Table of Contents for MMURTL V1.0

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CHAPTER 1, INTRODUCTION...................................... 3

OVERVIEW.................................................... 3

WHAT THIS BOOK IS ABOUT..................................... 4

WHO SHOULD USE THIS BOOK.................................... 5

MY BASIC DESIGN GOALS (YOURS MAY VARY)...................... 6

A BRIEF DESCRIPTION OF MMURTL............................... 7

USES FOR MMURTL............................................. 9

SIMILARITIES TO OTHER OPERATING SYSTEMS.................... 10

HARDWARE REQUIREMENTS...................................... 10

CHAPTER 2, GENERAL DISCUSSION AND BACKGROUND................ 11

WHERE DOES ONE BEGIN?...................................... 11

YOU ARE WHERE YOU WERE WHEN................................ 12

THE DEVELOPMENT PLATFORM AND THE TOOLS..................... 13

THE CHICKEN AND THE EGG.................................... 13

EARLY HARDWARE INVESTIGATION............................... 15

THE REAL TASK AT HAND (PUN INTENDED)....................... 17

A STARTING POINT........................................... 17

THE CRITICAL PATH.......................................... 17

WORKING ATTITUDE........................................... 18

CHAPTER 3, THE TASKING MODEL................................ 19

TERMS WE SHOULD AGREE ON................................... 19

RESOURCE MANAGEMENT........................................ 20

TASK MANAGEMENT............................................ 21

SINGLE VS. MULTI USER...................................... 21

THE HARDWARE STATE......................................... 22

THE SOFTWARE STATE......................................... 22

CPU TIME................................................... 23

SINGLE TASKING............................................. 23

MULTITASKING............................................... 23

COOPERATIVE MULTITASKING................................... 24

PREEMPTIVE MULTITASKING.................................... 24

TASK SCHEDULING............................................ 25

WHO, WHEN, AND HOW LONG?................................... 25

SCHEDULING TECHNIQUES...................................... 26

TIME SLICING............................................. 26

SIMPLE COOPERATIVE QUEUING............................... 27

PRIORITIZED COOPERATIVE SCHEDULING....................... 27

VARIABLE TIME SLICING.................................... 28

OTHER SCHEDULING FACTORS................................... 28

MIXED SCHEDULING TECHNIQUES................................ 29

FULLY TIME SLICED, SOME COOPERATION...................... 29

TIME SLICED, MORE COOPERATIVE............................ 29

PRIMARILY COOPERATIVE, LIMITED TIME SLICING.............. 30

PRIMARILY COOPERATIVE, MORE TIME SLICING................. 30

THE TASKING MODEL I CHOSE.................................. 30

INTERRUPT HANDLING......................................... 32

CHAPTER 4, INTERPROCESS COMMUNICATIONS...................... 33

INTRODUCTION............................................... 33

MESSAGING AND TASKS........................................ 34

SYNCHRONIZATION............................................ 34

SEMAPHORES................................................. 35

PIPES...................................................... 36

MESSAGES................................................... 36

SEND AND WAIT............................................ 36

REQUEST()................................................ 41

RESPOND()................................................ 43

LINK BLOCKS.............................................. 43

REENTRANCY ISSUES.......................................... 44

INTERRUPT LATENCY.......................................... 45

MEMORY MANAGEMENT ISSUES................................... 46

CHAPTER 5, MEMORY MANAGEMENT................................ 47

INTRODUCTION............................................... 47

BASIC TERMS................................................ 47

MEMORY MODEL............................................... 48

SIMPLE FLAT MEMORY....................................... 48

PAGED FLAT MEMORY........................................ 49

DEMAND-PAGED FLAT MEMORY................................. 50

VIRTUAL PAGED MEMORY..................................... 51

DEMAND PAGED VIRTUAL MEMORY.............................. 53

DEMAND-PAGED MEMORY MANAGEMENT........................... 53

SEGMENTED MEMORY......................................... 53

MEMORY MANAGEMENT.......................................... 54

TRACKING LINEAR MEMORY ALLOCATION.......................... 55

BASIC MEMORY ALLOCATION UNIT............................... 55

