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stdio: add stdioReadC
A routine to conveniently read lines from TTY. Extracted from shell. Will be used in other places.
This commit is contained in:
Virgil Dupras
parent
252d71f1b8
commit
e01ee170cb
@ -35,10 +35,6 @@
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; number of entries in shellCmdTbl
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.equ SHELL_CMD_COUNT 6+SHELL_EXTRA_CMD_COUNT
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; Size of the shell command buffer. If a typed command reaches this size, the
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; command is flushed immediately (same as pressing return).
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.equ SHELL_BUFSIZE 0x20
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; *** VARIABLES ***
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; Memory address that the shell is currently "pointing at" for peek, load, call
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; operations. Set with mptr.
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@ -48,13 +44,8 @@
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; written to after parsing.
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.equ SHELL_CMD_ARGS SHELL_MEM_PTR+2
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; Command buffer. We read types chars into this buffer until return is pressed
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; This buffer is null-terminated and we don't keep an index around: we look
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; for the null-termination every time we write to it. Simpler that way.
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.equ SHELL_BUF SHELL_CMD_ARGS+PARSE_ARG_MAXCOUNT
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; Pointer to a hook to call when a cmd name isn't found
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.equ SHELL_CMDHOOK SHELL_BUF+SHELL_BUFSIZE
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.equ SHELL_CMDHOOK SHELL_CMD_ARGS+PARSE_ARG_MAXCOUNT
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; Pointer to a routine to call at each shell loop interation
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.equ SHELL_LOOPHOOK SHELL_CMDHOOK+2
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@ -65,14 +56,13 @@ shellInit:
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xor a
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ld (SHELL_MEM_PTR), a
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ld (SHELL_MEM_PTR+1), a
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ld (SHELL_BUF), a
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ld hl, noop
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ld (SHELL_CMDHOOK), hl
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ld (SHELL_LOOPHOOK), hl
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; print welcome
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ld hl, .welcome
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jp printstr ; returns
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jp printstr
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.welcome:
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.db "Collapse OS", ASCII_CR, ASCII_LF, "> ", 0
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@ -84,52 +74,12 @@ shellLoop:
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ld ix, (SHELL_LOOPHOOK)
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call callIX
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; Then, let's wait until something is typed.
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call stdioGetC
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jr nz, shellLoop ; nothing typed? loop
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; got it. Now, is it a CR or LF?
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cp ASCII_CR
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jr z, .do ; char is CR? do!
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cp ASCII_LF
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jr z, .do ; char is LF? do!
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cp ASCII_DEL
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jr z, .delchr
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cp ASCII_BS
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jr z, .delchr
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; Echo the received character right away so that we see what we type
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call stdioPutC
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; Ok, gotta add it do the buffer
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; save char for later
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ex af, af'
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ld hl, SHELL_BUF
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xor a ; look for null
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call findchar ; HL points to where we need to write
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; A is the number of chars in the buf
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cp SHELL_BUFSIZE-1 ; -1 is because we always want to keep our
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; last char at zero.
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jr z, .do ; end of buffer reached? buffer is full. do!
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; bring the char back in A
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ex af, af'
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; Buffer not full, not CR or LF. Let's put that char in our buffer and
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; read again.
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ld (hl), a
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; Now, write a zero to the next byte to properly terminate our string.
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inc hl
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xor a
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ld (hl), a
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jr shellLoop
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.do:
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call stdioReadC
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jr nz, shellLoop ; not done? loop
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; We're done. Process line.
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call printcrlf
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ld hl, SHELL_BUF
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call stdioGetLine
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call shellParse
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; empty our buffer by writing a zero to its first char
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xor a
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ld (hl), a
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ld hl, .prompt
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call printstr
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jr shellLoop
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@ -137,28 +87,6 @@ shellLoop:
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.prompt:
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.db "> ", 0
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.delchr:
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ld hl, SHELL_BUF
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ld a, (hl)
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or a ; cp 0
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jr z, shellLoop ; buffer empty? nothing to do
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; buffer not empty, let's delete
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xor a ; look for null
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call findchar ; HL points to end of buf
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dec hl ; the char before it
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xor a
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ld (hl), a ; set to zero
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; Char deleted in buffer, now send BS + space + BS for the terminal
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; to clear its previous char
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ld a, ASCII_BS
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call stdioPutC
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ld a, ' '
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call stdioPutC
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ld a, ASCII_BS
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call stdioPutC
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jr shellLoop
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; Parse command (null terminated) at HL and calls it
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shellParse:
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push af
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111
kernel/stdio.asm
111
kernel/stdio.asm
@ -1,20 +1,36 @@
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; stdio
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;
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; Allows other modules to print to "standard out", and get data from "stamdard
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; Allows other modules to print to "standard out", and get data from "standard
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; in", that is, the console through which the user is connected in a decoupled
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; manner.
