也可以用"sendmail"指令來傳送mail

(
echo "From: ${from}";
echo "To: ${to}";
echo "Subject: ${subject}";
echo "Content-Type: text/html";
echo "MIME-Version: 1.0";
echo "";
echo "${message}";
) | sendmail -t

如

(message=`ls| txt2html`
echo "From: rene3210@gmail.com;"
echo "To: rene3210@gmail.com,rene3210@gov.tw;"
echo "Subject: Quota"
echo "Content-Type: text/html;"
echo "MIME-Version: 1.0;"
echo "${message}";
echo -e"\n\n"
) |sendmail -t

參考資料： How to send a html email with the bash command “sendmail”?

2017年4月30日星期日

pkg-config

簡介

現在的電腦系統使用許多library package供使用者使用，但是在不同的platform使用這些library package是一件很困難的事，pkg-config收集相關的資訊並且統一的API供開發人員使用。 pkg-config利用".pc"檔的格式，記錄了一些library相關的資訊，提供對應的information給開發人員使用，以ubuntu為例，這些檔案被放置在/usr/lib/x86_64-linux-gnu/pkgconfig、/usr/lib/i386-linux-gnu/pkgconfig與/usr/lib/pkgconfig等目錄，以下為directfb的.pc

brook@vista:~$ cat /usr/lib/x86_64-linux-gnu/pkgconfig/directfb.pc
prefix=/usr
exec_prefix=${prefix}
libdir=${prefix}/lib/x86_64-linux-gnu
includedir=${prefix}/include

Name: DirectFB
Description: Graphics and windowing library for the Linux frame buffer device
Version: 1.2.10
Requires: fusion direct
Libs: -L${libdir} -ldirectfb -lpthread
Libs.private: -L${libdir} -ldl
Cflags: -D_REENTRANT -I${prefix}/include/directfb
brook@vista:~$ pkg-config --list-all
file_name_of_library_or_package          Name_in_pc - Description_in_pc
...
direct                         Direct - DirectFB base development library
...

PC檔內容

.pc包含了事先定義好的variable(key=value)與description(Name: description)，description有以下資訊

Name: library的name。
Description: library的簡述。
URL: library的相關URL。
Version: library的版號資訊。
Requires: library所需要的library，可能會包含所需的版號資訊(=, <, >, <= or >=)。
Requires.private: 與 Requires相似，用於static link。
Conflicts: library可能與某個library衝突的資訊，可能會包含衝突的版號資訊(=, <, >, <= or >=)。
Cflags: 使用該library所需的compiler flags。
Libs: 使用該library所需的link flags。
Libs.private: 與Libs相似，用於static link。

pkg-config操作

基本語法為pkg-config [input parameters] [LIBRARIES...]相關input參數可以參考man page

brook@vista:~$ pkg-config --modversion --print-errors directfb
1.2.10
brook@vista:~$ pkg-config --cflags --print-errors directfb
-D_REENTRANT -I/usr/include/directfb
brook@vista:~$ pkg-config --libs --print-errors directfb
-ldirectfb -lpthread -lfusion -ldirect -lpthread
brook@vista:~$ pkg-config --libs --static --print-errors directfb
-ldirectfb -lpthread -ldl -lfusion -ldirect -lpthread -ldl
brook@vista:~$ pkg-config --print-requires --print-errors directfb
fusion
direct
brook@vista:~$ pkg-config --print-requires --print-errors "directfb > 1.3"
Requested 'directfb > 1.3' but version of DirectFB is 1.2.10
brook@vista:~$ pkg-config --exists --print-errors directfb
brook@vista:~$ echo $?
0
brook@vista:~$ pkg-config --exists --print-errors directfbxx
Package directfbxx was not found in the pkg-config search path.
Perhaps you should add the directory containing `directfbxx.pc'
to the PKG_CONFIG_PATH environment variable
No package 'directfbxx' found
brook@vista:~$ echo $?
1

pkg-config實際應用

With GCC

brook@vista:~$ pkg-config --cflags --libs directfb
-D_REENTRANT -I/usr/include/directfb -ldirectfb -lpthread -lfusion -ldirect -lpthread
brook@vista:~$ gcc `pkg-config --cflags --libs directfb` -o myapp myapp.c

