diff options
Diffstat (limited to 'devices/pic_8259.c')
| -rw-r--r-- | devices/pic_8259.c | 34 |
1 files changed, 21 insertions, 13 deletions
diff --git a/devices/pic_8259.c b/devices/pic_8259.c index 75a2d0e..75aaf6d 100644 --- a/devices/pic_8259.c +++ b/devices/pic_8259.c @@ -6,11 +6,11 @@ #define PIC2 0xa0 #define DATA 1 -// initialization +/* initialization */ #define ICW1_INIT 0x10 -// TODO +/* TODO */ #define ICW1_ICW4 0x01 -// 8086/88 mode +/* 8086/88 mode */ #define ICW4_8086 0x01 void @@ -19,31 +19,39 @@ pic_init() outb(ICW1_INIT | ICW1_ICW4, PIC1); outb(ICW1_INIT | ICW1_ICW4, PIC2); - outb(0x20, PIC1 + DATA); // offset 0x20 - outb(0x28, PIC2 + DATA); // offset 0x28 + outb(0x20, PIC1 + DATA); /* offset 0x20 */ + outb(0x28, PIC2 + DATA); /* offset 0x28 */ - outb(0x04, PIC1 + DATA); // tell master pic there is a slave pic - outb(0x02, PIC2 + DATA); // tell slave pic its cascade identity + outb(0x04, PIC1 + DATA); /* tell master pic there is a slave pic */ + outb(0x02, PIC2 + DATA); /* tell slave pic its cascade identity */ outb(ICW4_8086, PIC1 + DATA); outb(ICW4_8086, PIC2 + DATA); - // PIC masks + /* PIC masks */ outb(0xff, PIC1 + DATA); outb(0xff, PIC2 + DATA); } +static unsigned char +irq_mask(unsigned char irq) +{ + unsigned char mask = (unsigned char)~(1u << irq); + return 0xff & mask; +} + void pic_enable() { unsigned char mask1 = 0xff; - mask1 &= ~(1 << 0); // irq0 timer - mask1 &= ~(1 << 1); // irq1 keyboard - mask1 &= ~(1 << 2); // irq1 cascade + unsigned char mask2 = 0xff; + + mask1 &= irq_mask(0); /* irq0 timer */ + mask1 &= irq_mask(1); /* irq1 keyboard */ + mask1 &= irq_mask(2); /* irq2 cascade */ outb(mask1, PIC1 + DATA); - unsigned char mask2 = 0xff; - mask2 &= ~(1 << 4); // irq12 mouse + mask2 &= irq_mask(12 - 8); /* irq12 mouse */ outb(mask2, PIC2 + DATA); enable_interrupts(); |