解决printf无法打印输出的问题

FreeRTOS中直接使用newlib库是有问题的，相信使用过freertos进行printf都能发现这个问题，这个问题网上有两种方法：1、使用printf.stdarg.c，问题在于，这个库没有包含float型的输出！你没办法printf出浮点数。2、使用优化过的printf，这个能输出float型，但是在中断中如果使用float输出，就会莫名其妙的整个程序卡住，我找不出bug。

static int inHandlerMode (void) //若在中断中__get_IPSR()返回1，否则返回0{ return __get_IPSR();} void print_usart2(char *format, ...){ char buf[64]; if(inHandlerMode() != 0) { taskDISABLE_INTERRUPTS(); } else { while(HAL_UART_GetState(&huart2) == HAL_UART_STATE_BUSY_TX)//若串口忙则挂起此任务 taskYIELD(); } va_list ap; va_start(ap, format); vsprintf(buf, format, ap); HAL_UART_Transmit(&huart2, (uint8_t *)buf, strlen(buf), 100); va_end(ap); if(inHandlerMode() != 0) taskENABLE_INTERRUPTS();}

这破问题一直找不到bug在哪里，烦死了，我忍不了了！敲了个伪printf，思路很简单，遍历一遍要输出的字符串，这过程中遇到%就标记，再遇到'.'这个字符就记录一下'.'后面的数字，然后从va_list中根据%x 判断一下属于哪个类型，用va_arg读取到值，再将该值的每个十进制位读取成字符后放进输出字符串里面，就完成了！代码如下：

#include"iostream"#include "stdarg.h"using namespace std; void GetIntToString(char *target,int* target_site,int value,int num_value){char temp[20];int temp_site = 0,site = *target_site,flag = 0,neg_flag = 0;
if(num_value != 0)flag = 1;if(value < 0){neg_flag = 1;value = -value;}
while(value){temp[temp_site++] = (value % 10) + '0';value /= 10;}if(neg_flag)target[site++] = '-';while(temp_site--){if(flag){if(num_value != 0)num_value --;elsebreak;}target[site++] = temp[temp_site];}*target_site = site;} void my_sprintf(char* target,char* string,...){va_list next_value;int percent_flag = 0; // mark the emergence of percentage signint num_value = 0,num_flag = 0; // mark the value from the back of %.int target_site = 0,i = 0,value;double float_value;char *string_value;
va_start(next_value,string);while(string[i] != '\0'){if(string[i] == '%'){percent_flag = 1;}else if(percent_flag && string[i] == '.'){num_value = string[i+1] - '0';i++;}else if(percent_flag && percent_flag && (string[i] == 'd' || string[i] == 'c')){value = va_arg(next_value,int);if(value == 0)target[target_site++] = '0';elseGetIntToString(target,&target_site,value,num_value);
percent_flag = num_value = 0;}else if(percent_flag && string[i] == 's'){value = va_arg(next_value,int);string_value = (char *)value;for(int j = 0;string_value[j] != '\0';j++)target[target_site++] = string_value[j];
percent_flag = num_flag = num_value = 0;}else if(percent_flag && string[i] == 'f'){float_value = va_arg(next_value,double); // 2.14if((int)float_value == 0)target[target_site++] = '0';elseGetIntToString(target,&target_site,(int)float_value,0); // 2if(float_value < 0)float_value = -float_value;float_value -= (int)float_value;target[target_site++] = '.'; // 2.
