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Fix file writing; first pass at writing past end of files
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@ry755
ry755 committed Mar 24, 2024
1 parent 39a696e commit 73a1750
Showing 1 changed file with 138 additions and 52 deletions.
190 changes: 138 additions & 52 deletions RYFS.okm
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Original file line number Diff line number Diff line change
Expand Up @@ -11,14 +11,7 @@ MODULE RYFS;
reserved: CHAR;
END;

FileSectorHeader = RECORD
magic: CHAR;
alignment: CHAR;
nextSector: SHORT;
sectorSize: SHORT;
END;

EXTERN TEMP_SECTOR_BUF: POINTER TO FileSectorHeader;
EXTERN TEMP_SECTOR_BUF: POINTER TO CHAR;

EXTERN PROCEDURE check_disk: INT;
EXTERN PROCEDURE read_sector: INT;
Expand Down Expand Up @@ -79,51 +72,51 @@ MODULE RYFS;
END;

(* read the directory sector from disk *)
read_sector(1, diskId, TEMP_SECTOR_BUF);
read_sector(1, diskId, PTROF(TEMP_SECTOR_BUF));

(* write first file sector number *)
PUTSHORT(TEMP_SECTOR_BUF + firstFreeEntry, firstFreeSector);
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + firstFreeEntry, firstFreeSector);

(* write file size in sectors *)
sizeInSectors := ryfs_ceil(sizeInBytes, 506) /| 506;
PUTSHORT(TEMP_SECTOR_BUF + firstFreeEntry + 2, sizeInSectors);
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + firstFreeEntry + 2, sizeInSectors);

(* write filename *)
copy_memory_bytes(fileName, TEMP_SECTOR_BUF + firstFreeEntry + 4, 11);
PUTCHAR(TEMP_SECTOR_BUF + firstFreeEntry + 4 + 11, 0);
copy_memory_bytes(fileName, PTROF(TEMP_SECTOR_BUF) + firstFreeEntry + 4, 11);
PUTCHAR(PTROF(TEMP_SECTOR_BUF) + firstFreeEntry + 4 + 11, 0);

(* write the directory sector back out to disk *)
write_sector(1, diskId, TEMP_SECTOR_BUF);
write_sector(1, diskId, PTROF(TEMP_SECTOR_BUF));

sector := 0;
WHILE sector <| sizeInSectors DO
nextFreeSector := ryfs_find_free_sector(diskId);
ryfs_mark_used(nextFreeSector);
read_sector(nextFreeSector, diskId, TEMP_SECTOR_BUF);
read_sector(nextFreeSector, diskId, PTROF(TEMP_SECTOR_BUF));

(* file magic byte and alignment *)
PUTCHAR(TEMP_SECTOR_BUF, 0FFH);
PUTCHAR(TEMP_SECTOR_BUF + 1, 0);
PUTCHAR(PTROF(TEMP_SECTOR_BUF), 0FFH);
PUTCHAR(PTROF(TEMP_SECTOR_BUF) + 1, 0);
IF sector # sizeInSectors - 1 THEN
(* write a link to the next free sector coming up *)
PUTSHORT(TEMP_SECTOR_BUF + 2, ryfs_find_free_sector(diskId));
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + 2, ryfs_find_free_sector(diskId));
(* this is not the last sector in the file, write a zero to the "sector size" field *)
PUTSHORT(TEMP_SECTOR_BUF + 4, 0);
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + 4, 0);
ELSE
(* this is the last sector in the file, write a zero as the link and set the size of the last sector *)
PUTSHORT(TEMP_SECTOR_BUF + 2, 0);
PUTSHORT(TEMP_SECTOR_BUF + 4, sizeInBytes MOD 506);
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + 2, 0);
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + 4, sizeInBytes MOD 506);
END;

(* clear the file data *)
i := 6;
WHILE i <| 512 DO
PUTCHAR(TEMP_SECTOR_BUF + i, 0);
PUTCHAR(PTROF(TEMP_SECTOR_BUF) + i, 0);
i := i + 1;
END;

(* write the sector out to disk *)
write_sector(nextFreeSector, diskId, TEMP_SECTOR_BUF);
write_sector(nextFreeSector, diskId, PTROF(TEMP_SECTOR_BUF));

sector := sector + 1;
END;
Expand Down Expand Up @@ -154,6 +147,9 @@ MODULE RYFS;

