lflread.c

Go to the documentation of this file.

/* lflread.c - lflread */

#include <xinu.h>

/*------------------------------------------------------------------------
 * lflread  -  Read from a previously opened local file
 *------------------------------------------------------------------------
 */
devcall lflread (
      struct dentry *devptr,    /* Entry in device switch table */
      char  *buff,          /* Buffer to hold bytes     */
      int32 count           /* Max bytes to read        */
    )
{
    uint32  numread;        /* Number of bytes read     */
    int32   nxtbyte;        /* Character or SYSERR/EOF  */

    if (count < 0) {
        return SYSERR;
    }

    /* Iterate and use lflgetc to read individual bytes */

    for (numread=0 ; numread < count ; numread++) {
        nxtbyte = lflgetc(devptr);
        if (nxtbyte == SYSERR) {
            return SYSERR;
        } else if (nxtbyte == EOF) {    /* EOF before finished */
            if (numread == 0) {
            return EOF;
            } else {
            return numread;
            }
        } else {
            *buff++ = (char) (0xff & nxtbyte);
        }
    }
    return numread;
}