m68k/fpsp040/get_op.S

9 | determines the opclass (0, 2, or 3) and branches to the
24 | changed but passed to the next module.  The next module for
31 | number is packed and written to user memory.  For the other
32 | opclasses the number(s) are written back to the fsave stack
34 | '040 is then able to complete the instruction.
38 | The '040 takes an unsupported data trap and gets to this
40 | then an frestore is done to restore the instruction back into
47 | routine which converts the unnorm to a norm (called mk_norm)
49 | res_func sees the denorm tag and converts the denorm to a
77 |round to nearest
84 | round to zero;round to negative infinity
91 | round to positive infinity
99 |round to nearest
120 |round to minus infinity
141 |round to positive infinity
209 | The following lines of are coded to optimize on normalized operands
212 	bmis	dest_op_ck	|if so, some op needs to be fixed
231 	leal	FPTEMP(%a6),%a0	|point a0 to dop - used in mk_norm
242 |				;to the fsave stack and fall
243 |				;through to check source operand
259 	leal	ETEMP(%a6),%a0	|point a0 to sop - used in mk_norm
275 | do nothing to the input.
295 	orw	#0x0800,%d1	|set source specifier to extended prec
296 	movew	%d1,CMDREG1B(%a6)	|write back to the command word in stack
297 |				;this is needed to fix unsupp data stack
298 	leal	ETEMP(%a6),%a0	|point a0 to sop
300 	bsr	mk_norm		|convert sgl/dbl denorm to norm
309 |				;number to etemp slot
322 	fmovemx %d0,FPTEMP(%a6)	|write to FPTEMP
331 	andib	#0xf0,%d0		|strip to only dtag:fpte15
345 	clrb	DY_MO_FLG(%a6)	|set dyadic/monadic flag to monadic
368 	st	DY_MO_FLG(%a6)	|set the inst flag type to dyadic
371 	clrb	DY_MO_FLG(%a6)	|set the inst flag type to monadic
376 | Normalizes unnormalized numbers, sets tag to norm or denorm, sets unfl
403 |	a0 = points to operand to be normalized
426 	bgts	end_mk		|   fpte15/ete15 already set to 0
427 	bsetb	#4,L_SCR1(%a6)	|else set fpte15/ete15 to 1
437 	bsetb	#sign_bit,LOCAL_EX(%a0) |convert back to IEEE format
460 	orb	#norm_tag,L_SCR1(%a6) |set tag to norm
463 	orb	#dnrm_tag,L_SCR1(%a6) |set tag to denorm
473 	orb	#norm_tag,L_SCR1(%a6) |set tag to norm
476 	orb	#dnrm_tag,L_SCR1(%a6) |set tag to denorm
480 |	Decimal to binary conversion
486 |	ETEMP(a6)	- points to packed decimal string in memory
488 |	fp0	- contains packed string converted to extended precision
524 	movel	#0x80000000,ETEMP(%a6) |write neg zero to etemp
567 	moveb	#nan_tag,STAG(%a6)	|set stag to NaN
573 	bsetb	#signan_bit,ETEMP_HI(%a6) |force snans to qnans
592 	movel	#0x80000000,ETEMP(%a6) |write neg zero to etemp
612 	andw	#0xfbff,%d0	|change the source specifier field to
614 	movew	%d0,CMDREG1B(%a6)	|write command word back to fsave stack
615 |				;we need to do this so the 040 will