1 files changed, 64 insertions, 0 deletions
diff --git a/src/loader/pic.c b/src/loader/pic.c
new file mode 100644
index 0000000..18b248c
--- /dev/null
+++ b/src/loader/pic.c
@@ -0,0 +1,64 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <cpu.h>
+#include <pic.h>
+
+#define PIC1 0x20
+#define PIC1_COMMAND PIC1
+#define PIC1_OFFSET 0x20
+#define PIC1_DATA (PIC1 + 1)
+
+#define PIC2 0xa0
+#define PIC2_COMMAND PIC2
+#define PIC2_OFFSET 0x28
+#define PIC2_DATA (PIC2 + 1)
+
+#define ICW1_ICW4 0x01
+#define ICW1_INIT 0x10
+
+static void pic_wait(void)
+{
+	__asm__ volatile("jmp 1f\n\t"
+			 "1:\n\t"
+			 "    jmp 2f\n\t"
+			 "2:");
+}
+
+void pic_install(void)
+{
+	// Initialize
+	outb(PIC1_COMMAND, ICW1_INIT | ICW1_ICW4);
+	pic_wait();
+	outb(PIC2_COMMAND, ICW1_INIT | ICW1_ICW4);
+	pic_wait();
+
+	// Remap
+	outb(PIC1_DATA, PIC1_OFFSET);
+	pic_wait();
+	outb(PIC2_DATA, PIC2_OFFSET);
+	pic_wait();
+
+	outb(PIC1_DATA, 0x04);
+	pic_wait();
+	outb(PIC2_DATA, 0x02);
+	pic_wait();
+
+	// Set 8086 mode
+	outb(PIC1_DATA, 0x01);
+	pic_wait();
+	outb(PIC2_DATA, 0x01);
+	pic_wait();
+
+	outb(PIC1_DATA, 0x00);
+	pic_wait();
+	outb(PIC2_DATA, 0x00);
+	pic_wait();
+}
+
+void pic_ack(u32 int_no)
+{
+	if (int_no >= 40)
+		outb(PIC2, 0x20);
+
+	outb(PIC1, 0x20);
+}