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boot: make HERE point to RAMEND instead of CURRENT
The former was only used in the peculiar context of "/emul". The regular case is actually HERE pointing to RAMEND on boot.
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@ -29,7 +29,7 @@ $(BIN2C):
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forth/forth0.bin: $(SLATEST)
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cp forth/z80c.bin $@
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$(SLATEST) $@
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cat forth/emul.fs >> $@
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cat forth/pre.fs forth/emul.fs >> $@
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forth/forth0-bin.h: forth/forth0.bin $(BIN2C)
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$(BIN2C) KERNEL < forth/forth0.bin | tee $@ > /dev/null
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@ -43,14 +43,14 @@ forth/stage1dbg: forth/stage.c $(OBJS) forth/forth0-bin.h
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# We don't really need to use stripfc, but we do it anyway to test that we
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# don't mistakenly break our code with that tool. It's easier to debug here.
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forth/core.bin: $(FORTHSRC_PATHS) forth/stage1
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cat $(FORTHSRC_PATHS) ./forth/stop.fs | $(STRIPFC) | ./forth/stage1 | tee $@ > /dev/null
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cat $(FORTHSRC_PATHS) ./forth/stop.fs | $(STRIPFC) | ./forth/stage1 > $@
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forth/forth1.bin: forth/core.bin $(SLATEST)
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cat forth/z80c.bin forth/core.bin > $@
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$(SLATEST) $@
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forth/forth1-bin.h: forth/forth1.bin $(BIN2C)
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$(BIN2C) KERNEL < forth/forth1.bin | tee $@ > /dev/null
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$(BIN2C) KERNEL < forth/forth1.bin > $@
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forth/stage2: forth/stage.c $(OBJS) forth/forth1-bin.h
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$(CC) -DSTAGE2 forth/stage.c $(OBJS) -o $@
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2
emul/forth/pre.fs
Normal file
2
emul/forth/pre.fs
Normal file
@ -0,0 +1,2 @@
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CURRENT @ HERE !
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@ -1 +1 @@
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: INIT RDLN$ Z80A$ INTERPRET ;
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: INIT CURRENT @ HERE ! RDLN$ Z80A$ INTERPRET ;
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Binary file not shown.
@ -118,12 +118,14 @@ PC ORG @ 1 + ! ( main )
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SP 0xfffa LDddnn,
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RAMSTART SP LD(nn)dd, ( RAM+00 == INITIAL_SP )
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IX RS_ADDR LDddnn,
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( HERE begins at RAMEND )
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HL RAMSTART 0x80 + LDddnn,
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RAMSTART 0x04 + LD(nn)HL, ( RAM+04 == HERE )
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( LATEST is a label to the latest entry of the dict. It is
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written at offset 0x08 by the process or person building
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Forth. )
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0x08 LDHL(nn),
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RAMSTART 0x02 + LD(nn)HL, ( RAM+02 == CURRENT )
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RAMSTART 0x04 + LD(nn)HL, ( RAM+04 == HERE )
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EXDEHL,
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HL L1 @ LDddnn,
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0x03 CALLnn, ( 03 == find )
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19
notes.txt
19
notes.txt
@ -170,8 +170,11 @@ advanced to the address following the null.
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*** Initialization sequence
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On boot, we jump to the "main" routine in boot.fs which does very few things.
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It sets up the SP register, CURRENT and HERE to LATEST (saved in stable ABI),
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then look for the BOOT word and calls it.
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1. Set SP to 0x10000-6
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2. Sets HERE to RAMEND (RAMSTART+0x80).
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3. Sets CURRENT to value of LATEST field in stable ABI.
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4. Look for the word "BOOT" and calls it.
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In a normal system, BOOT is in icore and does a few things:
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@ -192,9 +195,9 @@ as such until you set a new (c<).
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Note that there is no EMIT in a bare system. You have to take care of supplying
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one before your load core.fs and its higher levels.
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Also note that this initialization code is fighting for space with HERE: New
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entries to the dict will overwrite that code! Also, because we're barebone, we
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can't have comments. This leads to peculiar code in this area. If you see weird
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whitespace usage, it's probably because not using those whitespace would result
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in dict entry creation overwriting the code before it has the chance to be
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interpreted.
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In the "/emul" binaries, "HERE" is readjusted to "CURRENT @" so that we don't
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have to relocate compiled dicts. Note that in this context, the initialization
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code is fighting for space with HERE: New entries to the dict will overwrite
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that code! Also, because we're barebone, we can't have comments. This can lead
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to peculiar code in this area where we try to "waste" space in initialization
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code.
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@ -1,4 +1,4 @@
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TARGET = os.bin
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TARGET = stage1.bin
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BASEDIR = ../..
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FDIR = $(BASEDIR)/forth
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EDIR = $(BASEDIR)/emul/forth
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@ -13,7 +13,7 @@ BOOTSRCS = conf.fs \
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$(FDIR)/icore.fs \
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$(EDIR)/xstop.fs
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PATHS = pre.fs \
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PATHS = \
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$(FDIR)/core.fs \
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$(FDIR)/cmp.fs \
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$(FDIR)/str.fs \
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@ -202,9 +202,9 @@ using our hex editor.
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Now are we ready yet? ALMOST! There's one last thing we need to do: add runtime
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source. In our case, because we have a compiled dict, the only source we need
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to include is `pre.fs` and `run.fs`:
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to include is `run.fs`:
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cat stage2.bin pre.fs run.fs > stage2r.bin
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cat stage2.bin run.fs > stage2r.bin
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That's it! our binary is ready to run!
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@ -212,7 +212,8 @@ That's it! our binary is ready to run!
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And there you have it, a stage2 binary that you've assembled yourself. Now,
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here's for your homework: use the same technique to add the contents of
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`readln.fs` to stage2 so that you have a full-featured interpreter.
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`readln.fs` and `adev.fs` to stage2 so that you have a full-featured
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interpreter.
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Name it `stage3.bin` (the version without any source code appended and no
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`INIT` word defined), you'll need this binary for sub-recipes written for the
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@ -221,8 +222,8 @@ RC2014.
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Here's a little cheatsheet, but seriously, you should figure most of it
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yourself. Tough love they call it.
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* `cat stage2.bin pre.fs ../../forth/readln.fs run.fs > stage2r.bin`
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* Don't forget `(c<$)`.
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* `cat stage2.bin ../../forth/readln.fs ../../forth/adev.fs run.fs > stage2r.bin`
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* Don't forget `RDLN$` and `ADEV$`.
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* `RLDICT` is like `RLCORE` but with a chosen target.
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[rc2014]: https://rc2014.co.uk
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@ -1 +0,0 @@
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128 RAM+ HERE !
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