Aryadev Chavali
525694bea7
A page is a flexibly allocated structure of bytes, with a count of the number of bytes already allocated (used) and number of bytes available overall (available), with a pointer to the next page, if any. heap_t is a linked list of pages. One may allocate a requested size off the heap which causes one of two things: 1) Either a page already exists with enough space for the requested size, in which case that page's pointer is used as the base for the requested pointer 2) No pages satisfy the requested size, so a new page is allocated which is the new end of the heap.
Oreo's Virtual Machine (OVM)
A stack based virtual machine in C11, with a dynamic register setup which acts as variable space. Deals primarily in bytes, doesn't make assertions about typing and is very simple to target.
How to build
Requires GNU make, a compliant C11 compiler. Code base has been
tested against gcc and clang, but given how the project has been
written without use of GNU'isms it shouldn't be an issue to compile
using something like tcc or another compiler (look at
here to change the compiler).
To build everything simply run make. This will build:
- instruction bytecode system which allows one to target the VM by writing and reading instruction bytecode
- VM executable which can execute bytecode (your
javaexecutable) - Assembler executable which can assemble compliant assembly code to VM bytecode
- Assembly examples which provide some source code examples on common programs one may write. Use this to figure out how to write compliant assembly.
One may also build each component individually through the corresponding recipe:
make libmake vmmake asmmake examples
Instructions to target the virtual machine
You need to link with the object files for
base.c, darr.c and
inst.c to be able to properly target the OVM.
The basic idea is to create instructions via inst_t then using the
inst(s)_write_* API to generate bytecode (and write to a file).
Then to execute the program, the virtual machine interpreter ovm.out
is used.
For clarity, one may build lib (make lib) then use the resulting
object files to link and create bytecode for the virtual machine.
Lines of code
| 216 | ./vm/runtime.h |
| 83 | ./vm/main.c |
| 718 | ./vm/runtime.c |
| 452 | ./lib/inst.c |
| 39 | ./lib/darr.h |
| 193 | ./lib/inst.h |
| 90 | ./lib/base.h |
| 39 | ./lib/base.c |
| 77 | ./lib/darr.c |
| 315 | ./asm/parser.c |
| 140 | ./asm/main.c |
| 68 | ./asm/lexer.h |
| 37 | ./asm/parser.h |
| 439 | ./asm/lexer.c |