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This commit is contained in:
Mark 2025-03-04 19:18:21 -08:00
parent 32070e9af4
commit cf60d6734a
Signed by: Mark
GPG Key ID: C6D63995FE72FD80
23 changed files with 303 additions and 317 deletions
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48
Makefile
View File

@ -2,7 +2,7 @@ BUILD=./build
# Default rule
.PHONY: default
default: all
default: $(BUILD)/disk.img
# Remove all build files
.PHONY: clean
@ -10,23 +10,18 @@ clean:
rm -drf $(BUILD)
cd tetros; cargo clean
# Make everything
# (but don't run qemu)
.PHONY: all
all: img
#
# MARK: boot
# MARK: disk
#
# Compile tetros as library
# Compile tetros as a library
# (so that we can link it with a custom linker script)
LIB_SRC = ./tetros/Cargo.toml ./tetros/Cargo.lock $(shell find ./tetros/src -type f)
$(BUILD)/tetros.lib: $(LIB_SRC)
@mkdir -p $(BUILD)
cd tetros && \
env RUSTFLAGS="-C soft-float" \
cargo rustc \
--manifest-path="./Cargo.toml" \
-Z build-std=core \
-Z build-std-features=compiler-builtins-mem \
--target "./targets/x86-unknown-none.json" \
@ -35,7 +30,7 @@ $(BUILD)/tetros.lib: $(LIB_SRC)
-- \
--emit link="$(CURDIR)/$@"
# Link tetros
# Link tetros using custom linker script
BIOS_LD = ./tetros/linkers/x86-unknown-none.ld
$(BUILD)/tetros.elf: $(BUILD)/tetros.lib $(BIOS_LD)
ld \
@ -49,13 +44,13 @@ $(BUILD)/tetros.elf: $(BUILD)/tetros.lib $(BIOS_LD)
objcopy --only-keep-debug "$@" "$@.sym"
objcopy --strip-debug "$@"
# Wrap tetros in three-stage BIOS loader
# Wrap tetros in BIOS loader
# Parameters:
# - BIOS_SRC: source directory of bios assembly
# - STAGE2_SECTOR: the index of the first sector of the stage 2 binary on the disk
BIOS_SRC = ./bios
STAGE2_SECTOR = 1
$(BUILD)/bios.bin: $(wildcard $(BIOS_SRC)/*.asm) $(BUILD)/tetros.elf
$(BUILD)/disk.img: $(wildcard $(BIOS_SRC)/*.asm) $(BUILD)/tetros.elf
@mkdir -p "$(BUILD)"
nasm \
-f bin \
@ -66,30 +61,12 @@ $(BUILD)/bios.bin: $(wildcard $(BIOS_SRC)/*.asm) $(BUILD)/tetros.elf
-i "$(BIOS_SRC)" \
"$(BIOS_SRC)/main.asm"
# Extract full mbr (first 512 bytes)
$(BUILD)/mbr.bin: $(BUILD)/bios.bin
@mkdir -p "$(BUILD)"
@echo ""
dd if="$<" bs=512 count=1 of="$@"
# Extract stage 2 (rest of file)
$(BUILD)/stage2.bin: $(BUILD)/bios.bin
@mkdir -p "$(BUILD)"
@echo ""
dd if="$<" bs=512 skip=1 of="$@"
#
# MARK: bundle
# MARK: qemu
#
# Do not use `-enable-kvm` or `-cpu host`,
# this confuses gdb.
#
# Make full disk image
.PHONY: img
img: $(BUILD)/disk.img
$(BUILD)/disk.img: $(BUILD)/mbr.bin $(BUILD)/stage2.bin
@mkdir -p $(BUILD)
@echo ""
dd if="$(BUILD)/mbr.bin" of=$@ conv=notrunc bs=512
dd if="$(BUILD)/stage2.bin" of=$@ conv=notrunc seek=$(STAGE2_SECTOR) bs=512
.PHONY: qemu
qemu: $(BUILD)/disk.img
@ -128,6 +105,3 @@ qemu-gdb: $(BUILD)/disk.img
-fda "$<" \
-gdb tcp::26000 \
-S
# Do not use `-enable-kvm` or `-cpu host`,
# this confuses gdb.

