COP 4600 Project obj2 Spring 2012

1. COP 4600 Project obj2Spring 2012 Instructor: Dr. Euripides Montagne TA: Yuan Li

2. Task: simulate booting the OS • Load and execute the boot program • Input file: boot.dat • (1) segment table info • (2) instructions • Procedures: • (1) Load the boot program from boot.dat • (2) Save the segment table info and instructions to memory • (3) Interpret and execute instructions of the program • What you need to do: • Implement 11 functions described in obj2.c University of Central Florida

3. Functions to implement • Functions include • void boot(); • void Get_Instr(int prog_id, struct instr_type* instruction); • void Cpu(); • void Exec_Program(struct state_type* state); • int Memory_Unit(); • void Set_MAR(struct addr_type* addr); • int Fetch(struct instr_type* instruction); • int Read(struct instr_type* instruction); • int Write(struct instr_type* instruction); • void Display_pgm(segment_type* seg_table, int seg_num, pcb_type* pcb)

4. Step (1): Load the boot program from boot.dat Detailed description • An example of boot.dat

5. Step (2): Initialize memory and save the boot data to memory • Save segment information to segment table (Mem_Map) • struct segment_type * Mem_Map • See osdef.h for prototype of struct segment_type • See externs.h for declaration of Mem_Map • See simulator.c for initilization of Mem_Map Save instructions to main memory (Mem) • Struct instr_type* Mem

6. Memory Structure 0 SIO 75 1 DISK 2000 SKIP 0 2 #Inst, Acc, Base 3 JUMP [2,0] 4 SKIP 1 0 4, 0x01, 0 JUMP [3,0] 5 6 SKIP 0 1 4, 0x02, 4 JUMP [2,6] 7 2 8, 0x03, 8 8 SIO 400 3 1, 0x04, 16 PRNT 150 9 10 WIO 500 Mem_Map REQ [0,1] 11 12 WIO 0 REQ [2,1] 13 Segment table 14 SKIP 0 JUMP [1,0] 15 Memory END 20 16 Mem University of Central Florida

7. Instruction Set • Instruction format: opcode oprand • opcode_type: SIO, WIO, END, Device, REQ, JUMP, SKIP • SIO n • CPU burst for n cycles and start IO • WIO n • CPU burst for n cycles and wait for IO • END n • CPU burst for n cycles and end program

8. Instruction Set Instruction set • Device n • Always follows SIO • n is the bytes transferred (used to calculate time needed) • Device can be DISK, PRNT…… • SIO 75 • DISK 2000 • REQ [segment, offset] • Always follows WIO • PRNT 150 • WIO 0 • REQ [2,1] University of Central Florida

9. Instruction Set • JUMP [seg, off] • Jump to memory [seg, off] • SKIP n • Skip the next instruction for n times • SKIP 1 • JUMP [3,0] • SIO 400 University of Central Florida

10. Program Skeleton • In simulator.c • Main() • { • …… • Boot(); // Load boot.dat into memory, print out memory layout • …… • while( new_events != NULL ) { • …… • Interrupt(); // take out one event, print it out (consume one event) • …… • Exec_Program( ….); // Simulate a cpu cycle (generate one event) • …… • } • } University of Central Florida

11. Description of functions • Boot() reads in the file boot.dat to load the kernel and initialize Mem_Map and Mem • Get_Instr() // Read one instruction from a program • Display_pgm() // Display memory layout • Exec_Program() simulates a context switch that places a user program in execution • CPU() // Simulate one CPU cycle Next University of Central Florida

12. Function: Get_Instr() • viod Get_Instr( int prog_id, struct instr_type* instruction ) • Read an instruction from file Prog_Files[prog_id] • Load the instruction to struct instr_type* instruction • Process different types of instructions according to their specific format Back

13. Function: Display_pgm() • void Display_pgm( segment_type* seg_table, int seg_num, pcb_type* pcb ) • Display a single segment to output file. • seg_table: the segment table • seg_num: the index of the segment within seg_table to display (seg_table[seg_num]) • pcb: process control block that the segment table belongs to • See intro.doc at eustis.eecs.ucf.edu for detailed format of output Back

14. Function: CPU() • CPU() simulates the Central processing Unit • Fetches the next instruction from memory • Fetch() • Interprets the instruction • SIO, WIO, END, SKIP, JUMP • Creates a further event and insert it to the event queue if the instruction is • SIO, WIO, END Back University of Central Florida

15. Functions used by CPU() • void Set_MAR(struct addr_type* addr ) • Set Memory Address Register (MAR) to the given address and prepare the next memory location for the next Fetch(), read() or Write() operation • MAR = [segment, offset], logic address • int Memory_Unit( ) • Simulate the Memory Management Unit (MMU) that translates the logic address in the Memory Address Register (MAR) to a real physical address. • Address = base of segment in Mem_Map + offset in MAR • int Fetch(struct instr_type* instruction) • Get the instruction from memory, Mem[Memory_Unit()] and save to struct instr_type* instruction Back

16. Summary obj2 • The simulator (the main() function of simulator.c) calls Boot() to load programs from boot.dat • Boot() • first initializes the memory, • then call Get_Instr() repeatedly to read instructions from boot.dat, • and finally call Display_pgm() to print out the memory layout

17. Summary of obj2 • After Boot() is done, the simulator calls Exec_Program() to simulate a context switch • Then Exec_Program() calls CPU() to simulate Central Processing Unit • CPU() calls Set_MAR() to set the memory address register (MAR) to the value of CPU.state.pc • CPU() calls Fetch() to the next instruction from memory

18. Summary of obj2 • Fetch() • Calls Memory_Unit() to convert the logic address in MAR to real physical address • Then fetch the instruction in Mem[Memory_Unit()] • Finally, return to CPU() • CPU() then processes the instruction accordingly • The simulator terminates when all the events are done

19. Compile, test and submit your code • Make copyfiles • You do not need to execute this command if your obj2.c already exists. • This command can copy *.h and *.c from Dr. Montagne's home folder to yours. • Be careful, if you have already modified any objx.c file, please back up your *.c files before you run this comment. Otherwise, your code will be lost. • Make data2files • Modify obj2.c • Reuse obj1.c, you may need to modify obj1.c • Make sim, then run “sim” • Make compare OBJ=2 • If error happens, manually check data2.out and ossim.out, see what is wrong • You should expect “Done. Looks OK to me...” • Make submit • You should see “If you dont get any error message,submit is successful.” University of Central Florida