The document summarizes different types of shifters used in microprocessor design including logical, arithmetic, barrel, and funnel shifters. It describes the function of each shifter type and provides examples. It then focuses on funnel shifters, explaining they can perform all shift operations, and describes two types of funnel shifter designs - array and multilevel funnel shifters. The array design uses an array of multiplexers while the multilevel design uses multiple levels of smaller multiplexers.

1. BANSAL COLLEGE OF ENGG. MANDIDEEP
SHIFTERS
PRESENTED BY: PRESENTED TO:
ATUL VERMA(EC25) MRS. RAVITESH MISHRA
BHARTI RAJPUT(EC29)
DEEPESH SHUKLA(EC32) A.P. BCE, MANDIDEEP
PARUL CHOUDHARY(EC63)
SANDESH GOHATIYA(EC88)
4/3/2013 1
DEEPESH

2. PRESENTATION CONTENT
Introduction of shifters
Types of shifters
• Logical shifter
• Arithmetic shifter
• Barrel shifter
• Funnel shifter
Types of funnel shifters
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3. INTRODUCTION OF SHIFTER
Shifters are important element in many microprocessor
design for arithmetic shifting, logical shifting, and
rotation (Barrel shifter) functions.
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4. TYPES OF SHIFTER
There are several commonly used shifters-
•Logical shifter
•Arithmetic shifter
•Barrel shifter(rotator)
•Funnel shifter
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5. LOGICAL SHIFTER
It shift the number to the left or right and fills empty spots
with 0’s.
Example-
Logic Shift Right 2
110110 → _ _1101 → 001101
Example-
Logic Shift Left 2
110110 → 0110_ _ → 011000
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6. ARITHMETIC SHIFTER
Same as logical shifter, but on right shift fills the most
significant bits with copies of the sign bit (to properly
sign, extend 2’s complement numbers when using
right shift by k for division by 2^k).
Example- Arithmetic Shift Right 2
110110 → _ _1101 → 111101
For Left shift, same as Logic Shifter.
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7. BARREL SHIFTER
•Barrel shifter is a very important part of a
combinational logic block.
•It have the ability to shift data work in a single
operation over standard shift left or right registers that
utilize more than one clock cycle.
•Rotates numbers in a cycle such that empty spots are
filled with bits shifted off the other end.
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8. Example-
Barrel Shift Right 2
110110 → _ _1101 → 101101
Example-
Barrel Shift Left 2
110110 → 0110_ _ → 011011
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9. FUNNEL SHIFTER
The funnel shifter perform all there such operations.
•Logic Shift Right
• Logic Shift Left
•Arithmetic Shift Right
• Arithmetic Shift Left
• Barrel Shift Right
• Barrel Shift Left.
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10. FUNCTION OF DESIGN
B is filled with bits based on original number is C
what kind of shifter we want. Output is Y.
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11. TABLE – FUNNEL SHIFTER
Table lists what inputs should be applied to
perform a left or right shift of an n-bit word A by k
bits.
Generating the offset for left shifts requires a 2’s
complement subtraction.
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12. TABLE- FUNNEL SHIFTER OPERATION
Right or left is determined by offset.
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13. TYPES OF FUNNEL SHITER
There are two different types of funnel shifters.
•Array funnel shifter
•Multilevel funnel shifter
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14. ARRAY FUNNEL SHIFTER
The simplest funnel shifter design consist o an array of
n- input multiplexers accepting 1 of n-hot select signals
(one multiplexer for each output bit ). Such an array
shifter is shown in figure using n- mos pass transistor
for a 4 bit shifter. The shift amount is conditionally
inverted and allocated into select signals that are fed
vertically across the array. The outputs are taken
horizontally. Each row of transistors attached to an
output forms one of the multiplexers.
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15. K[1:0]
Left Inverters and decoders
S3 S2 S1 S0
Y3
Y2
Z6
Y1
Z5
Y0
Z4
Z3 Z2 Z1 Z0
ARRAY FUNNEL SHIFTER 15
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16. The array funnel shifter works reasonably
well for medium sized shifters in transistor level
design, but has high parasitic capacitance in larger
shifters and is not amenable to standard cell designs.
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17. MULTILEVEL FUNNEL SHIFTER
K1 K0 determines offset
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18. Fig. shows a 4 bit shifter based on multiple levels of
smaller multiplexers (which of course, can be
transmission gates). In general, the first level shift
+n/2 the second by n/4, and so fourth until the find
level shift with such a structure, no decoder is
necessary. The XOR gates on the control inputs
conditionally invert the shifts.
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19. THANKYOU
BHARTI 19
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