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34f499184d
Also, remove zasm/test7 because it changes too much all time time (whenever zasm changes) and isn't precise enough. Too much noise, not worth it.
294 lines
6.9 KiB
NASM
294 lines
6.9 KiB
NASM
; I/Os in zasm
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;
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; As a general rule, I/O in zasm is pretty straightfoward. We receive, as a
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; parameter, two blockdevs: One that we can read and seek and one that we can
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; write to (we never seek into it).
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;
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; This unit also has the responsibility of counting the number of written bytes,
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; maintaining IO_PC and of properly disabling output on first pass.
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;
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; On top of that, this unit has the responsibility of keeping track of the
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; current lineno. Whenever GetC is called, we check if the fetched char is a
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; newline. If it is, we increase our lineno. This unit is the best place to
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; keep track of this because we have to handle ioRecallPos.
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;
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; zasm doesn't buffers its reads during tokenization, which simplifies its
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; process. However, it also means that it needs, in certain cases, a "putback"
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; mechanism, that is, a way to say "you see that character I've just read? that
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; was out of my bounds. Could you make it as if I had never read it?". That
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; buffer is one character big and is made with the expectation that ioPutBack
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; is always called right after a ioGetC (when it's called).
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;
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; ioPutBack will mess up seek and tell offsets, so thath "put back" should be
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; consumed before having to seek and tell.
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;
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; That's for the general rules.
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;
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; Now, let's enter includes. To simplify processing, we make include mostly
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; transparent to all other units. They always read from ioGetC and a include
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; directive should have the exact same effect as copy/pasting the contents of
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; the included file in the caller.
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;
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; By the way: we don't support multiple level of inclusion. Only top level files
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; can include.
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;
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; When we include, all we do here is open the file with fsOpen and set a flag
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; indicating that we're inside an include. When that flag is on, GetC, Seek and
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; Tell are transparently redirected to their fs* counterpart.
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;
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; When we reach EOF in an included file, we transparently unset the "in include"
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; flag and continue on the general IN stream.
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; *** Variables ***
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.equ IO_IN_BLK IO_RAMSTART
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.equ IO_OUT_BLK IO_IN_BLK+BLOCKDEV_SIZE
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; Save pos for ioSavePos and ioRecallPos
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.equ IO_SAVED_POS IO_OUT_BLK+BLOCKDEV_SIZE
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; File handle for included source
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.equ IO_INCLUDE_HDL IO_SAVED_POS+2
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; blkdev for include file
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.equ IO_INCLUDE_BLK IO_INCLUDE_HDL+FS_HANDLE_SIZE
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; see ioPutBack below
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.equ IO_PUTBACK_BUF IO_INCLUDE_BLK+BLOCKDEV_SIZE
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.equ IO_IN_INCLUDE IO_PUTBACK_BUF+1
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.equ IO_PC IO_IN_INCLUDE+1
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; Current lineno in top-level file
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.equ IO_LINENO IO_PC+2
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; Current lineno in include file
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.equ IO_INC_LINENO IO_LINENO+2
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; Line number (can be top-level or include) when ioSavePos was last called.
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.equ IO_SAVED_LINENO IO_INC_LINENO+2
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; Handle for the ioSpitBin
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.equ IO_BIN_HDL IO_SAVED_LINENO+2
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.equ IO_RAMEND IO_BIN_HDL+FS_HANDLE_SIZE
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; *** Code ***
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ioInit:
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xor a
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ld (IO_PUTBACK_BUF), a
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ld (IO_IN_INCLUDE), a
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ld de, IO_INCLUDE_BLK
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ld hl, _ioIncBlk
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call blkSet
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jp ioResetCounters
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ioGetC:
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ld a, (IO_PUTBACK_BUF)
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or a ; cp 0
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jr nz, .getback
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call ioInInclude
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jr z, .normalmode
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; We're in "include mode", read from FS
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ld ix, IO_INCLUDE_BLK
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call _blkGetC
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jr nz, .includeEOF
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cp 0x0a ; newline
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ret nz ; not newline? nothing to do
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; We have newline. Increase lineno and return (the rest of the
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; processing below isn't needed.
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push hl
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ld hl, IO_INC_LINENO
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inc (hl)
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pop hl
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ret
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.includeEOF:
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; We reached EOF. What we do depends on whether we're in Local Pass
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; mode. Yes, I know, a bit hackish. Normally, we *should* be
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; transparently getting of include mode and avoid meddling with global
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; states, but here, we need to tell main.asm that the local scope if
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; over *before* we get off include mode, otherwise, our IO_SAVED_POS
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; will be wrong (an include IO_SAVED_POS used in global IN stream).
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call zasmIsLocalPass
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ld a, 0 ; doesn't affect Z flag
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ret z ; local pass? return EOF
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; regular pass (first or second)? transparently get off include mode.
