Fit mips write return value

arch/mips.c

@@ -15,14 +15,15 @@ void exit(int8_t status){
 
 intptr_t write(int32_t fd, const void* buf, intptr_t size){
   intptr_t n_written = 0;
-  asm ( 
-    "move $a0, %2\n"
-    "move $a1, %0\n"
-    "move $a2, %1\n"
+  asm volatile ( 
+    "move $a0, %1\n"
+    "move $a1, %2\n"
+    "move $a2, %3\n"
     "li $v0, 4004\n"
     "syscall\n"
-    : //TODO: n_written
-    : "r"(buf), "r"(size), "r"(fd)
+    "move %0, $v0\n"
+    : "=r"(n_written)
+    : "r"(fd), "r"(buf), "r"(size)
     : "a0", "a1", "a2", "v0" //TODO: temp registers clobbered by syscall should probably also be listed but this fn returns right away so it should be fine?
   );
   return n_written;