void flush(BCB *b)
{
int n,d;
DMD *dm;
/* if buffer not in use or not dirty, no work to do */
if ((b->b_bufdrv == -1) || (!b->b_dirty)) {
b->b_bufdrv = -1;
return;
}
dm = b->b_dm; /* media descr for buffer */
n = b->b_buftyp;
d = b->b_bufdrv;
b->b_bufdrv = -1; /* invalidate in case of error */
longjmp_rwabs(1, (long)b->b_bufr, 1, b->b_bufrec+dm->m_recoff[n], d);
/* flush to both fats */
if (n == BT_FAT) {
longjmp_rwabs(1, (long)b->b_bufr, 1,
b->b_bufrec+dm->m_recoff[BT_FAT]-dm->m_fsiz, d);
}
b->b_bufdrv = d; /* re-validate */
b->b_dirty = 0;
}
/*
* getbcb - called by getrec() to get the BCB for the desired record
*
* buftype is BT_FAT, BT_ROOT, or BT_DATA
*/
BCB *getbcb(DMD *dmd,WORD buftype,RECNO recnum)
{
BCB *b;
BCB *p, *mtbuf, **q, **phdr;
int err;
mtbuf = 0;
phdr = &bufl[buftype==BT_FAT ? BI_FAT : BI_DATA];
/*
* See if the desired record for the desired drive is in memory.
* If it is, we will use it. Otherwise we will use
* the last invalid (available) buffer, or
* the last (least recently) used buffer.
*/
for (b = *(q = phdr); b; b = *(q = &b->b_link))
{
if ((b->b_bufdrv == dmd->m_drvnum) && (b->b_buftyp == buftype) && (b->b_bufrec == recnum))
break;
/*
* keep track of the last invalid buffer
*/
if (b->b_bufdrv == -1) /* if buffer not valid */
mtbuf = b; /* then it's 'empty' */
}
if (!b)
{
/*
* not in memory. If there was an 'empty' buffer, use it.
*/
if (mtbuf)
b = mtbuf;
/*
* find predecessor of mtbuf, or last guy in list, which
* is the least recently used.
*/
doio: for (p = *(q = phdr); p->b_link; p = *(q = &p->b_link))
if (b == p)
break;
b = p;
/*
* flush the current contents of the buffer, and read in the
* new record.
*/
flush(b);
longjmp_rwabs(0, (long)b->b_bufr, 1, recnum+dmd->m_recoff[buftype], dmd->m_drvnum);
/*
* make the new buffer current
*/
b->b_bufrec = recnum;
b->b_dirty = 0;
b->b_buftyp = buftype;
b->b_bufdrv = dmd->m_drvnum;
b->b_dm = dmd;
}
else
{ /* use a buffer, but first validate media */
err = Mediach(b->b_bufdrv);
if (err != 0) {
if (err == 1) {
goto doio; /* media may be changed */
} else if (err == 2) {
/* media definitely changed */
errdrv = b->b_bufdrv;
rwerr = E_CHNG; /* media change */
errcode = rwerr;
longjmp(errbuf,1);
}
}
}
/*
* now put the current buffer at the head of the list
*/
*q = b->b_link;
b->b_link = *phdr;
*phdr = b;
return b;
}
char *getrec(RECNO recn, OFD *of, int wrtflg)
{
DMD *dm = of->o_dmd;
register BCB *b;
BCB *p,*mtbuf,**q,**phdr;
int n,err;
#if DBGFSBUF
kprintf("getrec 0x%lx, %p, 0x%x\n", (long)recn, dm, wrtflg);
#endif
/* put bcb management here */
if (of->o_dmd->m_fatofd == of) /* is this the OFD for the 'FAT file'? */
n = BT_FAT; /* yes, must be FAT access */
else if (!of->o_dnode) /* no - do we have a dir node? */
n = BT_ROOT; /* no, must be root */
else n = BT_DATA; /* yes, must be normal dir/file */
#if DBGFSBUF
kprintf("n=%i , dm->m_recoff[n] = 0x%lx\n", n, dm->m_recoff[n]);
#endif
mtbuf = 0;
phdr = &bufl[n==BT_FAT ? BI_FAT : BI_DATA];
/*
* See, if the desired record for the desired drive is in memory.
* If it is, we will use it. Otherwise we will use
* the last invalid (available) buffer, or
* the last (least recently) used buffer.
*/
for (b = *(q = phdr); b; b = *(q = &b->b_link))
{
if ((b->b_bufdrv == dm->m_drvnum) && (b->b_buftyp == n) && (b->b_bufrec == recn))
break;
/*
* keep track of the last invalid buffer
*/
if (b->b_bufdrv == -1) /* if buffer not valid */
mtbuf = b; /* then it's 'empty' */
}
if (!b)
{
/*
* not in memory. If there was an 'empty' buffer, use it.
*/
if (mtbuf)
b = mtbuf;
/*
* find predecessor of mtbuf, or last guy in list, which
* is the least recently used.
*/
doio: for (p = *(q = phdr); p->b_link; p = *(q = &p->b_link))
if (b == p)
break;
b = p;
/*
* flush the current contents of the buffer, and read in the
* new record.
*/
flush(b);
longjmp_rwabs(0, (long)b->b_bufr, 1, recn+dm->m_recoff[n], dm->m_drvnum);
/*
* make the new buffer current
*/
b->b_bufrec = recn;
b->b_dirty = 0;
b->b_buftyp = n;
b->b_bufdrv = dm->m_drvnum;
b->b_dm = dm;
}
else
{ /* use a buffer, but first validate media */
err = Mediach(b->b_bufdrv);
if (err != 0) {
if (err == 1) {
goto doio; /* media may be changed */
} else if (err == 2) {
/* media definitely changed */
errdrv = b->b_bufdrv;
rwerr = E_CHNG; /* media change */
errcode = rwerr;
longjmp(errbuf,1);
}
}
}
/*
* now put the current buffer at the head of the list
*/
*q = b->b_link;
b->b_link = *phdr;
*phdr = b;
/*
* if we are writing to the buffer, dirty it.
*/
if (wrtflg) {
b->b_dirty = 1;
}
return(b->b_bufr);
}
