自己给libnfc库添加一个头文件 很波折

//log.h

/*-

 * Free/Libre Near Field Communication (NFC) library

 *

 * Libnfc historical contributors:

 * Copyright (C) 2009      Roel Verdult

 * Copyright (C) 2009-2013 Romuald Conty

 * Copyright (C) 2010-2012 Romain Tartière

 * Copyright (C) 2010-2013 Philippe Teuwen

 * Copyright (C) 2012-2013 Ludovic Rousseau

 * Additional contributors of this file:

 *

 * This program is free software: you can redistribute it and/or modify it

 * under the terms of the GNU Lesser 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 Lesser General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>

 */







#ifndef __LOG_H__

#define __LOG_H__



#ifdef HAVE_CONFIG_H

#  include "config.h"





#endif // HAVE_CONFIG_H



#include "nfc-internal.h"

//#include "MycharToInt.h" // by wangyong 2013-6-8
//上面就是我准备添加的头文件，头文件里定义了一个函数int MycharToInt(char *pch) ;
//MycharToInt.c实现了这个函数

#define NFC_LOG_PRIORITY_NONE   0

#define NFC_LOG_PRIORITY_ERROR  1

#define NFC_LOG_PRIORITY_INFO   2

#define NFC_LOG_PRIORITY_DEBUG  3



#define NFC_LOG_GROUP_GENERAL   1

#define NFC_LOG_GROUP_CONFIG    2

#define NFC_LOG_GROUP_CHIP      3

#define NFC_LOG_GROUP_DRIVER    4

#define NFC_LOG_GROUP_COM       5

#define NFC_LOG_GROUP_LIBUSB    6



/*

  To enable log only for one (or more) group, you can use this formula:

    log_level = NFC_LOG_PRIORITY(main) + NFC_LOG_PRIORITY(group) * 2 ^ (NFC_LOG_GROUP(group) * 2)



  Examples:

   * Main log level is NONE and only communication group log is set to DEBUG verbosity (for rx/tx trace):

       LIBNFC_LOG_LEVEL=3072  // 0+3072

   * Main log level is ERROR and driver layer log is set to DEBUG level:

       LIBNFC_LOG_LEVEL=769   // 1+768

   * Main log level is ERROR, driver layer is set to INFO and communication is set to DEBUG:

       LIBNFC_LOG_LEVEL=3585  // 1+512+3072

*/



//int log_priority_to_int(const char* priority);

const char *log_priority_to_str(const int priority);



char *getDataFrom_acBuf;



#if defined LOG



#  ifndef __has_attribute

#    define __has_attribute(x) 0

#  endif



#  if __has_attribute(format) || defined(__GNUC__)

#    define __has_attribute_format 1

#  endif



void log_init(const nfc_context *context);

void log_exit(void);

void log_put(const uint8_t group, const char *category, const uint8_t priority, const char *format, ...)

#  if __has_attribute_format

__attribute__((format(printf, 4, 5)))

#  endif

;

#else

// No logging

#define log_init(nfc_context) ((void) 0)

#define log_exit() ((void) 0)

#define log_put(group, category, priority, format, ...) do {} while (0)



#endif // LOG



/**

 * @macro LOG_HEX

 * @brief Log a byte-array in hexadecimal format

 * Max values:  pcTag of 121 bytes + ": " + 300 bytes of data+ "\0" => acBuf of 1024 bytes

 */

#  ifdef LOG

#    define LOG_HEX(group, pcTag, pbtData, szBytes) do { \

    size_t     __szPos; \

    char     __acBuf[4096]; \

    size_t     __szBuf = 0; \

    if ((int)szBytes < 0) { \

      fprintf (stderr, "%s:%d: Attempt to print %d bytes!\n", __FILE__, __LINE__, (int)szBytes); \

      log_put (group, LOG_CATEGORY, NFC_LOG_PRIORITY_ERROR, "%s:%d: Attempt to print %d bytes!\n", __FILE__, __LINE__, (int)szBytes); \

      abort(); \

      break; \

    } \

    snprintf (__acBuf + __szBuf, sizeof(__acBuf) - __szBuf, "%s: ", pcTag); \

    __szBuf += strlen (pcTag) + 2; \

    for (__szPos=0; (__szPos < (size_t)(szBytes)) && (__szBuf < sizeof(__acBuf)); __szPos++) { \

      snprintf (__acBuf + __szBuf, sizeof(__acBuf) - __szBuf, "%02x ",((uint8_t *)(pbtData))[__szPos]); \

