Sign-extension of immediate constants in an ALU using an adder i

Boots – shoes – and leggings

Patent

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

364784, G06F 750

Patent

active

054973414

ABSTRACT:
An arithmetic-logic unit (ALU) includes a Boolean logic unit and an integer logic unit, both of which are adapted to incorporate the sign extension function for immediate constants or reduced-width operands. The Boolean logic unit is constructed from 4:1 multiplexers (muxes), one mux for every bit in a full-width operand. The operands or constants are input to the select inputs for the muxes while signals representing the truth table for a predetermined Boolean operation are inputted to the four data inputs of each of the muxes. This allows for many different kinds of Boolean operations to be executed by the Boolean logic unit; each type of Boolean operation called for by an instruction opcode will have a corresponding set of truth table signals for input to the muxes. Sign-extension can be combined with the Boolean operation by using the sign bit of the reduced-width operand to select one of two modified sets of truth-table signals. The selected set of truth-table signals is applied to the data inputs of the muxes. An upper section of the truth-table sets has the sign bit of the reduced width operand encoded into the truth-table sets themselves. The integer arithmetic unit uses exclusive-OR gates, controlled by the sign bit, to selectively invert the reduced width operand. The output, which is always a positive number, is extended with zeros, then selectively inverted again before being added to a second operand in an adder. Addition or subtraction incorporating the sign-extension of one operand is thus possible with the modified integer arithmetic unit.

REFERENCES:
patent: 5224065 (1993-06-01), Yoshida
patent: 5333120 (1994-07-01), Gilbert
patent: 5418736 (1995-05-01), Widigen et al.

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Sign-extension of immediate constants in an ALU using an adder i does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Sign-extension of immediate constants in an ALU using an adder i, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sign-extension of immediate constants in an ALU using an adder i will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-1417027

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.