diff options
Diffstat (limited to 'libgloss/m68k/idp-inbyte.c')
-rw-r--r-- | libgloss/m68k/idp-inbyte.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/libgloss/m68k/idp-inbyte.c b/libgloss/m68k/idp-inbyte.c new file mode 100644 index 000000000..41db57fc9 --- /dev/null +++ b/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 */ +} |