82 lines
3 KiB
Markdown
82 lines
3 KiB
Markdown
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# MTGos Syscalls
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MTGos Syscalls is the method of requesting system resources under MTGos.
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## Basics
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It is based around C++ Objects and a set of Syscalls can be expressed as one Object.
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## List of Objects
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| Name | Object ID | Description |
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|-----------|------------|---------------------|
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| ScreenOut | 0 | interface to various screen-based output functions |
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| Keyboard | 1 | interface to both raw and translated Keyboard input |
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| Serial | 2 | i/o interface for a serial interface |
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| Disk | 3 | Raw disk i/o interface. Dangerous. |
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| MM | 4 | interface to request memory from the system |
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More objects may be added as MTGos evolves
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### ScreenOut
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class ScreenOut {
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public:
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ScreenOut(bool err);
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auto operator <<(string) -> Screen &; // puts(char *)
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auto clrscr() -> Screen &;
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auto setColor(BGColor, FGColor) -> Screen &;
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~ScreenOut();
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};
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Notes: The output function is not ANSI-Escape-Sequence compatible.
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### Keyboard
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class Keyboard {
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public:
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Keyboard();
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auto operator >>(char &) -> Screen &; // getc()
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auto operator >>(string &) -> Screen &; // gets an entire line
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auto getKeyCode() -> uint32_t; // gets a RAW keycode
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~Keyboard();
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};
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Note: RAW keycodes might be different per-model and per-architecture.
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### Serial
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class Serial {
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public:
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Serial();
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auto operator <<(string) -> Screen &; // puts(char *)
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auto operator >>(char &) -> Screen &; // getc()
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auto operator >>(string &) -> Screen &; // gets an entire line
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~Serial();
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};
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Note: The serial connection might silently fail. If no new character is got after 500 attempts, '\0' is returned.
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### Disk
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class Disk {
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public:
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Disk(char * diskName);
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auto readSector(uint64_t sectorNum, uint8_t buf[512]) -> Disk &;
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auto writeSector(uint64_t sectorNum, uint8_t buf[512]) -> Disk &;
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~Disk();
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};
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Note: A sector is 512 bytes in size.
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### MM
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class MM {
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public:
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MM();
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auto getPage() -> void *;
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auto freePage(void*) -> void;
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~MM();
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};
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Note: A page is 4KiB in size.
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## Calling Convention
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The first register is the syscall number. The syscall number is an at least 32-bit big register built the following way:
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OOOO OOOO OOOO OOOO SSSS SSSS SSSS SSSS
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where O is the object number and S the subnumber.
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The subnumber is the function number in the given object. The constructor is always 0x0000 and the deconstructor always 0xFFFF.
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* All arguments are pushed onto the stack.
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* All return values replace the value of the first register.
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* The second register contains the "Handle" returned from the constructor syscall.
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* The constructor syscall ignores the Handle register and will not change it.
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