temprature.c

miceteck_MPC860_BSP源码,基于VXWORK

#include <stdio.h>
#include <math.h>
double calculate_exponent();
int calculate_sign();
double calculate_mantissa();
double ieee_to_decimal();
double temprature();

double calculate_exponent(int eb)/*计算e的值*/
  {
    double exponent = 0;
    exponent = eb - 127;
    return (exponent);
  }
int calculate_sign(int high_byte)/*计算符号位*/
  {
    if(128 & high_byte)
      return (1);
    else
      return (0);
    }
double calculate_mantissa(int high_byte, int mid_byte, int low_byte)/*计算mantissa的值*/
  {
    int power = 0;
    int multiplier = 0;
    float mantissa = 0;
    long int mantissa_bits;
    long int index = 8388608; /* 0b 100000000000000000000000 */
    high_byte &= 127; /* strip off sign bit. */
    mantissa_bits = (low_byte + (mid_byte * 256) + (high_byte * 65536) + 8388608);/*组合成标准的long int*/
     for (power = 0; power >= -23; power--)/**/
       {
        if ((mantissa_bits & index)!=0)
          multiplier = 1;
        else
          multiplier = 0;
          mantissa = mantissa + (pow(2,power) * multiplier);
          index = index/2; /* index向右移一位 */
        }
    return (mantissa);
  }
double ieee_to_decimal(int eb, int high_byte, int mid_byte, int low_byte)
  {
     double decimal_result = 0;
     double mantissa = 0;
     double exponent = 0;
     int sign = 0; /* 0 = positive, 1 = negative */
     mantissa = calculate_mantissa(high_byte,mid_byte,low_byte);
     exponent = calculate_exponent(eb);
     sign = calculate_sign (high_byte);
     decimal_result = ((pow(-1,sign))*(mantissa)*pow(2,exponent));
     return (decimal_result);
  }
  /*double pow（x，y）是math.h里面的标准函数：是计算 x exp(y)的值  就是计算x的y次幂*/
double temprature(int temp,int ad2,int ad3,int ad1,int cal1_H,int cal1_L,int cal2_H,int cal2_L,int temp1_H,int temp1_L,int temp2_H,int temp2_L)
   {
    
     double cal1,cal2,temp1,temp2; /*要定义成全局变量*/
     double N1,Vin,tempbuf;
     int lowbyte,midbyte,highbyte,exp;
     lowbyte=(cal1_H>>8);
     midbyte=(cal1_H&0x0f);
     highbyte=(cal1_L>>8);	
     exp=(cal1_L&0x0f);
     cal1=ieee_to_decimal(exp, highbyte,midbyte, lowbyte);
     lowbyte=(cal2_H>>8);
     midbyte=(cal2_H&0x0f);
     highbyte=(cal2_L>>8);	
     exp=(cal2_L&0x0f);
     cal2=ieee_to_decimal(exp, highbyte,midbyte, lowbyte);
     lowbyte=(temp1_H>>8);
     midbyte=(temp1_H&0x0f);
     highbyte=(temp1_L>>8);	
     exp=(temp1_L&0x0f);
     temp1=ieee_to_decimal(exp, highbyte,midbyte, lowbyte);
     lowbyte=(temp2_H>>8);
     midbyte=(temp2_H&0x0f);
     highbyte=(temp2_L>>8);	
     exp=(temp2_L&0x0f);
     temp2=ieee_to_decimal(exp, highbyte,midbyte, lowbyte);
     
     N1=ad3-(ad2-ad3)*cal1;
     Vin=(temp-N1)/(ad1-N1)*cal2;
     tempbuf=25+(Vin-temp1)/temp2;
     return(tempbuf);
   }