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Source code

Details

Name: cr_div
Created: Feb 12, 2013
Updated: Feb 12, 2013
SVN Updated: Feb 12, 2013

Other project properties

Category: Arithmetic core
Language: Verilog
Development status: Alpha
Additional info:
WishBone Compliant: No
License: LGPL

Description

This core is a low latency divider that works by caching reciprocal values, then using a multiply to perform the divide rather than the usual divide operation. On first encountering a divide operation the reciprocal of the divisor is calculated, this takes the same amount of time as a normal divide. The next time the same divide is encountered the pre-calculated reciprocal is used. Reciprocals are stored in a small cache similar to a processor data cache.
a/b is the same as a * 1/b
In many cases the divisor 'b' remains the same within a loop. 1/b can be calculated to be essentially a constant; then all that's required is a multiply operation. As in the example, divides are performed using only three clock cycles when the reciprocal can be found in the cache.