With autoconf and automake

configure.ac:
PKG_CHECK_MODULES([DIRECTFB], [directfb])

Makefile.am:
myapp_CFLAGS = $(DIRECTFB_CFLAGS)
myapp_LDADD = $(DIRECTFB_LIBS)

簡介 pkg-config 的功能與用法, http://yczhuang.blogspot.tw/2007/04/pkg-config.html
Guide to pkg-config, https://people.freedesktop.org/~dbn/pkg-config-guide.html#writing
pkg-config 使用及建立方法, http://jyhshin.pixnet.net/blog/post/26588033-pkg-config-%E4%BD%BF%E7%94%A8%E5%8F%8A%E5%BB%BA%E7%AB%8B%E6%96%B9%E6%B3%95

2016年12月4日星期日

gmp-4.1.4 build error "automatic de-ANSI-fication support has been removed"

porting某些package時會出現"automatic de-ANSI-fication support has been removed"，這是因為automake1.12之後，就不再支援該功能了，也就是不再支援ansi2knr這個選項了。而且建議將AM_C_PROTOTYPES改成AC_C_PROTOTYPES的寫法，其範例如下

--- a/Makefile.am
+++ b/Makefile.am
@@ -20,7 +20,7 @@
# MA 02111-1307, USA.
-AUTOMAKE_OPTIONS = gnu no-dependencies $(top_builddir)/ansi2knr
+AUTOMAKE_OPTIONS = gnu no-dependencies

修改configure.in
--- a/configure.in
+++ b/configure.in
@@ -1501,7 +1501,9 @@ echo "      MPN_PATH=\"$path\""
# Automake ansi2knr support.
-AM_C_PROTOTYPES
+AC_C_PROTOTYPES
+AC_HEADER_STDC
+AC_CHECK_HEADERS("string.h")

https://autotools.io/forwardporting/automake.html

2016年10月9日星期日

Install Node.js on Openembedded

基本上Node.js在Openembedded上的recipes都已經寫好了，只要clone下來，並且加入IMAGE_INSTALL列表即可

brook@vista:~/projects/poky$ git clone https://github.com/imyller/meta-nodejs.git
Cloning into 'meta-nodejs'...
remote: Counting objects: 1575, done.
remote: Compressing objects: 100% (14/14), done.
remote: Total 1575 (delta 9), reused 0 (delta 0), pack-reused 1561
Receiving objects: 100% (1575/1575), 241.91 KiB | 368.00 KiB/s, done.
Resolving deltas: 100% (846/846), done.
Checking connectivity... done.
brook@vista:~/projects/poky$ . oe-init-build-env
You had no conf/local.conf file. This configuration file has therefore been
created for you with some default values. You may wish to edit it to, for
example, select a different MACHINE (target hardware). See conf/local.conf
for more information as common configuration options are commented.

You had no conf/bblayers.conf file. This configuration file has therefore been
created for you with some default values. To add additional metadata layers
into your configuration please add entries to conf/bblayers.conf.

The Yocto Project has extensive documentation about OE including a reference
manual which can be found at:
    http://yoctoproject.org/documentation

For more information about OpenEmbedded see their website:
    http://www.openembedded.org/


### Shell environment set up for builds. ###

You can now run 'bitbake <target>'

Common targets are:
    core-image-minimal
    core-image-sato
    meta-toolchain
    meta-ide-support

You can also run generated qemu images with a command like 'runqemu qemux86'

brook@vista:~/projects/poky/build$ vim conf/bblayers.conf
...下段說明
brook@vista:~/projects/poky/build$ vim conf/local.conf
...下段說明
brook@vista:~/projects/poky/build$ bitbake core-image-minimal
WARNING: Host distribution "Ubuntu-16.04" has not been validated with this version of the build system; you may possibly experience unexpected failures. It is recommended that you use a tested distribution.
Parsing recipes: 100% |#############################################################################################| Time: 00:00:28
Parsing of 876 .bb files complete (0 cached, 876 parsed). 1316 targets, 49 skipped, 0 masked, 0 errors.
NOTE: Resolving any missing task queue dependencies

