16-10-2012, 11:10 AM
Booth Multiplication Algorithm
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Booth Algorithm
Booth algorithm requires examination of the multiplier bits, and shifting of the partial product. Prior to the shifting, the multiplicand may be added to partial product, subtracted from the partial product, or left unchanged according to the following rules:
Look at the first least significant bits of the multiplier “X”, and the previous least significant bits of the multiplier “X - 1”.
I 0 0 Shift only
1 1 Shift only.
0 1 Add Y to U, and shift
1 0 Subtract Y from U, and shift or add (-Y) to U and shift
II Take U & V together and shift arithmetic right shift which preserves the sign bit of 2’s complement number. Thus a positive number remains positive, and a negative number remains negative.
III Shift X circular right shift because this will prevent us from using two registers for the X value.