Add support for MacOS Classic SANE FPU emulation

MacOS supported FPU emulation using a trap called FP68k (or Pack4). After some digging around, I finally found a book which -- although not an official reference -- contains information relevant to an implementation.

On Macintosh Programming Advanced Techniques, p166, has the following table:

Function	PACKs	68881	C	Pascal
Arithmetic	FP68K
Addition	$0000	FADD	+	+
Subtraction	$0002	FSUB	-	-
Multiplication	$0004	FMUL	*	*
Division	$0006	FDIV	/	/
Remainder, IEEE (md to nearest)	$000C	FREM
Remainder, modulo (md to zero)		FMOD	fmod
Negation	$000D	FNEG
Absolute value	$000F	FABS	fabs	abs
Copy sign	$0011
Square root	$0012	FSQRT	sqrt	sqrt
Nextafter	$0013
Integer part, cur. rounding mode	$0014	FINT
Integer part, rounded to zero	$0016	FINTRZ	trunc*	trunc
Integer part, rounded to -oo	floor
Integer part, rounded to +=	ceil
Round, ties round away from zero	round
Integer & fractional parts	modf
Scale x to [.5,1) and a power of 2	frexp
Scale x by 2^i (i: integer)	$0018	FSCALE	ldexp
Extract exponent (logb)	$001A	FGETEXP
Extract mantissa	FGETMAN
Logarithmic	Elems68K
Log base e (In or natural log)	$0000	FLOGN	log	ln
Log base 2	$0002	FLOG2	log2*
Log (I +x), base e	$0004	FLOGNPl	lnl*
Log (l+x), base 2	$0006
Log base 10 (common log)	FLOG10	log10
Exponential	Elems68K
e^x (exponential, natural antilog)	$0008	FETOX	exp	exp
2^x	$000A	FTWOTOX	exp2*
e^x -1	$000C	FETOXMl	expl*
2^x - 1	$000E
10^x (common antilog)	FTENTOX	exp10*
x^i (i: integer)	$8010
x^y	$8012	pow
Trigonometric	Elems68K
Sine	$0018	FSIN	sin	sin
Cosine	$001A	FCOS	cos	cos
Tangent	$001C	FTAN	tan	tan
Inverse sine		FASIN	asin
Inverse cosine	FACOS	acos
Inverse tangent	$001E	FATAN	atan	arctan
Angle of (x,y) in range [-7t,7t]			atan2
Hyperbolic sine	FSINH	sinh
Hyperbolic cosine	FCOSH	cosh
Hyperbolic tangent	FTANH	tanh
Hyperbolic inverse sine
Hyperbolic inverse cosine
Hyperbolic inverse tangent	FATANH	atanh*

Implementing this is a SMOP.

uxmal / reko

Add support for MacOS Classic SANE FPU emulation #493