if(num_value != 0)num_flag = 1;while(!(float_value >= -0.000001 && float_value <= 0.000001)){if(num_flag){if(num_value != 0)num_value --;elsebreak;}float_value *= 10;target[target_site++] = (int)float_value + '0';float_value -= (int)float_value;} // 2.14
percent_flag = num_flag = num_value = 0;}elsetarget[target_site++] = string[i];i++;}target[target_site] = '\0';va_end(next_value);} void my_printf(char* string,...){va_list next_value;int percent_flag = 0; // mark the emergence of percentage signint num_value = 0,num_flag = 0; // mark the value from the back of %.int target_site = 0,i = 0,value;double float_value;char target[100];char *string_value;
va_start(next_value,string);while(string[i] != '\0'){if(string[i] == '%'){percent_flag = 1;}else if(percent_flag && string[i] == '.'){num_value = string[i+1] - '0';i++;}else if(percent_flag && percent_flag && (string[i] == 'd' || string[i] == 'c')){value = va_arg(next_value,int);if(value == 0)target[target_site++] = '0';elseGetIntToString(target,&target_site,value,num_value);
percent_flag = num_value = 0;}else if(percent_flag && string[i] == 's'){value = va_arg(next_value,int);string_value = (char *)value;for(int j = 0;string_value[j] != '\0';j++)target[target_site++] = string_value[j];
percent_flag = num_flag = num_value = 0;}else if(percent_flag && string[i] == 'f'){float_value = va_arg(next_value,double); // 2.14if((int)float_value == 0)target[target_site++] = '0';elseGetIntToString(target,&target_site,(int)float_value,0); // 2if(float_value < 0)float_value = -float_value;float_value -= (int)float_value;target[target_site++] = '.'; // 2.
if(num_value != 0)num_flag = 1;while(!(float_value >= -0.000001 && float_value <= 0.000001)){if(num_flag){if(num_value != 0)num_value --;elsebreak;}float_value *= 10;target[target_site++] = (int)float_value + '0';float_value -= (int)float_value;} // 2.14
percent_flag = num_flag = num_value = 0;}elsetarget[target_site++] = string[i];i++;}target[target_site] = '\0';va_end(next_value);
for(int i = 0;i < target_site ;i ++) // 在devc++ 调试时的输出 printf("%c",target[i]);} int main(){uint8_t k = 10;char target[100];char a = -10,b = -100;my_printf("MotorRun,%d,%d\n",a,b);printf("%c %c",55,32);//my_printf("temp value is %c and %d\n",k,k);//my_printf("you are so %s,yes \n%f","handsome",0.09);}

