memory map: B [128,i/o] A [128,tokens] x [32,hexconv] o [224,registers]

Memory is "allocated" from the stack, by taking a local (stack) variable
and subtracting 64k -- thereby leaving plenty of room for even relatively
large stack frames during recursion.

i    main(i,c**) parse command line or stdin, assignments, print result, error recovery

i64  _		dot
c   *A		lexical tokens
c   *B		input buffer
td   C		unsigned
c    D		some state between funcs
c   *E		error string, end pointer
i64  F()	expr: + - ^ |
uc   G()	non-local goto
#d   H		unsigned
#d   I		typedef
td   J		jmp_buf
c   *K		pointer to cmd line args
td   L		char
v    M(u64)	detect errors, save answer in dot, format result in decimal and hex
c   *N		freebie NULL pointer
td   O		unsigned char
td   P		void
td   Q		int
#d   R		return
c    S		syntax error + tokens
c   *T		current token pointer
v    U(c*)	print the registers
td   V		long long
#d   W(x)	for(;x;)
td   X		long - only for rule2sp.c
td   Y		unsigned short
td   Z		unsigned long long
i64  a		derived: 32
i64  b		derived: 1
i64 _b(i64)	term: << >> >>>
i64  c		derived: 10
i64 _c(c*)	convert binary global j to ASCII decimal
i64  d		freebie: 0
v   _d(i64)	accumulate converted ASCII bytes into j in base passed in
i64  e		derived: 256
i64  f		derived: 2
i64 _f()	convert from ASCII to binary: selects convert base (10,8,16), result in j
u64  g(u16)	byte swap 16-bits
u64  h(u32)	byte swap 32-bits
i64  i(u64)	select size and byte swap minimal bytes
v   _i(c*)	conditional print
i64  j		holds partial/accumulated results
*()  k		ptr-to-func-getchar
i   _k()	get chars from saved cmd line
jb   l		for parser error recovery
c    m()	scans input for token, ignores whitespace
c    n()	get next input character
i64 *o		registers 
u32  p(c*)	writes to stdout until NUL, newline appended intelligently
v    q(**)	init
i64  r(c)	writes c to stdout
i64  s		derived: 8
i64  t		derived: 4
i64  u		derived: 3
c    v		current input token
i64  w()	read from stdin until newline or semi, skips blank lines + comments, return len
c   *x		aptly named hex conversion table
i64  y()	term: * / % & (<< >> >>>)
i64  z()	factor ~ ! ? -/+ () VAR NUM DOT