5
README.md
View File

@ -1,14 +1,11 @@
# TetrOS: bare-metal tetris
## TODO:
- Fix stage 1 loader
## Features
- Compiles to a standalone disk image
- Written from scratch using only Nasm and Rust
- Custom BIOS bootloader
- 32-bit x86 OS
- 🌟 Detailed comments. Read the [makefile](./Makefile), then start in [`./bios/main.asm`](./bios/main.asm).
- Detailed comments. Read the [makefile](./Makefile), then start in [`./bios/main.asm`](./bios/main.asm).
## Non-Features

59
bios/main.asm
View File

@ -1,30 +1,25 @@
sectalign off
; This program expects two external macros:
; The following code expects two external macros:
; STAGE3, a path to the stage3 binary
; STAGE2_SECTOR, the location of stage 2
; on the disk, in 512-byte sectors.
; On a gpt disk, this is probably 34.
; Stage 1 is MBR code, and should fit in LBA 0
; (512 bytes). Layout is as follows:
; (Format is `offset, length: purpose`)
; 0, 424: x86 boot code
; 440, 4: Unique disk signature
; 444, 2: unknown
; 446, 16*4: Array of four legacy MBR records
; 510, 2: signature 0x55 0xAA
; 512 to end of logical block: reserved
;
; See https://uefi.org/specs/UEFI/2.10/05_GUID_Partition_Table_Format.html
;
; Both of these are set in the makefile.
; BIOS loads stage 1 at 0x7C00
ORG 0x7C00
SECTION .text
; stage 1 is sector 0, loaded into memory at 0x7C00
; Stage 1 is MBR code, and should fit in LBA 0
; (i.e, in the first 512 bytes).
%include "stage1.asm"
; Stage 1 is at most 440 bytes
; This limit is set by the GPT spec.
; See https://uefi.org/specs/UEFI/2.10/05_GUID_Partition_Table_Format.html
;
; This `times` will throw an error if the subtraction is negative.
times 440-($-$$) db 0
db 0xee
@ -32,30 +27,38 @@ db 0xee
times 510-($-$$) db 0
; MBR signature.
; This isn't loaded into memory, it's
; only here for debugging.
; This tells the BIOS that this disk is bootable.
db 0x55
db 0xaa
; Include stage 2. This is loaded into memory by stage 1.
; (stage 1 loads both stage 2 and stage 3)
;
; Stage 2 sets up protected mode, sets up the GDT,
; and initializes a minimal environment for stage 3.
;
; On a "real" boot disk, this data will not immediately follow stage 1.
; It would be stored in a special disk partition.
;
; We don't need this kind of complexity here, though, so we store
; stage 2 right after stage 1. (This is why STAGE2_SECTOR is 1.)
;
; This is nice, because the layout of the code on our boot disk
; matches the layout of the code in memory. THIS IS NOT USUALLY THE CASE.
stage2:
%include "stage2.asm"
align 512, db 0
stage2.end:
; The maximum size of stage2 is 4 KiB,
; This fill will throw an error if the subtraction is negative.
times (4*1024)-($-stage2) db 0
; Pad to 0x9000.
; This needs to match the value configured in the stage3 linker script
times (0x9000 - 0x7c00)-($-$$) db 0
; Pad to 0x3000.
; This makes sure that state3 is loaded at the address
; the linker expects. Must match the value in `tetros/linkers/x86-unknown-none.ld`.
times (0x8000 - 0x7c00)-($-$$) db 0
; Include stage 3, the binary compiled from Rust sources.
stage3:
%defstr STAGE3_STR %[STAGE3]
incbin STAGE3_STR
align 512, db 0
.end:
; TODO: why? Of the disk, or of memory?
; the maximum size of the boot loader portion is 384 KiB
times (384*1024)-($-$$) db 0

29
bios/print.asm
View File

@ -1,22 +1,21 @@
SECTION .text
USE16
; provide function for printing in x86 real mode
; print a string and a newline
; CLOBBER
; ax
; Print a string and a newline
;
; Clobbers ax
print_line:
mov al, 13
call print_char
mov al, 10
jmp print_char
; print a string
; IN
; Print a string
;
; Input:
; si: points at zero-terminated String
; CLOBBER
; si, ax
;
; Clobbers si, ax
print:
pushf
cld
@ -30,8 +29,9 @@ print:
popf
ret
; print a character
; IN
; Print a character
;
; Input:
; al: character to print
print_char:
pusha
@ -42,10 +42,11 @@ print_char:
ret
; print a number in hex
; IN
;
; Input:
; bx: the number
; CLOBBER
; al, cx
;
; Clobbers al, cx
print_hex:
mov cx, 4
.lp:

