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fixed fcb random block read/write.

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Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@566
This commit is contained in:
Peter Veenstra 2002-12-11 19:54:45 +00:00
parent fecc2a4a8a
commit 9aafc9ae6f
1 changed files with 14 additions and 7 deletions
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21
src/dos/dos_files.cpp
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@ -720,13 +720,19 @@ Bit8u DOS_FCBWrite(Bit16u seg,Bit16u offset,Bit16u recno)
}
Bit8u DOS_FCBRandomRead(Bit16u seg,Bit16u offset,Bit16u numRec,bool restore) {
/* if restore is true :random read else random blok read.
* random read updates old block and old record to reflect the random data
* before the read!!!!!!!!! and the random data is not updated! (user must do this)
* Random block read updates these fields to reflect the state after the read!
*/
DOS_FCB fcb(seg,offset);
Bit32u random;Bit16u old_block;Bit8u old_rec;Bit8u error;
/* Set the correct record from the random data */
fcb.GetRandom(random);
if (restore) fcb.GetRecord(old_block,old_rec);
fcb.SetRecord((Bit16u)(random / 128),(Bit8u)(random & 127));
if (restore) fcb.GetRecord(old_block,old_rec);//store this for after the read.
// Read records
for (int i=0; i<numRec; i++) {
error = DOS_FCBRead(seg,offset,i);
@ -735,19 +741,20 @@ Bit8u DOS_FCBRandomRead(Bit16u seg,Bit16u offset,Bit16u numRec,bool restore) {
Bit16u new_block;Bit8u new_rec;
fcb.GetRecord(new_block,new_rec);
if (restore) fcb.SetRecord(old_block,old_rec);
/* Update the random record pointer with new position */
fcb.SetRandom(new_block*128+new_rec - (restore ? 1 : 0) ); //seems to be this way.. why ???
return error;
/* Update the random record pointer with new position only when restore is false*/
if(!restore) fcb.SetRandom(new_block*128+new_rec);
return error;
}
Bit8u DOS_FCBRandomWrite(Bit16u seg,Bit16u offset,Bit16u numRec,bool restore) {
/* see FCB_RandomRead */
DOS_FCB fcb(seg,offset);
Bit32u random;Bit16u old_block;Bit8u old_rec;Bit8u error;
/* Set the correct record from the random data */
fcb.GetRandom(random);
if (restore) fcb.GetRecord(old_block,old_rec);
fcb.SetRecord((Bit16u)(random / 128),(Bit8u)(random & 127));
if (restore) fcb.GetRecord(old_block,old_rec);
/* Write records */
for (int i=0; i<numRec; i++) {
error = DOS_FCBWrite(seg,offset,i);// dos_fcbwrite return 0 false when true...
@ -756,8 +763,8 @@ Bit8u DOS_FCBRandomWrite(Bit16u seg,Bit16u offset,Bit16u numRec,bool restore) {
Bit16u new_block;Bit8u new_rec;
fcb.GetRecord(new_block,new_rec);
if (restore) fcb.SetRecord(old_block,old_rec);
/* Update the random record pointer with new position */
fcb.SetRandom(new_block*128+new_rec - (restore ? 1 : 0) ); //seems to be this way.. need more games to test it.
/* Update the random record pointer with new position only when restore is false */
if(!restore) fcb.SetRandom(new_block*128+new_rec);
return error;
}