Apparatus and method for translating addresses
An apparatus and method is provided for translating addresses and rerouting them to preferably one of at least two destinations. This is accomplished through the use of a memory unit and a combination of logic operation units that essentially operate as a look-up translation table configurable by software. The apparatus includes an input to receive an address of a certain length and a memory unit that is adapted to receive a portion of the input address and output another address of a predetermined length which is mapped to the input. The method includes receiving input addresses of a certain length and performing an operation on a portion of the input address to determine its destination.
1 . An apparatus for translating addresses comprising:
an input bus to receive an input address of predetermined length;
a memory, in communication with the input bus, adapted to receive a first portion of the input address and to output an address of predetermined length mapped to the first portion of the input address; and
a multiplexer, in communication with the input bus and the memory, adapted to output either the input address or the output of the memory based on the status of a selection line;
wherein the status of the selection line is in response to a first operation on a second portion of the input address.
2 . The apparatus of claim 1 further comprising a destination select line, in communication with the memory and the input bus, wherein the status of the destination select line is in response to a second operation on a predetermined number of bits of the output from the memory and the second portion of the input address.
3 . The apparatus of claim 2 wherein the first and second operations are logical ‘OR’ operations.
4 . The apparatus of claim 1 wherein the first portion of the input address received at the memory comprises lower order bits.
5 . The apparatus of claim 1 wherein the second portion of the input address used to determine the status of the selection line comprises higher order bits.
6 . The apparatus of claim 5 wherein each address comprises 32 bits conforming to an address encoding standard.
7 . The apparatus of claim 1 wherein the memory is further configured to concatenate a predetermined number of additional bits to the output address.
8 . The apparatus of claim 1 wherein the predetermined number of additional bits equals one additional bit.
9 . The apparatus of claim 8 wherein the additional bit of the output address from the memory is combined with the second portion of the input address to determine the status of the destination select line.
10 . A method of translating addresses, comprising the steps of:
receiving an input address of predetermined length;
performing a table look-up based on a first portion of the input address;
producing a new address of predetermined length in response to the first portion of the input address;
selecting for transmission either the input address or a first portion of the new address based on a second portion of the input address; and
determining the destination of the input address or first portion of the new address in response to a second portion of the input address and a second portion of the new address.
11 . The method of claim 10 wherein the step of performing a table look-up based on a first portion of the input address use a preloaded look-up table.
12 . The method of claim 10 wherein the step of determining the destination of the input address or first portion of the new address comprises: performing a first logic on the second portion of the input address.
13 . The method of claim 12 wherein the step of determining the destination of the input address or first portion of the new address further comprises: performing a second logic operation on the output of the first logic operation and the second portion of the new address.
14 . The method of claim 13 wherein the first and second logic operations include one or more operations selected from a group consisting of OR, AND, NOT, NAND, NOR and XOR operations.
15 . The method of claim 13 wherein the first and second logic operations are ‘OR’ operations.
16 . The method of claim 13 further comprising the step of designating the output of the second logic operation as a destination select signal.