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SPIM simulator

SPIM simulator. SPIM. SPIM Simulator that runs programs written for MIPS R2000/R3000 processors Advantages to using a machine simulator MIPS workstation are not generally available. Provides better environment for low-level programming than an actual machine: detect more errors

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SPIM simulator

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  1. SPIM simulator

  2. SPIM • SPIM • Simulator that runs programs written for MIPS R2000/R3000 processors • Advantages to using a machine simulator • MIPS workstation are not generally available. • Provides better environment for low-level programming than an actual machine: • detect more errors • provide more features • give convenient edit-assemble-load development cycle, compared to using a circuit board. • easy to identify and fix the bugs. • Disadvantages • The programs run slower than on a real machine.

  3. OS vs Applications • An application program asks the kernel to do I/O by making system calls. • The kernel implements these system calls by talking directly to the hardware. Application programs Programs make system calls asking kernel to do I/O Kernel Kernel controls I/O devices directly Hardware

  4. SPIM’s System Calls • SIMP provides a small set of 10 OS-like system services through the system call (syscall) instruction. • How t get a system service? • $v0 : system call code • $a0...$a3 : arguments ($f12 <- floating point values) • syscall (initiate system service) • $v0 :results ($f0: for the floating point) • exit: stop running a program.

  5. 1 ## hello.a -prints out "hello world" 2 ## 3 ## 4 ## a0 - points to the string 5 ## 6 7 ############################################################ 8 # # 9 # text segment # 10 # # 11 ############################################################ 12 13 .text 14 .globl __start 15 __ start : # execution starts here 16 la $a0,str # put string address into a0 17 li $v0,4 # system call to print 18 syscall # out a string 19 20 li $v0,10 21 syscall # au revoir ... 22 23 24 ############################################################ 25 # # 26 # data segment # 27 # # 28 ############################################################ 29 30 .data 31 str .asciiz "hello world" 32 33 ## 34 ## end of file hello.a

  6. 3 kinds of SPIM • spim for UNIX(installed in adam & cain) • runs on any type of terminal • type command on terminal • xspim for UNIX(installed in adam & cain) • runs on X-window system • commands & results are always displayed • much easier to run • PCSpim for MS Windows • runs on MS Windows system • similar to xspim • must be installed in your PC to use

  7. PCSpim(starting) • Registers window • Text segment • Data Segment • Messages window

  8. PCSpim(4 Windows) • Registers window • shows the values of all registers in the MIPS CPU and FPU • Text segment • address of instruction (hexadecimal) • instruction’s numerical encoding (hexadecimal) • instruction’s mnemonic description • line number in assembly file • actual line of assembly file • Data Segment • data loaded into program’s memory • data on the program’s stack • Messages window • messages for SPIM(including error messages) [0x00400000] 0x8fa40000 lw $4, 0($29) ; 89 : lw $a0, 0($sp)

  9. PCSpim(Loading, Running, Debugging) • Loading • File -> Open • select assembly file • Running • Simulator -> Go • results are displayed in console • Single step • Simulator -> Single Step(F10) • run an instruction at a time • Multiple steps • Simulator -> Multiple Step…(F11) • run given number of instructions at a time • Breakpoint • Simulator -> Breakpoints(Ctrl + B) • stop program immediately before it executes a particular instruction

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