forth: Forth-ify ROT, a native word!

This requires us to significantly adjust our build process, which
now has 3 stages.

emul/.gitignore

@@ -1,6 +1,8 @@
 /shell/shell
 /forth/stage1
 /forth/stage1dbg
+/forth/stage2
+/forth/stage2dbg
 /forth/forth
 /zasm/zasm
 /zasm/avra

emul/Makefile

@@ -27,8 +27,8 @@ shell/shell-bin.h: shell/shell.bin
 shell/shell: shell/shell.c $(SHELLOBJS) shell/shell-bin.h 
 	$(CC) shell/shell.c $(SHELLOBJS) -o $@
 
-forth/forth0.bin: forth/glue0.asm $(ZASMBIN)
-	$(ZASMBIN) $(KERNEL) ../forth < forth/glue0.asm | tee $@ > /dev/null
+forth/forth0.bin: forth/stage0.asm $(ZASMBIN)
+	$(ZASMBIN) $(KERNEL) ../forth forth/stagec.asm < forth/stage0.asm | tee $@ > /dev/null
 
 forth/forth0-bin.h: forth/forth0.bin
 	./bin2c.sh KERNEL < forth/forth0.bin | tee $@ > /dev/null
@@ -39,16 +39,30 @@ forth/stage1: forth/stage.c $(OBJS) forth/forth0-bin.h
 forth/stage1dbg: forth/stage.c $(OBJS) forth/forth0-bin.h 
 	$(CC) -DDEBUG forth/stage.c $(OBJS) -o $@
 
-forth/core.bin: $(FORTHSRC_PATHS) forth/stage1
-	cat $(FORTHSRC_PATHS) | ./forth/stage1 | tee $@ > /dev/null
-
-forth/forth1.bin: forth/glue1.asm forth/core.bin $(ZASMBIN)
-	$(ZASMBIN) $(KERNEL) ../forth forth/core.bin < forth/glue1.asm | tee $@ > /dev/null
+# z80c.bin is not in the prerequisites because its a bootstrap binary that
+# should be updated manually through make fbootstrap.
+forth/forth1.bin: forth/stage1.asm forth/forth0.bin $(ZASMBIN)
+	$(ZASMBIN) $(KERNEL) ../forth forth/z80c.bin forth/stagec.asm < forth/stage1.asm | tee $@ > /dev/null
 
 forth/forth1-bin.h: forth/forth1.bin
 	./bin2c.sh KERNEL < forth/forth1.bin | tee $@ > /dev/null
 
-forth/forth: forth/forth.c $(OBJS) forth/forth1-bin.h 
+forth/stage2: forth/stage.c $(OBJS) forth/forth1-bin.h 
+	$(CC) -DSTAGE2 forth/stage.c $(OBJS) -o $@
+
+forth/stage2dbg: forth/stage.c $(OBJS) forth/forth1-bin.h 
+	$(CC) -DSTAGE2 -DDEBUG forth/stage.c $(OBJS) -o $@
+
+forth/core.bin: $(FORTHSRC_PATHS) forth/stage2
+	cat $(FORTHSRC_PATHS) | ./forth/stage2 | tee $@ > /dev/null
+
+forth/forth2.bin: forth/stage2.asm forth/core.bin $(ZASMBIN)
+	$(ZASMBIN) $(KERNEL) ../forth forth/core.bin forth/z80c.bin forth/stagec.asm < forth/stage2.asm | tee $@ > /dev/null
+
+forth/forth2-bin.h: forth/forth2.bin
+	./bin2c.sh KERNEL < forth/forth2.bin | tee $@ > /dev/null
+
+forth/forth: forth/forth.c $(OBJS) forth/forth2-bin.h 
 	$(CC) forth/forth.c $(OBJS) -o $@
 
 zasm/kernel-bin.h: zasm/kernel.bin
@@ -94,6 +108,10 @@ updatebootstrap: $(ZASMBIN)
 	$(ZASMBIN) $(KERNEL) < zasm/glue.asm > zasm/kernel.bin
 	$(ZASMBIN) $(KERNEL) $(APPS) zasm/user.h < $(APPS)/zasm/glue.asm > zasm/zasm.bin
 
+.PHONY: fbootstrap
+fbootstrap: forth/stage1
+	cat $(FORTHSRC_PATHS) ../forth/z80c.fs ../forth/dummy.fs | ./forth/stage1 | tee forth/z80c.bin > /dev/null
+
 .PHONY: clean
 clean:
 	rm -f $(TARGETS) $(SHELLTGTS) emul.o zasm/*-bin.h shell/*-bin.h

emul/README.md

@@ -80,6 +80,39 @@ code of the program is the value of `A` when the program halts.
 