LINKED LIST MANAGEMENT..................................... 55

MEMORY MANAGEMENT WITH TABLES.............................. 60

TRACKING PHYSICAL MEMORY................................... 60

INITIALIZATION OF MEMORY MANAGEMENT........................ 60

MEMORY PROTECTION.......................................... 62

AN INTEL BASED MEMORY MANAGEMENT IMPLEMENTATION............ 62

A FEW MORE WORDS ON SEGMENTATION......................... 61

HOW MMURTL USES PAGING..................................... 63

PAGE TABLES (PTS)........................................ 62

PAGE DIRECTORIES (PDS)................................... 62

THE MEMORY MAP........................................... 63

CHAPTER 6, HARDWARE INTERFACE............................... 72

HARDWARE ISOLATION......................................... 72

THE CPU.................................................... 73

THE BUS STRUCTURE.......................................... 74

SERIAL I/O................................................. 74

PARALLEL I/O............................................... 75

BLOCK-ORIENTED DEVICES..................................... 76

KEYBOARD................................................... 76

VIDEO...................................................... 77

DIRECT MEMORY ACCESS (DMA)................................. 79

TIMERS..................................................... 87

PRIORITY INTERRUPT CONTROLLER UNIT (PICU).................. 88

CHAPTER 7, OS INITIALIZATION................................ 89

BOOT ROM................................................... 89

THE BOOT SECTOR............................................ 90

OPERATING SYSTEM BOOT IMAGE............................... 100

OTHER BOOT OPTIONS........................................ 100

BASIC HARDWARE INITIALIZATION............................. 100

STATIC TABLES AND STRUCTURES.............................. 101

INITIALIZATION OF TASK MANAGEMENT......................... 101

INITIALIZATION OF MEMORY.................................. 102

DYNAMIC TABLES AND STRUCTURES............................. 103

CHAPTER 8, PROGRAMMING INTERFACES.......................... 104

APPLICATION PROGRAMMING INTERFACE......................... 104

MECHANICAL DETAILS........................................ 106

PORTABILITY CONSIDERATIONS................................ 107

ERROR HANDLING AND REPORTING.............................. 107

SYSTEMS PROGRAMMING INTERFACE............................. 108

INTERNAL COOPERATION...................................... 108

DEVICE DRIVER INTERFACES.................................. 108

A DEVICE-DRIVER INTERFACE EXAMPLE......................... 109

ANNOUNCING THE DRIVER TO THE OS......................... 110

A CALL TO THE DRIVER.................................... 112

CHAPTER 9, APPLICATION PROGRAMMING......................... 114

INTRODUCTION.............................................. 114

TERMINOLOGY............................................... 114

UNDERSTANDING 32-BIT SOFTWARE............................. 114

TABLE 9.1 - MEMORY ALIGNMENT............................ 115

OPERATING SYSTEM CALLING CONVENTIONS...................... 115

STACK USAGE............................................... 116

MEMORY MANAGEMENT......................................... 116

TABLE 9.2 - BASIC MEMORY MAP............................ 117

OPERATING SYSTEM PROTECTION............................... 118

APPLICATION MESSAGING..................................... 119

STARTING A NEW THREAD..................................... 119

JOB CONTROL BLOCK......................................... 120

BASIC KEYBOARD............................................ 121

BASIC VIDEO............................................... 122

TABLE 9.3 - FOREGROUND COLORS (LOW NIBBLE).............. 122

TABLE 9.4 - BACKGROUND COLORS (HIGH NIBBLE)............. 123

TERMINATING YOUR APPLICATION.............................. 123

REPLACING YOUR APPLICATION................................ 124

CHAPTER 10, SYSTEMS PROGRAMMING............................ 125

INTRODUCTION.............................................. 125

WRITING MESSAGE-BASED SYSTEM SERVICES..................... 125

INITIALIZING YOUR SYSTEM SERVICE.......................... 125

A SIMPLE SYSTEM SERVICE EXAMPLE........................... 126

LISTING 10.1 - A SYSTEM SERVICE......................... 126

THE REQUEST BLOCK......................................... 127

ITEMS IN THE REQUEST BLOCK................................ 127

THE SERVICE CODE.......................................... 128

CALLER INFORMATION IN A REQUEST........................... 128

ASYNCHRONOUS SERVICES..................................... 129

SYSTEM SERVICE ERROR HANDLING............................. 129