46
bios/protected_mode.asm
View File

@ -1,46 +0,0 @@
SECTION .text
USE16
protected_mode:
.func: dd 0
.entry:
; disable interrupts
cli
; load protected mode GDT
lgdt [gdtr]
; set protected mode bit of cr0
mov eax, cr0
or eax, 1
mov cr0, eax
; far jump to load CS with 32 bit segment
; (we are in 32-bit mode, but instruction pipeline
; has 16-bit instructions.
jmp gdt.pm32_code:.inner
; gdt.pm32_code is a multiple of 8, so it always ends with three zero bits.
; The GDT spec abuses this fact, and uses these last three bits to store other
; data (table type and privilege). In this case, 000 is what we need anyway.
;
; Also note that CS isn't an address in protected mode---it's a GDT descriptor.
USE32
.inner:
; load all the other segments with 32 bit data segments
mov eax, gdt.pm32_data
mov ds, eax
mov es, eax
mov fs, eax
mov gs, eax
mov ss, eax
; jump to specified function
mov eax, [.func]
jmp eax

121
bios/stage1.asm
View File

@ -1,37 +1,39 @@
USE16
stage1: ; dl comes with disk
; initialize segment registers
xor ax, ax
stage1:
; Initialize segment registers
xor ax, ax ; Set ax to 0
mov ds, ax
mov es, ax
mov ss, ax
; initialize stack
; Initialize stack pointer
; (stack grows up)
mov sp, 0x7C00
; initialize CS
; far jump sets both CS and IP to a known-good state,
; we don't know where the BIOS put us at startup.
; (could be 0x00:0x7C00, could be 0x7C00:0x00.
; Not everybody follows spec.)
push ax
; Initialize CS
;
; `retf` sets both CS and IP to a known-good state.
; This is necessary because we don't know where the BIOS put us at startup.
; (could be 0x00:0x7C00, could be 0x7C00:0x00. Not everybody follows spec.)
push ax ; `ax` is still 0
push word .set_cs
retf
.set_cs:
; save disk number
; Save disk number.
; BIOS sets `dl` to the number of
; the disk we're booting from.
mov [disk], dl
; Print "Stage 1"
mov si, stage_msg
call print
mov al, '1'
call print_char
call print_line
; read CHS gemotry
; read CHS gemotry, save into [chs]
; CL (bits 0-5) = maximum sector number
; CL (bits 6-7) = high bits of max cylinder number
; CH = low bits of maximum cylinder number
@ -51,11 +53,10 @@ stage1: ; dl comes with disk
and cl, 0x3f
mov [chs.s], cl
; disk address of stage 2
; (start sector)
; First sector of stage 2
mov eax, STAGE2_SECTOR
; where to load stage 2
; Where to load stage 2
mov bx, stage2
; length of stage2 + stage3
@ -63,36 +64,40 @@ stage1: ; dl comes with disk
mov cx, (stage3.end - stage2) / 512
mov dx, 0
; Consume eax, bx, cx, dx
; and load code from disk.
call load
jmp stage2.entry
; load some sectors from disk to a buffer in memory
; buffer has to be below 1MiB
; IN
; Load sectors from disk to memory.
; Cannot load more than 1MiB.
;
; Input:
; ax: start sector
; bx: offset of buffer
; cx: number of sectors (512 Bytes each)
; dx: segment of buffer
; CLOBBER
; ax, bx, cx, dx, si
; TODO rewrite to (eventually) move larger parts at once
; if that is done increase buffer_size_sectors in startup-common to that (max 0x80000 - startup_end)
;
; Clobbers ax, bx, cx, dx, si
load:
; replaced 127 with 1.
; see https://stackoverflow.com/questions/58564895/problem-with-bios-int-13h-read-sectors-from-drive
; TODO: fix later
; Every "replace 1" comment means that the `1`
; on that line could be bigger.
;
; See https://stackoverflow.com/questions/58564895/problem-with-bios-int-13h-read-sectors-from-drive
; We have to load one sector at a time to avoid the 1K boundary error.
; Would be nice to read more sectors at a time, though, that's faster.
cmp cx, 1 ;127
cmp cx, 1 ; replace 1
jbe .good_size
pusha
mov cx, 1; 127
mov cx, 1 ; replace 1
call load
popa
add eax, 1; 127
add dx, 1 * 512 / 16 ; 127
sub cx, 1;127
add eax, 1 ; replace 1
add dx, 1 * 512 / 16 ; replace 1
sub cx, 1 ; replace 1
jmp load
.good_size:
@ -101,44 +106,37 @@ load:
mov [DAPACK.count], cx
mov [DAPACK.seg], dx
; This should be a subroutine,
; but we don't call/ret to save a few bytes.
; (we only use this once)
;
;call print_dapack
;print_dapack:
mov bx, [DAPACK.addr + 2]
; Print the data we're reading
; Prints AAAAAAAA#BBBB CCCC:DDDD, where:
; - A..A is the lba we're reading (printed in two parts)
; - BBBB is the number of sectors we're reading
; - CCCC is the index we're writing to
; - DDDD is the buffer we're writing to
mov bx, [DAPACK.addr + 2] ; last two bytes
call print_hex
mov bx, [DAPACK.addr]
mov bx, [DAPACK.addr] ; first two bytes
call print_hex
mov al, '#'
call print_char
mov bx, [DAPACK.count]
call print_hex
mov al, ' '
call print_char
mov bx, [DAPACK.seg]
call print_hex
mov al, ':'
call print_char
mov bx, [DAPACK.buf]
call print_hex
call print_line
;ret
; End of print_dapack
; Read from disk.
; int13h, ah=0x42 does not work on some disks.
; use int13h, ah=0x02 in this case.
cmp byte [chs.s], 0
jne .chs
;INT 0x13 extended read does not work on CDROM!
mov dl, [disk]
mov si, DAPACK
mov ah, 0x42
@ -188,6 +186,10 @@ load:
jc error ; carry flag set on error
ret
;
; MARK: errors
;
error_chs:
mov ah, 0
@ -200,13 +202,18 @@ error:
mov si, stage1_error_msg
call print
call print_line
call print_line
; halt after printing error details
.halt:
cli
hlt
jmp .halt
;
; MARK: data
;
%include "print.asm"
stage_msg: db "Stage ",0
@ -215,9 +222,9 @@ stage1_error_msg: db " ERROR",0
disk: db 0
chs:
.c: dd 0
.h: dd 0
.s: dd 0
.c: dd 0
.h: dd 0
.s: dd 0
DAPACK:
db 0x10
@ -225,6 +232,4 @@ DAPACK:
.count: dw 0 ; int 13 resets this to # of blocks actually read/written
.buf: dw 0 ; memory buffer destination address (0:7c00)
.seg: dw 0 ; in memory page zero
.addr: dq 0 ; put the lba to read in this spot
db 0xff
.addr: dq 0 ; put the lba to read in this spot

