[Cyan]<CedarChest6.0>Robotics>RobotInstructionImpl.mesa!1

RobotInstructionImpl.mesa

Created Saturday, June 9, 1984 2:25 pm PDT

Last edited by Eric Nickell, October 25, 1984 9:51:09 pm PDT

DIRECTORY

RobotDefs USING [Instruction],

RobotEvaluator USING [ApplyBinaryFcn, NewValueFromInteger, opMOD, opPlus],

RobotInstruction;

RobotInstructionImpl: CEDAR PROGRAM

IMPORTS RobotEvaluator

EXPORTS RobotInstruction

~ {

OPEN RobotInstruction;

v256: Value ← RobotEvaluator.NewValueFromInteger[256];

Current encoding (and therefore decoding) scheme:

#^Ioooootttttttt, where

# is the immediate bit

^ is the indirect bit

I is the index bit

ooooo is the opcode number

tttttttt is the tag

EncodeStatement: PUBLIC PROC [opNum: INTEGER, tag: Value, immediate, indirect, indexed: BOOL] RETURNS [value: Value] ~ {

instruction: RobotDefs.Instruction ← [

immediate: immediate,

indirect: indirect,

indexed: indexed,

opNum: opNum,

tag: 0

];

insValue: INTEGER ← LOOPHOLE[instruction];

value ← RobotEvaluator.ApplyBinaryFcn[

RobotEvaluator.opPlus,

RobotEvaluator.ApplyBinaryFcn[RobotEvaluator.opMOD, tag, RobotEvaluator.NewValueFromInteger[256]],

RobotEvaluator.NewValueFromInteger[insValue]];

};

DecodeStatement: PUBLIC PROC [integer: INTEGER] RETURNS [opNum, tag: INTEGER, immediate, indirect, indexed: BOOL ← FALSE] ~ {

instruction: RobotDefs.Instruction ← LOOPHOLE[integer];

RETURN [

opNum: instruction.opNum,

tag: instruction.tag,

immediate: instruction.immediate,

indirect: instruction.indirect,

indexed: instruction.indexed

];

};