(* get the number of sectors to traverse before we reach our seek offset *)
sectorsToTraverse := ryfs_ceil(struct^.seekOffset, 506) / 506;
IF (struct^.seekOffset >| 0) & (struct^.seekOffset MOD 506 = 0) THEN
sectorsToTraverse := sectorsToTraverse + 1;
END;

(* traverse through linked sectors starting at struct^.firstSector *)
thisSector := struct^.firstSector;
Expand All @@ -162,7 +158,7 @@ MODULE RYFS;
ELSE WHILE sectorsToTraverse DO
read_sector(thisSector, struct^.diskId, PTROF(TEMP_SECTOR_BUF));
startSector := thisSector;
thisSector := PTROF(TEMP_SECTOR_BUF)^.nextSector;
thisSector := GETSHORT(PTROF(TEMP_SECTOR_BUF) + 2);
sectorsToTraverse := sectorsToTraverse - 1;
END; END;

Expand Down Expand Up @@ -197,18 +193,20 @@ MODULE RYFS;
END;

PROCEDURE ryfs_write(size: INT; struct: POINTER TO ROMFile; source: POINTER TO CHAR;);
VAR originalSize: INT;
sectorsToLoad: INT;
VAR sectorsToLoad: INT;
sectorsToTraverse: INT;
startSector: SHORT;
thisSector: SHORT;
bytesToLoad: INT;
temp: INT;
BEGIN
originalSize := size;
sectorsToLoad := ryfs_ceil(size, 506) / 506;

(* get the number of sectors to traverse before we reach our seek offset *)
sectorsToTraverse := ryfs_ceil(struct^.seekOffset, 506) / 506;
IF (struct^.seekOffset >| 0) & (struct^.seekOffset MOD 506 = 0) THEN
sectorsToTraverse := sectorsToTraverse + 1;
END;

(* traverse through linked sectors starting at struct^.firstSector *)
thisSector := struct^.firstSector;
Expand All @@ -217,22 +215,27 @@ MODULE RYFS;
ELSE WHILE sectorsToTraverse DO
read_sector(thisSector, struct^.diskId, PTROF(TEMP_SECTOR_BUF));
startSector := thisSector;
thisSector := PTROF(TEMP_SECTOR_BUF)^.nextSector;
thisSector := GETSHORT(PTROF(TEMP_SECTOR_BUF) + 2);
sectorsToTraverse := sectorsToTraverse - 1;
END; END;

thisSector := startSector;
WHILE sectorsToLoad DO
(* load the working sector into the temporary buffer *)
read_sector(thisSector, struct^.diskId, PTROF(TEMP_SECTOR_BUF));

IF size >|= 506 THEN
bytesToLoad := 506;
ELSE
bytesToLoad := size;
END;

(* copy from the temporary buffer to the caller's final buffer *)
temp := ryfs_get_size(struct);
IF struct^.seekOffset + bytesToLoad >| temp THEN
thisSector := ryfs_add_size_to_file(struct^.seekOffset - temp + bytesToLoad, struct);
END;

(* load the working sector into the temporary buffer *)
read_sector(thisSector, struct^.diskId, PTROF(TEMP_SECTOR_BUF));

(* copy from the caller's buffer to the temporary buffer *)
copy_memory_bytes(source, PTROF(TEMP_SECTOR_BUF) + 6 + (struct^.seekOffset MOD 506), bytesToLoad);

(* write the sector back out to disk *)
Expand All @@ -248,10 +251,10 @@ MODULE RYFS;
size := size - bytesToLoad;

sectorsToLoad := sectorsToLoad - 1;
END;

(* add to the file's seek offset *)
struct^.seekOffset := struct^.seekOffset + originalSize;
(* add to the file's seek offset *)
struct^.seekOffset := struct^.seekOffset + bytesToLoad;
END;
END;