50
bios/stage2.asm
View File

@ -1,6 +1,9 @@
SECTION .text
USE16
%include "gdt.asm"
%include "thunk.asm"
stage2.entry:
mov si, stage_msg
call print
@ -13,26 +16,57 @@ stage2.entry:
or al, 2
out 0x92, al
mov dword [protected_mode.func], stage3.entry
jmp protected_mode.entry
protected_mode:
; disable interrupts
cli
%include "gdt.asm"
%include "protected_mode.asm"
%include "thunk.asm"
; load protected mode GDT
lgdt [gdtr]
; set protected mode bit of cr0
mov eax, cr0
or eax, 1
mov cr0, eax
; far jump to load CS with 32 bit segment
; We need to do this because we are entering 32-bit mode,
; but the instruction pipeline still has 16-bit instructions.
;
; gdt.pm32_code is a multiple of 8, so it always ends with three zero bits.
; The GDT spec abuses this fact, and uses these last three bits to store other
; data (table type and privilege). In this case, 000 is what we need anyway.
;
; Also note that CS isn't an address in protected mode---it's a GDT descriptor.
jmp gdt.pm32_code:protected_mode_inner
; We can now use 32-bit instructions!
USE32
stage3.entry:
; stage3 stack at 448 KiB (512KiB minus 64KiB disk buffer)
protected_mode_inner:
; load all the other segments with 32 bit data segments
mov eax, gdt.pm32_data
mov ds, eax
mov es, eax
mov fs, eax
mov gs, eax
mov ss, eax
; Place stage 3 stack at 448 KiB
; (512KiB minus 64KiB disk buffer)
mov esp, 0x70000
; push arguments to `start()`
mov eax, thunk.int10
push eax
; Call `start()`.
; 0x18 skips ELF headers.
mov eax, [stage3 + 0x18]
call eax
.halt:
; Halt if `start()` ever returns (it shouldn't, but just in case)
; Without this, we'll try to execute whatever comes next in memory.
cli
hlt
jmp .halt

7
bios/thunk.asm
View File

@ -1,3 +1,10 @@
; Thunk allows stage 3 (rust code)
; to use interrupts that are not
; usually available in protected mode.
;
; "thunk": a subroutine used to inject
; a calculation into another subroutine.
SECTION .text
USE32