WRITING DEVICE DRIVERS.................................... 130

DEVICE DRIVER THEORY...................................... 131

BUILDING DEVICE DRIVERS................................... 131

HOW CALLERS REACH YOUR DRIVER............................. 132

DEVICE DRIVER SETUP AND INSTALLATION...................... 132

SYSTEM RESOURCES FOR DEVICE DRIVERS....................... 133

INTERRUPTS.............................................. 133

DIRECT MEMORY ACCESS DEVICE (DMA)....................... 134

TIMER FACILITIES........................................ 134

MESSAGE FACILITIES FOR DEVICE DRIVERS..................... 134

DETAILED DEVICE INTERFACE SPECIFICATION................... 135

DEVICE CONTROL BLOCK SETUP AND USE...................... 135

TABLE 10.1-. DEVICE CONTROL BLOCK DEFINITION............ 135

STANDARD DEVICE CALL DEFINITIONS.......................... 137

DEVICEOP FUNCTION IMPLEMENTATION........................ 138

DEVICESTAT FUNCTION IMPLEMENTATION...................... 139

DEVICEINIT FUNCTION IMPLEMENTATION...................... 139

INITIALIZING YOUR DRIVER.................................. 140

OS FUNCTIONS FOR DEVICE DRIVERS........................... 141

STANDARD DEVICE ERROR CODES............................... 141

CHAPTER 11, THE MONITOR PROGRAM............................ 142

INTRODUCTION.............................................. 142

ACTIVE JOB (VIDEO & KEYBOARD)............................. 142

INITIAL JOBS.............................................. 142

LISTING 11.1. SAMPLE INITIAL.JOB FILE................... 143

MONITOR FUNCTION KEYS..................................... 143

TABLE 11.1. MONITOR FUNCTION KEYS....................... 143

MONITOR PROGRAM THEORY.................................... 143

PERFORMANCE MONITORING.................................... 144

MONITOR SOURCE LISTING.................................... 145

LISTING 11.2.MONITOR PROGRAM SOURCE LISTING............. 145

CHAPTER 12, DEBUGGER....................................... 162

INTRODUCTION.............................................. 162

USING THE DEBUGGER........................................ 162

ENTERING THE DEBUGGER................................... 162

EXITING THE DEBUGGER.................................... 162

DEBUGGER DISPLAY........................................ 163

DEBUGGER FUNCTION KEYS.................................. 163

DEBUGGING YOUR APPLICATION................................ 165

DEBUGGER THEORY........................................... 165

TABLE 12.1.PROCESSOR EXCEPTIONS......................... 167

CHAPTER 13, KEYBOARD SERVICE............................... 169

INTRODUCTION.............................................. 169

AVAILABLE SERVICES........................................ 170

TABLE 13.1.AVAILABLE KEYBOARD SERVICES.................. 170

READ KEYBOARD........................................... 170

NOTIFY ON GLOBAL KEYS................................... 171

CANCEL NOTIFY ON GLOBAL KEYS............................ 171

ASSIGN KEYBOARD......................................... 171

KEY CODES AND STATUS...................................... 172

ALPHA-NUMERIC KEY VALUES................................ 172

TABLE 13.2 - .SHIFT STATE BITS.......................... 172

LOCK-STATE BYTE (THIRD BYTE)............................ 173

TABLE 13.3 - LOCK STATE BITS............................ 173

NUMERIC PAD INDICATOR................................... 173

KEY CODES................................................. 174

TABLE 13.4 - .KEYS VALUES............................... 174

FUNCTION STRIP KEY CODES................................ 175

TABLE 13.5 - FUNCTION KEY STRIP CODES................... 175

NUMERIC PAD KEY CODES................................... 176

TABLE 13.6 - NUMERIC PAD KEY CODES...................... 176

CURSOR, EDIT, AND SPECIAL PAD KEY CODES................. 176

13.7.ADDITIONAL KEY CODES............................... 176

YOUR KEYBOARD IMPLEMENTATION.............................. 177

CHAPTER 14, THE FILE SYSTEM SERVICE........................ 178

INTRODUCTION.............................................. 178

FILE SPECIFICATIONS....................................... 178

NETWORK FILE REQUEST ROUTING.............................. 178

FILE HANDLES.............................................. 179

FILE OPEN MODES........................................... 179

FILE ACCESS TYPE.......................................... 179

BLOCK MODE.............................................. 179

STREAM MODE............................................. 180

LOGICAL FILE ADDRESS...................................... 180

FILE SYSTEM REQUESTS...................................... 181

LISTING 14.1 - OPENFILE REQUEST IN C.................... 181

