recipes/rc2014/basic: new recipe

Also, fixed the cmd matching algo to not accept partial matches. For example,
to stop matching "input" when the command was "in".

apps/basic/README.md

@@ -103,3 +103,23 @@ stored where specified. For example, `input x` stores the result of the
 evaluation in variable `x`. Before the variable name, a quoted string literal
 can be specified. In that case, that string will be printed as-is just before
 the prompt.
+
+**peek/deek**: Put the value at specified memory address into specified
+variable. peek is for a single byte, deek is for a word (little endian). For
+example, `peek 42 a` puts the byte value contained in memory address 0x002a
+into variable `a`. `deek 42 a` does the same as peek, but also puts the value
+of 0x002b into `a`'s MSB.
+
+**poke/doke**: Put the value of specified expression into specified memory
+address. For example, `poke 42 0x102+0x40` puts `0x42` in memory address
+0x2a (MSB is ignored) and `doke 42 0x102+0x40` does the same as poke, but also
+puts `0x01` in memory address 0x2b.
+
+**in**: Same thing as `peek`, but for a I/O port. `in 42 a` generates an input
+I/O on port 42 and stores the byte result in `a`.
+
+**out**: Same thing as `poke`, but for a I/O port. `out 42 1+2` generates an
+output I/O on port 42 with value 3.
+
+**sleep**: Sleep a number of "units" specified by the supplied expression. A
+"unit" depends on the CPU clock speed. At 4MHz, it is roughly 8 microseconds.

apps/basic/main.asm

@@ -56,17 +56,17 @@ basCallCmd:
 	; let's see if it's a variable assignment.
 	call	varTryAssign
 	ret	z	; Done!
-	; Second, get cmd length
-	call	fnWSIdx
-	cp	7
-	jp	nc, unsetZ	; Too long, can't possibly fit anything.
-	; A contains whitespace IDX, save it in B
-	ld	b, a
-	ex	de, hl
+	push	de		; --> lvl 1.
+	ld	de, SCRATCHPAD
+	call	rdWord
+	; cmdname to find in (DE)
+	; How lucky, we have a legitimate use of "ex (sp), hl"! We have the
+	; cmd table in the stack, which we want in HL and we have the rest of
+	; the cmdline in (HL), which we want in the stack!
+	ex	(sp), hl
 	inc	hl \ inc hl
 .loop:
-	ld	a, b		; whitespace IDX
-	call	strncmp
+	call	strcmp
 	jr	z, .found
 	ld	a, 8
 	call	addHL
@@ -74,15 +74,14 @@ basCallCmd:
 	cp	0xff
 	jr	nz, .loop
 	; not found
+	pop	hl		; <-- lvl 1
 	jp	unsetZ
 .found:
 	dec	hl \ dec hl
 	call	intoHL
 	push	hl \ pop ix
-	; Bring back command string from DE to HL
-	ex	de, hl
-	ld	a, b	; cmd's length
-	call	addHL
+	; Bring back rest of the command string from the stack
+	pop	hl		; <-- lvl 1
 	call	rdSep
 	jp	(ix)
 
