X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?a=blobdiff_plain;f=src%2Fintr_asm.S;h=8434a8fa683214515bdb30d767b455a94bd065b7;hb=6e968b9e724d9626ed6bdf2119ac7de6a5248f14;hp=ea0be36d1561b53a3f6a32bce77371b065d782b1;hpb=a2f94f569a4c99204de02814a20098a71527e913;p=bootcensus

diff --git a/src/intr_asm.S b/src/intr_asm.S
index ea0be36..8434a8f 100644
--- a/src/intr_asm.S
+++ b/src/intr_asm.S
@@ -1,3 +1,19 @@
+# pcboot - bootable PC demo/game kernel
+# Copyright (C) 2018  John Tsiombikas <nuclear@member.fsf.org>
+# 
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY, without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
 	.data
 	.align 4
 	.short 0
@@ -88,7 +104,42 @@ intr_entry_fast_timer:
 	out %al, $0x20
 	pop %eax
 	iret
-	
+
+/* special case for IRQ 7 and IRQ 15, to catch spurious interrupts */
+	.set PIC1_CMD, 0x20
+	.set PIC2_CMD, 0xa0
+	.set OCW2_EOI, 0x20
+	.set OCW3_ISR, 0x0b
+
+	.extern intr_entry_irq7
+	.global irq7_entry_check_spurious
+irq7_entry_check_spurious:
+	push %eax
+	mov $OCW3_ISR, %al
+	out %al, $PIC1_CMD
+	in $PIC1_CMD, %al
+	and $0x80, %al
+	pop %eax
+	jnz intr_entry_irq7
+	iret
+
+	.extern intr_entry_irq15
+	.global irq15_entry_check_spurious
+irq15_entry_check_spurious:
+	push %eax
+	mov $OCW3_ISR, %al
+	out %al, $PIC2_CMD
+	in $PIC2_CMD, %al
+	and $0x80, %al
+	jnz 0f
+	# it was spurious, send EOI to master PIC and iret
+	mov $OCW2_EOI, %al
+	out %al, $PIC1_CMD
+	pop %eax
+	iret
+0:	pop %eax
+	jmp intr_entry_irq15
+
 
 /* XXX not necessary for now, just leaving it in in case it's useful
  * down the road.