 This is used for unit tests.
 
+## forth
+
+Collapse OS' Forth interpreter, which will probably soon replace the whole OS.
+
+At this point, it is not yet entirely self-hosting, but will be eventually.
+Because of that aim, it currently builds in a particular manner.
+
+There are 3 build stages.
+
+**Stage 0**: This stage is created with zasm by assembling `forth/forth.asm`
+through `stage0.asm`. This yields `forth0.bin`. We then wrap this binary with
+`stage.c` to create the `stage1` binary, which allows us to get to the next
+stage.
+
+The long term goal is to gradually extract contents from `forth.asm` and have
+nothing but Forth source files.
+
+**Stage 1**: The `stage1` binary allows us to augment `forth0.bin` with
+contents from `z80c.fs`, which compiles native words using Forth's Z80
+assembler. This yields `z80c.bin`.
+
+This is where there's a chiken-and-egg issue: Forth's assembler needs our full
+Forth interpreter, but that interpreter needs native words from `z80c.fs`. This
+is why `z80c.bin` is committed into the git repo and it's built automatically
+with `make`. Updating `z80c.bin` is a specific make rule, `fbootstrap`.
+
+Then, from there, we augment `forth0.bin` with `z80c.bin` and yield
+`forth1.bin`, from which we create `stage2`.
+
+**Stage 2**: From there, the way is clear to compile the dict of our full Forth
+interpreter, which we do using `stage2` and produce `forth2.bin`, from which we
+can create our final `forth` executable.
+
 ## Problems?
 
 If the libz80-wrapped zasm executable works badly (hangs, spew garbage, etc.),

emul/forth/forth.c

@@ -3,7 +3,7 @@
 #include <unistd.h>
 #include <termios.h>
 #include "../emul.h"
-#include "forth1-bin.h"
+#include "forth2-bin.h"
 
 // in sync with glue.asm
 #define RAMSTART 0x900

emul/forth/glue1.asm

@@ -1,31 +0,0 @@
-; Warning: The offsets of native dict entries must be exactly the same between
-;          glue0.asm and glue1.asm
-.equ	LATEST		RAMSTART	; override
-.equ	STDIO_PORT	0x00
-
-	jp	init
-
-.equ	GETC	emulGetC
-.equ	PUTC	emulPutC
-.inc "forth.asm"
-
-init:
-	di
-	; setup stack
-	ld	sp, 0xffff
-	call	forthMain
-	halt
-
-emulGetC:
-	; Blocks until a char is returned
-	in	a, (STDIO_PORT)
-	cp	a		; ensure Z
-	ret
-
-emulPutC:
-	out	(STDIO_PORT), a
-	ret
-
-.out $		; should be the same as in glue0
-.bin "core.bin"
-RAMSTART:

emul/forth/stage.c

@@ -2,7 +2,11 @@
 #include <stdio.h>
 #include <unistd.h>
 #include "../emul.h"
+#ifdef STAGE2
+#include "forth1-bin.h"
+#else
 #include "forth0-bin.h"
+#endif
 
 /* Staging binaries
 
@@ -32,7 +36,11 @@ trouble of compiling defs to binary.
 #define HERE_PORT 0x02
 
 static int running;
-static uint16_t ending_here = 0;
+// We support double-pokes, that is, a first poke to tell where to start the
+// dump and a second one to tell where to stop. If there is only one poke, it's
+// then ending HERE and we start at sizeof(KERNEL).
+static uint16_t start_here = 0;
+static uint16_t end_here = 0;
 
 static uint8_t iord_stdio()
 {
@@ -54,8 +62,10 @@ static void iowr_stdio(uint8_t val)
 
 static void iowr_here(uint8_t val)
 {
-    ending_here <<= 8;
-    ending_here |= val;
+    start_here <<=8;
+    start_here |= (end_here >> 8);
+    end_here <<= 8;
+    end_here |= val;
 }
 
 int main(int argc, char *argv[])
@@ -76,8 +86,10 @@ int main(int argc, char *argv[])
 