@@ -267,6 +266,89 @@ basINPUT:
 	cp	a		; ensure Z
 	ret
 
+basPEEK:
+	call	basDEEK
+	ret	nz
+	ld	d, 0
+	call	varAssign
+	cp	a		; ensure Z
+	ret
+
+basPOKE:
+	call	rdExpr
+	ret	nz
+	; peek address in IX. Save it for later
+	push	ix		; --> lvl 1
+	call	rdSep
+	call	rdExpr
+	push	ix \ pop hl
+	pop	ix		; <-- lvl 1
+	ret	nz
+	; Poke!
+	ld	(ix), l
+	ret
+
+basDEEK:
+	call	rdExpr
+	ret	nz
+	; peek address in IX. Let's peek and put result in DE
+	ld	e, (ix)
+	ld	d, (ix+1)
+	call	rdSep
+	ld	a, (hl)
+	call	varChk
+	ret	nz		; not in variable range
+	; All good assign
+	call	varAssign
+	cp	a		; ensure Z
+	ret
+
+basDOKE:
+	call	basPOKE
+	ld	(ix+1), h
+	ret
+
+basOUT:
+	call	rdExpr
+	ret	nz
+	; out address in IX. Save it for later
+	push	ix		; --> lvl 1
+	call	rdSep
+	call	rdExpr
+	push	ix \ pop hl
+	pop	bc		; <-- lvl 1
+	ret	nz
+	; Out!
+	out	(c), l
+	cp	a		; ensure Z
+	ret
+
+basIN:
+	call	rdExpr
+	ret	nz
+	push	ix \ pop bc
+	ld	d, 0
+	in	e, (c)
+	call	rdSep
+	ld	a, (hl)
+	call	varChk
+	ret	nz		; not in variable range
+	; All good assign
+	call	varAssign
+	cp	a		; ensure Z
+	ret
+
+basSLEEP:
+	call	rdExpr
+	ret	nz
+	push	ix \ pop hl
+.loop:
+	ld	a, h	; 4T
+	or	l	; 4T
+	ret	z	; 5T
+	dec	hl	; 6T
+	jr	.loop	; 12T
+
 ; direct only
 basCmds1:
 	.dw	basBYE
@@ -285,4 +367,18 @@ basCmds2:
 	.db	"if", 0, 0, 0, 0
 	.dw	basINPUT
 	.db	"input", 0
+	.dw	basPEEK
+	.db	"peek", 0, 0
+	.dw	basPOKE
+	.db	"poke", 0, 0
+	.dw	basDEEK
+	.db	"deek", 0, 0
+	.dw	basDOKE
+	.db	"doke", 0, 0
+	.dw	basOUT
+	.db	"out", 0, 0, 0
+	.dw	basIN
+	.db	"in", 0, 0, 0, 0
+	.dw	basSLEEP
+	.db	"sleep", 0
 	.db	0xff, 0xff, 0xff	; end of table

apps/basic/tok.asm

@@ -32,30 +32,6 @@ rdSep:
 	inc	a	; unset Z
 	ret
 
-; Find the first whitespace in (HL) and returns its index in A
-; Sets Z if whitespace is found, unset if end of string was found.
-; In the case where no whitespace was found, A returns the length of the string.
-fnWSIdx:
-	push	hl
-	push	bc
-	ld	b, 0
-.loop:
-	ld	a, (hl)
-	call	isSep
-	jr	z, .found
-	or	a
-	jr	z, .eos
-	inc	hl
-	inc	b
-	jr	.loop
-.eos:
-	inc	a	; unset Z
-.found:			; Z already set from isSep
-	ld	a, b
-	pop	bc
-	pop	hl
-	ret
-
 ; Advance HL to the next separator or to the end of string.
 toSep:
 	ld	a, (hl)
@@ -85,3 +61,15 @@ rdWord:
 	pop	de
 	pop	af
 	ret
+
+; Read word from HL in SCRATCHPAD and then intepret that word as an expression.
+; Put the result in IX.
+; Z for success.
+rdExpr:
+	ld	de, SCRATCHPAD
+	call	rdWord
+	push	hl
+	ex	de, hl
+	call	parseExpr
+	pop	hl
+	ret

recipes/rc2014/README.md

@@ -27,6 +27,7 @@ are other recipes related to the RC2014:
 * [Accessing a MicroSD card](sdcard/README.md)
 * [Assembling binaries](zasm/README.md)
 * [Interfacing a PS/2 keyboard](ps2/README.md)
+* [Replace shell by a BASIC interpreter](basic/README.md)
 
