allwinner script_parser_fetch（）函数

最近看allwinner方案。发现他们吧一些东西进行了修改。例如初始化之类的配置文件，allwinner把他们放在一起，这样做的好处就是 容易配置，所有初始化一目了然。非常方便，这个配置文件在哪提现到用呢？ALLwinner 在每个驱动初始化时候都加了这么一个函数：

int script_parser_fetch(char *main_name, char *sub_name, int value[], int count)

这个函数就是读取相应初始化的函数，在每个驱动初始化的时候加上它，就能吧之前的配置读取出来。下面分析下这个函数

int script_parser_fetch(char *main_name, char *sub_name, int value[], int count)

{
    char   main_bkname[32], sub_bkname[32];
    char   *main_char, *sub_char;
    script_main_key_t  *main_key = NULL;
    script_sub_key_t   *sub_key = NULL;
    int    i, j;
    int    pattern, word_count;

    pr_debug("enter script parse fetch. \n");

    /* check params */
    if(!script_mod_buf)
    {
        return SCRIPT_PARSER_EMPTY_BUFFER;
    }

    if((main_name == NULL) || (sub_name == NULL))
    {
        return SCRIPT_PARSER_KEYNAME_NULL;
    }

    if(value == NULL)
    {
        return SCRIPT_PARSER_DATA_VALUE_NULL;
    }

    /* truncate string if size >31 bytes */
    main_char = main_name;
    if(_test_str_length(main_name) > 31)   
    {
        memset(main_bkname, 0, 32);
        strncpy(main_bkname, main_name, 31);
        main_char = main_bkname;
    }
    sub_char = sub_name;
    if(_test_str_length(sub_name) > 31)
    {
        memset(sub_bkname, 0, 32);
        strncpy(sub_bkname, sub_name, 31);
        sub_char = sub_bkname;
    }
    pr_debug("gpio: main name is : %s, sub_name is: %s", main_char, sub_char);

    for(i=0;i<script_main_key_count;i++)
    {
        main_key = (script_main_key_t *)(script_mod_buf + (sizeof(script_head_t)) + i * sizeof(script_main_key_t));
        if(strcmp(main_key->main_name, main_char))
        {
            continue;//如果不是你要初始化的参数跳出去

        }
       
        /* now find sub key */
        for(j=0;j<main_key->lenth;j++)
        {
            sub_key = (script_sub_key_t *)(script_mod_buf + (main_key->offset<<2) + (j * sizeof(script_sub_key_t)));
            if(strcmp(sub_key->sub_name, sub_char))
            {
                continue;  //如果不是你要初始化的参数跳出去
            }
            pattern    = (sub_key->pattern>>16) & 0xffff; /* get datatype */
            word_count = (sub_key->pattern>> 0) & 0xffff; /*get count of word */
            pr_debug("pattern is: 0x%x, word_count is: 0x%x, ", pattern, word_count);

            switch(pattern)
            {
                case SCIRPT_PARSER_VALUE_TYPE_SINGLE_WORD:
                    value[0] = *(int *)(script_mod_buf + (sub_key->offset<<2));
                    break;

                case SCIRPT_PARSER_VALUE_TYPE_STRING:
                    if(count < word_count)
                    {
                        word_count = count;
                    }
                    memcpy((char *)value, script_mod_buf + (sub_key->offset<<2), word_count << 2);
                    break;

                case SCIRPT_PARSER_VALUE_TYPE_MULTI_WORD:
                    break;
                case SCIRPT_PARSER_VALUE_TYPE_GPIO_WORD:
                {
                    script_gpio_set_t  *user_gpio_cfg = (script_gpio_set_t *)value;
                    /* buffer space enough? */
                    if(sizeof(script_gpio_set_t) > (count<<2))
                    {
                        return SCRIPT_PARSER_BUFFER_NOT_ENOUGH;
                    }
                    strcpy( user_gpio_cfg->gpio_name, sub_char);
                    memcpy(&user_gpio_cfg->port, script_mod_buf + (sub_key->offset<<2),  sizeof(script_gpio_set_t) - 32);
                    break;
                }
            }

            return SCRIPT_PARSER_OK;
        }
    }

    return SCRIPT_PARSER_KEY_NOT_FIND;
}