EasyFlash 移植（一）

移植文件 ef_port.c

/*
 * This file is part of the EasyFlash Library.
 *
 * Copyright (c) 2015, Armink, <[e-mail]>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * 'Software'), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * Function: Portable interface for each platform.
 * Created on: 2015-01-16
 */

#include <easyflash.h>
#include <stdarg.h>

/* default environment variables set for user */
static const ef_env default_env_set[] = {

};

/**
 * Flash port for hardware initialize.
 *
 * @param default_env default ENV set for user
 * @param default_env_size default ENV size
 *
 * @return result
 */
EfErrCode ef_port_init(ef_env const **default_env, size_t *default_env_size) {
    EfErrCode result = EF_NO_ERR;

    *default_env = default_env_set;
    *default_env_size = sizeof(default_env_set) / sizeof(default_env_set[0]);

    return result;
}

/**
 * Read data from flash.
 * @note This operation's units is word.
 *
 * @param addr flash address
 * @param buf buffer to store read data
 * @param size read bytes size
 *
 * @return result
 */
EfErrCode ef_port_read(uint32_t addr, uint32_t *buf, size_t size) {
    EfErrCode result = EF_NO_ERR;

    EF_ASSERT(size % 4 == 0);

    /* You can add your code under here. */

    return result;
}

/**
 * Erase data on flash.
 * @note This operation is irreversible.
 * @note This operation's units is different which on many chips.
 *
 * @param addr flash address
 * @param size erase bytes size
 *
 * @return result
 */
EfErrCode ef_port_erase(uint32_t addr, size_t size) {
    EfErrCode result = EF_NO_ERR;

    /* make sure the start address is a multiple of EF_ERASE_MIN_SIZE */
    EF_ASSERT(addr % EF_ERASE_MIN_SIZE == 0);

    /* You can add your code under here. */

    return result;
}
/**
 * Write data to flash.
 * @note This operation's units is word.
 * @note This operation must after erase. @see flash_erase.
 *
 * @param addr flash address
 * @param buf the write data buffer
 * @param size write bytes size
 *
 * @return result
 */
EfErrCode ef_port_write(uint32_t addr, const uint32_t *buf, size_t size) {
    EfErrCode result = EF_NO_ERR;

    EF_ASSERT(size % 4 == 0);

    /* You can add your code under here. */

    return result;
}

/**
 * lock the ENV ram cache
 */
void ef_port_env_lock(void) {

    /* You can add your code under here. */

}

/**
 * unlock the ENV ram cache
 */
void ef_port_env_unlock(void) {

    /* You can add your code under here. */

}


/**
 * This function is print flash debug info.
 *
 * @param file the file which has call this function
 * @param line the line number which has call this function
 * @param format output format
 * @param ... args
 *
 */
void ef_log_debug(const char *file, const long line, const char *format, ...) {

#ifdef PRINT_DEBUG

    va_list args;

    /* args point to the first variable parameter */
    va_start(args, format);

    /* You can add your code under here. */

    va_end(args);

#endif

}

/**
 * This function is print flash routine info.
 *
 * @param format output format
 * @param ... args
 */
void ef_log_info(const char *format, ...) {
    va_list args;

    /* args point to the first variable parameter */
    va_start(args, format);

    /* You can add your code under here. */

    va_end(args);
}
/**
 * This function is print flash non-package info.
 *
 * @param format output format
 * @param ... args
 */
void ef_print(const char *format, ...) {
    va_list args;

    /* args point to the first variable parameter */
    va_start(args, format);

    /* You can add your code under here. */

    va_end(args);
}

    所谓的移植，是为了适应特殊的需求，而移植接口，往往是把特殊进行一般化，移植就是要把一般化的接口根据实际的情况来进行实例化。移植接口有点类似于C++里面的虚函数，我们在使用的时候要实现其函数。
    该移植文件里面只有一个变量default_env_set 用来存储默认的用户环境变量，有9个移植接口函数：
1.ef_port_init    //Flash port for hardware initialize.  硬件端口初始化
2.ef_port_read //Read data from flash.                  从flash中读数据
3.ef_port_erase    //Erase data on flash.                从flash中擦除数据                  
4.ef_port_write    //ef_port_write   写数据到flash
5.ef_port_env_lock // lock the ENV ram cache 锁定环境缓存
6.ef_port_env_unlock //unlock the ENV ram cache 解锁环境缓存
7.ef_log_debug //This function is print flash debug info. 打印flash调试信息
8.ef_log_info //This function is print flash routine info. 打印flash程序信息
9.ef_print //This function is print flash non-package info. 打印flash非包信息

    按传统操作flash的方式，对flash的硬件初始化是必不可少的，该部分对应于1函数；而flash的操作往往包括了读、写和擦除，该部分对应2、3和4函数；程序运行过程往往会有很多调试信息，在测试的时候打开调试选项，在发布的时候可以把调试选项关闭，该部分对应于7、8和9函数；在多线程中，往往需要对全局的变量或内存或设备采取防竞争的手段，在同一个时间点只允许一个或多个线程可以访问，避免数据出现不可预料的变化，函数5和6是对环境缓存的一种保护机制。

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