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/*

 * mbx-inbyte.c -- inbyte function for targets using the eppcbug monitor

 *

 * Copyright (c) 1998 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 "ppc-asm.h"

int inbyte(void)

{

    struct {

        unsigned clun;

        unsigned dlun;

        char     *data;

        unsigned len;

        unsigned rsrvd;

        char     buf[4];

    } ipb, *inpb;

    struct {

        int status;

        int cnt;

    } opb, *outpb;

    inpb = &ipb;

    outpb = &opb;

    do {

        inpb->clun = 0;

        inpb->dlun = 0;

        inpb->data = ipb.buf;

        inpb->len  = 1;

        inpb->rsrvd = 0;

        asm volatile (

            "mr  3,%0\n"

            "mr  4,%1\n"

            "li  10,0x200\n"

            "sc"

            : /* no outputs */

            : "r" (inpb), "r" (outpb)

            : "3", "4", "10"

        );

    } while (outpb->status == 0 && outpb->cnt == 0);

    if (outpb->status == 0)

        return ipb.buf[0] & 0xff;

    return -1;

}