Build Configuration:
BB_VERSION        = "1.30.0"
BUILD_SYS         = "x86_64-linux"
NATIVELSBSTRING   = "Ubuntu-16.04"
TARGET_SYS        = "i586-poky-linux"
MACHINE           = "qemux86"
DISTRO            = "poky"
DISTRO_VERSION    = "2.1.1"
TUNE_FEATURES     = "m32 i586"
TARGET_FPU        = ""
meta
meta-poky
meta-yocto-bsp    = "krogoth:8c69f7d56cbd496aa01ba0738675a170826a536b"
meta-nodejs       = "master:848b0defe8eba6e7ffa97b66e4316c17c92be9d4"
...
brook@vista:~/projects/poky/build$ ./tmp/sysroots/x86_64-linux/usr/bin/qemu-system-i386 -nographic -kernel ./tmp/deploy/images/qemux86/bzImage-qemux86.bin -cpu qemu32 -drive file=./tmp/deploy/images/qemux86/core-image-minimal-qemux86.ext4,if=virtio,format=raw -show-cursor -usb -usbdevice tablet -vga vmware -no-reboot -m 256 -append "vga=0 uvesafb.mode_option=640x480-32 root=/dev/vda rw mem=256M ip=192.168.7.2::192.168.7.1:255.255.255.0 oprofile.timer=1 rootfstype=ext4 "

Poky (Yocto Project Reference Distro) 2.1.1 qemux86 /dev/ttyS0

qemux86 login: root
root@qemux86:~# uname -a
Linux qemux86 4.4.11-yocto-standard #1 SMP PREEMPT Sun Oct 9 19:29:24 CST 2016 i686 GNU/Linux
root@qemux86:~# echo 'console.log("hello world");' > node.js
root@qemux86:~# node node.js
hello world

conf/bblayers.conf修改的內容

BBLAYERS ?= " \
  /home/brook/projects/poky/meta \
  /home/brook/projects/poky/meta-poky \
  /home/brook/projects/poky/meta-yocto-bsp \
  ${TOPDIR}/../meta-nodejs \
  "

conf/local.conf修改的內容

# This sets the default machine to be qemux86 if no other machine is selected:
MACHINE ??= "qemux86"
CORE_IMAGE_EXTRA_INSTALL += "nodejs"

meta-nodejs, Node.js的openembedded recipes。
JavaScript for IoT: Blinking LED on Raspberry Pi with Node.js , Node.js的demo影片。
「Node.js & IoT: Zero to One」是一本 Node.js 的入門電子書，內容定位為基礎教學，目標是介紹 Node.js 以及 Node.js + IoT 相關技術主題，每個主題都從基本觀念（Zero）開始，介紹到能撰寫簡單的程式為止（One）。不過目前只有介紹JS的基本語法。
Addons。教你如何擴充JS，用C/C++寫一個Node.js module。

2016年10月8日星期六

Using openembedded to build QEMU

這篇文章主要來說明如何使用Openembedded/Krogoth來build出QEMU for ARM。
步驟大概就是：
先下載yp-krogoth之後，source目錄下的oe-init-build-env，接著再編輯conf/local.conf，最後就是執行bitbake core-image-minimal。
我的Krogoth最後一個commit ID是e93596f。

brook@vista:~/projects$ git clone -b krogoth git://git.yoctoproject.org/poky.git yp-krogoth
Cloning into 'yp-krogoth'...
remote: Counting objects: 339411, done.
remote: Compressing objects: 100% (82247/82247), done.
remote: Total 339411 (delta 251486), reused 338934 (delta 251035)
Receiving objects: 100% (339411/339411), 127.65 MiB | 4.49 MiB/s, done.
Resolving deltas: 100% (251486/251486), done.
Checking connectivity... done.
brook@vista:~/projects$ cd yp-krogoth/
brook@vista:~/projects/yp-krogoth$ git log --oneline -1
e93596f binutils: fix AR issue when opkg is unpacking IPKs containing empty entries
brook@vista:~/projects/yp-krogoth$ . oe-init-build-env
You had no conf/local.conf file. This configuration file has therefore been
created for you with some default values. You may wish to edit it to, for
example, select a different MACHINE (target hardware). See conf/local.conf
for more information as common configuration options are commented.

