interrupts

src/idt.asm

@@ -0,0 +1,53 @@
+%macro isr_err_stub 1
+isr_stub_%+%1:
+    call exception_handler
+    iretq
+%endmacro
+
+%macro isr_no_err_stub 1
+isr_stub_%+%1:
+    call exception_handler
+    iretq
+%endmacro
+
+extern exception_handler
+isr_no_err_stub 0
+isr_no_err_stub 1
+isr_no_err_stub 2
+isr_no_err_stub 3
+isr_no_err_stub 4
+isr_no_err_stub 5
+isr_no_err_stub 6
+isr_no_err_stub 7
+isr_err_stub    8
+isr_no_err_stub 9
+isr_err_stub    10
+isr_err_stub    11
+isr_err_stub    12
+isr_err_stub    13
+isr_err_stub    14
+isr_no_err_stub 15
+isr_no_err_stub 16
+isr_err_stub    17
+isr_no_err_stub 18
+isr_no_err_stub 19
+isr_no_err_stub 20
+isr_no_err_stub 21
+isr_no_err_stub 22
+isr_no_err_stub 23
+isr_no_err_stub 24
+isr_no_err_stub 25
+isr_no_err_stub 26
+isr_no_err_stub 27
+isr_no_err_stub 28
+isr_no_err_stub 29
+isr_err_stub    30
+isr_no_err_stub 31
+
+global isr_stub_table
+isr_stub_table:
+%assign i 0 
+%rep    32 
+    dq isr_stub_%+i
+%assign i i+1 
+%endrep

src/idt.c

@@ -0,0 +1,65 @@
+#include "vga.h"
+#include <stdbool.h>
+#include <stdint.h>
+
+#define IDT_MAX_DESCRIPTORS 255
+
+typedef struct
+{
+    uint16_t isr_low;   // The lower 16 bits of the ISR's address
+    uint16_t kernel_cs; // The GDT segment selector that the CPU will load into CS before calling the ISR
+    uint8_t ist;        // The IST in the TSS that the CPU will load into RSP; set to zero for now
+    uint8_t attributes; // Type and attributes; see the IDT page
+    uint16_t isr_mid;   // The higher 16 bits of the lower 32 bits of the ISR's address
+    uint32_t isr_high;  // The higher 32 bits of the ISR's address
+    uint32_t reserved;  // Set to zero
+} __attribute__((packed)) idt_entry_t;
+
+typedef struct
+{
+    uint16_t limit;
+    uint64_t base;
+} __attribute__((packed)) idtr_t;
+
+static idt_entry_t idt[256];
+static idtr_t idtr;
+
+void exception_handler(void)
+{
+    vga_print_error("An unhandled exception occurred");
+    __asm__ volatile("cli; hlt");
+}
+
+void idt_set_descriptor(uint8_t vector, void* isr, uint8_t flags)
+{
+    idt_entry_t* descriptor = &idt[vector];
+
+    descriptor->isr_low = (uint64_t)isr & 0xFFFF;
+    descriptor->kernel_cs = 0x08;
+    descriptor->ist = 0;
+    descriptor->attributes = flags;
+    descriptor->isr_mid = ((uint64_t)isr >> 16) & 0xFFFF;
+    descriptor->isr_high = ((uint64_t)isr >> 32) & 0xFFFFFFFF;
+    descriptor->reserved = 0;
+}
+
+static bool vectors[IDT_MAX_DESCRIPTORS];
+
+extern void* isr_stub_table[];
+
+void idt_init(void)
+{
+    idtr.base = (uintptr_t)&idt[0];
+    idtr.limit = (uint16_t)sizeof(idt_entry_t) * IDT_MAX_DESCRIPTORS - 1;
+
+    for (uint8_t vector = 0; vector < 32; vector++)
+    {
+        idt_set_descriptor(vector, isr_stub_table[vector], 0x8E);
+        vectors[vector] = true;
+    }
+
+    __asm__ volatile("lidt %0" : : "m"(idtr));
+    __asm__ volatile("sti");
+
+    vga_print_success("IDT intialzied");
+}

src/idt.h

@@ -0,0 +1,5 @@
+#include <stdint.h>
+
+void idt_init(void);
+void exception_handler(void);
+void idt_set_descriptor(uint8_t vector, void* isr, uint8_t flags);

src/kernel.c

@@ -1,7 +1,13 @@
+#include "idt.h"
 #include "vga.h"
 
 void kernel_main(void)
 {
     vga_clear();
+
+    idt_init();
+
     vga_print("Welcome to nub OS\n");
+
+    int x = 1 / 0;
 }

src/vga.c

@@ -108,4 +108,22 @@ void vga_print_colored(const char* string, vga_color_t color)
 void vga_print(const char* string)
 {
     vga_print_colored(string, vga_default_color());
+}
+
+void vga_print_success(const char* message)
+{
+    vga_print("[ ");
+    vga_print_colored("success", VGA_GREEN);
+    vga_print(" ] ");
+    vga_print(message);
+    vga_print("\n");
+}
+
+void vga_print_error(const char* message)
+{
+    vga_print("[ ");
+    vga_print_colored("error", VGA_RED);
+    vga_print(" ] ");
+    vga_print(message);
+    vga_print("\n");
 }

src/vga.h

@@ -26,6 +26,8 @@ void vga_set_cursor_position(uint8_t row, uint8_t col);
 
 void vga_print_colored(const char* string, vga_color_t color);
 void vga_print(const char* string);
+void vga_print_success(const char* message);
+void vga_print_error(const char* message);
 
 static inline vga_color_t vga_color(vga_color_t fg_color, vga_color_t bg_color)
 {