m68k/fpsp040/decbin.S

5 |	register A6 to extended-precision value in FP0.
9 |	Output:	Exact floating-point representation of the packed bcd value.
11 |	Saves and Modifies: D2-D5
20 |	Expected is a normal bcd (i.e. non-exceptional; all inf, zero,
33 |	assumed following the least-significant digit.
43 |	SM = 0	a non-zero digit in the integer position
44 |	SM = 1	a non-zero digit in Mant0, lsd of the fraction
47 |	representation (ex. 0.1E2, 1E1, 10E0, 100E-1), is converted
121 	moveml	%d2-%d5,-(%a7)
135 |	(*)  d2: digit count
144 	movel	#EDIGITS,%d2	|# of nibbles (digits) in fraction part
157 	dbf	%d2,e_gd	|if we have used all 3 digits, exit loop
181 |	(*)  d2: digit count
208 	moveql	#FNIBS,%d2	|reset number of digits per a0 ptr
215 |  If all the digits (8) in that long word have been converted (d2=0),
217 |  to initialize the digit offset, and set d2 to 7 for the digit count;
221 	dbf	%d2,md2b		|check for last digit in this lw
248 |   3. Add one for each zero encountered until a non-zero digit.
255 |   3. Add one for each zero encountered until a non-zero digit.
260 |  *Why 27?  If the adjusted exponent is within -28 < expA < 28, than
271 |	(*)  d2: digit count
282 | and do append (+) or strip (-) zeros accordingly.
294 	bnes	ap_p_fx		|if M16 is non-zero, go fix exp
304 	moveql	#7,%d2		|init digit counter
307 	bnes	ap_p_fx		|if non-zero, go to fix exp
310 	dbf	%d2,ap_p_gd	|get next digit
312 	movel	%d1,%d0		|copy counter to d2
325 	movel	#PTENRN,%a1	|get address of power-of-ten table
328 	moveql	#3,%d2		|init d2 to count bits in counter
352 	moveql	#7,%d2		|init digit counter
355 	bnes	ap_n_fx		|if non-zero, go to exp fix
358 	dbf	%d2,ap_n_gd	|get next digit
373 	movel	#PTENRN,%a1	|get address of power-of-ten table
376 	moveql	#3,%d2		|init d2 to count bits in counter
388 | Calculate power-of-ten factor from adjusted and shifted exponent.
395 |	(*)  d2: {FPCR[6:5],SM,SE} as index in RTABLE; temp
405 |	(*) fp1: power-of-ten accumulator
415 |	 -	   +	RP	RM
416 |	 +	   -	RP	RM
417 |	 -	   -	RP	RP
420 |	 -	   +	RM	RP
421 |	 +	   -	RM	RP
422 |	 -	   -	RM	RM
425 |	 -	   +	RZ	RM
426 |	 +	   -	RZ	RP
427 |	 -	   -	RZ	RP
432 	bfextu	%d3{#26:#2},%d2	|isolate rounding mode bits
434 	asll	#2,%d2		|format d2 to be
436 	addl	%d0,%d2		|in d2 as index into RTABLE
438 	moveb	(%a1,%d2),%d0	|load new rounding bits from table
479 |	( ) fp1: scaling factor - 10**(abs(exp))
503 	moveml	(%a7)+,%d2-%d5