 ## Recipe
 

recipes/rc2014/basic/Makefile

@@ -0,0 +1,10 @@
+TARGET = os.bin
+ZASM = ../../../tools/zasm.sh
+KERNEL = ../../../kernel
+APPS = ../../../apps
+
+.PHONY: all
+all: $(TARGET)
+$(TARGET): glue.asm
+	$(ZASM) $(KERNEL) $(APPS) < $< > $@
+

recipes/rc2014/basic/README.md

@@ -0,0 +1,46 @@
+# BASIC as a shell
+
+This recipe demonstrate the replacement of the usual shell with the BASIC
+interpreter supplied in Collapse OS. To make things fun, we play with I/Os
+using RC2014's Digital I/O module.
+
+## Gathering parts
+
+* Same parts as in the base recipe
+* (Optional) RC2014's Digital I/O module
+
+The Digital I/O module is only used in the example BASIC code. If you don't
+have the module, just use BASIC in another fashion.
+
+## Build the image
+
+As usual, building `os.bin` is a matter of running `make`. Then, you can get
+that image to your EEPROM like you did in the base recipe.
+
+## Usage
+
+Upon boot, you'll directy be in a BASIC prompt. See documentation in
+`apps/basic/README.md` for details.
+
+For now, let's have some fun with the Digital I/O module. Type this:
+
+```
+> a=0
+> 10 out 0 a
+> 20 sleep 0xffff
+> 30 a=a+1
+> 40 goto 10
+> run
+```
+
+You now have your Digital I/O lights doing a pretty dance, forever.
+
+## Looking at the glue code
+
+If you look at the glue code, you'll see that it's very similar to the one in
+the base recipe, except that the shell includes have been replaced by the basic
+includes. Those includes have been copy/pasted from `apps/basic/glue.asm` and
+`USER_RAMSTART` has been replaced with `STDIO_RAMEND` so that BASIC's memory
+gets placed properly (that is, right after the kernel's memory).
+
+Simple, isn't it?

recipes/rc2014/basic/glue.asm

@@ -0,0 +1,56 @@
+.equ	RAMSTART	0x8000
+.equ	RAMEND		0xffff
+.equ	ACIA_CTL	0x80	; Control and status. RS off.
+.equ	ACIA_IO		0x81	; Transmit. RS on.
+.equ	DIGIT_IO	0x00	; digital I/O's port
+
+jp	init
+
+; interrupt hook
+.fill	0x38-$
+jp	aciaInt
+
+.inc "err.h"
+.inc "ascii.h"
+.inc "core.asm"
+.inc "str.asm"
+.equ	ACIA_RAMSTART	RAMSTART
+.inc "acia.asm"
+
+.equ	STDIO_RAMSTART	ACIA_RAMEND
+.equ	STDIO_GETC	aciaGetC
+.equ	STDIO_PUTC	aciaPutC
+.inc "stdio.asm"
+
+; *** BASIC ***
+
+; RAM space used in different routines for short term processing.
+.equ	SCRATCHPAD_SIZE	0x20
+.equ	SCRATCHPAD	STDIO_RAMEND
+.inc "lib/util.asm"
+.inc "lib/ari.asm"
+.inc "lib/parse.asm"
+.inc "lib/fmt.asm"
+.equ	EXPR_PARSE	parseLiteralOrVar
+.inc "lib/expr.asm"
+.inc "basic/util.asm"
+.inc "basic/parse.asm"
+.inc "basic/tok.asm"
+.equ	VAR_RAMSTART	SCRATCHPAD+SCRATCHPAD_SIZE
+.inc "basic/var.asm"
+.equ	BUF_RAMSTART	VAR_RAMEND
+.inc "basic/buf.asm"
+.equ	BAS_RAMSTART	BUF_RAMEND
+.inc "basic/main.asm"
+
+init:
+	di
+	; setup stack
+	ld	sp, RAMEND
+	im 1
+
+	call	aciaInit
+	ei
+	jp	basStart
+
+