Trailing or leading digit anticipator

A method of estimating a number of leading zeros in a result of an arithmetic operation performed on two or more fixed point numbers, the method comprising:

• generating, using an input-encoding circuit, an encoded input string from the two or more fixed point numbers;
• generating, using a surrogate string generation circuit, a surrogate string whose leading one is an estimate of a leading one in the result of the arithmetic operation by examining consecutive windows of the encoded input string;
• setting a selected bit of the surrogate string to a predetermined value when the corresponding window of the encoded input string comprises a pattern that indicates that the selected bit or a further bit of the result of the arithmetic operation will have the predetermined value;
• and
• outputting an estimate of the number of leading zeros in the result of the arithmetic operation based on the leading one in the surrogate string.

A non-transitory computer readable storage medium having stored thereon a computer readable dataset description of an integrated circuit that, when processed in an integrated circuit manufacturing system, causes the integrated circuit manufacturing system to manufacture the leading zero anticipator configured to estimate a number of leading zeros in a result of an arithmetic operation performed on two or more fixed point numbers, the leading zero anticipator comprising:

• an input encoding circuit configured to generate an encoded input string from the two or more fixed point numbers;
• a surrogate string generation circuit configured to:
• generate a surrogate string whose leading one is an estimate of a leading one in the result of the arithmetic operation by examining consecutive windows of the encoded input string;
• and
• setting a selected bit of the surrogate string to a predetermined value when the corresponding window of the encoded input string comprises a pattern that indicates that the selected bit or a further bit of the result of the arithmetic operation will have the predetermined value;
• and
• an output configured to provide the estimate of the number of leading zeros in the result of the arithmetic operation based on the leading one in the surrogate string.