不过精度的问题，不知道怎么改，所以使用这个程序输出float应该限制小数点长度。代码应该不难看懂，不过这段代码还没有实现字符宽度输出，也就是没有实现%后跟着数字的输出，在用该代码也不应该在%后加数字。突然发现这个函数的target字符串 就可以作为sprintf的输出耶，把得到target字符串的那一大串代码包装一下，就是sprintf了。在单片机的代码：通过uart2输出：

static char getint_temp[20];void GetIntToString(char *target,int* target_site,int value,int num_value){int temp_site = 0,site = *target_site;uint8_t flag = 0,neg_flag = 0; if(num_value != 0)flag = 1;if(value < 0){neg_flag = 1;value = -value;}while(value){getint_temp[temp_site++] = (value % 10) + '0';value /= 10;}if(neg_flag)target[site++] = '-';while(temp_site--){if(flag){if(num_value != 0)num_value --;elsebreak;}target[site++] = getint_temp[temp_site];}*target_site = site;} uint8_t percent_flag; // mark the emergence of percentage signuint8_t num_value,num_flag; // mark the value from the back of %.int target_site;int i,value;double float_value;char* string_value;char target[100];void my_printf(char* string,...){#if USE_PRINTF if(inHandlerMode() != 0){ taskDISABLE_INTERRUPTS();} else {while(HAL_UART_GetState(&huart2) == HAL_UART_STATE_BUSY_TX) //若串口忙则挂起此任务taskYIELD();} va_list next_value;i = target_site = percent_flag = num_flag = num_value = 0; va_start(next_value,string);while(string[i] != '\0'){if(string[i] == '%'){percent_flag = 1;}else if(percent_flag && string[i] == '.'){num_value = string[i+1] - '0';i++;}else if(percent_flag && (string[i] == 'd' || string[i] == 'c')){value = va_arg(next_value,int);if(value == 0)target[target_site++] = '0';elseGetIntToString(target,&target_site,value,num_value); percent_flag = num_value = 0;}else if(percent_flag && string[i] == 's'){value = va_arg(next_value,int);string_value = (char *)value;for(int j = 0;string_value[j] != '\0';j++)target[target_site++] = string_value[j]; percent_flag = num_flag = num_value = 0;}else if(percent_flag && string[i] == 'f'){float_value = va_arg(next_value,double); // 2.14if((int)float_value == 0)target[target_site++] = '0';elseGetIntToString(target,&target_site,(int)float_value,0); // 2if(float_value < 0)float_value = -float_value;float_value -= (int)float_value;target[target_site++] = '.'; // 2. if(num_value != 0)num_flag = 1;while(!(float_value >= -0.000001 && float_value <= 0.000001)){if(num_flag){if(num_value != 0)num_value --;elsebreak;}float_value *= 10;target[target_site++] = (int)float_value + '0';float_value -= (int)float_value;} // 2.14 percent_flag = num_flag = num_value = 0;}elsetarget[target_site++] = string[i];i++;}//target[target_site++] = '\0';va_end(next_value); HAL_UART_Transmit(&PRINTF_UART, (uint8_t *)target, target_site, 100); if(inHandlerMode() != 0)taskENABLE_INTERRUPTS();#endif} void my_sprintf(char* target,char* string,...){ if(inHandlerMode() != 0){ taskDISABLE_INTERRUPTS();} else{while(HAL_UART_GetState(&huart2) == HAL_UART_STATE_BUSY_TX) //若串口忙则挂起此任务taskYIELD();} va_list next_value;uint8_t percent_flag = 0; // mark the emergence of percentage signuint8_t num_value = 0,num_flag = 0; // mark the value from the back of %.int target_site = 0;int i = 0,value;double float_value;char *string_value; va_start(next_value,string);while(string[i] != '\0'){if(string[i] == '%'){percent_flag = 1;}else if(percent_flag && string[i] == '.'){num_value = string[i+1] - '0';i++;}else if(percent_flag && percent_flag && (string[i] == 'd' || string[i] == 'c')){value = va_arg(next_value,int);if(value == 0)target[target_site++] = '0';elseGetIntToString(target,&target_site,value,num_value); percent_flag = num_value = 0;}else if(percent_flag && string[i] == 's'){value = va_arg(next_value,int);string_value = (char *)value;for(int j = 0;string_value[j] != '\0';j++)target[target_site++] = string_value[j]; percent_flag = num_flag = num_value = 0;}else if(percent_flag && string[i] == 'f'){float_value = va_arg(next_value,double); // 2.14if((int)float_value == 0)target[target_site++] = '0';elseGetIntToString(target,&target_site,(int)float_value,0); // 2if(float_value < 0)float_value = -float_value;float_value -= (int)float_value;target[target_site++] = '.'; // 2. if(num_value != 0)num_flag = 1;while(!(float_value >= -0.000001 && float_value <= 0.000001)){if(num_flag){if(num_value != 0)num_value --;elsebreak;}float_value *= 10;target[target_site++] = (int)float_value + '0';float_value -= (int)float_value;} // 2.14 percent_flag = num_flag = num_value = 0;}elsetarget[target_site++] = string[i];i++;}target[target_site] = '\0';va_end(next_value); if(inHandlerMode() != 0)taskENABLE_INTERRUPTS();}

在freertos两个任务中输出，并且在串口中断中输出浮点数成功（突然发现，task拼成了tast。。

彻底解决！目前使用没有bug，有bug我再来改文章。存在个bug，当传入过多参数时，后面的参数会出现乱码，如下

最后一个%d会出现乱码。将其分成两个printf输出，可以成功输出。