From 3491c2613244b541f21910ca574bccf9e8a625ef Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Sat, 13 Jul 2019 11:29:06 -0400
Subject: [PATCH] apps/ed: start implementing I/O

---
 apps/ed/glue.asm            |  3 +++
 apps/ed/io.asm              | 43 +++++++++++++++++++++++++++++++++++++
 apps/ed/main.asm            | 24 +++++++++++++++++----
 tools/emul/shell/shell_.asm |  2 ++
 tools/emul/shell/user.h     |  2 ++
 5 files changed, 70 insertions(+), 4 deletions(-)
 create mode 100644 apps/ed/io.asm

diff --git a/apps/ed/glue.asm b/apps/ed/glue.asm
index 568d6cf..9ba9bec 100644
--- a/apps/ed/glue.asm
+++ b/apps/ed/glue.asm
@@ -1,7 +1,10 @@
 #include "user.h"
+#include "err.h"
 .org	USER_CODE
 
 	jp	edMain
 
+.equ	IO_RAMSTART	USER_RAMSTART
+#include "ed/io.asm"
 #include "ed/main.asm"
 
diff --git a/apps/ed/io.asm b/apps/ed/io.asm
new file mode 100644
index 0000000..4e582d4
--- /dev/null
+++ b/apps/ed/io.asm
@@ -0,0 +1,43 @@
+; io - handle ed's I/O
+
+; *** Consts ***
+;
+; Max length of a line
+.equ	IO_MAXLEN	0x7f
+
+; *** Variables ***
+; Buffer for lines read from I/O.
+.equ	IO_LINE		IO_RAMSTART
+.equ	IO_RAMEND	IO_LINE+IO_MAXLEN+1	; +1 for null
+; *** Code ***
+
+; Given an offset HL, read the line in IO_LINE, without LF and null terminates
+; it. Make HL point to IO_LINE.
+ioGetLine:
+	push	af
+	push	de
+	push	bc
+	ld	de, 0		; limit ourselves to 16-bit for now
+	xor	a		; absolute seek
+	call	blkSeek
+	ld	hl, IO_LINE
+	ld	b, IO_MAXLEN
+.loop:
+	call	blkGetC
+	jr	nz, .loopend
+	or	a		; null? hum, weird. same as LF
+	jr	z, .loopend
+	cp	0x0a
+	jr	z, .loopend
+	ld	(hl), a
+	inc	hl
+	djnz	.loop
+.loopend:
+	; null-terminate the string
+	xor	a
+	ld	(hl), a
+	ld	hl, IO_LINE
+	pop	bc
+	pop	de
+	pop	af
+	ret
diff --git a/apps/ed/main.asm b/apps/ed/main.asm
index 6a7761c..2b3862c 100644
--- a/apps/ed/main.asm
+++ b/apps/ed/main.asm
@@ -19,23 +19,39 @@
 ; memory usage.
 ;
 ; So here's what we do. First, we have two scratchpads. The first one is the
-; file being read itself. The second one is is memory, for modifications we
+; file being read itself. The second one is memory, for modifications we
 ; make to the file. When reading the file, we note the offset at which it ends.
 ; All offsets under this limit refer to the first scratchpad. Other offsets
 ; refer to the second.
 ;
-; Then, our line list if just an array of 16-bit offsets. This means that we
+; Then, our line list is just an array of 16-bit offsets. This means that we
 ; don't have an easy access to line length and we have to move a lot of memory
 ; around whenever we add or delete lines. Hopefully, "LDIR" will be our friend
 ; here...
 ;
+; *** Usage ***
+;
+; ed takes no argument. It reads from the currently selected blkdev and writes
+; to it. It repeatedly presents a prompt, waits for a command, execute the
+; command. 'q' to quit.
+;
 ; *** Requirements ***
+; BLOCKDEV_SIZE
+; blkGetC
+; blkSeek
 ; printstr
 ; printcrlf
 ; stdioReadC
 ; stdioGetLine
 
 edMain:
+	; Dummy test. Read first line of file
+	ld	hl, 0
+	call	ioGetLine
+	call	printstr
+	call	printcrlf
+	; Continue to loop
+
 edLoop:
 	ld	hl, .prompt
 	call	printstr
@@ -45,7 +61,7 @@ edLoop:
 	; We're done. Process line.
 	call	printcrlf
 	call	stdioGetLine
-	call	edProcessLine
+	call	.processLine
 	ret	z
 	jr	edLoop
 
@@ -53,7 +69,7 @@ edLoop:
 	.db	":", 0
 
 ; Sets Z if we need to quit
-edProcessLine:
+.processLine:
 	call	printstr
 	ld	a, (hl)
 	cp	'q'
diff --git a/tools/emul/shell/shell_.asm b/tools/emul/shell/shell_.asm
index d10785c..97df063 100644
--- a/tools/emul/shell/shell_.asm
+++ b/tools/emul/shell/shell_.asm
@@ -37,6 +37,8 @@
 	jp	printcrlf
 	jp	stdioReadC
 	jp	stdioGetLine
+	jp	blkGetC
+	jp	blkSeek
 
 #include "core.asm"
 #include "err.h"
diff --git a/tools/emul/shell/user.h b/tools/emul/shell/user.h
index 792cb9e..6f42a14 100644
--- a/tools/emul/shell/user.h
+++ b/tools/emul/shell/user.h
@@ -30,3 +30,5 @@
 .equ	printcrlf		0x48
 .equ	stdioReadC		0x4b
 .equ	stdioGetLine	0x4e
+.equ	blkGetC			0x51
+.equ	blkSeek			0x54