Start cleaning up kernel assembly mixins & start ISR/interrupts

asm/boot.asm

@@ -5,4 +5,4 @@
 [extern main]  ; going to call main in kernel.c
 
 call main
-jmp $
+jmp $

asm/idt.asm

@@ -0,0 +1,89 @@
+[bits 32]
+[extern isr_handler]
+
+%macro ISR_NOERRORCODE 1  ; define a macro, taking one parameter
+  [GLOBAL isr%1]        ; %1 accesses the first parameter.
+  isr%1:
+    cli
+    push byte 0
+    push byte %1
+    jmp isr_common_stub
+%endmacro
+
+%macro ISR_ERRORCODE 1
+  [GLOBAL isr%1]
+  isr%1:
+    cli
+    push byte %1
+    jmp isr_common_stub
+%endmacro
+
+ISR_NOERRORCODE 0
+ISR_NOERRORCODE 1
+ISR_NOERRORCODE 2
+ISR_NOERRORCODE 3
+ISR_NOERRORCODE 4
+ISR_NOERRORCODE 5
+ISR_NOERRORCODE 6
+ISR_NOERRORCODE 7
+ISR_ERRORCODE 8
+ISR_NOERRORCODE 9
+ISR_ERRORCODE 10
+ISR_ERRORCODE 11
+ISR_ERRORCODE 12
+ISR_ERRORCODE 13
+ISR_ERRORCODE 14
+ISR_NOERRORCODE 15
+ISR_NOERRORCODE 16
+ISR_NOERRORCODE 17
+ISR_NOERRORCODE 18
+ISR_NOERRORCODE 19
+ISR_NOERRORCODE 20
+ISR_NOERRORCODE 21
+ISR_NOERRORCODE 22
+ISR_NOERRORCODE 23
+ISR_NOERRORCODE 24
+ISR_NOERRORCODE 25
+ISR_NOERRORCODE 26
+ISR_NOERRORCODE 27
+ISR_NOERRORCODE 28
+ISR_NOERRORCODE 29
+ISR_NOERRORCODE 30
+ISR_NOERRORCODE 31
+
+ ; In isr.c
+[EXTERN isr_handler]
+
+; This is our common ISR stub. It saves the processor state, sets
+; up for kernel mode segments, calls the C-level fault handler,
+; and finally restores the stack frame.
+isr_common_stub:
+   pusha                    ; Pushes edi,esi,ebp,esp,ebx,edx,ecx,eax
+
+   mov ax, ds               ; Lower 16-bits of eax = ds.
+   push eax                 ; save the data segment descriptor
+
+   mov ax, 0x10  ; load the kernel data segment descriptor
+   mov ds, ax
+   mov es, ax
+   mov fs, ax
+   mov gs, ax
+
+   call isr_handler
+
+   pop eax        ; reload the original data segment descriptor
+   mov ds, ax
+   mov es, ax
+   mov fs, ax
+   mov gs, ax
+
+   popa                     ; Pops edi,esi,ebp...
+   add esp, 8     ; Cleans up the pushed error code and pushed ISR number
+   sti
+   iret           ; pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP
+
+[GLOBAL idt_flush]
+idt_flush:
+    mov eax, [esp + 4]
+    lidt [eax]
+    ret

asm/kasm.asm

@@ -0,0 +1,5 @@
+; NOT part of the bootloader
+; this is the kernel entry code that calls main() in kernel.cpp
+
+%include "boot.asm"
+%include "idt.asm"