20000317 sourceware import

libgloss/m68k/idp-inbyte.c

@@ -0,0 +1,41 @@
+/* idp-inbyte.c -- 
+ * Copyright (c) 1995 Cygnus Support
+ *
+ * The authors hereby grant permission to use, copy, modify, distribute,
+ * and license this software and its documentation for any purpose, provided
+ * that existing copyright notices are retained in all copies and that this
+ * notice is included verbatim in any distributions. No written agreement,
+ * license, or royalty fee is required for any of the authorized uses.
+ * Modifications to this software may be copyrighted by their authors
+ * and need not follow the licensing terms described here, provided that
+ * the new terms are clearly indicated on the first page of each file where
+ * they apply.
+ */
+
+#include <_ansi.h>
+#include "mc68681reg.h"
+
+/* 
+ * The DUART is mapped into the IDP address space in an unusual 
+ * manner.  The mc68681 is an 8 bit device located on the least
+ * significant byte (byte0) of the data bus.  Bytes 3, 2, and 
+ * one have nothing in them and writes to these locations are
+ * not valid.
+ */
+
+#define DUART_ADDR	0x00B00000
+#define READREG(x)	(*((volatile char *) DUART_ADDR + (x * 4) + 3))
+#define WRITEREG(x, y)	(*((char *) DUART_ADDR + (x * 4) + 3) = y)
+
+/*
+ * inbyte -- get a byte from the DUART RX buffer. This only reads
+ *           from channel A
+ */
+char
+_DEFUN_VOID (inbyte)
+{
+  while ((READREG (DUART_SRA) & 0x01) == 0x00)
+    ;
+
+  return (READREG (DUART_RBA));		/* read the byte */
+}