From b8f00b77e965c73a047e71193c8c6e2d7488f34d Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Fri, 4 Sep 2020 15:50:21 +0200
Subject: Added mandelbrot demo and fpu driver

---
 kernel/drivers/fpu.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 kernel/drivers/fpu.c

(limited to 'kernel/drivers/fpu.c')

diff --git a/kernel/drivers/fpu.c b/kernel/drivers/fpu.c
new file mode 100644
index 0000000..d8a2b79
--- /dev/null
+++ b/kernel/drivers/fpu.c
@@ -0,0 +1,24 @@
+// MIT License, Copyright (c) 2020 Marvin Borner
+
+#include <def.h>
+
+void set_fpu_cw(const u16 cw)
+{
+	__asm__ volatile("fldcw %0" ::"m"(cw));
+}
+
+void fpu_install()
+{
+	__asm__ volatile("clts");
+	u32 t;
+	__asm__ volatile("mov %%cr0, %0" : "=r"(t));
+	t &= ~(1 << 2);
+	t |= (1 << 1);
+	__asm__ volatile("mov %0, %%cr0" ::"r"(t));
+
+	__asm__ volatile("mov %%cr4, %0" : "=r"(t));
+	t |= 3 << 9;
+	__asm__ volatile("mov %0, %%cr4" ::"r"(t));
+
+	__asm__ volatile("fninit");
+}
-- 
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