plat/e6800: Add MC6800 emulator emu6800 support

plat/e6800/README

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+The emu6800 platform
+====================
+
+This port targets the emu6800 emulator and generates code for the Motorola 6800 architecture. It is intended to run within the emu6800 environment.
+
+This implementation is currently **under development and does not work yet**. Many features are incomplete or missing.
+
+**File I/O is not implemented and will not be supported in the future,** because the emu6800 environment does not provide any file input/output functionality.
+
+**Floating point support is not available yet.** Any attempt to use floating-point numbers will result in a build error or undefined behavior. Floating-point functionality may be added in the future.
+
+The code generator is designed specifically for the MC6800, which has a simple architecture and a limited register set. The compiler translates source code to EM (stack-based intermediate code), and then to MC6800 assembly. Arguments and local variables are accessed relative to the frame pointer (Local Base, LB), **which resides in zero page**.
+
+**Temporary results are kept either on the stack or in AccAB (the stack top).** See the source for details on stack frame layout and accumulator usage.
+
+This port is intended to be tested using the emu6800 emulator.
+
+Example command line
+====================
+
+ack -mm6800 -O -o hello.bin examples/hello.c
+
+The file hello.bin can then be run using emu6800.
+
+(Please note that this port is experimental and most programs will not yet function as expected.)
+
+----
+
+Work in progress. Contributions and bug reports are welcome.
+
+@zu2

plat/e6800/boot.s

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+.define BASE, EM_BSIZE
+.define NBYTES
+.define hol0, IGNMASK, ADDR, PROGNAME
+.define LB, LBl, ERRPROC
+.define	ARTH, RETURN, SIGN
+.define RETSIZE, TRAPVAL, BRANCH
+.define START
+.define TMP, TMP2
+.define	__exit, EXIT
+.define	_putchar, _getchar, _print, _cpu_counter, _errno
+.define _putstr, _puthexl,_puthexi, _puthexc
+.define _emu6800_conout, _emu6800_conin
+
+BASE    = 240
+EM_BSIZE = 4
+
+.sect .zero
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+.sect .end
+
+
+.sect .zero
+hol0:   .space 16       ! the hol0 block
