More-working syscall logic (parameters work!)

2 files changed, 10 insertions, 16 deletions

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
diff --git a/src/userspace/start.asm b/src/userspace/start.asm
index 498f5f5..488101c 100644
--- a/src/userspace/start.asm
+++ b/src/userspace/start.asm
@@ -8,15 +8,4 @@ section .text
     _start:
         mov esp, ebp
         call user_main
-
-    global syscall
-    syscall:
-        mov eax, 1
-        lea edi, [ebp+welcome]
-        mov esi, welcome_sz
-        int 0x80
-        ret
-
-section .data
-        welcome db "Welcome to the userspace", 0x0A, 0x0A
-        welcome_sz equ $ - welcome
\ No newline at end of file
+        jmp $
\ No newline at end of file