fixed soundblaster output (DMA bug)

[bootcensus] / src / intr.c

diff --git a/src/intr.c b/src/intr.c
index 1ace71e..e04a177 100644 (file)
--- a/src/intr.c
+++ b/src/intr.c
@@ -1,3 +1,20 @@
+/*
+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/>.
+*/
 #include <stdio.h>
 #include "intr.h"
 #include "desc.h"
@@ -43,6 +60,8 @@ static void gate_desc(desc_t *desc, uint16_t sel, uint32_t addr, int dpl, int ty
 /* defined in intr_asm.S */
 void set_idt(uint32_t addr, uint16_t limit);
 void intr_entry_default(void);
+void irq7_entry_check_spurious(void);
+void irq15_entry_check_spurious(void);
 
 /* the IDT (interrupt descriptor table) */
 static desc_t idt[256] __attribute__((aligned(8)));
@@ -73,6 +92,12 @@ void init_intr(void)
         */
 #include "intrtab.h"
 
+       /* change irq7 and irq15 to special entry points which first
+        * make sure we didn't get a spurious interrupt before proceeding
+        */
+       set_intr_entry(IRQ_TO_INTR(7), irq7_entry_check_spurious);
+       set_intr_entry(IRQ_TO_INTR(15), irq15_entry_check_spurious);
+
        /* initialize the programmable interrupt controller
         * setting up the maping of IRQs [0, 15] to interrupts [32, 47]
         */
@@ -91,7 +116,10 @@ struct intr_frame *get_intr_frame(void)
 /* set an interrupt handler function for a particular interrupt */
 void interrupt(int intr_num, intr_func_t func)
 {
+       int iflag = get_intr_flag();
+       disable_intr();
        intr_func[intr_num] = func;
+       set_intr_flag(iflag);
 }
 
 /* this function is called from all interrupt entry points