+IGNMASK: .space 2	! can hold the ingnore mask
+ADDR: .space 4          ! used for indirect addressing
+LB: .space 2            ! the localbase
+LBl: .space 2           ! the second localbase (localbase-BASE)
+ERRPROC: .space 2	! can hold the address of the error handler
+ARTH: .space 16         ! used for arithmetic
+RETURN: .space 4        ! the return area
+SIGN: .space 1
+RETSIZE: .space 1
+TRAPVAL: .space 1
+BRANCH: .space 2
+NBYTES: .space 2
+TMP: .space 2
+TMP2: .space 2
+exitsp: .space 2
+
+_errno: .space 2
+
+.define Earray, Erange, Eset
+.define Eiovfl, Eidivz, Eiund, Econv
+.define Estack, Eheap, Eillins, Eoddz
+.define Ecase , Ebadmon
+.define Ebadlin, Ebadgto
+Earray  = 0
+Erange  = 1
+Eset    = 2
+Eiovfl  = 3
+Eidivz  = 6
+Eiund   = 8
+Econv   = 10
+Estack  = 16
+Eheap   = 17
+Eillins = 18
+Eoddz   = 19 
+Ecase   = 20
+Ebadmon = 25
+Ebadlin = 26
+Ebadgto = 27
+
+.define F_DUM
+F_DUM	= 0		! Dummy floating point constant
+
+!.base 0x0100            ! where to start in the emu6800
+.sect .text
+! GENERAL PURPOSE ROUTINES
+START:
+	sts	exitsp
+	lds	#0xefff
+!
+	clrb
+	clra
+	pshb		! envp
+	psha
+	pshb		! argv
+	psha
+	pshb		! argc
+	psha
+	jsr     __m_a_i_n	! see.  lang/cem/libcc/gen/head_cc.e
+	ins
+	ins
+	ins
+	ins
+___exit:
+EXIT:
+	lds exitsp
+	staa 0xfefb
+	ldab RETURN+1
+	stab 0xfeff
+	rts
+__exit:
+	tsx
+	ldab 3,x
+	stab RETURN+1
+	bra ___exit
+!
+!	minimal I/O routine
+!
+_puthexc:
+	tsx
+	bra	_puthexi3
+_puthexl:
+	tsx
+	bsr	_puthexi2
+	inx
+	inx
+	bra	_puthexi2
+_puthexi:
+	tsx
+_puthexi2:
+	ldaa	2,x
+	bsr	_puthex2
+_puthexi3:
+	ldaa	3,x
+_puthex2:			! put AccA in 2 hexdigit
+	bsr	_puthexhi
+	tab
+	bra	_puthexlo
+_puthexhi:
+	tab
+	lsrb
+	lsrb
+	lsrb
+	lsrb
+_puthexlo:
+	andb	#0x0f
+	cmpb	#0x0a
+	bcs	1f
+	addb	#'A'-'9'-1
+1:	addb	#'0'
+	stab	0xfefe
+	rts
+_putstr:
+	stab	<TMP+1
+	staa	<TMP
+	ldx	<TMP
+	bra	2f
+1:	stab	0xfefe
+	inx
+2:	ldab	0,x
+	bne	1b
+	rts
+_emu6800_conout:
+_putchar:
+	tsx
+	ldab	3,x
+	stab	0xfefe
+	rts
+_emu6800_conin:
+_getchar:
+	ldab	0xfefe
+	stab	RETURN+1
+	clr	RETURN
+	rts
+_print:
+	tsx
+	ldab	3,x
+	ldaa	2,x
+	staa	0xfefc
+	stab	0xfefd
+	rts
+_cpu_counter:
+	staa	0xfefb
+	rts
+.sect .data
+.define _emu6800_ram
+_emu6800_ram: .data2 __end
+PROGNAME:               ! for initialising the programname pointer
+.asciz "emu6800"
+.sect .bss
+beginbss:

