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b745f49186
The goal is to avoid mixing those routines with "character devices" (acia, vpd, kbd) which aren't block devices and have routines that have different expectations. This is a first step to fixing #64.
198 lines
3.9 KiB
NASM
198 lines
3.9 KiB
NASM
; ed - line editor
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;
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; A text editor modeled after UNIX's ed, but simpler. The goal is to stay tight
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; on resources and to avoid having to implement screen management code (that is,
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; develop the machinery to have ncurses-like apps in Collapse OS).
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;
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; ed has a mechanism to avoid having to move a lot of memory around at each
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; edit. Each line is an element in an doubly-linked list and each element point
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; to an offset in the "scratchpad". The scratchpad starts with the file
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; contents and every time we change or add a line, that line goes to the end of
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; the scratch pad and linked lists are reorganized whenever lines are changed.
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; Contents itself is always appended to the scratchpad.
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;
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; That's on a resourceful UNIX system.
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;
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; That doubly linked list on the z80 would use 7 bytes per line (prev, next,
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; offset, len), which is a bit much.
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;
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; We sacrifice speed for memory usage by making that linked list into a simple
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; array of pointers to line contents in scratchpad. This means that we
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; don't have an easy access to line length and we have to move a lot of memory
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; around whenever we add or delete lines. Hopefully, "LDIR" will be our friend
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; here...
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;
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; *** Requirements ***
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; BLOCKDEV_SIZE
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; FS_HANDLE_SIZE
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; _blkGetB
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; _blkPutB
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; _blkSeek
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; _blkTell
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; addHL
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; cpHLDE
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; fsFindFN
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; fsOpen
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; fsGetB
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; fsPutB
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; fsSetSize
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; intoHL
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; printstr
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; printcrlf
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; stdioReadLine
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; stdioPutC
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; unsetZ
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;
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; *** Variables ***
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;
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.equ ED_CURLINE ED_RAMSTART
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.equ ED_RAMEND @+2
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edMain:
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; because ed only takes a single string arg, we can use HL directly
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call ioInit
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ret nz
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; diverge from UNIX: start at first line
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ld hl, 0
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ld (ED_CURLINE), hl
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call bufInit
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.mainLoop:
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ld a, ':'
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call stdioPutC
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call stdioReadLine ; --> HL
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; Now, process line.
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call printcrlf
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call cmdParse
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jp nz, .error
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ld a, (CMD_TYPE)
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cp 'q'
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jr z, .doQ
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cp 'w'
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jr z, .doW
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; The rest of the commands need an address
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call edReadAddrs
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jr nz, .error
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ld a, (CMD_TYPE)
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cp 'i'
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jr z, .doI
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; The rest of the commands don't allow addr == cnt
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push hl ; --> lvl 1
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ld hl, (BUF_LINECNT)
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call cpHLDE
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pop hl ; <-- lvl 1
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jr z, .error
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ld a, (CMD_TYPE)
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cp 'd'
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jr z, .doD
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cp 'a'
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jr z, .doA
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jr .doP
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.doQ:
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xor a
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ret
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.doW:
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ld a, 3 ; seek beginning
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call ioSeek
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ld de, 0 ; cur line
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.wLoop:
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push de \ pop hl
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call bufGetLine ; --> buffer in (HL)
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jr nz, .wEnd
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call ioPutLine
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jr nz, .error
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inc de
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jr .wLoop
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.wEnd:
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; Set new file size
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call ioTell
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call ioSetSize
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; for now, writing implies quitting
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; TODO: reload buffer
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xor a
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ret
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.doD:
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ld (ED_CURLINE), de
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; bufDelLines expects an exclusive upper bound, which is why we inc DE.
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inc de
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call bufDelLines
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jr .mainLoop
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.doA:
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inc de
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.doI:
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call stdioReadLine ; --> HL
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call bufScratchpadAdd ; --> HL
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; insert index in DE, line offset in HL. We want the opposite.
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ex de, hl
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ld (ED_CURLINE), hl
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call bufInsertLine
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call printcrlf
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jr .mainLoop
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.doP:
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push hl
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call bufGetLine
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jr nz, .error
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call printstr
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call printcrlf
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pop hl
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call cpHLDE
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jr z, .doPEnd
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inc hl
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jr .doP
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.doPEnd:
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ld (ED_CURLINE), hl
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jp .mainLoop
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.error:
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ld a, '?'
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call stdioPutC
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call printcrlf
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jp .mainLoop
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; Transform an address "cmd" in IX into an absolute address in HL.
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edResolveAddr:
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ld a, (ix)
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cp RELATIVE
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jr z, .relative
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cp EOF
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jr z, .eof
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; absolute
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ld l, (ix+1)
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ld h, (ix+2)
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ret
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.relative:
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ld hl, (ED_CURLINE)
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push de
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ld e, (ix+1)
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ld d, (ix+2)
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add hl, de
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pop de
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ret
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.eof:
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ld hl, (BUF_LINECNT)
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dec hl
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ret
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; Read absolute addr1 in HL and addr2 in DE. Also, check bounds and set Z if
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; both addresses are within bounds, unset if not.
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edReadAddrs:
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ld ix, CMD_ADDR2
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call edResolveAddr
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ld de, (BUF_LINECNT)
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ex de, hl ; HL: cnt DE: addr2
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call cpHLDE
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jp c, unsetZ ; HL (cnt) < DE (addr2). no good
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ld ix, CMD_ADDR1
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call edResolveAddr
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ex de, hl ; HL: addr2, DE: addr1
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call cpHLDE
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jp c, unsetZ ; HL (addr2) < DE (addr1). no good
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ex de, hl ; HL: addr1, DE: addr2
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cp a ; ensure Z
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ret
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