/arch/m68k/fpsp040/x_snan.S

  1|
  2|	x_snan.sa 3.3 7/1/91
  3|
  4| fpsp_snan --- FPSP handler for signalling NAN exception
  5|
  6| SNAN for float -> integer conversions (integer conversion of
  7| an SNAN) is a non-maskable run-time exception.
  8|
  9| For trap disabled the 040 does the following:
 10| If the dest data format is s, d, or x, then the SNAN bit in the NAN
 11| is set to one and the resulting non-signaling NAN (truncated if
 12| necessary) is transferred to the dest.  If the dest format is b, w,
 13| or l, then garbage is written to the dest (actually the upper 32 bits
 14| of the mantissa are sent to the integer unit).
 15|
 16| For trap enabled the 040 does the following:
 17| If the inst is move_out, then the results are the same as for trap
 18| disabled with the exception posted.  If the instruction is not move_
 19| out, the dest. is not modified, and the exception is posted.
 20|
 21
 22|		Copyright (C) Motorola, Inc. 1990
 23|			All Rights Reserved
 24|
 25|       For details on the license for this file, please see the
 26|       file, README, in this same directory.
 27
 28X_SNAN:	|idnt    2,1 | Motorola 040 Floating Point Software Package
 29
 30	|section	8
 31
 32#include "fpsp.h"
 33
 34	|xref	get_fline
 35	|xref	mem_write
 36	|xref	real_snan
 37	|xref	real_inex
 38	|xref	fpsp_done
 39	|xref	reg_dest
 40
 41	.global	fpsp_snan
 42fpsp_snan:
 43	link		%a6,#-LOCAL_SIZE
 44	fsave		-(%a7)
 45	moveml		%d0-%d1/%a0-%a1,USER_DA(%a6)
 46	fmovemx	%fp0-%fp3,USER_FP0(%a6)
 47	fmoveml	%fpcr/%fpsr/%fpiar,USER_FPCR(%a6)
 48
 49|
 50| Check if trap enabled
 51|
 52	btstb		#snan_bit,FPCR_ENABLE(%a6)
 53	bnes		ena		|If enabled, then branch
 54
 55	bsrl		move_out	|else SNAN disabled
 56|
 57| It is possible to have an inex1 exception with the
 58| snan.  If the inex enable bit is set in the FPCR, and either
 59| inex2 or inex1 occurred, we must clean up and branch to the
 60| real inex handler.
 61|
 62ck_inex:
 63	moveb	FPCR_ENABLE(%a6),%d0
 64	andb	FPSR_EXCEPT(%a6),%d0
 65	andib	#0x3,%d0
 66	beq	end_snan
 67|
 68| Inexact enabled and reported, and we must take an inexact exception.
 69|
 70take_inex:
 71	moveb		#INEX_VEC,EXC_VEC+1(%a6)
 72	moveml		USER_DA(%a6),%d0-%d1/%a0-%a1
 73	fmovemx	USER_FP0(%a6),%fp0-%fp3
 74	fmoveml	USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
 75	frestore	(%a7)+
 76	unlk		%a6
 77	bral		real_inex
 78|
 79| SNAN is enabled.  Check if inst is move_out.
 80| Make any corrections to the 040 output as necessary.
 81|
 82ena:
 83	btstb		#5,CMDREG1B(%a6) |if set, inst is move out
 84	beq		not_out
 85
 86	bsrl		move_out
 87
 88report_snan:
 89	moveb		(%a7),VER_TMP(%a6)
 90	cmpib		#VER_40,(%a7)	|test for orig unimp frame
 91	bnes		ck_rev
 92	moveql		#13,%d0		|need to zero 14 lwords
 93	bras		rep_con
 94ck_rev:
 95	moveql		#11,%d0		|need to zero 12 lwords
 96rep_con:
 97	clrl		(%a7)
 98loop1:
 99	clrl		-(%a7)		|clear and dec a7
100	dbra		%d0,loop1
101	moveb		VER_TMP(%a6),(%a7) |format a busy frame
102	moveb		#BUSY_SIZE-4,1(%a7)
103	movel		USER_FPSR(%a6),FPSR_SHADOW(%a6)
104	orl		#sx_mask,E_BYTE(%a6)
105	moveml		USER_DA(%a6),%d0-%d1/%a0-%a1
106	fmovemx	USER_FP0(%a6),%fp0-%fp3
107	fmoveml	USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
108	frestore	(%a7)+
109	unlk		%a6
110	bral		real_snan
111|
112| Exit snan handler by expanding the unimp frame into a busy frame
113|
114end_snan:
115	bclrb		#E1,E_BYTE(%a6)
116
117	moveb		(%a7),VER_TMP(%a6)
118	cmpib		#VER_40,(%a7)	|test for orig unimp frame
119	bnes		ck_rev2
120	moveql		#13,%d0		|need to zero 14 lwords
121	bras		rep_con2
122ck_rev2:
123	moveql		#11,%d0		|need to zero 12 lwords
124rep_con2:
125	clrl		(%a7)
126loop2:
127	clrl		-(%a7)		|clear and dec a7
128	dbra		%d0,loop2
129	moveb		VER_TMP(%a6),(%a7) |format a busy frame
