diff --git a/mwrite.c b/mwrite.c
new file mode 100644
index 0000000..78ea502
--- /dev/null
+++ b/mwrite.c
@@ -0,0 +1,58 @@
+#include "marignotti.h"
+#include <gno/kerntool.h>
+#include <sys/signal.h>
+#include <errno.h>
+
+
+#pragma noroot
+#pragma optimize 79
+
+// called through GSOS.
+int mwrite(int ipid, void *p1, void *p2, void *p3, void *p4, void *p5)
+{
+    Entry *e;
+    Word terr;
+    Word t;
+    int xerrno;
+    
+    char *buffer = (char *)p1;
+    LongWord nbytes = *(LongWord *)p2;
+    
+    *(LongWord *)p2 = 0;
+    
+    e = find_entry(ipid);
+    
+    if (!e)
+    {
+        return EBADF;
+    }
+    
+    // todo -- queue up if pending >= _SNDLOWAT?
+    // todo -- push?
+    
+    IncBusy();
+    terr = TCPIPWriteTCP(ipid, buffer, nbytes, 0, 0);
+    t = _toolErr;
+    DecBusy();
+    
+    if (t) terr = t;
+    
+    if (t || terr == tcperrBadConnection)
+        return ENOTCONN;
+
+    if (terr == tcperrNoResources)
+        return ENOMEM;
+    
+    if (terr == tcperrConClosing)
+    {
+        int xerrno;
+        if (!e->_NOSIGPIPE)
+            Kkill(Kgetpid(), SIGPIPE, &xerrno);
+            
+        return EPIPE;
+    }
+    
+    *(LongWord *)p2 = nbytes;
+        
+    return 0;
+}
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