data out: out
+== TeX ==============================================================
+
+The {\tt Memory} ship represents an interface to a storage space,
+which can be used to read from it or write to it. This storage space
+might be a fast on-chip cache, off chip DRAM, or perhaps even a disk drive.
+
+There may be multiple {\tt Memory} ships which interface to the same
+physical storage space. An implementation of Fleet must provide
+additional documentation to the programmer indicating which {\tt
+Memory} ships correspond to which storage spaces. A single {\tt
+Memory} ship may also access a ``virtual storage space'' formed by
+concatenating multiple physical storage spaces.
+
+\subsection*{Code Bag Fetch}
+
+When a word appears at the {\tt inCBD} port, it is treated as a {\it
+code bag descriptor}, as shown below:
+
+\begin{center}
+\setlength{\bitwidth}{3mm}
+{\tt
+\begin{bytefield}{37}
+ \bitheader[b]{36,6,5,0}\\
+ \bitbox{31}{Address}
+ \bitbox{6}{size}
+\end{bytefield}
+}
+\end{center}
+
+When a word arrives at the {\tt inCBD} port, it is treated as a memory
+read with {\tt inAddrRead=Address}, {\tt inStride=1}, and {\tt
+inCount=size}.
+
+\subsection*{Reading}
+
+When a word is delivered to {\tt inAddrRead}, the word residing in
+memory at that address is provided at {\tt out}.
+
+\subsection*{Writing}
+
+When a word is delivered to {\tt inAddrWrite} and {\tt inDataWrite},
+the word at {\tt inDataWrite} is written to the address specified by
+{\tt inAddrWrite}. Once the word is successfully committed to memory,
+the value {\tt inAddr+inStride} is provided at {\tt out} (that is, the
+address of the next word to be written).
+
+\subsection*{To Do}
+
+Stride and count are not implemented.
+
+We need a way to do an ``unordered fetch'' -- a way to tell the memory
+unit to retrieve some block of words in any order it likes. This can
+considerably accelerate fetches when the first word of the region is
+not cached, but other parts are cached. This can also be used for
+dispatching codebags efficiently -- but how will we make sure that
+instructions destined for a given pump are dispatched in the correct
+order (source sequence guarantee)?
+
+A more advanced form would be ``unordered fetch of ordered records''
+-- the ability to specify a record size (in words), the offset of the
+first record, and the number of records to be fetched. The memory
+unit would then fetch the records in any order it likes, but would be
+sure to return the words comprising a record in the order in which
+they appear in memory. This feature could be used to solve the source
+sequence guarantee problem mentioned in the previous paragraph.
+
== Fleeterpreter ====================================================
private long[] mem = new long[0];
public long readMem(int addr) { return mem[addr]; }
long size = val & 0x3f;
dispatch((int)addr, (int)size);
}
- if (count > 0 && writing) {
- if (box_inDataWrite.dataReadyForShip() && box_out.readyForDataFromShip()) {
- writeMem((int)addr, box_inDataWrite.removeDataForShip());
- box_out.addDataFromShip(0);
- count--;
- addr += stride;
+ if (count > 0) {
+ if (writing) {
+ if (box_inDataWrite.dataReadyForShip() && box_out.readyForDataFromShip()) {
+ writeMem((int)addr, box_inDataWrite.removeDataForShip());
+ box_out.addDataFromShip(0);
+ count--;
+ addr += stride;
+ }
+ } else {
+ if (box_out.readyForDataFromShip()) {
+ box_out.addDataFromShip(readMem((int)addr));
+ count--;
+ addr += stride;
+ }
}
- } else if (count > 0 && !writing) {
- if (box_out.readyForDataFromShip()) {
- box_out.addDataFromShip(readMem((int)addr));
- count--;
- addr += stride;
- }
-
- } else if (box_inAddrRead.dataReadyForShip() && box_out.readyForDataFromShip()) {
- Packet packet = box_inAddrRead.peekPacketForShip();
- if (packet.destination.getDestinationName().equals("read")) {
- box_out.addDataFromShip(readMem((int)box_inAddrRead.removeDataForShip()));
- } else if (packet.destination.getDestinationName().equals("write") && box_inDataWrite.dataReadyForShip()) {
- writeMem((int)box_inAddrRead.removeDataForShip(),
- box_inDataWrite.removeDataForShip());
- box_out.addDataFromShip(0);
- } else if (packet.destination.getDestinationName().equals("writeMany")
- && box_inStride.dataReadyForShip()
- && box_inCount.dataReadyForShip()) {
- addr = box_inAddrRead.removeDataForShip();
- stride = box_inStride.removeDataForShip();
- count = box_inCount.removeDataForShip();
- writing = true;
- } else if (packet.destination.getDestinationName().equals("readMany")
- && box_inStride.dataReadyForShip()
- && box_inCount.dataReadyForShip()) {
- addr = box_inAddrRead.removeDataForShip();
- stride = box_inStride.removeDataForShip();
- count = box_inCount.removeDataForShip();
- writing = false;
- }
+ } else if (box_inAddrRead.dataReadyForShip()) {
+ addr = box_inAddrRead.removeDataForShip();
+ stride = 0;
+ count = 1;
+ writing = false;
+
+ } else if (box_inAddrWrite.dataReadyForShip()) {
+ addr = box_inAddrWrite.peekPacketForShip().value;
+ box_inAddrWrite.removeDataForShip();
+ stride = 0;
+ count = 1;
+ writing = true;
}
}
command_valid <= 0;
command = ramread;
ihorn_full <= 1;
- `packet_data(ihorn_d) <= `instruction_data(command);
- `packet_dest(ihorn_d) <= `instruction_dest(command);
- end
+ `packet_data(ihorn_d) <= `instruction_data(command);
+ `packet_dest(ihorn_d) <= `instruction_dest(command);
end else if (cbd_pos < cbd_size) begin
current_instruction_read_from <= cbd_base+cbd_pos;
== Constants ========================================================
-== TeX ==============================================================
-\begin{verbatim}
-TODO: count/stride
-TODO: multiple interfaces to a single memory
-\end{verbatim}
== Contributors =========================================================
Adam Megacz <megacz@cs.berkeley.edu>
projects / fleet.git / blobdiff