implement Writeflash; include "sys.m";	sys: Sys; include "draw.m"; include "string.m";	str: String; Writeflash: module{	init:	fn(nil: ref Draw->Context, args: list of string);}; Region: adt {	base:	int;	limit:	int;}; # could come from file or #F/flash/flashctlFLASHSEG: con 256*1024;kernelregion := Region(FLASHSEG, FLASHSEG+2*FLASHSEG);bootregion := Region(0, FLASHSEG); stderr: ref Sys->FD;prog := "qflash";damaged := 0; usage(){	sys->fprint(stderr, "Usage: %s [-b] [-o offset] [-f flashdev] file\n", prog);	exit;} err(s: string){	sys->fprint(stderr, "%s: %s", prog, s);	if(!damaged)		sys->fprint(stderr, "; flash not modified\n");	else		sys->fprint(stderr, "; flash might now be invalid\n");	exit;} init(nil: ref Draw->Context, args: list of string){	sys = load Sys Sys->PATH;	sys->pctl(Sys->FORKFD|Sys->NEWPGRP, nil);	stderr = sys->fildes(2);	if(args != nil){		prog = hd args;		args = tl args;	}	str = load String String->PATH;	if(str == nil)		err(sys->sprint("can't load %s: %r", String->PATH));	region := kernelregion;	flash := "#F/flash/flash";	offset := 0;	save := 0;		for(; args != nil && (hd args)[0] == '-'; args = tl args)		case hd args {		"-b" =>			region = bootregion;			offset = 16r100 - 8*4;	# size of exec header			save = 1;		"-h" =>			region.limit += FLASHSEG;		"-f" =>			if(tl args == nil)				usage();			flash = hd args;			args = tl args;		"-o" =>			if(tl args == nil)				usage();			args = tl args;			s := hd args;			v: int;			rs: string;			if(str->prefix("16r", s))				(v, rs) = str->toint(s[3:], 16);			else if(str->prefix("0x", s))				(v, rs) = str->toint(s[2:], 16);			else if(str->prefix("0", s))				(v, rs) = str->toint(s[1:], 8);			else				(v, rs) = str->toint(s, 10);			if(v < 0 || len rs != 0)				err(sys->sprint("bad offset: %s", s));			offset = v;		"-s" =>			save = 1;		* =>			usage();		}	if(args == nil)		usage();	fname := hd args;	fd := sys->open(fname, Sys->OREAD);	if(fd == nil)		err(sys->sprint("can't open %s: %r", fname));	(r, dir) := sys->fstat(fd);	if(r < 0)		err(sys->sprint("can't stat %s: %r", fname));	length := int dir.length;	avail := region.limit - (region.base+offset);	if(length > avail)		err(sys->sprint("%s contents %ud bytes, exceeds flash region %ud bytes", fname, length, avail));	# check fname's contents...	where := region.base+offset;	saved: list of (int, array of byte);	if(save){		saved = saveflash(flash, region.base, where) :: saved;		saved = saveflash(flash, where+length, region.limit) :: saved;	}	for(i := (region.base+offset)/FLASHSEG; i < region.limit/FLASHSEG; i++)		erase(flash, i);	out := sys->open(flash, Sys->OWRITE);	if(out == nil)		err(sys->sprint("can't open %s for writing: %r", flash));	if(sys->seek(out, big where, 0) != big where)		err(sys->sprint("can't seek to #%6.6ux on flash: %r", where));	if(length)		sys->print("writing %ud bytes to %s at #%6.6ux\n", length, flash, where);	buf := array[Sys->ATOMICIO] of byte;	total := 0;	while((n := sys->read(fd, buf, len buf)) > 0) {		if(total+n > avail)			err(sys->sprint("file %s too big for region of %ud bytes", fname, avail));		r = sys->write(out, buf, n);		damaged = 1;		if(r != n){			if(r < 0)				err(sys->sprint("error writing %s at byte %ud: %r", flash, total));			else				err(sys->sprint("short write on %s at byte %ud", flash, total));		}		total += n;	}	if(n < 0)		err(sys->sprint("error reading %s: %r", fname));	sys->print("wrote %ud bytes from %s to flash %s (#%6.6ux-#%6.6ux)\n", total, fname, flash, region.base, region.base+total);	for(l := saved; l != nil; l = tl l){		(addr, data) := hd l;		n = len data;		if(n == 0)			continue;		sys->print("restoring %ud bytes at #%6.6ux\n", n, addr);		if(sys->seek(out, big addr, 0) != big addr)			err(sys->sprint("can't seek to #%6.6ux on %s: %r", addr, flash));		r = sys->write(out, data, n);		if(r < 0)			err(sys->sprint("error writing %s: %r", flash));		else if(r != n)			err(sys->sprint("short write on %s at byte %ud/%ud", flash, r, n));		else			sys->print("restored %ud bytes at #%6.6ux\n", n, addr);	}} erase(flash: string, seg: int){	ctl := sys->open(flash+"ctl", Sys->OWRITE);	if(ctl == nil)		err(sys->sprint("can't open %sctl: %r\n", flash));	if(sys->fprint(ctl, "erase %ud", seg*FLASHSEG) < 0)		err(sys->sprint("can't erase flash %s segment %d: %r\n", flash, seg));} saveflash(flash: string, base: int, limit: int): (int, array of byte){	fd := sys->open(flash, Sys->OREAD);	if(fd == nil)		err(sys->sprint("can't open %s for reading: %r", flash));	nb := limit - base;	if(nb <= 0)		return (base, nil);	if(sys->seek(fd, big base, 0) != big base)		err(sys->sprint("can't seek to #%6.6ux to save flash contents: %r", base));	saved := array[nb] of byte;	if(sys->read(fd, saved, len saved) != len saved)		err(sys->sprint("can't read flash #%6.6ux to #%6.6ux: %r", base, limit));	sys->print("saved %ud bytes at #%6.6ux\n", len saved, base);	return (base, saved);}