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apps/ed: start implementing I/O
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@ -1,7 +1,10 @@
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#include "user.h"
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#include "err.h"
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.org USER_CODE
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jp edMain
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.equ IO_RAMSTART USER_RAMSTART
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#include "ed/io.asm"
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#include "ed/main.asm"
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43
apps/ed/io.asm
Normal file
43
apps/ed/io.asm
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@ -0,0 +1,43 @@
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; io - handle ed's I/O
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; *** Consts ***
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;
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; Max length of a line
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.equ IO_MAXLEN 0x7f
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; *** Variables ***
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; Buffer for lines read from I/O.
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.equ IO_LINE IO_RAMSTART
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.equ IO_RAMEND IO_LINE+IO_MAXLEN+1 ; +1 for null
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; *** Code ***
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; Given an offset HL, read the line in IO_LINE, without LF and null terminates
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; it. Make HL point to IO_LINE.
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ioGetLine:
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push af
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push de
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push bc
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ld de, 0 ; limit ourselves to 16-bit for now
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xor a ; absolute seek
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call blkSeek
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ld hl, IO_LINE
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ld b, IO_MAXLEN
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.loop:
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call blkGetC
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jr nz, .loopend
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or a ; null? hum, weird. same as LF
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jr z, .loopend
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cp 0x0a
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jr z, .loopend
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ld (hl), a
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inc hl
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djnz .loop
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.loopend:
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; null-terminate the string
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xor a
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ld (hl), a
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ld hl, IO_LINE
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pop bc
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pop de
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pop af
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ret
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@ -19,23 +19,39 @@
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; memory usage.
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;
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; So here's what we do. First, we have two scratchpads. The first one is the
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; file being read itself. The second one is is memory, for modifications we
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; file being read itself. The second one is memory, for modifications we
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; make to the file. When reading the file, we note the offset at which it ends.
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; All offsets under this limit refer to the first scratchpad. Other offsets
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; refer to the second.
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;
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; Then, our line list if just an array of 16-bit offsets. This means that we
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; Then, our line list is just an array of 16-bit offsets. 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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; *** Usage ***
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;
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; ed takes no argument. It reads from the currently selected blkdev and writes
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; to it. It repeatedly presents a prompt, waits for a command, execute the
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; command. 'q' to quit.
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;
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; *** Requirements ***
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; BLOCKDEV_SIZE
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; blkGetC
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; blkSeek
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; printstr
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; printcrlf
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; stdioReadC
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; stdioGetLine
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edMain:
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; Dummy test. Read first line of file
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ld hl, 0
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call ioGetLine
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call printstr
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call printcrlf
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; Continue to loop
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edLoop:
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ld hl, .prompt
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call printstr
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@ -45,7 +61,7 @@ edLoop:
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; We're done. Process line.
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call printcrlf
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call stdioGetLine
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call edProcessLine
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call .processLine
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ret z
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jr edLoop
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@ -53,7 +69,7 @@ edLoop:
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.db ":", 0
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; Sets Z if we need to quit
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edProcessLine:
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.processLine:
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call printstr
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ld a, (hl)
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cp 'q'
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@ -37,6 +37,8 @@
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jp printcrlf
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jp stdioReadC
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jp stdioGetLine
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jp blkGetC
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jp blkSeek
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#include "core.asm"
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#include "err.h"
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@ -30,3 +30,5 @@
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.equ printcrlf 0x48
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.equ stdioReadC 0x4b
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.equ stdioGetLine 0x4e
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.equ blkGetC 0x51
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.equ blkSeek 0x54
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