QtMips ====== MIPS CPU simulator for education purposes. Documentation ------------- The project has started as diploma theses work of Karel Kočí. The complete text of the thesis [Graphical CPU Simulator with Cache Visualization](https://dspace.cvut.cz/bitstream/handle/10467/76764/F3-DP-2018-Koci-Karel-diploma.pdf) is available from the online archive of the [Czech Technical University in Prague](https://www.cvut.cz/). The document provides analysis of available alternative simulators, overview of the project architecture and basic usage information. The used [MIPS CPU](https://en.wikipedia.org/wiki/MIPS_architecture) building block diagram, and a pipeline model matches lecture slides prepared by Michal Štepanovský for the subject [Computer Architectures](https://cw.fel.cvut.cz/wiki/courses/b35apo/start). The course is based on the book [Computer Organization and Design, The HW/SW Interface](https://www.elsevier.com/books/computer-organization-and-design-mips-edition/patterson/978-0-12-407726-3) written by professors Paterson and Henessy. Additional documentation can be found in subdirectory ['docs'](docs) of the project. Build Dependencies ------------------ * Qt 5 * elfutils (libelf works too but there can be some problems) General Compilation ------------------- To compile whole project just run these commands: ``` qmake /path/to/qtmips make ``` Where `/path/to/qtmips` is path to this project root. (Be sure to use qt5 qmake.) Compilation for Local Execution ------------------------------- Because simulator it self and operating system stub are implemented as libraries you need to have that libraries in path where loader can found them. Binary looks for library at system libary paths (on Windows in actual directory as well) and on compiled in RPATH which is `../lib` (i.e., install into 'bin' and 'lib' directory is assumed): ``` qmake /path/to/qtmips "QMAKE_RPATHDIR += ../qtmips_machine ../qtmips_osemu" make ``` Or compile the application with static libraries ``` mkdir QtMips-build cd QtMips-build qmake CONFIG+=static" "CONFIG+=staticlib" -recursive ../QtMips/qtmips.pro ``` Alternativelly, you can setup ``` LD_LIBRARY_PATH=/path_to_QtMips/qtmips_machine /path_to_QtMips/qtmips_osemu ``` Accepted binary formats ------------------------ The simulator accepts ELF statically linked executables compiled for 32-bit big-endian MISP target. Optimal is use of plain mips-elf GCC toolchain. For more reffer to the [supported executable formats](docs/exec-formats-and-tools.md) documentation in the ['docs'](docs) projects subdirectory. Tests ----- There are two types of tests in QtMips. One type are unit tests for simulator it self and second one are integration tests with command line client and real compiled elf binaries. All these tests can be executed using script `tests/run-all.sh` or one by one by running respective `test.sh` scripts. Source files for unit tests can be found in path `qtmips_machine/tests` and integration tests are located in `tests` directory. Peripherals ----------- The simulator implements emulation of two peripherals for now. The firs is simple serial port (UART) which transmission (Tx) support only for now. It provides two registers, the first is status port. Bit 0 is reserved for notification that UART is busy and cannot accept next character. The second register is actual Tx buffer. The LSB byte of writtent word is transmitted to terminal window. Definition of peripheral base address and registers offsets follows. ``` #define SERIAL_PORT_BASE 0xffffc000 #define SERP_ST_REG_o 0x00 #define SERP_ST_REG_TX_BUSY_m 0x1 #define SERP_TX_REG_o 0x04 ``` The another peripheral allows to set three byte values concatenated to single word (read-only KNOBS_8BIT register) from user panel set by knobs and display one word in hexadecimal, decimal and binary format ('LED_LINE' register). There are two other words writtable which control color of RGB LED 1 and 2 (registers 'LED_RGB1' and 'LED_RGB2'). ``` #define SPILED_REG_BASE 0xffffc100 #define SPILED_REG_LED_LINE_o 0x004 #define SPILED_REG_LED_RGB1_o 0x010 #define SPILED_REG_LED_RGB2_o 0x014 #define SPILED_REG_LED_KBDWR_DIRECT_o 0x018 #define SPILED_REG_KBDRD_KNOBS_DIRECT_o 0x020 #define SPILED_REG_KNOBS_8BIT_o 0x024 ``` Limitations of the Implementation --------------------------------- * Only 'rdhwr' privileged instruction is implemented for now. All other privileged instructions and features dependent on them are not implemented. * Coprocessors (so no floating point unit nor any other type) * Memory access stall (stalling execution because of cache miss would be pretty annoying for users so difference between cache and memory is just in collected statistics) * Only limited support for interrupts and exceptions. When 'syscall' or 'break' instruction is recognized, emulation stops. Single step proceed after instruction. * Complete binary instruction check (we check only minimal set of bites to decode instruction, we don't check if zero sections are really zero unless we need it), but instruction decoder can be easily extended to distinguish instructions according additional subfiled. List of Actually Supported Instructions --------------------------------------- ADD ADDI ADDIU ADDU AND ANDI BEQ BEQL BGEZ BGEZAL BGEZALL BGEZL BGTZ BGTZL BLEZ BLEZL BLTZ BLTZAL BLTZALL BLTZL BNE BNEL BREAK CACHE CLO CLZ DIV DIVU EXT INS J JAL JALR JR LB LBU LH LHU LL LUI LW LWC1 LWD1 LWL LWR MADD MADDU MFHI MFLO MOVN MOVZ MSUB MSUBU MTHI MTLO MUL MULT MULTU NOR OR ORI PREF RDHWR ROTR ROTRV SB SC SDC1 SEB SEH SH SLL SLLV SLT SLTI SLTIU SLTU SRA SRAV SRL SRLV SUB SUBU SW SWC1 SWL SWR SYNC SYNCI SYSCALL TEQ TEQI TGE TGEI TGEIU TGEU TLT TLTI TLTIU TLTU TNE TNEI WSBH XOR XORI.