 #ifndef DEBUG
     // We're done, now let's spit dict data
-    fprintf(stderr, "hey, %x\n", ending_here);
-    for (int i=sizeof(KERNEL); i<ending_here; i++) {
+    if (start_here == 0) {
+        start_here = sizeof(KERNEL);
+    }
+    for (int i=start_here; i<end_here; i++) {
         putchar(m->mem[i]);
     }
 #endif

emul/forth/stage0.asm

@@ -0,0 +1,7 @@
+	jp	init
+
+.inc "stagec.asm"
+.inc "forth.asm"
+
+CODE_END:
+.out $		; should be the same as in stage{1,2}

emul/forth/stage1.asm

@@ -0,0 +1,8 @@
+	jp	init
+
+.inc "stagec.asm"
+.inc "forth.asm"
+
+.out $		; should be the same as in stage{0,2}
+.bin "z80c.bin"
+CODE_END:

emul/forth/stage2.asm

@@ -0,0 +1,10 @@
+	jp	init
+
+.inc "stagec.asm"
+.inc "forth.asm"
+
+.out $		; should be the same as in stage{0,1}
+.bin "z80c.bin"
+.bin "core.bin"
+CODE_END:
+

emul/forth/stagec.asm

@@ -1,13 +1,8 @@
 .equ	RAMSTART	0xe800
 .equ	HERE_INITIAL	CODE_END	; override
+.equ	LATEST		CODE_END	; override
 .equ	STDIO_PORT	0x00
 
-	jp	init
-
-.equ	GETC	emulGetC
-.equ	PUTC	emulPutC
-.inc "forth.asm"
-
 init:
 	di
 	; setup stack
@@ -25,6 +20,5 @@ emulPutC:
 	out	(STDIO_PORT), a
 	ret
 
-CODE_END:
-.out LATEST
-.out $		; should be the same as in glue1
+.equ	GETC	emulGetC
+.equ	PUTC	emulPutC

forth/forth.asm

@@ -1487,25 +1487,9 @@ OVER2:
 	push	bc	; B
 	jp	next
 
-; ( a b c -- b c a)
-	.db "ROT"
-	.fill 4
-	.dw $-OVER2
-	.db 0
-ROT:
-	.dw nativeWord
-	pop	hl	; C
-	pop	de	; B
-	pop	bc	; A
-	call	chkPS
-	push	de	; B
-	push	hl	; C
-	push	bc	; A
-	jp	next
-
 	.db	">R"
 	.fill	5
-	.dw	$-ROT
+	.dw	$-OVER2
 	.db	0
 P2R:
 	.dw	nativeWord

forth/z80a.fs

@@ -1,11 +1,5 @@
 ( Z80 assembler )
 
-: CODE
-    ( same as CREATE, but with ROUTINE V )
-    (entry)
-    ROUTINE V [LITN] ,
-;
-
 ( Splits word into msb/lsb, lsb being on TOS )
 : SPLITB
     DUP 0x100 /
@@ -130,3 +124,12 @@
 ( Specials )
 : JRe, 0x18 A, 2 - A, ;
 : JPNEXT, ROUTINE N [LITN] JPnn, ;
+
+: CODE
+    ( same as CREATE, but with ROUTINE V )
+    (entry)
+    ROUTINE V [LITN] ,
+;
+
+: ;CODE JPNEXT, ;
+

forth/z80c.fs

@@ -0,0 +1,33 @@
+( Core words in z80. This requires a full Forth interpreter
+  to run, but is also necessary for core.fs. This means that
+  it needs to be compiled from a prior bootstrapped binary.
+
+  This stage is tricky due to the fact that references in
+  Forth are all absolute, except for prev word refs. This
+  means that there are severe limitations to the kind of code
+  you can put here.
+
+  You shouldn't define any word with reference to other words.
+  This means no regular definition. You can, however, execute
+  any word from our high level Forth, as long as it doesn't
+  spit word references.
+
+  ROUTINE stuff is fine. It's not supposed to change.
+
+  These restrictions are temporary, I'll figure something out
+  so that we can end up fully bootstrap Forth from within
+  itself.
+)
+
+( a b c -- b c a )
+CODE ROT
+    HL POPqq,       ( C )
+    DE POPqq,       ( B )
+    BC POPqq,       ( A )
+    ROUTINE P CALLnn,
+    DE PUSHqq,      ( B )
+    HL PUSHqq,      ( C )
+    BC PUSHqq,      ( A )
+;CODE
+
+