foo

[ld45_start_nothing] / src / intr.asm

diff --git a/src/intr.asm b/src/intr.asm
index 1bbf319..58ef37f 100644 (file)
--- a/src/intr.asm
+++ b/src/intr.asm
@@ -1,8 +1,14 @@
 ; vi:filetype=nasm ts=8 sts=8 sw=8:
        section .text
 
+%define INTR_ASM_
 %include "intr.inc"
 
+GATE_INTR equ 0600h
+GATE_TRAP equ 0700h
+GATE_DEFAULT equ 0800h
+GATE_PRESENT equ 8000h
+
        global init_intr
 init_intr:
        call init_pic
@@ -10,12 +16,53 @@ init_intr:
 
        global set_intr
 set_intr:
+       push ebp
+       mov ebp, esp
+       push ebx
+
+       mov ebx, [ebp + 8]
+       mov eax, GATE_TRAP
+       cmp ebx, 32     ; determine if it's an IRQ or an exception (trap)
+       jb .notirq
+       mov eax, GATE_INTR
+.notirq:
+       shl ebx, 1
+       lea ebx, [ebx * 8 + idt] ; ebx <- pointer to gate descriptor
+       ; type|dpl goes to the 3rd dword of the descriptor (dpl is 0)
+       or eax, (GATE_DEFAULT | GATE_PRESENT)
+       mov [ebx + 8], eax
+       ; address low 16bits go to the first dword of the descriptor
+       mov eax, [ebp + 12]
+       mov [ebx], ax
+       ; address high 16bits go to the last dword of the descriptor
+       shr eax, 16
+       mov [ebx + 12], eax
+       ; selector (kcode:1) goes to the second dword of the descriptor
+       mov dword [ebx + 4], 08h
+
+       ; install dummy interrupt handlers for all IRQ vectors
+%assign i 0
+%rep 8
+       set_irq_vector i, dummy_intr_pic1
+       set_irq_vector i+8, dummy_intr_pic2
+%assign i i+1
+%endrep
+
+       pop ebx
+       pop ebp
        ret
 
-PIC1_CMD equ 20h
-PIC1_DATA equ 21h
-PIC2_CMD equ 0a0h
-PIC2_DATA equ 0a1h
+dummy_intr_pic1:
+       push eax
+       end_of_irq 0
+       pop eax
+       iret
+
+dummy_intr_pic2:
+       push eax
+       end_of_irq 8
+       pop eax
+       iret
 
 ; PIC initialization command word 1 bits
 ICW1_ICW4_NEEDED       equ 01h
@@ -29,8 +76,6 @@ ICW4_AUTO_EOI         equ 02h
 ICW4_BUF_SLAVE         equ 08h
 ICW4_BUF_MASTER                equ 0ch
 ICW4_SPECIAL           equ 10h
-; PIC operation command word 2 bits
-OCW2_EOI               equ 20h
 
 init_pic:
        ; send ICW1 saying we'll follow with ICW4 later on