plans

Spiffy: Yet another ZX Spectrum emulator
Ideas & Future Plans

CORE:

DEBUGGER:
Disabled & single-shot breakpoints.
Funky breakpoints in debugger: break on memory read/write in range, port read/write in range (or matching bits), execution of RET, RETurn from current function (effectively just single-shot (SP) read trap).
Breakpoint conditions, like Tstate count, register-has-value, memory-location-has-value.  Allow conditions to be ANDed together (eg. Break on port read !A0 while Tstate between foo and bar and regB nonzero).
Arguments to t[race] interpreted like p, with the semantics of gdb 'display'.
Command to refresh (ie. SDL_Flip()) the screen.
Macros.
Attaching macros (and single commands?) to breakpoints (on this breakpoint, run that macro).
Search for JP/CALL/JR to an address.
Search for literal NN in LD.
Search for [NN] in LD.

UI:
Debugger frontend harness: user-friendly debugger frontends (curses?  GUI?)

DPRINT:
	Stuff still todo: autocast in =, shifts/rotates
	Stuff still to document: casting rules, common {integer, numeric} type rules
Examples:
	.b 8ccc            - byte at 0x8ccc.
	.f dead            - 5-byte float at 0xdead.
	.w @VARS           - word at VARS.
	.8 + .w @CHARS 118 - 8 bytes from 280 bytes after the address pointed to by CHARS (0x5c36).
	.b + #IX 25        - byte at IX+0x25.
	= .b #DE .b #HL    - copies a byte from [HL] to [DE], and prints the byte copied.
	.b:AY 5            - byte from AY register 5.  (However, the 'a' (and 'u') commands will be kept as they perform decoding of these values).
	>> #A 1            - value of A, shifted right once (logical shift, not arithmetic shift)
	<<< #A 3           - value of A, rotated left three times
Syntax:
<expression> ::= <unop> <expression> | <binop> <expression> <expression> | <sysvar> | <register> | <literal>
<unop>       ::= '~' | <indirection> | <cast>
<binop>      ::= '+' | '-' | '*' | '/' | '%' | '&' | '|' | '^' | '<<' | '>>' | '<<<' | '>>>' | '<<|' | '>>|' | '='
<cast>       ::= '\'' <type>
<indirection>::= '.'<type> | '.'<type>':'<far>
<type>       ::= 'b' | 'w' | 'f' | '8' | 'R'
<far>        ::= 'AY' | 'ULAPLUS'
<sysvar>     ::= '@'<sysvarname>
<register>   ::= '#'<registername>
<literal>    ::= <hex-literal> | <float-lit>
<hex-literal>::= <xdigit>*{1,4}
<float-lit>  ::= '_'<float-val>
Semantics:
	op	types		description & return type
	~	bw8R		Bitwise Complement.  Return has type of operand.
	+	numeric		Sum.  Common numeric type rules apply.
	-	As +		Difference.  Return type as +.
	*	As +		Product.  Return type as +.
	/	As +		Quotient.  Return type as +.
	%	integer		Remainder.  Common integer type rules apply.
	&	As %		Bitwise AND.  Return type as %.
	|	As %		Bitwise OR.  Return type as %.
	^	As %		Bitwise XOR.  Return type as %.
	<<	(bw)b		Left shift.  Return has type of first operand.
	>>	As <<		Right shift.  Return type as <<.
	<<<	As <<		Left rotate.  Return type as <<.
	>>>	As <<		Right rotate.  Return type as <<.
	<<|	As <<		Left shift set (ie. left shift, then set the lsb).  Return type as <<.
	>>|	As <<		Right shift arithmetic.  Return type as <<.
	=	lvalue		Assignment.  First operand must be an lvalue.  Second operand must be castable to type of first operand.  Returns first operand.
	'T	T-castable	Typecast.  Return type given by T.
	.T	bw			Indirection.  Return type given by T, and is an lvalue.
	@				Return type is w, and is the address of the sysvar.
	#				Return type is b for 8-bit registers, w for 16-bit.
	hex-literal		Return type is b if <=2 xdigits, else w.
	_float-lit		Return type is f.