mirror of https://github.com/hsoft/collapseos.git
Make blockdev pointers 32 bits
This allows us to break through the 64K limit for includes CFS in zasm, a limit we were dangerously close to breaking. In fact, this commit makes us go over that limit. Right in time!
This commit is contained in:
Virgil Dupras
parent
6b1679c811
commit
328f44814e
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@ -33,10 +33,12 @@
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; Unsuccessful writes generally mean that we reached EOF.
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;
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; Seek:
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; Place device "pointer" at position dictated by HL.
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; Place device "pointer" at position dictated by HL (low 16 bits) and DE (high
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; 16 bits).
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;
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; Tell:
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; Return the position of the "pointer" in HL
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; Return the position of the "pointer" in HL (low 16 bits) and DE (high 16
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; bits).
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;
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; All routines are expected to preserve unused registers.
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@ -197,12 +199,14 @@ _blkWrite:
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ret
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; Seeks the block device in one of 5 modes, which is the A argument:
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; 0 : Move exactly to X, X being the HL argument.
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; 1 : Move forward by X bytes, X being the HL argument
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; 2 : Move backwards by X bytes, X being the HL argument
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; 0 : Move exactly to X, X being the HL/DE argument.
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; 1 : Move forward by X bytes, X being the HL argument (no DE)
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; 2 : Move backwards by X bytes, X being the HL argument (no DE)
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; 3 : Move to the end
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; 4 : Move to the beginning
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; Set position of selected device to the value specified in HL
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; Set position of selected device to the value specified in HL (low) and DE
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; (high). DE is only used for mode 0.
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;
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; When seeking to an out-of-bounds position, the resulting position will be
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; one position ahead of the last valid position. Therefore, GetC after a seek
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@ -214,6 +218,8 @@ blkSeek:
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ld ix, (BLOCKDEV_SEEK)
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ld iy, (BLOCKDEV_TELL)
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_blkSeek:
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; we preserve DE so that it's possible to call blkSeek in mode != 0
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; while not discarding our current DE value.
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push de
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cp BLOCKDEV_SEEK_FORWARD
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jr z, .forward
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@ -224,30 +230,41 @@ _blkSeek:
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cp BLOCKDEV_SEEK_END
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jr z, .end
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; all other modes are considered absolute
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jr .seek ; for absolute mode, HL is already correct
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jr .seek ; for absolute mode, HL and DE are already
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; correct
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.forward:
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ex de, hl ; DE has our offset
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push bc
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push hl
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; We want to be able to plug our own TELL function, which is why we
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; don't call blkTell directly here.
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; Calling TELL
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call callIY ; HL has our curpos
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add hl, de
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jr nc, .seek ; no carry? alright!
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; we have carry? out of bounds, set to maximum
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ld de, 0 ; in case out Tell routine doesn't return DE
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call callIY ; HL/DE now have our curpos
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pop bc ; pop HL into BC
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add hl, bc
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pop bc ; pop orig BC back
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jr nc, .seek ; no carry? let's seek.
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; carry, adjust DE
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inc de
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jr .seek
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.backward:
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; TODO - subtraction are more complicated...
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jr .seek
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.beginning:
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ld hl, 0
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ld de, 0
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jr .seek
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.end:
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ld hl, 0xffff
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ld de, 0xffff
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.seek:
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call _blkCall
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pop de
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jp _blkCall
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ret
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; Returns the current position of the selected device in HL.
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; Returns the current position of the selected device in HL (low) and DE (high).
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blkTell:
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ld de, 0 ; in case device ignores DE.