You had no conf/bblayers.conf file. This configuration file has therefore been
created for you with some default values. To add additional metadata layers
into your configuration please add entries to conf/bblayers.conf.

The Yocto Project has extensive documentation about OE including a reference
manual which can be found at:
    http://yoctoproject.org/documentation

For more information about OpenEmbedded see their website:
    http://www.openembedded.org/


### Shell environment set up for builds. ###

You can now run 'bitbake <target>'

Common targets are:
    core-image-minimal
    core-image-sato
    meta-toolchain
    meta-ide-support

You can also run generated qemu images with a command like 'runqemu qemux86'
brook@vista:~/projects/yp-krogoth/build$ vim conf/local.conf
...內容請看一段
brook@vista:~/projects/yp-krogoth/build$ bitbake core-image-minimal
WARNING: Host distribution "Ubuntu-16.04" has not been validated with this version of the build system; you may possibly experience unexpected failures. It is recommended that you use a tested distribution.
Parsing recipes...done.
Parsing of 871 .bb files complete (0 cached, 871 parsed). 1301 targets, 66 skipped, 0 masked, 0 errors.
NOTE: Resolving any missing task queue dependencies

Build Configuration:
BB_VERSION        = "1.30.0"
BUILD_SYS         = "x86_64-linux"
NATIVELSBSTRING   = "Ubuntu-16.04"
TARGET_SYS        = "arm-poky-linux-gnueabi"
MACHINE           = "qemuarm"
DISTRO            = "poky"
DISTRO_VERSION    = "2.1.1"
TUNE_FEATURES     = "arm armv5 thumb dsp"
TARGET_FPU        = "soft"
meta
meta-poky
meta-yocto-bsp    = "krogoth:e93596fe74927e2e2f4dd7f671994ccb9744cff8"

NOTE: Fetching uninative binary shim from http://downloads.yoctoproject.org/releases/uninative/1.0.1/x86_64-nativesdk-libc.tar.bz2;sha256sum=acf1e44a0ac2e855e81da6426197d36358bf7b4e88e552ef933128498c8910f8
NOTE: Preparing RunQueue
NOTE: Executing SetScene Tasks
...略
brook@vista:~/projects/yp-krogoth/build$ ./tmp/sysroots/x86_64-linux/usr/bin/qemu-system-arm -kernel ./tmp/deploy/images/qemuarm/zImage-qemuarm.bin -M versatilepb -drive file=/home/jpr/projects/yp-krogoth/build/tmp/deploy/images/qemuarm/core-image-minimal-qemuarm.ext4,if=virtio,format=raw -no-reboot -show-cursor -usb -usbdevice tablet -m 128 -nographic -append 'root=/dev/vda rw console=ttyAMA0,115200 console=tty ip=192.168.7.2::192.168.7.1:255.255.255.0 mem=128M highres=off rootfstype=ext4 ' 
audio: Could not init `oss' audio driver
ALSA lib ../../alsa-lib-1.1.0/src/confmisc.c:768:(parse_card) cannot find card '0'
...略
qemuarm login: root
root@qemuarm:~# uname -a
Linux qemuarm 4.4.11-yocto-standard #1 PREEMPT Sun Oct 9 11:36:44 CST 2016 armv5tejl GNU/Linux

conf/local.conf相關修改

change MACHINE for "qemux86" to "qemuarm"
MACHINE ?= "qemuarm"
#MACHINE ?= "qemuarm64"
#MACHINE ?= "qemumips"
#MACHINE ?= "qemumips64"
#MACHINE ?= "qemuppc"
#MACHINE ?= "qemux86"
#MACHINE ?= "qemux86-64"
#
# There are also the following hardware board target machines included for
# demonstration purposes:
#
#MACHINE ?= "beaglebone"
#MACHINE ?= "genericx86"
#MACHINE ?= "genericx86-64"
#MACHINE ?= "mpc8315e-rdb"
#MACHINE ?= "edgerouter"
#
# This sets the default machine to be qemux86 if no other machine is selected:
#MACHINE ??= "qemux86"
...
commout out these 2 lines
#PACKAGECONFIG_append_pn-qemu-native = " sdl"
#PACKAGECONFIG_append_pn-nativesdk-qemu = " sdl"

