added fn get string param

src/kernel/exception.rs

@@ -120,6 +120,24 @@ fn syscall(machine: &Machine) -> Result<MachineOk, MachineError> {
     }
 }
 
+fn get_string_param(addr: i64, maxlen: i64, machine: &Machine) -> Vec<char>{
+    let mut dest = Vec::with_capacity(maxlen as usize);
+
+    let mut i = 0;
+    let mut c = 1;
+
+    while c != 0 && i < maxlen {
+        c = machine.read_memory(1, (addr + i) as usize);
+        //dest.push(c as char);
+        dest[i] = c as char;
+        i += 1;
+    }
+
+    dest[maxlen - 1] = '\0';
+
+    dest
+}
+
 #[cfg(test)]
 mod test {
     use crate::kernel::exception::{SC_SHUTDOWN, SC_WRITE};