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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [libgloss/] [m68k/] [idp-inbyte.c] - Rev 158
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/* 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 */ }