2
tetros/Cargo.toml
View File

@ -29,7 +29,7 @@ absolute_paths_not_starting_with_crate = "deny"
explicit_outlives_requirements = "warn"
unused_crate_dependencies = "warn"
redundant_lifetimes = "warn"
missing_docs = "allow"
missing_docs = "warn"
[lints.clippy]
needless_return = "allow"

5
tetros/linkers/x86-unknown-none.ld
View File

@ -1,9 +1,10 @@
/* This is the name of the Rust function we start in */
ENTRY(start)
OUTPUT_FORMAT(elf32-i386)
SECTIONS {
/* The start address must match bootloader.asm */
. = 0x9000;
/* The start address must match main.asm */
. = 0x8000;
. += SIZEOF_HEADERS;
. = ALIGN(4096);

30
tetros/src/drivers/pic.rs
View File

@ -1,18 +1,25 @@
//! Control routines for the x86
//! 8259 Programmable Interrupt Controller
//!
//! This helps us configure interrupts that receive
//! keyboard input and timer pulses.
use crate::os::util::outb;
/// IO base address for master PIC
const PIC_A: u32 = 0x20;
/// Command address for master PIC
const PIC_A_COMMAND: u32 = PIC_A;
/// Data address for master PIC
const PIC_A_DATA: u32 = PIC_A + 1;
/// IO base address for slave PIC
const PIC_B: u32 = 0xA0;
/// Command address for slave PIC
const PIC_B_COMMAND: u32 = PIC_B;
/// Data address for slave PIC
const PIC_B_DATA: u32 = PIC_B + 1;
/// PIC `EOI` command
const CMD_EOI: u8 = 0x20;
/// A driver for the PIC
///
/// Reference:
@ -24,6 +31,7 @@ pub struct PICDriver {
}
impl PICDriver {
/// Create a PIC driver with the given offsets
pub const fn new(offset_pic_a: u8, offset_pic_b: u8) -> Self {
Self {
offset_pic_a,
@ -47,14 +55,20 @@ impl PICDriver {
unsafe { outb(PIC_B_DATA, cmd) }
}
pub fn send_eoi(&self, irq: u8) {
if irq > 8 {
self.send_b_cmd(CMD_EOI);
/// Send an EOI for the given IRQ.
///
/// This needs to be called at the end of each interrupt handler.
/// If `both` is true, reset both PICs. This is only necessary
/// when we handle interrupts from PIC_B.
pub fn send_eoi(&self, both: bool) {
if both {
self.send_b_cmd(0x20);
}
self.send_a_cmd(CMD_EOI);
self.send_a_cmd(0x20);
}
/// Initialize this PIC driver.
/// This should be called as early as possible.
pub fn init(&mut self) {
const ICW1_ICW4: u8 = 0x01; /* Indicates that ICW4 will be present */
const ICW1_INIT: u8 = 0x10; /* Initialization - required! */

7
tetros/src/drivers/serial.rs
View File

@ -1,3 +1,10 @@
//! Serial port driver, for debug.
//!
//! This file provides the usual `print`
//! and `println` macros (which are usually
//! provided by `std`) that send messages out
//! of the serial port.
use lazy_static::lazy_static;
use spin::Mutex;
use uart_16550::SerialPort;

4
tetros/src/drivers/vga.rs
View File

@ -3,7 +3,6 @@ use rand::seq::IndexedRandom;
use crate::RNG;
#[repr(u8)]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum VgaColor {
Black,
@ -73,6 +72,9 @@ impl Vga13h {
pub const HEIGHT: usize = 200;
pub const ADDR: usize = 0xA0000;
/// Initialize a new VGA driver.
///
/// Only one of these should exist.
pub const unsafe fn new() -> Self {
Self {
fb_a: [0; Vga13h::WIDTH * Vga13h::HEIGHT],

