swissChili | d813792 | 2021-02-17 15:34:07 -0800 | [diff] [blame] | 1 | #include "descriptor_tables.h" |
| 2 | #include "vga.h" |
swissChili | 9b3584b | 2021-02-18 13:57:27 -0800 | [diff] [blame] | 3 | #include "io.h" |
swissChili | defeb0d | 2021-02-18 15:28:36 -0800 | [diff] [blame^] | 4 | #include "log.h" |
swissChili | 9b3584b | 2021-02-18 13:57:27 -0800 | [diff] [blame] | 5 | #include "pic.h" |
swissChili | d813792 | 2021-02-17 15:34:07 -0800 | [diff] [blame] | 6 | |
| 7 | extern void gdt_flush(uint gdt); |
| 8 | extern void idt_flush(uint idt); |
| 9 | |
| 10 | static void gdt_set_gate(uint i, uint base, uint limit, uchar access, uchar gran); |
| 11 | static void idt_set_gate(uchar num, uint base, ushort selector, uchar flags); |
| 12 | |
| 13 | struct gdt_entry gdt_entries[5]; |
| 14 | struct gdt_pointer gdt_pointer; |
| 15 | |
| 16 | struct idt_entry idt_entries[256]; |
| 17 | struct idt_pointer idt_pointer; |
| 18 | |
swissChili | 9b3584b | 2021-02-18 13:57:27 -0800 | [diff] [blame] | 19 | static void (*isrs[32])() = { |
| 20 | isr0, isr1, isr2, isr3, isr4, isr5, isr6, isr7, isr8, isr9, isr10, |
| 21 | isr11, isr12, isr13, isr14, isr15, isr16, isr17, isr18, isr19, isr20, isr21, |
| 22 | isr22, isr23, isr24, isr25, isr26, isr27, isr28, isr29, isr30, isr31}; |
| 23 | |
| 24 | static void (*irqs[16])() = {irq0, irq1, irq2, irq3, irq4, irq5, |
| 25 | irq6, irq7, irq8, irq9, irq10, irq11, |
| 26 | irq12, irq13, irq14, irq15}; |
swissChili | d813792 | 2021-02-17 15:34:07 -0800 | [diff] [blame] | 27 | |
| 28 | void init_gdt() |
| 29 | { |
swissChili | 0b35bf2 | 2021-02-18 12:49:40 -0800 | [diff] [blame] | 30 | vga_write("Initializing GDT...\n"); |
swissChili | d813792 | 2021-02-17 15:34:07 -0800 | [diff] [blame] | 31 | gdt_pointer.limit = sizeof(struct gdt_entry) * 5 - 1; |
| 32 | gdt_pointer.base = (uint)&gdt_entries; |
| 33 | |
| 34 | gdt_set_gate(0, 0, 0, 0, 0); // Null segment |
| 35 | gdt_set_gate(1, 0, ~0, 0x9a, 0xcf); // Code segment |
| 36 | gdt_set_gate(2, 0, ~0, 0x92, 0xcf); // Data segment |
| 37 | gdt_set_gate(3, 0, ~0, 0xfa, 0xcf); // User mode code segment |
| 38 | gdt_set_gate(4, 0, ~0, 0xf2, 0xcf); // User mode data segment |
| 39 | |
swissChili | 0b35bf2 | 2021-02-18 12:49:40 -0800 | [diff] [blame] | 40 | for (volatile uint i = 0; i < 0x1000; i++) |
| 41 | {} // waste some time, for some reason this helps |
| 42 | |
swissChili | d813792 | 2021-02-17 15:34:07 -0800 | [diff] [blame] | 43 | gdt_flush((uint) &gdt_pointer); |
| 44 | |
| 45 | vga_write("GDT Initialized\n"); |
| 46 | } |
| 47 | |
| 48 | static void gdt_set_gate(uint i, uint base, uint limit, uchar access, uchar gran) |
| 49 | { |
| 50 | struct gdt_entry *e = &gdt_entries[i]; |
| 51 | |
| 52 | e->base_low = base & 0xffff; |
| 53 | e->base_middle = (base >> 16) & 0xff; |
| 54 | e->base_high = (base >> 24) & 0xff; |
| 55 | |
| 56 | e->limit_low = limit & 0xffff; |
| 57 | e->granularity = ((limit >> 16) & 0x0f) | (gran & 0xf0); |
| 58 | |
| 59 | e->access = access; |
| 60 | } |
| 61 | |
| 62 | void init_idt() |
| 63 | { |
| 64 | idt_pointer.limit = sizeof(struct idt_entry) * 256 - 1; |
| 65 | idt_pointer.base = (uint)&idt_entries; |
| 66 | |
| 67 | memset(&idt_entries, 0, sizeof(idt_entries)); |
| 68 | |
swissChili | defeb0d | 2021-02-18 15:28:36 -0800 | [diff] [blame^] | 69 | // Remap PIC |
| 70 | pic_remap(); |
swissChili | d813792 | 2021-02-17 15:34:07 -0800 | [diff] [blame] | 71 | |
swissChili | defeb0d | 2021-02-18 15:28:36 -0800 | [diff] [blame^] | 72 | vga_set_color(CYAN, BLACK); |
| 73 | for (int i = 0; i < 16; i++) |
| 74 | { |
| 75 | kprintf("Setting gate irq=%d,\tint=%d\n", i, IRQ_TO_INT(i)); |
| 76 | idt_set_gate(IRQ_TO_INT(i), (uint)irqs[i], 0x08, 0x8e); |
| 77 | } |
| 78 | vga_set_color(WHITE, BLACK); |
swissChili | d813792 | 2021-02-17 15:34:07 -0800 | [diff] [blame] | 79 | |
| 80 | for (int i = 0; i < 32; i++) |
| 81 | { |
| 82 | idt_set_gate(i, (uint)isrs[i], 0x08, 0x8e); |
| 83 | } |
| 84 | |
| 85 | idt_flush((uint)&idt_pointer); |
| 86 | |
swissChili | d813792 | 2021-02-17 15:34:07 -0800 | [diff] [blame] | 87 | vga_write("IDT Initialized!\n"); |
| 88 | } |
| 89 | |
| 90 | static void idt_set_gate(uchar num, uint base, ushort selector, uchar flags) |
| 91 | { |
| 92 | struct idt_entry *e = &idt_entries[num]; |
| 93 | |
| 94 | e->base_low = base & 0xffff; |
| 95 | e->base_high = (base >> 16) & 0xffff; |
| 96 | |
| 97 | e->selector = selector; |
| 98 | e->zero = 0; |
| 99 | e->flags = flags /* | 0x60 */; |
| 100 | } |
| 101 | |
| 102 | void init_descriptor_tables() |
| 103 | { |
| 104 | init_gdt(); |
| 105 | init_idt(); |
| 106 | } |