Desktop/xinu_mips-1.0.2.tar/xinu_mips-1.0.2/tty/ttyWrite.c

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/* Embedded XINU, Copyright (C) 2007.  All rights reserved. */

#include <kernel.h>
#include <device.h>
#include <tty.h>

devcall ttyWrite(device *pdev, uchar *buf, ushort len)
{
        struct tty *ptty;
        device     *phw = NULL;
        ushort     i    = 0;
        uchar      last = 0;

        /* Setup and error check pointers to structures */
        ptty = (struct tty *)pdev->controlblk;
        ASSERT((NULL != ptty) && (TTY_STATE_ALLOC == ptty->state));
        
        phw = ptty->tty_phw;
        ASSERT(NULL != phw);

        for (i = 0; i < len; i++)
    {
                /* If not in RAW mode, then 'cook' special characters    */
                if (!(ptty->oflags & TTY_OFLAG_RAW))
                        {
                                /* Cook Line Feed and/or Carriage Return         */
                                if ( ('\r' == buf[i]) 
                                         || (('\n' == buf[i]) 
                                                 && ('\r' != last) ))
                                {
                                        /* LF's are converted to CRLF's,        */
                                        /* CR's are converted to CRLF's,        */
                                        /* CRLF's have the CR expanded to CRLF, */
                                        /* and the LF dropped below.            */
                                        /* Thus, only CRLF's are output.        */
                                        if (SYSERR == (*phw->putc)(phw, '\r')) break;
                                        if (SYSERR == (*phw->putc)(phw, '\n')) break;
                                        last = buf[i];
                                        continue;
                                }

                                /* Drop null characters or LF */
                                if (('\0' == buf[i]) || ('\n' == buf[i]))
                                {
                                        last = buf[i];
                                        continue;
                                }

                                /* Cook Backspace and Delete */
                                if (('\b' == buf[i]) || (0x7F == buf[i]))
                                {
                                        /* BS or DEL becomes 'BS, SP, BS' */
                                        if (SYSERR == (*phw->putc)(phw, '\b')) break;
                                        if (SYSERR == (*phw->putc)(phw, ' '))  break;
                                        if (SYSERR == (*phw->putc)(phw, '\b')) break;
                                        last = buf[i];
                                        continue;
                                }
                        }

                /* Write character to underlying device */
                if (SYSERR == (*phw->putc)(phw, buf[i])) break;
                
                /* Remember last character for cooking checks */
                last = buf[i];
    }

        return i;
}

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