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;
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; *** VARIABLES ***
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; *** Consts ***
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; Size of the readline buffer. If a typed line reaches this size, the line is
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; flushed immediately (same as pressing return).
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.equ STDIO_BUFSIZE 0x20
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; *** Variables ***
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; Used to store formatted hex values just before printing it.
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.equ STDIO_HEX_FMT STDIO_RAMSTART
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.equ STDIO_GETC STDIO_HEX_FMT+2
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.equ STDIO_PUTC STDIO_GETC+2
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.equ STDIO_RAMEND STDIO_PUTC+2
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; Line buffer. We read types chars into this buffer until return is pressed
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; This buffer is null-terminated and we don't keep an index around: we look
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; for the null-termination every time we write to it. Simpler that way.
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.equ STDIO_BUF STDIO_PUTC+2
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; Index where the next char will go in stdioGetC.
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.equ STDIO_BUFIDX STDIO_BUF+STDIO_BUFSIZE
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.equ STDIO_RAMEND STDIO_BUFIDX+1
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; Sets GetC to the routine where HL points to and PutC to DE.
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stdioInit:
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ld (STDIO_GETC), hl
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ld (STDIO_PUTC), de
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xor a
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ld (STDIO_BUF), a
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ld (STDIO_BUFIDX), a
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ret
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stdioGetC:
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@ -88,3 +104,92 @@ printHexPair:
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call printHex
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pop af
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ret
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; Call stdioGetC and put the result in the buffer. Sets Z according to whether
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; the buffer is "complete", that is, whether CR or LF have been pressed or if
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; the the buffer is full. Z is set if the line is "complete", unset if not.
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; The next call to stdioReadC after a completed line will start a new line.
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;
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; This routine also takes care of echoing received characters back to the TTY.
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;
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; Note that this routine doesn't bother returning the typed character.
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stdioReadC:
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; Let's wait until something is typed.
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call stdioGetC
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jr nz, stdioReadC ; nothing typed? loop
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; got it. Now, is it a CR or LF?
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cp ASCII_CR
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jr z, .complete ; char is CR? buffer complete!
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cp ASCII_LF
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jr z, .complete
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cp ASCII_DEL
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jr z, .delchr
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cp ASCII_BS
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jr z, .delchr
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; Echo the received character right away so that we see what we type
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call stdioPutC
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; Ok, gotta add it do the buffer
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; save char for later
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ex af, af'
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ld a, (STDIO_BUFIDX)
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push hl ;<|
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ld hl, STDIO_BUF ; |
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; make HL point to dest spot |
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call addHL ; |
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; Write our char down |
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ex af, af' ; |
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ld (hl), a ; |
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; follow up with a null char |
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inc hl ; |
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xor a ; |
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ld (hl), a ; |
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pop hl ;<|
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; inc idx, which still is in AF'
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ex af, af'
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inc a
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cp STDIO_BUFSIZE-1 ; -1 is because we always want to keep our
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; last char at zero.
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jr z, .complete ; end of buffer reached? buffer is full.
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; not complete. save idx back
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ld (STDIO_BUFIDX), a
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; Z already unset
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ret
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.complete:
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; The line in our buffer is complete.
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xor a ; sets Z
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ld (STDIO_BUFIDX), a
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ret
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.delchr:
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ld a, (STDIO_BUFIDX)
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or a
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jp z, unsetZ ; buf empty? nothing to do
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; buffer not empty, let's go back one char and set a null char there.
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dec a
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ld (STDIO_BUFIDX), a
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push hl ;<|
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ld hl, STDIO_BUF ; |
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; make HL point to dest spot |
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call addHL ; |
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xor a ; |
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ld (hl), a ; |
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pop hl ;<|
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; Char deleted in buffer, now send BS + space + BS for the terminal
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; to clear its previous char
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ld a, ASCII_BS
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call stdioPutC
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ld a, ' '
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call stdioPutC
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ld a, ASCII_BS
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call stdioPutC
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jp unsetZ
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; Make HL point to the line buffer. It is always null terminated.
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stdioGetLine:
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ld hl, STDIO_BUF
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ret
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