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,
32 |	The mantissa digits will be converted with the decimal point
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
75 |DECBIN    idnt    2,1 | Motorola 040 Floating Point Software Package
93 	.byte	2,3,2,3
94 	.byte	2,3,3,2
95 	.byte	3,2,2,3
121 	moveml	%d2-%d5,-(%a7)
126 |  3. Correct for exponent sign.
128 |     (i.e., all digits assumed left of the decimal point.)
148 	movel	ETEMP_HI(%a6),4(%a0) |save words 2 and 3
157 	dbf	%d2,e_gd	|if we have used all 3 digits, exit loop
174 |     (i.e., all digits assumed left of the decimal point.)
183 |	( )  d4: words 2 and 3 of bcd
216 |  then inc d1 (=2) to point to the next long word and reset d3 to 0
247 |   2. Check M16 and the digits in lwords 2 and 3 in descending order.
248 |   3. Add one for each zero encountered until a non-zero digit.
250 |   5. Check if the exp has crossed zero in #3 above; make the exp abs
254 |   2. Check the digits in lwords 3 and 2 in descending order.
255 |   3. Add one for each zero encountered until a non-zero digit.
257 |   5. Check if the exp has crossed zero in #3 above; clear SE.
260 |  *Why 27?  If the adjusted exponent is within -28 < expA < 28, than
282 | and do append (+) or strip (-) zeros accordingly.
294 	bnes	ap_p_fx		|if M16 is non-zero, go fix exp
301 	movel	(%a0,%d5.L*4),%d4	|get lword 3 to d4
307 	bnes	ap_p_fx		|if non-zero, go to fix exp
308 	addql	#4,%d3		|point to next digit
325 	movel	#PTENRN,%a1	|get address of power-of-ten table
328 	moveql	#3,%d2		|init d2 to count bits in counter
344 	moveql	#2,%d5		|set up d5 to point to lword 3
345 	movel	(%a0,%d5.L*4),%d4	|get lword 3
347 	subl	#1,%d5		|dec d5 to point to lword 2
351 	movel	#28,%d3		|point to last digit
355 	bnes	ap_n_fx		|if non-zero, go to exp fix
356 	subql	#4,%d3		|point to previous 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.
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
479 |	( ) fp1: scaling factor - 10**(abs(exp))
503 	moveml	(%a7)+,%d2-%d5