From ed3da12bb378d82878fff1d50e5e9e7af3d7265d Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Wed, 4 Dec 2019 20:38:10 +0100
Subject: More-working syscall logic (parameters work!)

---
 src/userspace/main.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

(limited to 'src/userspace/main.c')

diff --git a/src/userspace/main.c b/src/userspace/main.c
index 22bb42a..5df961f 100644
--- a/src/userspace/main.c
+++ b/src/userspace/main.c
@@ -1,10 +1,15 @@
-#include <stddef.h>
-
-extern void syscall();
+void write(const char *str, int len)
+{
+    int ret;
+    asm volatile ("push %%ebx; movl %2,%%ebx; int $0x80; pop %%ebx" \
+                : "=a" (ret) \
+                : "0" (1), "b" ((int) (str)), "c"((int) (len)));
+}
 
 void user_main()
 {
-    syscall();
+    const char hello[] = "Switched to usermode!\n";
+    write(hello, sizeof(hello));
 
     while (1) {};
 }
\ No newline at end of file
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