| asm | ||
| include | ||
| scripts | ||
| src | ||
| trainscript | ||
| .gitignore | ||
| Depfile | ||
| kernel.ld | ||
| LICENSE | ||
| Makefile | ||
| README.md | ||
| trainOS.pro | ||
| trainscript.md | ||
trainOS
Description
An operating system built around the language "trainscript" which is used to execute all user code in a virtual machine.
Current status:
The vm can execute some code and is able to call native code. Also it leaks memory. A lot of memory.
Todo List
- Fixing Memory Leaks
- Adding support for Modules
- Adding support for Pointer Types
- Adding support for String Type
Guidlines
- Calls to
dieordie_extrashould follow the following scheme:ContextName.ErrorName
Kernel Architecture
The kernel is a simple kernel that does not utilize paging. It has simple interrupt management where an interrupt handler can be registerd for each interrupt.
Bootstrapping
- Setup 16 kB stack space
- Clear screen and print boot message
- Initialize physical memory management (page allocator)
- Initialize interrupts
- Enable hardware interrupts
- Initialize timer
- Initialize C++ support
- Register status bar timer callback
- Start virtual machine (and run OS)
- Disable hardware interrupts
- Print stop message
Memory Allocation
The kernel features a simple malloc structure that allocates memor between 0x400000 and 0x800000 (4 MB heap space).
The allocator can be configured to "secure" its allocation list with a magic number by defining USE_MAGIC_SECURED_MALLOC in config.h.
It also features a surveillance mode that logs all allocations / frees. It can be enabled by defining USE_VERBOSE_MALLOC and USE_VERBOSE_FREE in config.h.
Interrupt Mapping
| Number | Interrupt |
|---|---|
| 0x00 - 0x1F | System Interrupts |
| 0x20 - 0x27 | IRQ0 - IRQ7 |
| 0x28 - 0x2F | IRQ8 - IRQ15 |
Virtual Machine Architecture
Type Format
The virtual machine supports 5 base types:
| Name | Description | Size |
|---|---|---|
| Void | A type that specifies a non-existent value. | 0 |
| Int | An integral number. | 32 |
| Real | A decimal number. | 32/64¹ |
| Text | A string value containing a sequence of bytes. | any² |
| Bool | A boolen value, either true or false. |
1³ |
¹) A real number is either a float (32 bits) or a double (64 bits) depending on the configuration in types.hpp.
²) A string value is sized the length of the string in bytes plus the size of the length specifier (32 bits).
³) A boolean is representet as a 1 bit value but due to architecture limitations it is stored with 32 bits.
Variable Format
Variables are stored in a type+pointer format where type stores the type of the variable and pointer either a pointer to the variable value or, if type is a pointer type, the pointer value of the variable.
OS Architecture
To be done.