SPIM
SPIM is a MIPS processor simulator, designed to run assembly language code for this architecture. The program simulates R2000 and R3000 processors, and was written by James R. Larus while a professor at the University of Wisconsin-Madison.[1] The MIPS machine language is often taught in college-level assembly courses, especially those using the textbook Computer Organization and Design: The Hardware/Software Interface by David A. Patterson and John L. Hennessy (ISBN 1-55860-428-6).
The name of the simulator is a reversal of the letters "MIPS".
SPIM simulators are available for Windows (PCSpim), Mac OS X and Unix/Linux-based (xspim) operating systems. As of release 8.0 in January 2010, the simulator is licensed under the standard BSD license.
In January, 2011, a major release version 9.0 features QtSpim that has a new user interface built on the cross-platform Qt UI framework and runs on Windows, GNU/Linux, and Mac OS X. From this version, the project has also been moved to SourceForge for better maintenance. Precompiled versions of QtSpim for Linux (32-bit), Windows, and Mac OS X, as well as PCSpim for Windows are provided.
The SPIM operating system
The SPIM simulator comes with a rudimentary operating system, which allows the programmer usage of common used functions in a comfortable way. Such functions are invoked by the syscall-instruction. Then the OS acts depending on the values of specific registers.
| service | Trap code | Input | Output | Notes |
|---|---|---|---|---|
| print_int | $v0 = 1 | $a0 = integer to print | prints $a0 to standard output | base = 10 |
| print_string | $v0 = 4 | $a0 = address of first character | prints a character string to standard output | |
| read_int | $v0 = 5 | integer read from standard input placed in $v0 | base = 10 | |
| sbrk | $v0 = 9 | $a0 = number of bytes required | $v0= address of allocated memory | Allocates memory from the heap |
| exit | $v0 = 10 | |||
| file_open | $v0 = 13 | $a0 = full path, $a1 = flags, $a2 = UNIX octal file mode | $v0 = file descriptor | example; there are read/write/close functions, too |
The SPIM OS expects a label named main as a handover point from the OS-preamble.
SPIM Alternatives/Competitors
MARS (MIPS Assembler and Runtime Simulator)[2] is a Java-based IDE for the MIPS Assembly Programming Language and an alternative to SPIM. Its initial release was in 2005 and is under active development.
Imperas is a suite of embedded software development tools for MIPS architecture which uses Just-in-time compilation emulation and simulation technology. The simulator was initially released in 2008 and is under active development. There are over 30 open source models of the MIPS 32 bit [3] and 64 bit [4] cores.
See also
- GXemul (formerly known as mips64emul), another MIPS emulator. Unlike SPIM, which focuses on emulating a bare MIPS instruction set implementation, GXemul is written to emulate full computer systems based on MIPS microprocessors—for example, GXemul can emulate a DECstation 5000 Model 200 workstation
- OVPsim also emulates MIPS, and where all the MIPS models are verified by MIPS Technologies
- QEMU also emulates MIPS
- MIPS architecture