lidt

3 files changed, 44 insertions, 1 deletions

diff --git a/devices/meson.build b/devices/meson.build
index c52c389..de0230d 100644
--- a/devices/meson.build
+++ b/devices/meson.build
@@ -1,5 +1,5 @@
 devices = declare_dependency(
-  sources: ['vga.c', 'uart_16550.c'],
+  sources: ['vga.c', 'uart_16550.c', 'pic_8259.c'],
   include_directories: '.'
 )
 
diff --git a/devices/pic.h b/devices/pic.h
new file mode 100644
index 0000000..685a85b
--- /dev/null
+++ b/devices/pic.h
@@ -0,0 +1,4 @@
+#pragma once
+
+void pic_init();
+void pic_clear(unsigned char irq);
diff --git a/devices/pic_8259.c b/devices/pic_8259.c
new file mode 100644
index 0000000..43b090f
--- /dev/null
+++ b/devices/pic_8259.c
@@ -0,0 +1,39 @@
+#include "pic.h"
+#include <sys/io.h>
+
+#define PIC1 0x20
+#define PIC2 0xa0
+#define DATA 1
+
+// initialization
+#define ICW1_INIT 0x10
+// TODO
+#define ICW1_ICW4 0x01
+// 8086/88 mode
+#define ICW4_8086 0x01
+
+void
+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(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
+  outb(0xff, PIC1 + DATA);
+  outb(0xff, PIC2 + DATA);
+}
+
+void
+pic_clear(unsigned char irq)
+{
+  outb(0x20, PIC1);
+}