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ld ix, (BLOCKDEV_TELL)
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jp _blkCall
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@ -57,6 +57,19 @@ addHL:
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pop af
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ret
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; subtract the value of A from HL
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subHL:
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push af
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; To avoid having to swap L and A, we sub "backwards", that is, we add
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; a NEGated value. This means that the carry flag is inverted
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neg
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add a, l
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jr c, .end ; if carry, no carry. :)
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dec h
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.end:
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ld l, a
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pop af
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ret
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; Write the contents of HL in (DE)
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writeHLinDE:
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108
kernel/fs.asm
108
kernel/fs.asm
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@ -85,12 +85,9 @@
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.equ FS_META_FSIZE_OFFSET 4
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.equ FS_META_FNAME_OFFSET 6
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; Size in bytes of a FS handle:
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; * 2 bytes for current position. (absolute)
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; * 2 bytes for starting offset, after metadata
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; * 2 bytes for maximum offset
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; * 2 bytes for file size (we could fetch it from metadata all the time, but it
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; could be time consuming depending on the underlying device).
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.equ FS_HANDLE_SIZE 8
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; * 4 bytes for starting offset of the FS block
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; * 2 bytes for current position relative to block's position
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.equ FS_HANDLE_SIZE 6
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.equ FS_ERR_NO_FS 0x5
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.equ FS_ERR_NOT_FOUND 0x6
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@ -101,14 +98,17 @@
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.equ FS_SEEK FS_PUTC+2
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.equ FS_TELL FS_SEEK+2
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; Offset at which our FS start on mounted device
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; This pointer is 32 bits. 32 bits pointers are a bit awkward: first two bytes
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; are high bytes *low byte first*, and then the low two bytes, same order.
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; When loaded in HL/DE, the four bytes are loaded in this order: E, D, L, H
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.equ FS_START FS_TELL+2
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; Offset at which we are currently pointing to with regards to our routines
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; below, which all assume this offset as a context. This offset is not relative
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; to FS_START. It can be used directly with fsblkSeek.
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.equ FS_PTR FS_START+2
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; to FS_START. It can be used directly with fsblkSeek. 32 bits.
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.equ FS_PTR FS_START+4
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; This variable below contain the metadata of the last block FS_PTR was moved
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; to. We read this data in memory to avoid constant seek+read operations.
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.equ FS_META FS_PTR+2
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.equ FS_META FS_PTR+4
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.equ FS_HANDLES FS_META+FS_METASIZE
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.equ FS_RAMEND FS_HANDLES+FS_HANDLE_COUNT*FS_HANDLE_SIZE
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@ -133,10 +133,11 @@ fsBegin:
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push hl
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ld hl, (FS_START)
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ld (FS_PTR), hl
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ld hl, (FS_START+2)
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ld (FS_PTR+2), hl
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pop hl
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call fsReadMeta
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call fsIsValid ; sets Z
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ret
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jp fsIsValid ; sets Z, returns
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; Change current position to the next block with metadata. If it can't (if this
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; is the last valid block), doesn't move.
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@ -156,8 +157,9 @@ fsNext:
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call fsblkSeek
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djnz .loop
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; Good, were here. We're going to read meta from our current position.
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call fsblkTell ; --> HL
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ld (FS_PTR), hl
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call fsblkTell ; --> HL, --> DE
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ld (FS_PTR), de
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ld (FS_PTR+2), hl
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call fsReadMeta
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jr nz, .createChainEnd
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call fsIsValid
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@ -226,13 +228,16 @@ fsInitMeta:
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pop af
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ret
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; Make sure that our underlying blockdev is correcly placed.
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; Make sure that our underlying blockdev is correctly placed.
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fsPlace:
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push af
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push hl
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push de
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xor a
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ld hl, (FS_PTR)
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ld de, (FS_PTR)
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ld hl, (FS_PTR+2)
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call fsblkSeek
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pop de
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pop hl
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pop af
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ret
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@ -284,7 +289,8 @@ fsAlloc:
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; Good, FS_META ready. Now, let's update FS_PTR because it hasn't been
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; changed yet.
