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Basic questions on dsp processors

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Member level 1
Dec 20, 2005
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hi guys
i am a newbie in field of DSP
i wanted to know what is VLIW architecture and why is it so popular in dsp
also what is a barrel shifter in a dsp processor

A Very Long Instruction Word or VLIW CPU architecture implements a form of instruction level parallelism. Similar to superscalar architectures, it uses several execution units (e.g. two multipliers), which enables the CPU to execute several instructions at the same time (e.g. two multiplications).

For more information go through the links:
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Barrel Shifter:
A barrel shifter is a hardware device that can shift a data word by any number of bits in a single operation. It is implemented like a multiplexer, each output can be connected to any input depending on the shift distance.

Take for example a 4-bit barrel shifter, with inputs A, B, C and D. The shifter can cyclicly alter the order of the outputs. i.e. it can 'shift' all of the outputs up to 3 units to the right (and thus make any cyclic combination of A, B, C and D). Barrel shifters have a variety of implementations, including being a vital component in digital filtering (alongside the ALU).

The barrel shifter is vital in floating point arithmetic hardware operations. For a floating point add and subtract operation, the mantissa of the number needs to be aligned n bits. If a conventional shifter is used, shifting a 32-bit number, in a worse case scenario, would require 32 clock cyles, creating way too much overhead.

& also checkout this link:

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