46
tetros/src/game/board.rs
View File

@ -2,21 +2,26 @@ use crate::drivers::vga::{Vga13h, VgaColor};
use super::FallingTetromino;
#[repr(u8)]
/// The state of a cell in the game board
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum TetrisCell {
Empty,
Filled { color: VgaColor },
}
/// The tetris board
pub struct TetrisBoard {
board: [TetrisCell; TetrisBoard::BOARD_WIDTH * TetrisBoard::BOARD_HEIGHT],
}
impl TetrisBoard {
/// The width of this board, in cells
const BOARD_WIDTH: usize = 10;
/// The height of this board, in cells
const BOARD_HEIGHT: usize = 20;
/// The side length of a (square) cell, in pixels
const CELL_SIZE: usize = 9;
pub const fn new() -> Self {
@ -25,6 +30,8 @@ impl TetrisBoard {
}
}
/// Find and remove all filled rows,
/// shifting upper rows down.
pub fn collapse(&mut self) {
let mut y = Self::BOARD_HEIGHT - 1;
'outer: loop {
@ -58,6 +65,11 @@ impl TetrisBoard {
}
}
/// Place the given tetromino on the board,
/// filling the cells it occupies.
///
/// If the tetromino cells that overlap
/// non-empty board cells are ignored.
pub fn place_tetromino(&mut self, tetromino: FallingTetromino) {
for (x, y) in tetromino.tiles() {
let cell = self.get_cell_mut(x, y);
@ -82,32 +94,26 @@ impl TetrisBoard {
return true;
}
/// Get the value of the cell at the given position.
/// Returns [`None`] if (x, y) exceeds the board's bounds.
pub fn get_cell(&self, x: usize, y: usize) -> Option<&TetrisCell> {
if y >= TetrisBoard::BOARD_HEIGHT {
return None;
}
if x >= TetrisBoard::BOARD_WIDTH {
return None;
}
return Some(&self.board[y * TetrisBoard::BOARD_WIDTH + x]);
return self.board.get(y * TetrisBoard::BOARD_WIDTH + x);
}
/// Get a mutable reference to the cell at the given position.
/// Returns [`None`] if (x, y) exceeds the board's bounds.
pub fn get_cell_mut(&mut self, x: usize, y: usize) -> Option<&mut TetrisCell> {
if y >= TetrisBoard::BOARD_HEIGHT {
return None;
}
if x >= TetrisBoard::BOARD_WIDTH {
return None;
}
return Some(&mut self.board[y * TetrisBoard::BOARD_WIDTH + x]);
return self.board.get_mut(y * TetrisBoard::BOARD_WIDTH + x);
}
}
//
// MARK: draw routines
//
impl TetrisBoard {
/// Draw a cell of the given color on `fb`.
/// (x, y) is the pixel position of the cell (NOT board coordinates).
fn draw_cell(&self, fb: &mut [u8], color: VgaColor, x: usize, y: usize) {
let color = color.as_u8();
for yo in 0..TetrisBoard::CELL_SIZE {
@ -117,6 +123,7 @@ impl TetrisBoard {
}
}
/// Draw the tetris board's frame
fn draw_frame(&self, fb: &mut [u8], x: usize, y: usize) {
let color = VgaColor::Gray.as_u8();
for yo in 0..TetrisBoard::CELL_SIZE {
@ -126,6 +133,7 @@ impl TetrisBoard {
}
}
/// Draw this tetris board using the given VGA driver.
pub fn draw(&self, vga: &mut Vga13h, falling: Option<&FallingTetromino>) {
let fb = vga.get_fb();

22
tetros/src/game/falling.rs
View File

@ -53,6 +53,7 @@ pub enum Direction {
}
impl Direction {
/// Rotate this direction clockwise
pub fn rot_cw(self) -> Self {
match self {
Self::North => Self::East,
@ -61,17 +62,6 @@ impl Direction {
Self::West => Self::North,
}
}
/*
pub fn rot_ccw(self) -> Self {
match self {
Self::North => Self::West,
Self::West => Self::South,
Self::South => Self::East,
Self::East => Self::North,
}
}
*/
}
#[derive(Debug, Clone)]
@ -85,6 +75,7 @@ pub struct FallingTetromino {
}
impl FallingTetromino {
/// Make a new falling tetromino
pub fn new(tetromino: Tetromino, color: VgaColor, center_x: usize, center_y: usize) -> Self {
Self {
tetromino,
@ -95,6 +86,7 @@ impl FallingTetromino {
}
}
/// Generate a random tetromino at the given position
pub fn random(center_x: usize, center_y: usize) -> Self {
Self::new(
Tetromino::choose_rand(),
@ -104,6 +96,7 @@ impl FallingTetromino {
)
}
// Move this tetromino
pub fn translate(&mut self, x: i16, y: i16) {
if x > 0 {
let x = usize::try_from(x).unwrap();
@ -122,16 +115,11 @@ impl FallingTetromino {
}
}
/// Rotate this tetromino clockwise
pub fn rotate_cw(&mut self) {
self.direction = self.direction.rot_cw()
}
/*
pub fn rotate_ccw(&mut self) {
self.direction = self.direction.rot_ccw()
}
*/
/// Returns the positions of this falling tetromino's tiles.
pub fn tiles(&self) -> [(usize, usize); 4] {
match (&self.tetromino, self.direction) {

3
tetros/src/game/mod.rs
View File

@ -1,3 +1,6 @@
//! This crate contains all tetris game logic.
//! No low-level magic here.
mod board;
pub use board::*;