plat/e6800/build.py

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+from build.ab import export
+from build.ack import ackcfile, exportheaders
+from mach.proto.cg.build import build_cg
+from plat.build import build_plat_libs
+import importlib
+
+build_as = importlib.import_module("mach.proto.as.build").build_as
+
+build_as(name="as", arch="mc6800")
+build_cg(name="cg", arch="mc6800")
+build_plat_libs(name="plat_libs", arch="mc6800", plat="e6800")
+
+ackcfile(name="boot", srcs=["./boot.s"], plat="e6800")
+
+export(
+    name="tools",
+    items={
+        "$(PLATDEP)/e6800/as$(EXT)": ".+as",
+        "$(PLATDEP)/e6800/cg$(EXT)": ".+cg",
+        "$(PLATIND)/descr/e6800": "./descr",
+    },
+)
+
+export(
+    name="all",
+    items={
+        "$(PLATIND)/e6800/boot.o": ".+boot",
+        "$(PLATIND)/e6800/libsys.a": "./libsys",
+    },
+    deps=[
+        ".+tools",
+        ".+plat_libs",
+        "util/ack+all",
+        "plat/e6800/include+all",
+    ],
+)
+

plat/e6800/descr

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+# $Source$
+# $State$
+# $Revision$
+
+var w=2
+var wa=2
+var p=2
+var pa=2
+var s=2
+var sa=2
+var l=4
+var la=2
+var f=4
+var fa=2
+var d=8
+var da=2
+var x=8
+var xa=2
+var ARCH=mc6800
+var PLATFORM=e6800
+var PLATFORMDIR={EM}/share/ack/{PLATFORM}
+#var CPP_F=-D__unix
+var ALIGN=-a0:1 -a1:1 -a2:1 -a3:1 -b0:0 -b1:0x100
+# see. util/opt/em_opt.6: replace multiplies with constants n times.
+var MACHOPT_F=-m0
+
+# Override the setting in fe so that files compiled for linux386 can see
+# the platform-specific headers.
+
+var C_INCLUDES=-I{EM}/share/ack/{PLATFORM}/include -I{EM}/share/ack/include/ansi
+
+name be
+	from .m.g
+	to .s
+	program {EM}/lib/ack/{PLATFORM}/cg
+	args <
+	stdout
+	need .e
+end
+#name asopt
+#        from .s
+#        to .so
+#        program /usr/bin/cat
+#        args > <
+#        optimizer
+#        stdin
+#        stdout
+#end
+name as
+	from .s.so
+        to .o
+        program {EM}/lib/ack/{PLATFORM}/as
+        args - -o > <
+        prep cond
+end
+name led
+	from .o.a
+	to .out
+	program {EM}/lib/ack/em_led
+	mapflag -l* LNAME={PLATFORMDIR}/lib*
+#	mapflag -i SEPID=-b1:0
+	mapflag -fp FLOATS={PLATFORMDIR}/libfp.a
+	args {ALIGN} {SEPID?} \
+		({RTS}:.b=-u _i_main) \
+	    (.e:{HEAD}={PLATFORMDIR}/boot.o) \
+		({RTS}:.ocm.bas.b={PLATFORMDIR}/c-ansi.o) \
+		({RTS}:.c={PLATFORMDIR}/c-ansi.o) \
+		({RTS}:.mod={PLATFORMDIR}/modula2.o) \
+		({RTS}:.p={PLATFORMDIR}/pascal.o) \
+		-o > < \
+		(.p:{TAIL}={PLATFORMDIR}/libpascal.a) \
+		(.b:{TAIL}={PLATFORMDIR}/libb.a) \
+		(.bas:{TAIL}={PLATFORMDIR}/libbasic.a) \
+		(.mod:{TAIL}={PLATFORMDIR}/libmodula2.a) \
+		(.ocm:{TAIL}={PLATFORMDIR}/liboccam.a) \
+		(.ocm.bas.mod.b.c.p:{TAIL}={PLATFORMDIR}/libc.a) \
+		{FLOATS?} \
+		(.e:{TAIL}={PLATFORMDIR}/libem.a \
+		           {PLATFORMDIR}/libsys.a \
+				   {PLATFORMDIR}/libc.a \
+				   {PLATFORMDIR}/libem.a \
+		           {PLATFORMDIR}/libsys.a \
+		           {PLATFORMDIR}/libend.a)
+	linker
+end
+name cv
+	from .out
+	to .img
+	program {EM}/bin/aslod68
+	args -v -v -me6800 < >
+	outfile e6800.img
+end

plat/e6800/include/ack/plat.h

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+/* $Source$
+ * $State$
+ * $Revision$
+ */
+
+#ifndef _ACK_PLAT_H
+#define _ACK_PLAT_H
+
+#define ACKCONF_WANT_STDIO_FLOAT 0
+#define ACKCONF_WANT_EMULATED_TIME 1
+#define ACKCONF_WANT_EMULATED_POPEN 0
+#define ACKCONF_WANT_EMULATED_FILE 1
+
+/* We have a very small address space, so override the default buffer size. */
+
+#define BUFSIZ 256
+
+#endif

plat/e6800/include/build.py

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+from build.ab import export
+from build.c import clibrary
+from glob import glob
+from build.ack import exportheaders
+
+headers = glob("**/*.h", root_dir="plat/e6800/include", recursive=True)
+
+clibrary(
+    name="include",
+    hdrs={k: f"./{k}" for k in headers},
+)
+
+export(
+    name="all",
+    items=exportheaders(".+include", prefix="$(PLATIND)/e6800/include"),
+)