Browse Prior Art Database

Fast and Flexible Address Generator for Indexing Multiple Non-Equally-Sized Tables

IP.com Disclosure Number: IPCOM000015307D
Original Publication Date: 2002-Jan-26
Included in the Prior Art Database: 2003-Jun-20
Document File: 4 page(s) / 245K

Publishing Venue

IBM

Abstract

The proposal deals with the problem of mapping multiple tables in a physical memory such that the individual table entries can be indexed efficiently without the requirement of an expensive and slow adder function. The novel aspect of the proposal is to realize

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  Fast and Flexible Address Generator for Indexing Multiple Non-Equally-Sized Tables

   The proposal deals with the problem of mapping multiple tables in
a physical memory such that the individual table entries can be
indexed efficiently without the requirement of an expensive and
slow adder function. The novel aspect of the proposal is to realize
a dynamic mapping, that can be changed through modification of the
contents of a small table. The proposal can also be used to
generate a static mapping by using the table as a "truth
table"-input to the synthesis process.

The proposed dynamic table mapping function is shown in figure 1,
which maps every table entry identified by a table identifier and
an index, on a unique memory address. One part of the address is
taken directly from the table index after removing the Y portion.
The other part of the address is obtained by a lookup operation
on a lookup table (LUT) using the table identifier and the X and
Y portions of the table index, as indices.

An application example is shown in figures 2, 3, and 4. Figure 2
shows a set of seven tables, having sizes of 80000h
(hexadecimal), 100000h, 180000h, and 200000h entries, which
corresponds to a total of 800000h entries. These table entries
are mapped on a contiguous address space from 0 to 7FFFFFh. The
address on which each table entry is mapped, is written in that
table entry in figure 2. The same mapping is also illustrated in
figure 3, which shows part of the address space. The table entry
that is...