lib/libvdelta/vdio.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*          Copyright (c) 1995-2012 AT&T Intellectual Property          *
*                      and is licensed under the                       *
*                 Eclipse Public License, Version 1.0                  *
*                    by AT&T Intellectual Property                     *
*                                                                      *
*                A copy of the License is available at                 *
*          http://www.eclipse.org/org/documents/epl-v10.html           *
*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#include    "vdelhdr.h"

/*  IO subsystem for the delta routines
**
**  Written by Kiem-Phong Vo (12/15/94)
*/

#if __STD_C
static void _vdinit(reg Vdio_t* io)
#else
static void _vdinit(io)
reg Vdio_t* io;
#endif
{
    if((io->data = (uchar*)io->delta->data) )
        io->size = io->delta->size;
    else
    {   io->data = io->buf;
        io->size = sizeof(io->buf);
    }
    io->next = io->data;
    io->endb = io->data + io->size;
    io->left = io->delta->size;
}

#if __STD_C
static int _vdfilbuf(reg Vdio_t* io)
#else
static int _vdfilbuf(io)
reg Vdio_t* io;
#endif
{   reg int n;

    if(!io->data)
        _vdinit(io);

    if(io->data != io->buf) /* all data was given in core */
        return REMAIN(io);

    if ((n = SIZE(io)) > LEFT(io))
        n = LEFT(io);
    if((n = (*READF(io))(DATA(io),n,HERE(io),DELTA(io))) > 0)
    {   ENDB(io) = (NEXT(io) = DATA(io)) + n;
        HERE(io) += n;
        LEFT(io) -= n;
    }
    return n;
}

#if __STD_C
static int _vdflsbuf(reg Vdio_t* io)
#else
static int _vdflsbuf(io)
reg Vdio_t* io;
#endif
{   reg int n;

    if(!io->data )
        _vdinit(io);

    if(io->data != io->buf) /* all space was given  */
        return REMAIN(io);

    if((n = NEXT(io) - DATA(io)) > 0 &&
       (*WRITEF(io))(DATA(io),n,HERE(io),DELTA(io)) != n)
        return -1;

    HERE(io) += n;
    NEXT(io) = DATA(io);
    return SIZE(io);
}

#if __STD_C
static ulong _vdgetu(reg Vdio_t* io, reg ulong v)
#else
static ulong _vdgetu(io,v)
reg Vdio_t* io;
reg ulong   v;
#endif
{   reg int     c;

    for(v &= I_MORE-1;;)
    {   if((c = VDGETC(io)) < 0)
            return (ulong)(-1L);
        if(!(c&I_MORE) )
            return ((v<<I_SHIFT) | c);
        v = (v<<I_SHIFT) | (c & (I_MORE-1));
    }
}

#if __STD_C
static int _vdputu(reg Vdio_t* io, ulong v)
#else
static int _vdputu(io, v)
reg Vdio_t* io;
reg ulong   v;
#endif
{
    reg uchar   *s, *next;
    reg int     len;
    uchar       c[sizeof(ulong)+1];

    s = next = &c[sizeof(c)-1];
    *s = I_CODE(v);
    while((v >>= I_SHIFT) )
        *--s = I_CODE(v)|I_MORE;
    len = (next-s) + 1;

    if(REMAIN(io) < len && _vdflsbuf(io) < len)
        return -1;

    next = io->next;
    switch(len)
    {
    default: memcpy((Void_t*)next,(Void_t*)s,len); next += len; break;
    case 3: *next++ = *s++;
    case 2: *next++ = *s++;
    case 1: *next++ = *s;
    }
    io->next = next;

    return len;
}

#if __STD_C
static int _vdread(Vdio_t* io, reg uchar* s, reg int n)
#else
static int _vdread(io, s, n)
Vdio_t*     io;
reg uchar*  s;
reg int     n;
#endif
{
    reg uchar*  next;
    reg int     r, m;

    for(m = n; m > 0; )
    {   if((r = REMAIN(io)) <= 0 && (r = _vdfilbuf(io)) <= 0)
            break;
        if(r > m)
            r = m;

        next = io->next;
        MEMCPY(s,next,r);
        io->next = next;

        m -= r;
    }
    return n-m;
}

#if __STD_C
static int _vdwrite(Vdio_t* io, reg uchar* s, reg int n)
#else
static int _vdwrite(io, s, n)
Vdio_t*     io;
reg uchar*  s;
reg int     n;
#endif
{
    reg uchar*  next;
    reg int     w, m;

    for(m = n; m > 0; )
    {   if((w = REMAIN(io)) <= 0 && (w = _vdflsbuf(io)) <= 0)
            break;
        if(w > m)
            w = m;

        next = io->next;
        MEMCPY(next,s,w);
        io->next = next;

        m -= w;
    }
    return n-m;
}


Vdbufio_t   _Vdbufio =
{   _vdfilbuf,
    _vdflsbuf,
    _vdgetu,
    _vdputu,
    _vdread,
    _vdwrite
};