TABLE 14.1 - FILE SYSTEM SERVICE CODES.................. 181

PROCEDURAL INTERFACES..................................... 182

DEVICE ACCESS THROUGH THE FILE SYSTEM..................... 182

TABLE 14.2 - DEVICE STREAM ACCESS....................... 182

FILE SYSTEM FUNCTIONS IN DETAIL........................... 183

OPENFILE................................................ 183

CLOSEFILE............................................... 183

READBLOCK............................................... 184

WRITEBLOCK.............................................. 185

READBYTES............................................... 185

WRITEBYTES.............................................. 186

GETFILELFA.............................................. 187

SETFILELFA.............................................. 187

GETFILESIZE............................................. 188

SETFILESIZE............................................. 188

CREATEFILE.............................................. 189

RENAMEFILE.............................................. 190

DELETEFILE.............................................. 190

CREATEDIRECTORY......................................... 191

DELETEDIRECTORY......................................... 191

GETDIRSECTOR............................................ 192

FILE SYSTEM THEORY........................................ 193

INTERNAL FILE SYSTEM STRUCTURES......................... 193

FILE CONTROL BLOCKS................................... 193

FILE USER BLOCKS...................................... 193

FAT BUFFERS........................................... 194

FILE OPERATIONS......................................... 195

READ.................................................. 195

WRITE................................................. 195

CLOSE................................................. 195

CHAPTER 15, API SPECIFICATION.............................. 197

INTRODUCTION.............................................. 197

PUBLIC CALLS.............................................. 197

PARAMETERS TO CALLS (ARGS).............................. 197

TABLE 15.1 - SIZE AND TYPE PREFIXES................... 197

TABLE 15.2 - ADDITIONAL PREFIXES...................... 198

TABLE1 5.3 - COMPOUND PREFIXES........................ 198

ALPHABETICAL CALL LISTING................................. 202

ADDCALLGATE............................................. 202

ADDIDTGATE.............................................. 202

ALARM................................................... 203

ALIASMEM................................................ 203

ALLOCDMAPAGE............................................ 204

ALLOCEXCH............................................... 204

ALLOCOSPAGE............................................. 204

ALLOCPAGE............................................... 205

BEEP.................................................... 205

CHAIN................................................... 205

CHECKMSG................................................ 206

CLRSCR.................................................. 206

COMPARE................................................. 207

COMPARENCS.............................................. 207

COPYDATA................................................ 207

COPYDATAR............................................... 207

DEALIASMEM.............................................. 208

DEALLOCEXCH............................................. 208

DEALLOCPAGE............................................. 208

DEVICEINIT.............................................. 208

DEVICEOP................................................ 209

DEVICESTAT.............................................. 209

DMASETUP................................................ 210

FILLDATA................................................ 211

GETCMDLINE.............................................. 212

GETCMOSTIME............................................. 212

GETCMOSDATE............................................. 212

GETDMACOUNT............................................. 213

GETEXITJOB.............................................. 213

GETIRQVECTOR............................................ 213

GETJOBNUM............................................... 214

GETNORMVID.............................................. 214

GETPATH................................................. 214

GETPHYADD............................................... 215

GETPJCB................................................. 215

GETSYSIN................................................ 215

GETSYSOUT............................................... 215

GETTIMERTICK............................................ 216

GETTSSEXCH.............................................. 216

