C language to convert float data into BCD data

One . sketch

   Use BCD The encoding method can save byte space to a greater extent , Save a decimal number with four binary digits . This paper completes float Type data is converted to BCD Conversion of coding mode , And make the corresponding conversion according to the number of digits after the decimal point .

Two . Code implementation

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 /** * @brief  take float To bcd * * @param input： Input float Type data  * decimal_num： The number of decimal places to keep  * output_buf： Output buffer  * output_num： Final conversion output bytes  * * @return void * */
void float_to_bcd(const float input, int decimal_num, char* output_buf,int *output_num)
{
    
	 int i = 0;
	 int len_temp = 0;
	 int len_final = 0; 	 // Most intermediate strbuf length 
	 char string_buffer[20] = {
    0};  // Define temporary cache 
	 // Do different operations according to the reserved decimal places 
	 switch (decimal_num)
	 {
    
		 case 0:
		  sprintf_s(string_buffer, "%.0f", input);   // Will input float Type variable for formatted output 
		  break;
		 case 1:
		  sprintf_s(string_buffer, "%.2f", input);   // Will input float Type variable for formatted output 
		  len_temp = strlen(string_buffer);          // Get the formatted data length 
		  memmove(string_buffer + len_temp - 3, string_buffer + len_temp - 2, 1);   // Memory move , Can overlap 
		  string_buffer[len_temp - 2] = 0;   // Add Terminator 
		  break;
		 case 2:// Two decimal places 
		  sprintf_s(string_buffer, "%.3f", input);   // Will input float Type variable for formatted output 
		  len_temp = strlen(string_buffer);         // Get the formatted data length 
		  memmove(string_buffer + len_temp - 4, string_buffer + len_temp - 3, 2);   // Memory move , Can overlap 
		  string_buffer[len_temp - 2] = 0;    // Add Terminator 
		  break;
		 case 3:
		  sprintf_s(string_buffer, "%.4f", input);   // Will input float Type variable for formatted output 
		  len_temp = strlen(string_buffer);         // Get the formatted data length 
		  memmove(string_buffer + len_temp - 5, string_buffer + len_temp - 4, 3);   // Memory move , Can overlap 
		  string_buffer[len_temp - 2] = 0;   // Add Terminator 
		  break;
		 default:break;
	 }
			
	 len_final = strlen(string_buffer);
	 printf("len_final = %d string_buffer = %s\n", len_final, string_buffer);
	 //string To BCD Transformation 
	 if (len_final % 2)   // There are odd digits in total 
	 {
    
		  output_buf[0] = string_buffer[0] - '0';
		  for (i = 0; i < (len_final - 1) / 2; i++)
		  {
    
		   output_buf[i + 1] = (string_buffer[2 * i + 1] - '0') << 4 | (string_buffer[2 * i + 2] - '0');
		  }
	}
	 else   // There are even digits 
	 {
    
	  	for (i = 0; i < len_final / 2; i++)
	  	{
    
	   		output_buf[i] = (string_buffer[2 * i] - '0') << 4 | (string_buffer[2 * i + 1] - '0');
	  	}
	 }
	 *output_num = len_final % 2 + len_final / 2;   // Get the number of bytes finally generated 
}
int main(void)
{
    
 	int i = 0;
 	int len_final = 0;
 	float a = 12142.01023;
 	char bcd_buffer[10];
 	//float_to_bcd(a, 0, bcd_buffer, &len_final); // Retain 0 Decimal place 
 	//float_to_bcd(a, 1, bcd_buffer, &len_final); // Retain 1 Decimal place 
 	//float_to_bcd(a, 2, bcd_buffer, &len_final); // Retain 2 Decimal place 
 	float_to_bcd(a, 3, bcd_buffer, &len_final);      // Retain 3 Decimal place 
 	for (i = 0; i < len_final; i++)
 	{
    
  		printf("%x ", bcd_buffer[i]);
 	}
 	return 0;
}

3、 ... and . Execution results

// Retain 0 Decimal place 
len_final = 5   string_buffer = 12142
 Output BCD data ：01 21 42
// Retain 1 Decimal place 
len_final = 6   string_buffer = 121420
 Output BCD data ：12 14 20
// Retain 2 Decimal place 
len_final = 7   string_buffer = 1214201
 Output BCD data ：01 21 42 01
// Retain 3 Decimal place 
len_final = 8   string_buffer = 12142009
 Output BCD data ：12 14 20 09