PROCEDURE ryfs_read_whole_file(struct: POINTER TO ROMFile; destination: POINTER TO CHAR;);
Expand Down Expand Up @@ -289,15 +292,15 @@ MODULE RYFS;
fileCounter: INT;
BEGIN
(* load directory sector into temp buffer *)
read_sector(1, diskId, TEMP_SECTOR_BUF);
read_sector(1, diskId, PTROF(TEMP_SECTOR_BUF));

i := 31;
bufferOffset := 0;
sectorOffset := 20; (* point to first file name *)
fileCounter := 0;
WHILE i DO
IF GETCHAR(TEMP_SECTOR_BUF + sectorOffset) # 0 THEN
copy_memory_bytes(TEMP_SECTOR_BUF + sectorOffset, buffer + bufferOffset, 11);
IF GETCHAR(PTROF(TEMP_SECTOR_BUF) + sectorOffset) # 0 THEN
copy_memory_bytes(PTROF(TEMP_SECTOR_BUF) + sectorOffset, buffer + bufferOffset, 11);
fileCounter := fileCounter + 1;
bufferOffset := bufferOffset + 11;
END;
Expand All @@ -308,6 +311,89 @@ MODULE RYFS;
RETURN(fileCounter);
END;

(* `size` must be no larger than 506 *)
(* returns destination sector *)
(* clobbers sector buffer!! *)
PROCEDURE ryfs_add_size_to_file(size: INT; struct: POINTER TO ROMFile;): INT;
VAR sizeInSectorsBefore: INT;
sizeInSectorsAfter: INT;
sizeInBytesBefore: INT;
sizeInBytesAfter: INT;
sectorsToTraverse: INT;
thisSector: INT;
oldThisSector: INT;
i: INT;
temp: INT;
BEGIN
sizeInBytesBefore := ryfs_get_size(struct);
sizeInBytesAfter := sizeInBytesBefore + size;
sizeInSectorsBefore := ryfs_ceil(sizeInBytesBefore, 506) /| 506;
sizeInSectorsAfter := ryfs_ceil(sizeInBytesAfter, 506) /| 506;

IF sizeInSectorsAfter # sizeInSectorsBefore THEN
read_sector(1, struct^.diskId, PTROF(TEMP_SECTOR_BUF));
(* reverse-find the directory sector entry from the passed struct *)
i := 1;
WHILE i <| 32 DO
IF GETSHORT(PTROF(TEMP_SECTOR_BUF) + (i * 16)) = struct^.firstSector THEN
(* we found it!! *)
temp := GETSHORT(PTROF(TEMP_SECTOR_BUF) + (i * 16) + 2);
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + (i * 16) + 2, temp + 1);
END;
i := i + 1;
END;
write_sector(1, struct^.diskId, PTROF(TEMP_SECTOR_BUF));
END;

(* get the number of sectors to traverse before we reach the end *)
sectorsToTraverse := ryfs_ceil(sizeInBytesBefore, 506) / 506;

(* traverse through linked sectors starting at struct^.firstSector *)
thisSector := struct^.firstSector;
WHILE sectorsToTraverse DO
read_sector(thisSector, struct^.diskId, PTROF(TEMP_SECTOR_BUF));
oldThisSector := thisSector;
thisSector := GETSHORT(PTROF(TEMP_SECTOR_BUF) + 2);
sectorsToTraverse := sectorsToTraverse - 1;
END;

IF sizeInSectorsAfter # sizeInSectorsBefore THEN
(* we need to find another sector to link to this file *)
(* TODO: we assume success here, that is bad. add error checking *)
temp := ryfs_find_free_sector(struct^.diskId);

(* re-read the previously-last sector back into the buffer *)
read_sector(oldThisSector, struct^.diskId, PTROF(TEMP_SECTOR_BUF));

(* link the newly-found sector to the end of the file *)
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + 2, temp);

(* write out the changes to disk *)
write_sector(oldThisSector, struct^.diskId, PTROF(TEMP_SECTOR_BUF));

(* prepare an empty sector of remaining size for the file *)
PUTCHAR(PTROF(TEMP_SECTOR_BUF), 0FFH); (* magic *)
PUTCHAR(PTROF(TEMP_SECTOR_BUF) + 1, 0); (* alignment *)
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + 2, 0); (* next sector *)
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + 4, sizeInBytesAfter MOD 506); (* remaining size *)
i := 6;
WHILE i <| 512 DO
PUTCHAR(PTROF(TEMP_SECTOR_BUF) + i, 0);
i := i + 1;
END;

(* return the new sector *)
RETURN(temp);
ELSE
(* at this point the last file sector is loaded into the buffer, add to the size *)
PUTSHORT(PTROF(TEMP_SECTOR_BUF) + 4, sizeInBytesAfter MOD 506);
write_sector(oldThisSector, struct^.diskId, PTROF(TEMP_SECTOR_BUF));

