// 以下是宏定义的一些用法
11.4.2 #if defined… #else …#endif 此编译指令为#ifdef … #else …#endif的等价编译指令。其语法格式如下： #if defined 常量表达式 代码段1 #else 代码段2 #endif 或 #if defined (常量表达式) 代码段1 #else 代码段2 #endif 此编译指令的简单形式为单分支的条件编译指令，其语法形式如下： #if defined常量表达式 代码段1 #endif
因为对于一个大程序而言,我们可能要定义很多常量( 不管是放在源文件还是头文件 ),那么我们有时考虑定义某个常量时,我们就必须返回检查原来此常量是否定义,但这样做很麻烦.if defined宏正是为这种情况提供了解决方案.举个例子,如下: #define .... #define .... ........ ........ #define a 100 ....... 此时，我们要检查a是否定义（假设我们已经记不着这点了）,或者我们要给a一个不同的值，就加入如下句子 #if defined a #undef a #define a 200 #endif 上述语句检验a是否被定义，如果被定义，则用#undef语句解除定义，并重新定义a为200 同样，检验a是否定义： #ifndef a //如果a没有被定义 #define a 100 #endif 以上所用的宏中：#undef为解除定义，#ifndef是if not defined的缩写，即如果没有定义。 这就是#if defined 的唯一作用！
#include <lcm_drv.h>
extern LCM_DRIVER nt35510_lcm_drv;
extern LCM_DRIVER hx8369_lcm_drv;
extern LCM_DRIVER bm8578_lcm_drv;
extern LCM_DRIVER nt35582_mcu_lcm_drv;
extern LCM_DRIVER hx8357b_lcm_drv;
extern LCM_DRIVER hx8369_dsi_lcm_drv;
extern LCM_DRIVER hx8369_hvga_lcm_drv;
extern LCM_DRIVER ili9481_lcm_drv;
extern LCM_DRIVER nt35582_lcm_drv;
extern LCM_DRIVER s6d0170_lcm_drv;
extern LCM_DRIVER spfd5461a_lcm_drv;
extern LCM_DRIVER ta7601_lcm_drv;
extern LCM_DRIVER tft1p3037_lcm_drv;
extern LCM_DRIVER zte6516_lcm_drv;
extern LCM_DRIVER r61408_lcm_drv;
extern LCM_DRIVER lg4572b_lcm_drv;
LCM_DRIVER* lcm_driver_list[] =
{
#if defined(LCM_DRIVER_CUST)
&nt35510_lcm_drv,// 0
&r61408_lcm_drv, //1
&lg4572b_lcm_drv,// 2
&hx8369_lcm_drv,//3
#endif
#if defined(NT35510)
&nt35510_lcm_drv,
#endif
#if defined(NT35510)
&nt35510_lcm_drv,
#endif
#if defined(HX8369)
&hx8369_lcm_drv,
#endif
#if defined(BM8578)
&bm8578_lcm_drv,
#endif
#if defined(NT35582_MCU)
&nt35582_mcu_lcm_drv,
#endif
#if defined(HX8357B)
&hx8357b_lcm_drv,
#endif
#if defined(HX8369_DSI)
&hx8369_dsi_lcm_drv,
#endif
#if defined(HX8369_HVGA)
&hx8369_hvga_lcm_drv,
#endif
#if defined(ILI9481)
&ili9481_lcm_drv,
#endif
#if defined(NT35582)
&nt35582_lcm_drv,
#endif
#if defined(S6D0170)
&s6d0170_lcm_drv,
#endif
#if defined(SPFD5461A)
&spfd5461a_lcm_drv,
#endif
#if defined(TA7601)
&ta7601_lcm_drv,
#endif
#if defined(TFT1P3037)
&tft1p3037_lcm_drv,
#endif
#if defined(ZTE6516)
&zte6516_lcm_drv,
#endif
#if defined(HX8357B_LENOVO)
&hx8357b_lcm_drv,
#endif
#if defined(R61408)
&r61408_lcm_drv,
#endif
#if defined(LG4572B)
&lg4572b_lcm_drv
#endif
};
#define LCM_COMPILE_ASSERT(condition) LCM_COMPILE_ASSERT_X(condition, __LINE__)
#define LCM_COMPILE_ASSERT_X(condition, line) LCM_COMPILE_ASSERT_XX(condition, line)
#define LCM_COMPILE_ASSERT_XX(condition, line) char assertion_failed_at_line_##line[(condition)?1:-1]
unsigned int lcm_count = sizeof(lcm_driver_list)/sizeof(LCM_DRIVER*);
LCM_COMPILE_ASSERT(0 != sizeof(lcm_driver_list)/sizeof(LCM_DRIVER*));
extern LCM_DRIVER* lcm_driver_list[];
extern unsigned int lcm_count;
const char str[]="JBLCM#1#AAAA";
LCM_DRIVER *disp_drv_get_lcm_driver(const char* lcm_name)
{
LCM_DRIVER *lcm = NULL;
printf("[LCM Auto Detect], we have %d lcm drivers built in\n", lcm_count);
int g_lcm_number;
g_lcm_number = (int)(str[6])-'0';
#if defined(LCM_DRIVER_CUST)
{
if (g_lcm_number>-1)
{ lcm = lcm_driver_list[g_lcm_number];// 0
