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Instruction Class Reference

#include <machine.h>

List of all members.

Public Member Functions

void Decode ()

Public Attributes

unsigned int value
char opCode
char rs
char rt
char rd
int extra

Member Function Documentation

void Instruction::Decode (   ) 
 

Definition at line 590 of file mipssim.cc.

References BCOND, extra, OpInfo::format, IFMT, OP_BGEZ, OP_BGEZAL, OP_BLTZ, OP_BLTZAL, OP_UNIMP, OpInfo::opCode, opCode, rd, RFMT, rs, rt, SPECIAL, and value.

Referenced by Machine::OneInstruction().

00591 {
00592     OpInfo *opPtr;
00593     
00594     rs = (value >> 21) & 0x1f;
00595     rt = (value >> 16) & 0x1f;
00596     rd = (value >> 11) & 0x1f;
00597     opPtr = &opTable[(value >> 26) & 0x3f];
00598     opCode = opPtr->opCode;
00599     if (opPtr->format == IFMT) {
00600         extra = value & 0xffff;
00601         if (extra & 0x8000) {
00602            extra |= 0xffff0000;
00603         }
00604     } else if (opPtr->format == RFMT) {
00605         extra = (value >> 6) & 0x1f;
00606     } else {
00607         extra = value & 0x3ffffff;
00608     }
00609     if (opCode == SPECIAL) {
00610         opCode = specialTable[value & 0x3f];
00611     } else if (opCode == BCOND) {
00612         int i = value & 0x1f0000;
00613 
00614         if (i == 0) {
00615             opCode = OP_BLTZ;
00616         } else if (i == 0x10000) {
00617             opCode = OP_BGEZ;
00618         } else if (i == 0x100000) {
00619             opCode = OP_BLTZAL;
00620         } else if (i == 0x110000) {
00621             opCode = OP_BGEZAL;
00622         } else {
00623             opCode = OP_UNIMP;
00624         }
00625     }
00626 }

Member Data Documentation

int Instruction::extra
 

Definition at line 90 of file machine.h.

Referenced by Decode(), and Machine::OneInstruction().

char Instruction::opCode
 

Definition at line 87 of file machine.h.

Referenced by Decode(), and Machine::OneInstruction().

char Instruction::rd
 

Definition at line 89 of file machine.h.

Referenced by Decode(), and Machine::OneInstruction().

char Instruction::rs
 

Definition at line 89 of file machine.h.

Referenced by Decode(), and Machine::OneInstruction().

char Instruction::rt
 

Definition at line 89 of file machine.h.

Referenced by Decode(), and Machine::OneInstruction().

unsigned int Instruction::value
 

Definition at line 85 of file machine.h.

Referenced by Decode(), and Machine::OneInstruction().

The documentation for this class was generated from the following files:
Generated on Thu Sep 16 12:33:48 2004 for NachOS by doxygen 1.3.8