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/*
Low level precision floating point lib
Author: Henrik Schiøler
*/
//low precision floating pt type
typedef struct myfloat
{
signed char mantissa;
signed char exponent;
} myfloat_type;
//convert from double to low precision type
void doub2mydouble(double arg, myfloat_type *res)
{
int exponent;
double temp;
exponent = ceil(log(abs(arg))/log(2)); //base 2 logarithm
temp=arg*pow(2,7-exponent);
res->mantissa = (signed char)temp;
res->exponent = exponent-7;
}
//convert from low precision type to double
double myfloat2double(myfloat_type *arg1)
{
double res = (double)(arg1->mantissa) * pow(2,arg1->exponent);
return res;
}
//multiply to low precision types
void mult_float(myfloat_type *arg1,myfloat_type *arg2,myfloat_type *result)
{
int temp;
unsigned char sign;
sign=0x80 & ((unsigned char)arg1-> mantissa ^ (unsigned char)arg2-> mantissa); //find sign of result
char i=0;
temp = (int)(arg1-> mantissa) * (int)(arg2-> mantissa);
temp = temp & 0x7f00; //take away sign from product
while(abs(temp)>128)
{
i++;
temp=temp>>1;
}
result->mantissa = (unsigned char) temp;
result->mantissa = result->mantissa | sign; //add recorded sign
result->exponent = arg1->exponent + arg2->exponent + i;
}
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