lcm->set_util_funcs(&lcm_utils);
lcm->get_params(&s_lcm_params);
lcm_params = &s_lcm_params;
lcm_drv = lcm;
isLCMFound = TRUE;
printf("[LCM Specified]\t[%s]\n", (lcm->name==NULL)?"unknown":lcm->name);
goto done;
}
else
{
LCM_PARAMS s_lcm_params_new = {0};
LCM_PARAMS *lcm_params_new = &s_lcm_params_new;
lcm = lcm_driver_list[0];
memset((void*)lcm_params, 0, sizeof(LCM_PARAMS));
lcm->get_params(lcm_params);
int i;
for(i = 1;i < lcm_count;i++)
{
memset((void*)lcm_params_new, 0, sizeof(LCM_PARAMS));
lcm_driver_list[i]->get_params(lcm_params_new);
if((lcm_params->width * lcm_params->height) >
(lcm_params_new->width * lcm_params_new->height))
{
lcm = lcm_driver_list[i];
memset((void*)lcm_params, 0, sizeof(LCM_PARAMS));
lcm->get_params(lcm_params);
}
}
}
printf("[LCM Auto Detect] no lcm device found\n");
printf("[LCM Auto Detect] we will using the lcm driver with minimum resolution\n");
// if we are here, it means:
// 1.there is no correct driver for the lcm used;
// 2.there is no lcm device connected.
// we will find the lcm with minimum resolution to use,
// in case physical memory is not enough
// goto done;
}
#else {
if(lcm_count ==1)
{
// we need to verify whether the lcm is connected
// even there is only one lcm type defined
lcm = lcm_driver_list[0];
lcm->set_util_funcs(&lcm_utils);
lcm->get_params(&s_lcm_params);
lcm_params = &s_lcm_params;
lcm_drv = lcm;
isLCMFound = TRUE;
printf("[LCM Specified]\t[%s]\n", (lcm->name==NULL)?"unknown":lcm->name);
goto done;
}
else
{
int i;
for(i = 0;i < lcm_count;i++)
{
lcm_params = &s_lcm_params;
lcm = lcm_driver_list[i];
printf("[LCM Auto Detect] [%d] - [%s]\t",
i,
(lcm->name==NULL)?"unknown":lcm->name);
lcm->set_util_funcs(&lcm_utils);
memset((void*)lcm_params, 0, sizeof(LCM_PARAMS));
lcm->get_params(lcm_params);
disp_drv_init_ctrl_if();
disp_drv_set_driving_current(lcm_params);
disp_drv_init_io_pad(lcm_params);
if(lcm_name != NULL)
{
if(!strcmp(lcm_name,lcm->name))
{
printf("\t\t[success]\n");
isLCMFound = TRUE;
lcm_drv = lcm;
goto done;
}
else
{
printf("\t\t[fail]\n");
}
}
else
{
if(lcm->compare_id != NULL && lcm->compare_id())
{
printf("\t\t[success]\n");
isLCMFound = TRUE;
lcm_drv = lcm;
goto done;
}
else
{
printf("\t\t[fail]\n");
}
}
}
printf("[LCM Auto Detect] no lcm device found\n");
printf("[LCM Auto Detect] we will using the lcm driver with minimum resolution\n");
// if we are here, it means:
// 1.there is no correct driver for the lcm used;
// 2.there is no lcm device connected.
// we will find the lcm with minimum resolution to use,
// in case physical memory is not enough
{
LCM_PARAMS s_lcm_params_new = {0};
LCM_PARAMS *lcm_params_new = &s_lcm_params_new;
lcm = lcm_driver_list[0];
memset((void*)lcm_params, 0, sizeof(LCM_PARAMS));
lcm->get_params(lcm_params);
for(i = 1;i < lcm_count;i++)
{
memset((void*)lcm_params_new, 0, sizeof(LCM_PARAMS));
lcm_driver_list[i]->get_params(lcm_params_new);
if((lcm_params->width * lcm_params->height) >
(lcm_params_new->width * lcm_params_new->height))
{
lcm = lcm_driver_list[i];
memset((void*)lcm_params, 0, sizeof(LCM_PARAMS));
lcm->get_params(lcm_params);
}
}
}
}
}