8
tetros/src/idt/stackframe.rs
View File

@ -1,16 +1,14 @@
use core::{fmt, ops::Deref};
use crate::os::EFlags;
use super::VirtAddr;
use crate::os::EFlags;
/// Wrapper type for the interrupt stack frame pushed by the CPU.
///
/// This type derefs to an [`InterruptStackFrameValue`], which allows reading the actual values.
///
/// This wrapper type ensures that no accidental modification of the interrupt stack frame
/// occurs, which can cause undefined behavior (see the [`as_mut`](InterruptStackFrame::as_mut)
/// method for more information).
/// This wrapper ensures that the stack frame cannot be modified.
/// This prevents undefined behavior.
#[repr(transparent)]
pub struct InterruptStackFrame(InterruptStackFrameValue);

20
tetros/src/idt/table.rs
View File

@ -5,17 +5,6 @@ use super::{
HandlerFuncWithErrCode, PageFaultHandlerFunc,
};
// TODO: comments
#[repr(C, packed(2))]
struct Idtr {
size: u16,
offset: u32,
}
//
// MARK: idt
//
// spell:off
#[derive(Clone, Debug)]
#[repr(C)]
@ -467,12 +456,17 @@ impl InterruptDescriptorTable {
/// # Safety
///
/// As long as it is the active IDT, you must ensure that:
///
/// - `self` is never destroyed.
/// - `self` always stays at the same memory location.
/// It is recommended to wrap it in a `Box`.
#[inline]
pub unsafe fn load_unsafe(&self) {
/// The data we push to the IDTR register
#[repr(C, packed(2))]
struct Idtr {
size: u16,
offset: u32,
}
let idtr = {
Idtr {
size: (size_of::<InterruptDescriptorTable>() - 1) as u16,

42
tetros/src/idt/virtaddr.rs
View File

@ -1,7 +1,4 @@
use core::{
fmt::{self},
ops::{Add, AddAssign, Sub, SubAssign},
};
use core::fmt::{self};
/// A canonical 32-bit virtual memory address.
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
@ -57,40 +54,3 @@ impl fmt::UpperHex for VirtAddr {
fmt::UpperHex::fmt(&self.0, f)
}
}
impl fmt::Pointer for VirtAddr {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Pointer::fmt(&(self.0 as *const ()), f)
}
}
impl Add<u32> for VirtAddr {
type Output = Self;
#[inline]
fn add(self, rhs: u32) -> Self::Output {
VirtAddr(self.0.checked_add(rhs).unwrap())
}
}
impl AddAssign<u32> for VirtAddr {
#[inline]
fn add_assign(&mut self, rhs: u32) {
*self = *self + rhs;
}
}
impl Sub<u32> for VirtAddr {
type Output = Self;
#[inline]
fn sub(self, rhs: u32) -> Self::Output {
VirtAddr(self.0.checked_sub(rhs).unwrap())
}
}
impl SubAssign<u32> for VirtAddr {
#[inline]
fn sub_assign(&mut self, rhs: u32) {
*self = *self - rhs;
}
}