GETUSERNAME............................................. 216

GETVIDCHAR.............................................. 217

GETVIDOWNER............................................. 217

GETXY................................................... 217

INBYTE.................................................. 217

INDWORD................................................. 217

INWORD.................................................. 218

INWORDS................................................. 218

INITDEVDR............................................... 218

ISENDMSG................................................ 219

KILLALARM............................................... 220

LOADNEWJOB.............................................. 220

MASKIRQ................................................. 220

MICRODELAY.............................................. 220

MOVEREQUEST............................................. 221

NEWTASK................................................. 221

OUTBYTE................................................. 222

OUTDWORD................................................ 222

OUTWORD................................................. 222

PUTVIDATTRS............................................. 223

PUTVIDCHARS............................................. 223

QUERYPAGES.............................................. 224

READCMOS................................................ 224

READKBD................................................. 224

REGISTERSVC............................................. 224

REQUEST................................................. 225

RESPOND................................................. 226

SCROLLVID............................................... 226

SENDMSG................................................. 227

SETCMDLINE.............................................. 227

SETEXITJOB.............................................. 228

SETIRQVECTOR............................................ 229

TABLE 15.4 - HARDWARE IRQS............................ 230

SETJOBNAME.............................................. 230

SETNORMVID.............................................. 231

SETPATH................................................. 231

SETPRIORITY............................................. 231

SETSYSIN................................................ 232

SETSYSOUT............................................... 232

SETUSERNAME............................................. 232

SETVIDOWNER............................................. 232

SETXY................................................... 233

SLEEP................................................... 233

SPAWNTASK............................................... 233

TONE.................................................... 234

TTYOUT.................................................. 234

UNMASKIRQ............................................... 234

UNREGISTERSVC........................................... 235

WAITMSG................................................. 236

CHAPTER 16, MMURTL SAMPLE SOFTWARE......................... 237

INTRODUCTION.............................................. 237

COMMAND LINE INTERPRETER (CLI)............................ 237

INTERNAL COMMANDS....................................... 237

CLS (CLEAR SCREEN).................................... 238

COPY (COPY A FILE)................................... 238

DIR (DIRECTORY LISTING).............................. 238

DEBUG (ENTER DEBUGGER)................................ 239

DEL (DELETE A FILE)................................... 239

DUMP (HEX DUMP OF A FILE)............................. 239

EXIT (EXIT THE CLI)................................... 239

HELP (LIST INTERNAL COMMANDS)......................... 239

MONITOR (RETURN TO MONITOR)........................... 239

MD (MAKE DIRECTORY)................................... 240

PATH (SET FILE ACCESS PATH)........................... 240

RD (REMOVE DIRECTORY)................................. 240

RENAME (RENAME A FILE)................................ 241

RUN (EXECUTE A .RUN FILE)............................. 241

TYPE (VIEW A TEXT FILE ON THE SCREEN)................. 241

EXTERNAL COMMANDS......................................... 241

COMMANDS.CLI FILE....................................... 241

GLOBAL "HOT KEYS"....................................... 242

CLI SOURCE LISTING........................................ 242

LISTING 16.1.CLI SOURCE CODE LISTING VER. 1.0........... 242

A SIMPLE EDITOR........................................... 259

EDITOR SCREEN........................................... 259

EDITOR COMMANDS......................................... 259

TABLE 16.1 - FILE MANAGEMENT AND GENERAL COMMANDS....... 260