      __szBuf += 3; \

    } \

    log_put (group, LOG_CATEGORY, NFC_LOG_PRIORITY_DEBUG, "acBuf: %s endofacBuf", __acBuf); \     

    getDataFrom_acBuf = __acBuf; \ 

    if (getDataFrom_acBuf[0] == 'R' && getDataFrom_acBuf[1] == 'X' && getDataFrom_acBuf[2] == 'X' && getDataFrom_acBuf[3] == ':'  \

        && getDataFrom_acBuf[4] == ' ' && getDataFrom_acBuf[5] == 0x30 && getDataFrom_acBuf[6] == 0x30 && getDataFrom_acBuf[7] == ' ' \

        && getDataFrom_acBuf[8] == 0x34 && getDataFrom_acBuf[9] == 0x33 && getDataFrom_acBuf[10] == ' ' && getDataFrom_acBuf[11]==0x32 \

        && getDataFrom_acBuf[12]==0x30 && getDataFrom_acBuf[13]==' ' && getDataFrom_acBuf[14]==0x30 && getDataFrom_acBuf[15]==0x30) { \        

        printf("log.h __acBuf:%s\n",__acBuf); \        

        int len = strlen(__acBuf); \

        int i; \

        for (i=68;i<len;) \

        { \

            char tmp[3]; \

            strncpy(tmp,__acBuf+i,2); \

            tmp[2]='\0'; \

            int res = MycharToInt(tmp); \ //这里对 MycharToInt 调用

printf("%c",res); \ i += 3; \ } \ }\ } while (0); # else # define LOG_HEX(group, pcTag, pbtData, szBytes) do { \ (void) group; \ (void) pcTag; \ (void) pbtData; \ (void) szBytes; \ } while (0); # endif #endif // __LOG_H__

头文件MycharToInt.h:

#ifndef __MYCHARTOINT_H__

#define __MYCHARTOINT_H__

#endif



int MycharToInt(char *pch) ;

MycharToInt.c:

#include "MycharToInt.h"


//十六进制字符数组转为int型

int MycharToInt(char *pch) {

    int result=0;

    char ch1 = pch[0];

    char ch2 = pch[1];

    int shiwei,gewei;

    switch(ch1) {

        case '0': shiwei=0; break;

        case '1': shiwei=1; break;

        case '2': shiwei=2; break;

        case '3': shiwei=3; break;

        case '4': shiwei=4; break;

        case '5': shiwei=5; break;

        case '6': shiwei=6; break;

        case '7': shiwei=7; break;

        case '8': shiwei=8; break;

        case '9': shiwei=9; break;

        case 'a': shiwei=10; break;

        case 'b': shiwei=11; break;

        case 'c': shiwei=12; break;

        case 'd': shiwei=13; break;

        case 'e': shiwei=14; break;

        case 'f': shiwei=15; break;

    }

    

    switch(ch2) {

        case '0': gewei=0; break;

        case '1': gewei=1; break;

        case '2': gewei=2; break;

        case '3': gewei=3; break;

        case '4': gewei=4; break;

        case '5': gewei=5; break;

        case '6': gewei=6; break;

        case '7': gewei=7; break;

        case '8': gewei=8; break;

        case '9': gewei=9; break;

        case 'a': gewei=10; break;

        case 'b': gewei=11; break;

        case 'c': gewei=12; break;

        case 'd': gewei=13; break;

        case 'e': gewei=14; break;

        case 'f': gewei=15; break;

    }

    

    result = shiwei*16+gewei;

    return result;

}

添加好了，然后在libnfc目录下：

sudo ./configure --with-drivers=pn532_uart --enable-debug

sudo make clean all

sudo make install

总算没有报错，之前一直报错说“multiple definition of MychatToInt”,因为之前我没有MychatToInt.c这个文件，函数定义和实现都在MychatToInt.h里。

 

虽然这里没报错，但是运行这个库上的函数就报错了，在libllcp的examples下：

sudo ./npp-server

就会报“ no symbol of MychatToInt”。

 

最后解决方法是，在log.h包含的头文件nfc-internal.h里添加我们自己定义的函数：

int MycharToInt(char *pch) ;

然后在nfc-internal.c里面加上我们的 MycharToInt(char *pch)具体实现。

 

这样之后在log.h里就能使用 MycharToInt 这个方法了。