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mirror of https://github.com/hsoft/collapseos.git synced 2024-12-24 14:38:05 +11:00

fs: always read whole block meta in memory to avoid seeking

This commit is contained in:
Virgil Dupras 2019-04-23 10:54:56 -04:00
parent c0dbee78de
commit 1a6d285d2d

View File

@ -92,9 +92,10 @@ FS_START .equ FS_BLKSEL+2
; below, which all assume this offset as a context. This offset is not relative
; to FS_START. It can be used directly with blkSeek.
FS_PTR .equ FS_START+2
; A place to store tmp data
FS_TMP .equ FS_PTR+2
FS_HANDLES .equ FS_TMP+0x20
; This variable below contain the metadata of the last block FS_PTR was moved
; to. We read this data in memory to avoid constant seek+read operations.
FS_META .equ FS_PTR+2
FS_HANDLES .equ FS_META+0x20
FS_RAMEND .equ FS_HANDLES+(FS_HANDLE_COUNT*FS_HANDLE_SIZE)
; *** CODE ***
@ -108,9 +109,8 @@ fsBegin:
ld hl, (FS_START)
ld (FS_PTR), hl
pop hl
call fsPlace
call fsReadMeta
call fsIsValid ; sets Z
call fsPlace
ret
; Change current position to the next block with metadata. If it can't (if this
@ -120,8 +120,20 @@ fsNext:
call unsetZ
ret
; Reads metadata at current FS_PTR and place it in FS_META.
; Returns Z according to whether the blkRead operation succeeded.
fsReadMeta:
call fsPlace
push bc
push hl
ld b, 0x20
ld hl, FS_META
call blkRead ; Sets Z
pop hl
pop bc
ret
; Make sure that our underlying blockdev is correcly placed.
; All other routines assumer a properly placed blkdev cursor.
fsPlace:
push af
push hl
@ -150,28 +162,23 @@ fsAlloc:
pop af ; now we want our A arg
call blkPutC
pop hl
call fsPlace
ret
; *** Metadata ***
; Sets Z according to whether the current block is valid.
; Sets Z according to whether the current block in FS_META is valid.
; Don't call other FS routines without checking block validity first: other
; routines don't do checks.
fsIsValid:
push hl
ld b, 0x3
ld hl, FS_TMP
call blkRead
jr nz, .error
push de
ld a, 3
ld hl, FS_META
ld de, .magic
call strncmp
jr nz, .error
; success
jr .end ; Z is set at this point
.error:
call unsetZ
.end:
; The result of Z is our result.
pop de
pop hl
ret
.magic:
@ -179,25 +186,41 @@ fsIsValid:
; Return, in A, the number of allocated blocks at current position.
fsAllocatedBlocks:
ld a, (FS_META+3)
ret
; Return, in HL, the file size at current position.
fsFileSize:
ld hl, (FS_META+4)
ret
; Return HL, which points to a null-terminated string which contains the
; filename at current position.
fsFileName:
ld hl, FS_META+6
ret
; Change name of current file to name in (HL)
fsRename:
push af
push hl ; save filename for later
call fsPlace
ld a, BLOCKDEV_SEEK_FORWARD
ld hl, 6
call blkSeek
ld b, FS_MAX_NAME_SIZE
ld hl, FS_TMP
call blkRead
pop hl ; now we need the filename
push hl ; ... but let's preserve it for the caller
.loop:
ld a, (hl)
cp 0
jr z, .end
call blkPutC
inc hl
jr .loop
.end:
pop hl
pop af
ret
; *** Handling ***
; Open file at current position into handle at (HL)
@ -234,7 +257,8 @@ fsOnCmd:
push hl
call blkTell
ld (FS_PTR), hl
call fsPlace
call fsReadMeta
jr nz, .error
call fsIsValid
jr nz, .error
; success
@ -273,21 +297,8 @@ fnewCmd:
inc de
call intoDE
ex de, hl
push hl ; save the filename for later
call fsAlloc
call fsPlace
ld a, BLOCKDEV_SEEK_FORWARD
ld hl, 6
call blkSeek
pop hl ; now we need the filename
.loop:
ld a, (hl)
cp 0
jr z, .end
call blkPutC
inc hl
jr .loop
.end:
call fsRename
pop de
pop hl
xor a