TABLE 16.2 - CURSOR AND SCREEN MANAGEMENT COMMANDS...... 260

LISTING 16.2.EDITOR SOURCE CODE......................... 261

DUMBTERM.................................................. 285

LISTING 16.3 - DUMBTERM SOURCE CODE..................... 285

PRINT..................................................... 288

LISTING 16.4.PRINT SOURCE CODE.......................... 288

SYSTEM SERVICE EXAMPLE.................................... 292

SERVICE.C LISTING....................................... 293

LISTING 16.5 - SIMPLE SERVICE SOURCE CODE............... 293

TESTSVC.C LISTING......................................... 295

LISTING 16.6 - TESTSVC.C................................ 295

CHAPTER 17, INTRODUCTION TO THE SOURCE CODE................ 296

COMMENTS IN THE CODE...................................... 296

CALLING CONVENTIONS....................................... 296

ORGANIZATION.............................................. 296

BUILDING MMURTL........................................... 299

LISTING 17.1 - ASSEMBLER TEMPLATE FILE.................. 300

USING PIECES OF MMURTL IN YOUR OS......................... 301

USING PIECES OF MMURTL IN OTHER PROJECTS.................. 301

CHAPTER 18, THE KERNEL..................................... 302

INTRODUCTION.............................................. 302

NAMING CONVENTIONS...................................... 302

KERNEL DATA............................................... 302

LISTING 18.1.KERNEL DATA SEGMENT SOURCE................. 303

LOCAL KERNEL HELPER FUNCTIONS............................. 303

ENQUEUEMSG................................................ 304

LISTING 18.2.QUEUEING FOR MESSAGES AT AN EXCHANGE....... 304

DEQUEUEMSG................................................ 305

LISTING 18.3.DE-QUEUEING A MESSAGE FROM AN EXCHANGE..... 305

DEQUEUETSS................................................ 305

LISTING 18.4.DE-QUEUEING A TASK FROM AN EXCHANGE........ 305

ENQUEUERDY................................................ 306

LISTING 18.5.ADDING A TASK TO THE READY QUEUE........... 306

DEQUEUERDY................................................ 307

LISTING 18.6.DE-QUEUEING THE HIGHEST PRIORITY TASK...... 307

CHKRDYQ................................................... 307

INTERNAL PUBLIC HELPER FUNCTIONS.......................... 308

REMOVERDYJOB............................................ 308

LISTING 18.8.REMOVING A TERMINATED TASK FROM THE READY

QUEUE................................................. 308

GETEXCHOWNER............................................ 309

LISTING 18.9.FINDING THE OWNER OF AN EXCHANGE......... 311

SETEXCHOWNER............................................ 312

LISTING 18.10.CHANGING THE OWNER OF AN EXCHANGE....... 312

SENDABORT............................................... 312

PUBLIC KERNEL FUNCTIONS................................... 314

REQUEST()............................................... 314

LISTING 18.12.REQUEST KERNEL PRIMITIVE CODE........... 314

RESPOND()............................................... 317

LISTING 18.13.RESPOND KERNEL PRIMITIVE CODE........... 317

MOVEREQUEST()........................................... 320

SENDMSG()............................................... 321

LISTING 18.15.SENDMSG KERNEL PRIMITIVE CODE........... 321

ISENDMSG().............................................. 323

LISTING 18.16.ISENDMSG KERNEL PRIMITIVE CODE.......... 324

WAITMSG()............................................... 325

CHECKMSG().............................................. 329

LISTING 18.18 -CHECKMSG KERNEL PRIMITIVE CODE......... 330

NEWTASK()............................................... 332

SPAWNTASK()............................................. 334

ALLOCEXCH()............................................. 337

DEALLOCEXCH()........................................... 338

GETTSSEXCH()............................................ 339

LISTING 18.23.GETTSS EXCHANGE CODE.................... 339

SETPRIORITY()........................................... 340

LISTING 18.24.SET PRIORITY CODE....................... 340

GETPRIORITY()........................................... 340

LISTING 18.25.GET PRIORITY CODE....................... 340

CHAPTER 19, MEMORY MANAGEMENT CODE......................... 342

INTRODUCTION.............................................. 342

MEMORY MANAGEMENT DATA.................................. 342

INTERNAL CODE............................................. 343

INITMEMMGMT............................................. 343

LISTING 19.3.CONTINUATION OF MEMORY MANAGEMENT INIT... 344

LISTING 19.4.CONTINUATION OF MEMORY MANAGEMENT INIT... 344

LISTING 19.6.ALLOCATION OF MEMORY MANAGEMENT EXCHANGE. 345

LISTING 19.7.FINISHING MEMORY MANAGEMENT INITI........ 345

