CSE 378 HW7 - The Memory Mapping Container

Introduction

The container is intended to be easily integrated into your machine, requiring only that you connect to the set of input and output passerelle components that lie along its exterior. However, once you have added it to your model, you should immediately connect the Mem input port of the Block Controller device to your memory. It won't matter until Part C of the assignment, but do it now so you don't forget and become frustrated later because things aren't working.

The container always provides outputs that correspond to having read some memory mapped resource. When you're executing, mostly these are not needed, but they do no harm.

The container's inputs control when it writes the mapped resources, as described below.

Container Inputs

Name	What You Should Provide To It
Address	The effective address computed by the current instruction, if it is a load or store. Irrelevant otherwise.
Write Requested	Should be 1 when the current instruction is a store, 0 otherwise.
Data In	The contents of the source register on a store. Irrelevant otherwise.
IsRFE	Should be 1 if the current instruction is an rfe, 0 otherwise.
Exception	Should be 1 if an exception/interrupt/trap is being raised during this instruction, 0 otherwise.
NewEPC	Should be the PC of the currently executing instruction.
NewCause	If Exception is asserted, should be the exception cause number. Irrelevant otherwise.
Memory Size	Attach this to the Sz output of the Memory Interface component in your model. (It provides the size of physical memory.)

If your inputs are connected like this, and work, the container will handle setting the EPC, Cause, and Status registers correctly when Exception is asserted. It will also cause the correct mapped resource to be written by store instructions whose effective addresses name such a resource.

Container Outputs

The outputs are always valid, no matter what.

Name	Meaning
WasHandled	The container "owns" memory addresses 0x40000000 through 0x4000003f. The EffectiveAddress input was for an address in that range.
HandlerAddrOut	The current value of the Handler Address register.
StatusOut	The current value of the Status Register.
BaseRegOut	The current value of the Memory Base Register.
LengthOut	The current value of the Memory Length Register.
EPC Out	The current value of the EPC register.
Read Out	Assuming the EffectiveAddress is a valid mapped resource address, the current value of that resource. Undefined otherwise.