//Linda Cobb
//Winter 98-99
//http://www.timestocome.com
//This program converts floating point numbers in base ten
//to thier binary floating point format in single precision

// (sign bit) (8 exponent bits) (23 bit mantissa)

#include <stdio.h>
#include <math.h>

#define	MAX	32					//size of array

//prototypes
void ConvertExpBinary(int array1[MAX], int exp);
void PrintData(int array2[MAX],float data);
void ConvertManBinary(int array3[MAX], float data, double mantissa);



void main (void){

	float	input;
	int		array[MAX];			//hold converted number for output
	int		i;					//loop control
	int		exponent;			//exponent part of number
	double	temp;				//for short term calculations
	double	fraction;			//fractional part of number (mantissa)

	//initalize array
	for(i=0; i<MAX; i++){
		array[i] = 0;
	}

	//get number to convert
	printf("\n Enter a floating point number to convert:> ");
	scanf("%f", &input);


  //convert number
	//first take care of sign bit...
	if(input < 0 ){		array[0] = 1;	}

	//calc exponent
	exponent = 0;
	temp = sqrt(input*input);		//convert to absolute value
	if((temp > 0.1)&&(temp < 1)){	//exponent must be zero
		exponent = 0;
	}else if( temp > 1){			//+ exponent
		while(temp > 1){
			exponent += 1;
			temp /= 10;	
		}
	}else{							//- exponent
		exponent = 1;
		while(temp < 1){
			exponent -= 1;
			temp *= 10;
		}

	}
	
	fraction = temp;
	
	ConvertExpBinary(array, exponent);	//convert exponent to binary

	ConvertManBinary(array, input, fraction);//convert mantissa to binary

	PrintData(array, input);			//print out data to screen

}



void ConvertExpBinary(int array1[MAX], int exp){

	double	temp;	
	int		i,j;

	temp = sqrt(exp*exp);
//*** not as elegant as a loop but faster...
	if(temp > 127){		array1[1] = 1;		temp -= 128;}
	if(temp > 63){		array1[2] = 1;		temp -= 64;	}
	if(temp > 31){		array1[3] = 1;		temp -= 32;	}
	if(temp > 15){		array1[4] = 1;		temp -= 16;	}
	if(temp > 7){		array1[5] = 1;		temp -= 8;	}
	if(temp > 3){		array1[6] =1;		temp -= 4;	}
	if(temp > 1){		array1[7] = 1;		temp -= 2;	}
	if(temp > 0){		array1[8] = 1;	}

	
	//convert exponent to two's complement
	if(exp < 0){
		i = 8;
		
		while(array1[i] != 1){			//locate leftmost bit
			i--;
		}
		
		for(j=i; j>0; j--){				//flip bits...
			if(array1[j] == 1){
				array1[j] = 0;
			}else{
				array1[j] = 1;
			}
		}
	}


}


void PrintData(int array2[MAX], float data){

	int i;				//loop control

	printf( "\n you entered:>  %f\n\n", data);
	printf( "The way this number is stored in the computer is...\n");
	for(i=0; i<MAX; i++){
		if((i%4 == 0)&&(i != 0)){
			printf(" ");
		}
		printf("%d", array2[i]);	
	}
	printf("\n\n");
}



void ConvertManBinary(int array3[MAX], float data, double mantissa){

	data = mantissa;
//***  sigh MS C5.0 won't subtract fractions... had to use decimals
	//what a pain!!!
	if(data >= .5){		array3[9] = 1;		data -= .5;	}	
	if(data >= .25){		array3[10] = 1;		data -= .25;	}
	if(data >= .125){		array3[11] = 1;		data -= .125;	}
	if(data >= .0625){		array3[12] = 1;		data -= .0625;	}
	if(data >= .03215){		array3[13] = 1;		data -= .03215;	}
	if(data >= .015625){		array3[14] = 1;		data -= .015625;	}
	if(data >= .0078125){		array3[15] = 1;		data -= .0078125;	}
	if(data >= .00390625){		array3[16] = 1;		data -= .00390625;	}
	if(data >= .001953125){		array3[17] = 1;		data -= .001953125;	}
	if(data >= .000965625){		array3[18] = 1;		data -= .000965625;	}
	if(data >= .00048828125){	array3[19] = 1;		data -= .00048828125;	}
	if(data >= .000244140625){	array3[20] = 1;		data -= .000244140625;	}
	if(data >= .000122070312){	array3[21] = 1;		data -= .000122070312;	}
	if(data >= .000061035156){	array3[22] = 1;		data -= .000061035156;	}
	if(data >= .000030517578){	array3[23] = 1;		data -= .000030517578;	}
	if(data >= .000015258789){	array3[24] = 1;		data -= .000015258789;	}
	if(data >= .000007629394){	array3[25] = 1;		data -= .000007629394;	}
	if(data >= .000003814697){	array3[26] = 1;		data -= .000003814697;	}
	if(data >= .000001907348){	array3[27] = 1;		data -= .000001907348;	}
	if(data >= .000000953675){	array3[28] = 1;		data -= .000000953675;	}
	if(data >= .000000476837){	array3[29] = 1;		data -= .000000476837;	}
	if(data >= .000000238418){	array3[30] = 1;		data -= .000000238418;	}
	if(data >= .000000238418){  array3[31] = 1;     data -= .000000238418;	}
}