51
tetros/src/lib.rs
View File

@ -1,3 +1,5 @@
//! The main code of tetris
#![no_std]
#![feature(int_roundings)]
#![feature(lang_items)]
@ -23,12 +25,18 @@ mod os;
#[macro_use]
mod drivers;
const PIC_OFFSET: u8 = 32;
//
// MARK: globals
//
// This code has no parallelism, so we don't _really_
// need locks. The Mutexes here satisfy Rust's
// "no mutable global state" rule.
//
// They also help prevent bugs, since we get deadlocks
// instead of hard-to-debug surprising behavior.
//
const PIC_OFFSET: u8 = 32;
static VGA: Mutex<Vga13h> = Mutex::new(unsafe { Vga13h::new() });
static PIC: Mutex<PICDriver> = Mutex::new(PICDriver::new(PIC_OFFSET, PIC_OFFSET + 8));
static TICK_COUNTER: Mutex<u32> = Mutex::new(0);
@ -36,6 +44,8 @@ static BOARD: Mutex<TetrisBoard> = Mutex::new(TetrisBoard::new());
static FALLING: Mutex<Option<FallingTetromino>> = Mutex::new(None);
static LAST_INPUT: Mutex<Option<InputKey>> = Mutex::new(None);
// These values can't be initialized statically,
// so we cheat with `lazy_static`
lazy_static! {
static ref RNG: Mutex<SmallRng> = Mutex::new(SmallRng::seed_from_u64(1337));
static ref IDT: InterruptDescriptorTable = {
@ -50,10 +60,26 @@ lazy_static! {
};
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum InputKey {
Left,
Right,
Up,
Down,
}
//
// MARK: interrupts
//
// These functions are called when we receive interrupts.
// This can occur between ANY two instructions---which is
// why we use `without_interrupts` when acquiring locks.
//
// Notice how we do as little work as possible in our
// interrupt handlers. All our business logic goes into
// the main loop.
#[expect(missing_docs)]
#[derive(Debug, Clone, Copy)]
#[repr(u8)]
pub enum InterruptIndex {
@ -72,22 +98,20 @@ impl InterruptIndex {
}
extern "x86-interrupt" fn divide_handler(stack_frame: InterruptStackFrame) {
// Simple interrupt handler, as an example.
// This can be triggered manually using `asm!("int 0")`,
// even if interrupts are disabled.
println!("DIVIDE ERROR {:?}", stack_frame);
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum InputKey {
Left,
Right,
Up,
Down,
}
extern "x86-interrupt" fn keyboard_handler(_stack_frame: InterruptStackFrame) {
{
// Re-seed our rng using user input.
// This is a simple hack that makes our
// "random" tile selector less deterministic.
//
// Getting random seeds from hardware is
// more trouble than its worth.
let mut rng = RNG.lock();
let past: u64 = rng.random();
let tcr = u64::from(*TICK_COUNTER.lock());
@ -125,13 +149,13 @@ extern "x86-interrupt" fn keyboard_handler(_stack_frame: InterruptStackFrame) {
*LAST_INPUT.lock() = key;
}
PIC.lock().send_eoi(InterruptIndex::Keyboard.as_u8());
PIC.lock().send_eoi(false);
}
extern "x86-interrupt" fn timer_handler(_stack_frame: InterruptStackFrame) {
let mut t = TICK_COUNTER.lock();
*t = (*t).wrapping_add(1);
PIC.lock().send_eoi(InterruptIndex::Timer.as_u8());
PIC.lock().send_eoi(false);
}
extern "x86-interrupt" fn double_fault_handler(
@ -145,6 +169,7 @@ extern "x86-interrupt" fn double_fault_handler(
// MARK: main
//
#[expect(missing_docs)]
#[no_mangle]
pub unsafe extern "C" fn start(thunk10: extern "C" fn()) -> ! {
println!("Entered Rust, serial ready.");
@ -190,6 +215,7 @@ pub unsafe extern "C" fn start(thunk10: extern "C" fn()) -> ! {
}
last_t = t;
// MARK: input
// Handle user input
without_interrupts(|| {
if let Some(fall) = &mut *FALLING.lock() {
@ -236,6 +262,7 @@ pub unsafe extern "C" fn start(thunk10: extern "C" fn()) -> ! {
}
});
// MARK: update board
// Update board
without_interrupts(|| {
let mut v = VGA.lock();

1
tetros/src/os/eflags.rs
View File

@ -80,6 +80,7 @@ bitflags! {
}
impl EFlags {
/// Read the EFLAGS register
#[inline]
pub fn read() -> EFlags {
EFlags::from_bits_truncate(EFlags::read_raw())

6
tetros/src/os/panic.rs
View File

@ -1,8 +1,12 @@
//! Intrinsics for panic handling
//! Rust intrinsics for panic handling.
//!
//! These are usually provided by `std`,
//! but we don't have that luxury!
use core::arch::asm;
use core::panic::PanicInfo;
// Use serial println
use crate::println;
#[lang = "eh_personality"]

8
tetros/src/os/util.rs
View File

@ -18,11 +18,13 @@ pub fn sti() {
}
}
/// Run a closure with disabled interrupts.
///
/// Run the given closure, disabling interrupts before running it (if they aren't already disabled).
/// Afterwards, interrupts are enabling again if they were enabled before.
///
/// This helps us prevent deadlocks, which can occur if
/// an interrupt handler tries to acquire a lock that was
/// locked at the time of the interrupt.
///
/// If you have other `enable` and `disable` calls _within_ the closure, things may not work as expected.
#[inline]
pub fn without_interrupts<F, R>(f: F) -> R
@ -46,6 +48,7 @@ where
ret
}
/// Wraps the `in` instruction
pub unsafe fn inb(port: u32) -> u8 {
let mut out;
@ -58,6 +61,7 @@ pub unsafe fn inb(port: u32) -> u8 {
return out;
}
/// Wraps the `out` instruction
pub unsafe fn outb(port: u32, value: u8) {
asm!(
"out dx, al",