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call fsblkTell
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ld (FS_PTR), hl
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ld (FS_PTR), de
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ld (FS_PTR+2), hl
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; Ok, now we can write our metadata
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call fsWriteMeta
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.end:
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@ -361,6 +367,7 @@ fsblkSeek:
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jp _blkSeek
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fsblkTell:
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ld de, 0
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ld ix, (FS_TELL)
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jp _blkCall
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@ -368,57 +375,56 @@ fsblkTell:
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; Open file at current position into handle at (HL)
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fsOpen:
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push bc
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push hl
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push de
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push af
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ex de, hl
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ld hl, (FS_PTR)
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ld a, FS_METASIZE
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call addHL
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call writeHLinDE
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inc de
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inc de
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call writeHLinDE
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inc de
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inc de
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; Maximum offset is starting offset + (numblocks * 0x100) - 1
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ld a, (FS_META+FS_META_ALLOC_OFFSET)
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; Because our blocks are exactly 0x100 in size, we simple have to
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; increase the H in HL to have our result.
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add a, h
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ld h, a
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call writeHLinDE
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inc de
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inc de
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ld hl, (FS_META+FS_META_FSIZE_OFFSET)
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; Starting pos
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ld hl, FS_PTR
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ld bc, 4
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ldir
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; Current pos
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ld hl, FS_METASIZE
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call writeHLinDE
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pop af
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pop de
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pop hl
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pop bc
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ret
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; Place FS blockdev at proper position for file handle in (DE).
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fsPlaceH:
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push af
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push bc
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push hl
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push de
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pop ix
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push ix
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ld l, (ix)
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ld h, (ix+1)
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ld e, (ix)
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ld d, (ix+1)
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ld l, (ix+2)
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ld h, (ix+3)
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ld c, (ix+4)
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ld b, (ix+5)
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add hl, bc
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jr nc, .nocarry
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inc de
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.nocarry:
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ld a, BLOCKDEV_SEEK_ABSOLUTE
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call fsblkSeek
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pop ix
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pop hl
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pop bc
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pop af
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ret
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; Advance file handle in (IX) by one byte
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fsAdvanceH:
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push af
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inc (ix)
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inc (ix+4)
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jr nz, .end
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inc (ix+1)
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inc (ix+5)
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.end:
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pop af
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ret
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@ -426,6 +432,7 @@ fsAdvanceH:
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; Read a byte in handle at (DE), put it into A and advance the handle's
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; position.
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; Z is set on success, unset if handle is at the end of the file.
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; TODO: detect end of file
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fsGetC:
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push ix
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call fsPlaceH
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@ -441,6 +448,7 @@ fsGetC:
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; Write byte A in handle (DE) and advance the handle's position.
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; Z is set on success, unset if handle is at the end of the file.
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; TODO: detect end of block alloc
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fsPutC:
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call fsPlaceH
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push ix
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@ -455,15 +463,18 @@ fsPutC:
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; Sets Z if offset is within bounds, unsets Z if it isn't.
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fsSeek:
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push de \ pop ix
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ld (ix), l
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ld (ix+1), h
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ld a, FS_METASIZE
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call addHL
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ld (ix+4), l
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ld (ix+5), h
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ret
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fsTell:
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push de \ pop ix
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ld l, (ix)
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ld h, (ix+1)
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ret
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ld l, (ix+4)
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ld h, (ix+5)
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ld a, FS_METASIZE
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jp subHL ; returns
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; Mount the fs subsystem upon the currently selected blockdev at current offset.
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; Verify is block is valid and error out if its not, mounting nothing.
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@ -479,8 +490,10 @@ fsOn:
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ld bc, 8 ; we have 8 bytes to copy
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ldir ; copy!
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call fsblkTell
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ld (FS_START), hl
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ld (FS_PTR), hl
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ld (FS_START), de
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ld (FS_START+2), hl
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ld (FS_PTR), de
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ld (FS_PTR+2), hl
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call fsReadMeta
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jr nz, .error
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call fsIsValid
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@ -491,8 +504,7 @@ fsOn:
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.error:
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; couldn't mount. Let's reset our variables.
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xor a
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ld b, 10 ; blkdev routines + FS_START which is just
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; after.
