Fast shifter method and structure

A structure for normalizing a floating point number having an exponent and a mantissa comprising:

• shifter means for storing said floating point number, capable of performing from 1 to N-1 bit shifts in a single clock cycle, where N is an integer less than a length of the mantissa and greater than 2;
• means for analyzing the N most significant bits of the mantissa of the floating point number and providing central signals to said shifter means to cause from 1 to N-1 bit shifts of the mantissa if said floating point number is not normalized;
• and
• a shift counter for counting the number of bit shifts performed during the normalization of said floating point number.

A method of scaling a floating point number having an exponent and a mantissa comprising the steps of;

• determining the number of bit shifts required on the mantissa;
• performing a single bit shift on the mantissa if the number of bit shifts required is odd;
• and
• performing double bit shifts on the mantissa until no further bit shifts are required.

A structure for scaling a floating point number having an exponent and a mantissa comprising:

• shift means for performing one or two bit shifts on the mantissa of said floating point number;
• a scaling counter for storing the number of bit shifts required for scaling the number;
• means for providing a first control signal to said shift means in response to the least significant bit of said scaling counter, indicating that a single bit shift is required;
• means for disabling said scaling counter in response to said least significant bit of said scaling counter;
• means for resetting said least significant bit of said scaling counter when said single bit shift is performed;
• and
• means for causing said scaling counter to decrement its count by two and provide a count and signal to said shift means, indicating that a double bit shift is required.