130	moveb		#BUSY_SIZE-4,1(%a7) |write busy size
131	movel		USER_FPSR(%a6),FPSR_SHADOW(%a6)
132	orl		#sx_mask,E_BYTE(%a6)
133	moveml		USER_DA(%a6),%d0-%d1/%a0-%a1
134	fmovemx	USER_FP0(%a6),%fp0-%fp3
135	fmoveml	USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
136	frestore	(%a7)+
137	unlk		%a6
138	bral		fpsp_done
139
140|
141| Move_out
142|
143move_out:
144	movel		EXC_EA(%a6),%a0	|get <ea> from exc frame
145
146	bfextu		CMDREG1B(%a6){#3:#3},%d0 |move rx field to d0{2:0}
147	cmpil		#0,%d0		|check for long
148	beqs		sto_long	|branch if move_out long
149
150	cmpil		#4,%d0		|check for word
151	beqs		sto_word	|branch if move_out word
152
153	cmpil		#6,%d0		|check for byte
154	beqs		sto_byte	|branch if move_out byte
155
156|
157| Not byte, word or long
158|
159	rts
160|
161| Get the 32 most significant bits of etemp mantissa
162|
163sto_long:
164	movel		ETEMP_HI(%a6),%d1
165	movel		#4,%d0		|load byte count
166|
167| Set signalling nan bit
168|
169	bsetl		#30,%d1
170|
171| Store to the users destination address
172|
173	tstl		%a0		|check if <ea> is 0
174	beqs		wrt_dn		|destination is a data register
175
176	movel		%d1,-(%a7)	|move the snan onto the stack
177	movel		%a0,%a1		|load dest addr into a1
178	movel		%a7,%a0		|load src addr of snan into a0
179	bsrl		mem_write	|write snan to user memory
180	movel		(%a7)+,%d1	|clear off stack
181	rts
182|
183| Get the 16 most significant bits of etemp mantissa
184|
185sto_word:
186	movel		ETEMP_HI(%a6),%d1
187	movel		#2,%d0		|load byte count
188|
189| Set signalling nan bit
190|
191	bsetl		#30,%d1
192|
193| Store to the users destination address
194|
195	tstl		%a0		|check if <ea> is 0
196	beqs		wrt_dn		|destination is a data register
197
198	movel		%d1,-(%a7)	|move the snan onto the stack
199	movel		%a0,%a1		|load dest addr into a1
200	movel		%a7,%a0		|point to low word
201	bsrl		mem_write	|write snan to user memory
202	movel		(%a7)+,%d1	|clear off stack
203	rts
204|
205| Get the 8 most significant bits of etemp mantissa
206|
207sto_byte:
208	movel		ETEMP_HI(%a6),%d1
209	movel		#1,%d0		|load byte count
210|
211| Set signalling nan bit
212|
213	bsetl		#30,%d1
214|
215| Store to the users destination address
216|
217	tstl		%a0		|check if <ea> is 0
218	beqs		wrt_dn		|destination is a data register
219	movel		%d1,-(%a7)	|move the snan onto the stack
220	movel		%a0,%a1		|load dest addr into a1
221	movel		%a7,%a0		|point to source byte
222	bsrl		mem_write	|write snan to user memory
223	movel		(%a7)+,%d1	|clear off stack
224	rts
225
226|
227|	wrt_dn --- write to a data register
228|
229|	We get here with D1 containing the data to write and D0 the
230|	number of bytes to write: 1=byte,2=word,4=long.
231|
232wrt_dn:
233	movel		%d1,L_SCR1(%a6)	|data
234	movel		%d0,-(%a7)	|size
235	bsrl		get_fline	|returns fline word in d0
236	movel		%d0,%d1
237	andil		#0x7,%d1		|d1 now holds register number
238	movel		(%sp)+,%d0	|get original size
239	cmpil		#4,%d0
240	beqs		wrt_long
241	cmpil		#2,%d0
242	bnes		wrt_byte
243wrt_word:
244	orl		#0x8,%d1
245	bral		reg_dest
246wrt_long:
247	orl		#0x10,%d1
248	bral		reg_dest
249wrt_byte:
250	bral		reg_dest
251|
252| Check if it is a src nan or dst nan
253|
254not_out:
255	movel		DTAG(%a6),%d0
256	bfextu		%d0{#0:#3},%d0	|isolate dtag in lsbs
257
258	cmpib		#3,%d0		|check for nan in destination
259	bnes		issrc		|destination nan has priority
260dst_nan:
261	btstb		#6,FPTEMP_HI(%a6) |check if dest nan is an snan
262	bnes		issrc		|no, so check source for snan
263	movew		FPTEMP_EX(%a6),%d0
264	bras		cont
265issrc:
266	movew		ETEMP_EX(%a6),%d0
267cont:
268	btstl		#15,%d0		|test for sign of snan
269	beqs		clr_neg
270	bsetb		#neg_bit,FPSR_CC(%a6)
271	bra		report_snan
272clr_neg:
273	bclrb		#neg_bit,FPSR_CC(%a6)
274	bra		report_snan
275
276	|end