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ld b, FS_META-FS_GETC ; reset routine pointers and FS ptrs
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ld hl, FS_GETC
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call fill
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@ -31,12 +31,13 @@
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#define FS_DATA_PORT 0x01
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#define FS_SEEKL_PORT 0x02
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#define FS_SEEKH_PORT 0x03
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#define FS_SEEKE_PORT 0x04
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static Z80Context cpu;
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static uint8_t mem[0xffff] = {0};
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static uint8_t fsdev[0xffff] = {0};
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static uint16_t fsdev_size = 0;
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static uint16_t fsdev_ptr = 0;
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static uint8_t fsdev[0x20000] = {0};
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static uint32_t fsdev_size = 0;
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static uint32_t fsdev_ptr = 0;
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static int running;
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static uint8_t io_read(int unused, uint16_t addr)
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@ -57,7 +58,9 @@ static uint8_t io_read(int unused, uint16_t addr)
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} else if (addr == FS_SEEKL_PORT) {
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return fsdev_ptr & 0xff;
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} else if (addr == FS_SEEKH_PORT) {
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return fsdev_ptr >> 8;
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return (fsdev_ptr >> 8) & 0xff;
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} else if (addr == FS_SEEKE_PORT) {
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return (fsdev_ptr >> 16) & 0xff;
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} else {
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fprintf(stderr, "Out of bounds I/O read: %d\n", addr);
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return 0;
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@ -78,9 +81,11 @@ static void io_write(int unused, uint16_t addr, uint8_t val)
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fsdev[fsdev_ptr++] = val;
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}
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} else if (addr == FS_SEEKL_PORT) {
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fsdev_ptr = (fsdev_ptr & 0xff00) | val;
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fsdev_ptr = (fsdev_ptr & 0xffff00) | val;
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} else if (addr == FS_SEEKH_PORT) {
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fsdev_ptr = (fsdev_ptr & 0x00ff) | (val << 8);
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fsdev_ptr = (fsdev_ptr & 0xff00ff) | (val << 8);
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} else if (addr == FS_SEEKE_PORT) {
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fsdev_ptr = (fsdev_ptr & 0x00ffff) | (val << 16);
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} else {
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fprintf(stderr, "Out of bounds I/O write: %d / %d\n", addr, val);
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}
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@ -5,6 +5,7 @@
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.equ FS_DATA_PORT 0x01
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.equ FS_SEEKL_PORT 0x02
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.equ FS_SEEKH_PORT 0x03
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.equ FS_SEEKE_PORT 0x04
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jp init
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@ -80,6 +81,8 @@ fsdevSeek:
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out (FS_SEEKL_PORT), a
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ld a, h
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out (FS_SEEKH_PORT), a
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ld a, e
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out (FS_SEEKE_PORT), a
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pop af
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ret
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@ -89,6 +92,8 @@ fsdevTell:
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ld l, a
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in a, (FS_SEEKH_PORT)
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ld h, a
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in a, (FS_SEEKE_PORT)
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ld e, a
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pop af
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ret
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@ -98,6 +98,8 @@ fsdevPutC:
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fsdevSeek:
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push af
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ld a, e
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out (FS_SEEK_PORT), a
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ld a, h
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out (FS_SEEK_PORT), a
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ld a, l
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@ -108,6 +110,8 @@ fsdevSeek:
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fsdevTell:
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push af
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in a, (FS_SEEK_PORT)
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ld e, a
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in a, (FS_SEEK_PORT)
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ld h, a
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in a, (FS_SEEK_PORT)
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ld l, a
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Binary file not shown.