(* return the old sector *)
RETURN(oldThisSector);
END;
END;

PROCEDURE ryfs_ceil(number, ceilNumber: INT;): INT;
VAR remainder: INT;
BEGIN
Expand All @@ -330,14 +416,14 @@ MODULE RYFS;
firstClearBit: CHAR;
firstFreeSector: INT;
BEGIN
read_sector(1, diskId, TEMP_SECTOR_BUF);
totalBitmapSectors := GETCHAR(TEMP_SECTOR_BUF);
read_sector(1, diskId, PTROF(TEMP_SECTOR_BUF));
totalBitmapSectors := GETCHAR(PTROF(TEMP_SECTOR_BUF));
bitmapSector := 0;
WHILE bitmapSector <| totalBitmapSectors DO
bitmapByte := 0;
read_sector(bitmapSector + 2, diskId, TEMP_SECTOR_BUF);
read_sector(bitmapSector + 2, diskId, PTROF(TEMP_SECTOR_BUF));
WHILE bitmapByte <| 512 DO
firstClearBit := ryfs_find_first_clear_in_byte(GETCHAR(TEMP_SECTOR_BUF + bitmapByte));
firstClearBit := ryfs_find_first_clear_in_byte(GETCHAR(PTROF(TEMP_SECTOR_BUF) + bitmapByte));
IF firstClearBit # 0FFH THEN
firstFreeSector := (bitmapSector * 4096) + (bitmapByte * 8) + firstClearBit;
RETURN(firstFreeSector);
Expand All @@ -355,11 +441,11 @@ MODULE RYFS;
VAR i: INT;
offset: INT;
BEGIN
read_sector(1, diskId, TEMP_SECTOR_BUF);
read_sector(1, diskId, PTROF(TEMP_SECTOR_BUF));
i := 0;
offset := 16; (* point to first entry *)
WHILE i <| 30 DO
IF GETSHORT(TEMP_SECTOR_BUF + offset) = 0 THEN
IF GETSHORT(PTROF(TEMP_SECTOR_BUF) + offset) = 0 THEN
RETURN(offset);
END;
offset := offset + 16;
Expand Down Expand Up @@ -395,11 +481,11 @@ MODULE RYFS;
bitmapByte := ((ryfs_ceil(sector + 1, 8) /| 8) - 1) MOD 512;
bitmapBit := sector MOD 8;

read_sector(bitmapSector, diskId, TEMP_SECTOR_BUF);
bitmap := GETCHAR(TEMP_SECTOR_BUF + bitmapByte);
read_sector(bitmapSector, diskId, PTROF(TEMP_SECTOR_BUF));
bitmap := GETCHAR(PTROF(TEMP_SECTOR_BUF) + bitmapByte);
bitmap := bitmap OR LSH(1, bitmapBit);
PUTCHAR(TEMP_SECTOR_BUF + bitmapByte, bitmap);
write_sector(bitmapSector, diskId, TEMP_SECTOR_BUF);
PUTCHAR(PTROF(TEMP_SECTOR_BUF) + bitmapByte, bitmap);
write_sector(bitmapSector, diskId, PTROF(TEMP_SECTOR_BUF));
END;

(* clobbers sector buffer!! *)
Expand All @@ -413,10 +499,10 @@ MODULE RYFS;
bitmapByte := ((ryfs_ceil(sector + 1, 8) /| 8) - 1) MOD 512;
bitmapBit := sector MOD 8;

read_sector(bitmapSector, diskId, TEMP_SECTOR_BUF);
bitmap := GETCHAR(TEMP_SECTOR_BUF + bitmapByte);
read_sector(bitmapSector, diskId, PTROF(TEMP_SECTOR_BUF));
bitmap := GETCHAR(PTROF(TEMP_SECTOR_BUF) + bitmapByte);
bitmap := bitmap & ~(LSH(1, bitmapBit));
PUTCHAR(TEMP_SECTOR_BUF + bitmapByte, bitmap);
write_sector(bitmapSector, diskId, TEMP_SECTOR_BUF);
PUTCHAR(PTROF(TEMP_SECTOR_BUF) + bitmapByte, bitmap);
write_sector(bitmapSector, diskId, PTROF(TEMP_SECTOR_BUF));
END;
END.

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