Yocto Project Quick Start
Yocto Project Build System/Download

2016年10月1日星期六

QC的partition table大小設定與實際大小對應關係

這裡記錄一下QC的9x40 partition table configure file(common/build/partition_nand.xml)size與實際的大小怎麼換算。大概就兩類tag，一個tag是size_blks，以eraseblock為單位。另一個是tag是size_kb，所以實際大小還要轉成eraseblock。如：

/ # cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00280000 00040000 "sbl"
mtd1: 00280000 00040000 "mibib"
mtd2: 00c00000 00040000 "efs2"
mtd3: 00140000 00040000 "tz"
mtd4: 00100000 00040000 "rpm"
mtd5: 00140000 00040000 "aboot"
...

partition table configure file內容

<partition>
    <name length="16" type="string">0:SBL</name>
    <size_blks length="4">0x8</size_blks>
    <pad_blks length="4">0x2</pad_blks>
    ...
</partition>
...
<partition>
    <name length="16" type="string">0:EFS2</name>
    <size_kb length="4">11264</size_kb>
    <pad_kb length="4">1024</pad_kb>
    ....
</partition>

SBL的設定為0x8+0x2個eraseblock，所以/proc/mtd大小為 (8 + 2) * 256 * 1024 = 0x280000。 EFS2的設定為11264+1024 KB，所以/proc/mtd大小為ceiling(11264 / 256)+ceiling(1024 / 256) = 48個eraseblock，所以/proc/mtd大小為48 * 256 * 1024 = 0xC0000。 eraseblock就是上面的erasesize，0x40000 / 1024 = 256kb。

2016年9月17日星期六

build 32bit app on 64bit Machine -- /usr/bin/ld: skipping incompatible

我將Ubuntu從14.04換到16.04後，系統好像移除了一些package，導致build 32bit的程式會failed。安裝lib32gcc-4.7-dev之後就解了。

brook@vista:~$ uname -a
Linux vista 4.4.0-36-generic #55-Ubuntu SMP Thu Aug 11 18:01:55 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
brook@vista:~$ cat /etc/issue
Ubuntu 16.04.1 LTS \n \l
brook@vista:~$ gcc -m32 x.c
/usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/4.7/libgcc.a when searching for -lgcc
/usr/bin/ld: cannot find -lgcc
/usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/4.7/libgcc_s.so when searching for -lgcc_s
/usr/bin/ld: cannot find -lgcc_s
collect2: error: ld returned 1 exit status
brook@vista:~$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.7.4-3ubuntu12' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.7 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-gnu-unique-object --disable-libmudflap --enable-plugin --with-system-zlib --enable-objc-gc --with-cloog --enable-cloog-backend=ppl --disable-cloog-version-check --disable-ppl-version-check --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.7.4 (Ubuntu/Linaro 4.7.4-3ubuntu12)
brook@vista:~$ sudo apt-get install lib32gcc-4.7-dev

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2018年1月28日 星期日

2018年1月7日 星期日

CH6, Making Comments Precise and Compact

2018年1月1日 星期一

CH5, Knowing What to Comment

2017年12月23日 星期六

CH3, Names That Can’t Be Misconstrued

Actively scrutinize your names by asking yourself, “What other meanings could someone interpret from this name?”

CH4, Aesthetics

CH1, Code Should Be Easy to Understand

Code should be written to minimize the time it would take for someone else to understand it.

CH2, Pack information into your names

Pack information into your names的幾個重點

2017年12月9日 星期六

範例

2017年11月25日 星期六

brook-log.h

brook-log.c

main.c

結果

Sample code for publisher

Sample code subscriber

2017年11月5日 星期日

MQTT Architecture(Publish/Subscribe with broker)

Topic wildcards

Deom the MQTT - mosquitto

mosquitto - Broker log notes

2017年7月29日 星期六

2017年7月8日 星期六

2017年4月30日 星期日

簡介

PC檔內容

pkg-config操作

pkg-config實際應用

2016年12月4日 星期日

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