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@ -47,10 +47,10 @@ static int inpt_size;
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static int inpt_ptr;
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static uint8_t middle_of_seek_tell = 0;
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static uint8_t fsdev[0xffff] = {0};
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static uint16_t fsdev_size = 0;
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static uint16_t fsdev_ptr = 0;
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static uint8_t fsdev_middle_of_seek_tell = 0;
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static uint8_t fsdev[0x20000] = {0};
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static uint32_t fsdev_size = 0;
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static uint32_t fsdev_ptr = 0;
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static uint8_t fsdev_seek_tell_cnt = 0;
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static uint8_t io_read(int unused, uint16_t addr)
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{
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@ -79,15 +79,18 @@ static uint8_t io_read(int unused, uint16_t addr)
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return 0;
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}
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} else if (addr == FS_SEEK_PORT) {
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if (fsdev_middle_of_seek_tell) {
|
||||
fsdev_middle_of_seek_tell = 0;
|
||||
return fsdev_ptr & 0xff;
|
||||
} else {
|
||||
if (fsdev_seek_tell_cnt == 0) {
|
||||
#ifdef DEBUG
|
||||
fprintf(stderr, "FS tell %d\n", fsdev_ptr);
|
||||
#endif
|
||||
fsdev_middle_of_seek_tell = 1;
|
||||
return fsdev_ptr >> 8;
|
||||
fsdev_seek_tell_cnt = 1;
|
||||
return fsdev_ptr >> 16;
|
||||
} else if (fsdev_seek_tell_cnt == 1) {
|
||||
fsdev_seek_tell_cnt = 2;
|
||||
return (fsdev_ptr >> 8) & 0xff;
|
||||
} else {
|
||||
fsdev_seek_tell_cnt = 0;
|
||||
return fsdev_ptr & 0xff;
|
||||
}
|
||||
} else {
|
||||
fprintf(stderr, "Out of bounds I/O read: %d\n", addr);
|
||||
|
|
@ -119,15 +122,18 @@ static void io_write(int unused, uint16_t addr, uint8_t val)
|
|||
fsdev[fsdev_ptr++] = val;
|
||||
}
|
||||
} else if (addr == FS_SEEK_PORT) {
|
||||
if (fsdev_middle_of_seek_tell) {
|
||||
if (fsdev_seek_tell_cnt == 0) {
|
||||
fsdev_ptr = val << 16;
|
||||
fsdev_seek_tell_cnt = 1;
|
||||
} else if (fsdev_seek_tell_cnt == 1) {
|
||||
fsdev_ptr |= val << 8;
|
||||
fsdev_seek_tell_cnt = 2;
|
||||
} else {
|
||||
fsdev_ptr |= val;
|
||||
fsdev_middle_of_seek_tell = 0;
|
||||
fsdev_seek_tell_cnt = 0;
|
||||
#ifdef DEBUG
|
||||
fprintf(stderr, "FS seek %d\n", fsdev_ptr);
|
||||
#endif
|
||||
} else {
|
||||
fsdev_ptr = (val << 8) & 0xff00;
|
||||
fsdev_middle_of_seek_tell = 1;
|
||||
}
|
||||
} else if (addr == STDERR_PORT) {
|
||||
fputc(val, stderr);
|
||||
|
|
|
|||
|
|
@ -0,0 +1,56 @@
|
|||
jp test
|
||||
|
||||
#include "core.asm"
|
||||
|
||||
testNum: .db 1
|
||||
|
||||
test:
|
||||
ld hl, 0xffff
|
||||
ld sp, hl
|
||||
|
||||
ld hl, 0x123
|
||||
ld a, 0x25
|
||||
call subHL
|
||||
ld a, h
|
||||
cp 0
|
||||
jp nz, fail
|
||||
ld a, l
|
||||
cp 0xfe
|
||||
jp nz, fail
|
||||
call nexttest
|
||||
|
||||
ld hl, 0x125
|
||||
ld a, 0x23
|
||||
call subHL
|
||||
ld a, h
|
||||
cp 1
|
||||
jp nz, fail
|
||||
ld a, l
|
||||
cp 0x02
|
||||
jp nz, fail
|
||||
call nexttest
|
||||
|
||||
ld hl, 0x125
|
||||
ld a, 0x25
|
||||
call subHL
|
||||
ld a, h
|
||||
cp 1
|
||||
jp nz, fail
|
||||
ld a, l
|
||||
cp 0
|
||||
jp nz, fail
|
||||
call nexttest
|
||||
|
||||
; success
|
||||
xor a
|
||||
halt
|
||||
|
||||
nexttest:
|
||||
ld a, (testNum)
|
||||
inc a
|
||||
ld (testNum), a
|
||||
ret
|
||||
|
||||
fail:
|
||||
ld a, (testNum)
|
||||
halt
|
||||
Loading…
Reference in New Issue