Lines Matching refs:F

30 |	Step 2. X = 2**k * Y where 1 <= Y < 2. Define F to be the first seven
31 |		significant bits of Y plus 2**(-7), i.e. F = 1.xxxxxx1 in base
32 |		2 where the six "x" match those of Y. Note that |Y-F| <= 2**(-7).
34 |	Step 3. Define u = (Y-F)/F. Approximate log(1+u) by a polynomial in u,
37 |	Step 4. Reconstruct log(X) = log( 2**k * Y ) = k*log(2) + log(F) + log(1+u)
38 |		by k*log(2) + (log(F) + poly). The values of log(F) are calculated
45 |	Step 2: Let 1+X = 2**k * Y, where 1 <= Y < 2. Define F as done in Step 2
47 |		k*log(2) + log(F) + poly where poly approximates log(1+u),
48 |		u = (Y-F)/F. 
51 |	Note 1. There are 64 different possible values for F, thus 64 log(F)'s
344 |--WE DEFINE F = 1.XXXXXX1, I.E. FIRST 7 BITS OF Y AND ATTACH A 1.
346 |--			 = K*LOG2 + LOG(F) + LOG(1 + (Y-F)/F).
347 |--NOTE THAT U = (Y-F)/F IS VERY SMALL AND THUS APPROXIMATING
349 |--ALSO NOTE THAT THE VALUE 1/F IS STORED IN A TABLE SO THAT NO
350 |--DIVISION IS NEEDED TO CALCULATE (Y-F)/F. 
352 |--GET K, Y, F, AND ADDRESS OF 1/F.
357 	lea	LOGTBL,%a0 	| ...BASE ADDRESS OF 1/F AND LOG(F)
360 |--WHILE THE CONVERSION IS GOING ON, WE GET F AND ADDRESS OF 1/F
364 	oril	#0x01000000,FFRAC(%a6) | ...GET F: ATTACH A 1 AT THE EIGHTH BIT
365 	movel	FFRAC(%a6),%d0	| ...READY TO GET ADDRESS OF 1/F
370 	addal	%d0,%a0		| ...A0 IS THE ADDRESS FOR 1/F
373 	movel	#0x3fff0000,F(%a6)
374 	clrl	F+8(%a6)
375 	fsubx	F(%a6),%fp0		| ...Y-F
377 |--SUMMARY: FP0 IS Y-F, A0 IS ADDRESS OF 1/F, FP1 IS K
382 	fmulx	(%a0),%fp0	| ...FP0 IS U = (Y-F)/F
408 	addal	#16,%a0		| ...ADDRESS OF LOG(F)
414 	faddx	(%a0),%fp1	| ...LOG(F)+U*V*(A2+V*(A4+V*A6))
416 	faddx	%fp1,%fp0		| ...FP0 IS LOG(F) + LOG(1+U)