FINDHIPAGE.............................................. 346

LISTING 19.8.FIND HIGHEST PHYSICAL PAGE CODE.......... 346

FINDLOPAGE.............................................. 347

LISTING 19.9.FIND LOWEST PHYSICAL PAGE CODE........... 347

MARKPAGE................................................ 348

LISTING 19.10.CODE TO MARK A PHYSICAL PAGE IN USE..... 348

UNMARKPAGE.............................................. 348

LISTING 19.11.CODE TO FREE A PHYSICAL PAGE OFR REUSE.. 349

LINTOPHY................................................ 349

LISTING 19.12.CODE TO CONVERT LINEAR TO PHYSICAL

ADDRESSES............................................. 349

FINDRUN................................................. 350

LISTING 19.13.CODE TO FIND A FREE RUN OF LINEAR MEMORY 350

ADDRUN.................................................. 352

ADDALIASRUN............................................. 353

LISTING 19.15.ADDING AN ALIASED RUN OF LINEAR MEMORY.. 353

ADDUSERPT............................................... 355

LISTING 19.16.ADDING A PAGE TABLE FOR USER MEMORY..... 355

ADDOSPT................................................. 356

LISTING 19.17.ADDING AN OPERATING SYSTEM PAGE TABLE... 357

PUBLIC MEMORY MANAGEMENT CALLS............................ 359

ADDGDTCALLGATE.......................................... 359

LISTING 19.18.ADDING A CALL GATE TO THE GDT........... 359

ADDIDTGATE.............................................. 360

LISTING 19.19.ADDING ENTRIES TO THE IDT............... 360

ALLOCOSPAGE............................................. 361

LISTING 19.20.ALLOCATING A PAGE OF LINEAR MEMORY...... 361

ALIASMEM................................................ 362

LISTING 19.21.CODE TO ALIAS MEMORY.................... 362

DEALIASMEM.............................................. 365

LISTING 19.22.CODE TO REMOVE ALIAS PTES............... 365

DEALLOCPAGE............................................. 366

LISTING 19.23.DEALLOCATING LINEAR MEMORY.............. 366

QUERYMEMPAGES........................................... 368

LISTING 19.24.CODE TO FIND NUMBER OF FREE PAGES....... 368

GETPHYADD............................................... 369

CHAPTER 20, TIMER MANAGEMENT SOURCE CODE................... 370

INTRODUCTION.............................................. 370

CHOOSING A STANDARD INTERVAL.............................. 370

LISTING 20.1.LOOP IN TIMER ISR.......................... 371

TIMER DATA................................................ 371

LISTING 20.2 - DATA AND CONSTANTS FOR TIMER CODE........ 372

TIMER CODE................................................ 372

LISTING 20.3 - EXTERNAL FUNCTIONS FOR TIMER CODE........ 372

THE TIMER INTERRUPT..................................... 372

LISTING 20.4 - THE TIMER INTERRUPT SERVICE ROUTINE 373

SLEEP()................................................. 375

LISTING 20.5 - CODE FOR THE SLEEP FUNCTION............ 375

ALARM()................................................. 376

LISTING 20.6 - CODE FOR THE ALARM FUNCTION............ 376

KILLALARM()............................................. 377

LISTING 20.7 - CODE FOR THE KILLALARM FUNCTION........ 377

MICRODELAY()............................................ 377

LISTING 20.8 - CODE FOR THE MICRDELAY FUNCTION........ 378

GETCMOSTIME()........................................... 378

LISTING 20.9.CODE TO READ THE CMOS TIME............... 378

GETCMOSDATE()........................................... 379

LISTING 20.10 - CODE TO READ THE CMOS DATE............ 379

GETTIMERTICK().......................................... 380

LISTING 20.11.CODE TO RETURN THE TIMER TICK........... 380

BEEP_WORK()............................................. 381

LISTING 20.12.HELPER FUNCTION FOR BEEP() AND TONE() 381

BEEP().................................................. 382

LISTING 20.13.CODE TO PRODUCE A BEEP.................. 382

TONE().................................................. 382

LISTING 20.14 - CODE TO PRODUCE A TONE................ 382

CHAPTER 21, INITIALIZATION CODE............................ 384

INTRODUCTION.............................................. 384

OS GLOBAL DATA............................................ 384

LISTING 21.1 - MAIN OPERATING SYSTEM DATA............... 385

OPERATING SYSTEM ENTRY POINT.............................. 386

LISTING 21.5 - END OF INITIALIZATION CODE............... 393

INITIALIZATION HELPERS.................................... 393

LISTING 21.6 - INITIALIZATION SUBROUTINES............... 394

LISTING 21.7 - INITIALIZE CALL GATES AMD THE IDT........ 397

CHAPTER 22, JOB MANAGEMENT CODE............................ 403

INTRODUCTION.............................................. 403

RECLAMATION OF RESOURCES.................................. 403