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ld (IO_IN_INCLUDE), a ; A already 0
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ld (IO_INC_LINENO), a
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ld (IO_INC_LINENO+1), a
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; continue on to "normal" reading. We don't want to return our zero
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.normalmode:
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; normal mode, read from IN stream
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ld ix, IO_IN_BLK
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call _blkGetC
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cp 0x0a ; newline
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ret nz ; not newline? return
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; inc current lineno
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push hl
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ld hl, IO_LINENO
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inc (hl)
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pop hl
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cp a ; ensure Z
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ret
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.getback:
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push af
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xor a
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ld (IO_PUTBACK_BUF), a
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pop af
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ret
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_callIX:
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jp (ix)
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ret
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; Put back non-zero character A into the "ioGetC stack". The next ioGetC call,
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; instead of reading from IO_IN_BLK, will return that character. That's the
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; easiest way I found to handle the readWord/gotoNextLine problem.
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ioPutBack:
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ld (IO_PUTBACK_BUF), a
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ret
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ioPutC:
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push hl
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ld hl, (IO_PC)
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inc hl
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ld (IO_PC), hl
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pop hl
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push af
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call zasmIsFirstPass
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jr z, .skip
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pop af
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ld ix, IO_OUT_BLK
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jp _blkPutC
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.skip:
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pop af
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cp a ; ensure Z
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ret
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ioSavePos:
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ld hl, (IO_LINENO)
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call ioInInclude
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jr z, .skip
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ld hl, (IO_INC_LINENO)
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.skip:
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ld (IO_SAVED_LINENO), hl
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call _ioTell
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ld (IO_SAVED_POS), hl
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ret
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ioRecallPos:
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ld hl, (IO_SAVED_LINENO)
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call ioInInclude
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jr nz, .include
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ld (IO_LINENO), hl
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jr .recallpos
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.include:
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ld (IO_INC_LINENO), hl
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.recallpos:
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ld hl, (IO_SAVED_POS)
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jr _ioSeek
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ioRewind:
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call ioResetCounters ; sets HL to 0
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jr _ioSeek
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ioResetCounters:
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ld hl, 0
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ld (IO_PC), hl
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ld (IO_LINENO), hl
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ld (IO_SAVED_LINENO), hl
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ret
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; always in absolute mode (A = 0)
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_ioSeek:
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call ioInInclude
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ld a, 0 ; don't alter flags
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jr nz, .include
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; normal mode, seek in IN stream
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ld ix, IO_IN_BLK
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jp _blkSeek
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.include:
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; We're in "include mode", seek in FS
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ld ix, IO_INCLUDE_BLK
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jp _blkSeek ; returns
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_ioTell:
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call ioInInclude
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jp nz, .include
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; normal mode, seek in IN stream
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ld ix, IO_IN_BLK
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jp _blkTell
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.include:
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; We're in "include mode", tell from FS
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ld ix, IO_INCLUDE_BLK
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jp _blkTell ; returns
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; Sets Z according to whether we're inside an include
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; Z is set when we're *not* in includes. A bit weird, I know...
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ioInInclude:
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ld a, (IO_IN_INCLUDE)
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or a ; cp 0
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ret
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; Open include file name specified in (HL).
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; Sets Z on success, unset on error.
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ioOpenInclude:
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call ioPrintLN
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call fsFindFN
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ret nz
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ld ix, IO_INCLUDE_HDL
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call fsOpen
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ld a, 1
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ld (IO_IN_INCLUDE), a
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ld hl, 0
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ld (IO_INC_LINENO), hl
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xor a
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ld ix, IO_INCLUDE_BLK
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call _blkSeek
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cp a ; ensure Z
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ret
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; Open file specified in (HL) and spit its contents through ioPutC
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; Sets Z on success.
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ioSpitBin:
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call fsFindFN
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ret nz
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push hl ; --> lvl 1
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ld ix, IO_BIN_HDL
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call fsOpen
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ld hl, 0
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.loop:
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ld ix, IO_BIN_HDL
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call fsGetC
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jr nz, .loopend
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call ioPutC
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inc hl
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jr .loop
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.loopend:
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pop hl ; <-- lvl 1
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cp a ; ensure Z
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ret
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; Return current lineno in HL and, if in an include, its lineno in DE.
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; If not in an include, DE is set to 0
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ioLineNo:
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push af
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ld hl, (IO_LINENO)
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ld de, 0
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call ioInInclude
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jr z, .end
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ld de, (IO_INC_LINENO)
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.end:
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pop af
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ret
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_ioIncGetC:
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ld ix, IO_INCLUDE_HDL
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jp fsGetC
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_ioIncBlk:
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.dw _ioIncGetC, unsetZ
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; call printstr followed by newline
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ioPrintLN:
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push hl
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call printstr
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ld hl, .sCRLF
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call printstr
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pop hl
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ret
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.sCRLF:
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.db 0x0a, 0x0d, 0
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