一个尚不完善的printf

最新推荐文章于 2023-01-16 22:43:59 发布

原创最新推荐文章于 2023-01-16 22:43:59 发布 · 342 阅读

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#C语言 #输出函数 #printf

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本文详细介绍了如何使用C语言中的printf_UART函数进行字符串输出操作，包括宏定义解释、函数参数解析及实际应用示例。

#ifndef __PRINTF_UART_H__
#define __PRINTF_UART_H__
#define PSTR(x)  x
typedef void*  va_list;
#define _INTSIZEOF(n)   ((sizeof(n)+sizeof(int)-1)&~(sizeof(int) - 1))
#define va_start(ap,v)  ( ap = (va_list)&v + _INTSIZEOF(v) )
#define va_arg(ap,t)    ( *(t *)((ap += _INTSIZEOF(t)) - _INTSIZEOF(t)))
#define va_end(ap)      ( ap = (va_list)0 )
#endif
 
#include "printf_uart.h"
unsigned long  ltostr(unsigned long Val,char *pString,unsigned char Base,unsigned long Length);
char ss[10]={0};
int tm_printf (const  char *format, ...)
{
    unsigned int d;
             int count = 0;
    char  c;
    char* s;

    va_list ap;
    va_start(ap, format);
    while(0 != *format){
        if('%' != *format){
            tm_putchar(*format);
        }
        else{
           switch(*++format){
               case 'd':
                   d = va_arg(ap, unsigned int);
                   ltostr((unsigned long)d,ss,16,10);
                   tm_putstring((unsigned char *)ss);
                   break;
               case 'c':
                   c = va_arg(ap, char);
                   tm_putchar((int)c);
                   break;
               case 's':
                   s = va_arg(ap, char*);
                   tm_putstring((unsigned char *)s);
                   break;
               default:
                   break;
                    }
                }
                count++;
                format++;
            }
            va_end(ap);
            return count;
}
 
unsigned long ltostr(unsigned long Val,char *pString,unsigned char Base,unsigned long Length)
{
 char  c, *pInit;
 unsigned char  i,j;
 unsigned long Len,SwapLen;
 *pString='\0';
 pInit=pString;
 if(Val==0) {
     *pString++='0';
     *pString='\0';                       
 }
 switch(Base) {
  case 10:                   
      for(;Val>0;) {
          i=Val�se;
          Val=Val/Base;
          *pString++=(char)((unsigned char)'0'+i);
      }
      *pString='\0';
      break;
  case 16:                   
      for(;Val>0;) {
          i=Val�se;
          Val=Val/Base;
          if(i<=9) {
              *pString++=(char)((unsigned char)'0'+i);
          } else {
              *pString++=(char)((unsigned char)'A'+i-10);
          }
      }
      *pString='\0';
      break;
  default:
      break;
 }
 Len=strlen(pInit);
 SwapLen=Len;
 
 if(Length>Len) {
  for(i=Len;i
   *(pInit+i)='\0';
  }
  *(pInit+Length)='\0';
 }
 
 if(SwapLen>0) {
  for(i=0,j=SwapLen - 1;i
      c=*(pInit+i);
      *(pInit+i)=*(pInit+j);
      *(pInit+j)=c;
  }
 }
    return SwapLen;
}