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25|	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
26|	The copyright notice above does not evidence any
27|	actual or intended publication of such source code.
28
29X_SNAN:	|idnt    2,1 | Motorola 040 Floating Point Software Package
30
31	|section	8
32
33	.include "fpsp.h"
34
35	|xref	get_fline
36	|xref	mem_write
37	|xref	real_snan
38	|xref	real_inex
39	|xref	fpsp_done
40	|xref	reg_dest
41
42	.global	fpsp_snan
43fpsp_snan:
44	link		%a6,#-LOCAL_SIZE
45	fsave		-(%a7)
46	moveml		%d0-%d1/%a0-%a1,USER_DA(%a6)
47	fmovemx	%fp0-%fp3,USER_FP0(%a6)
48	fmoveml	%fpcr/%fpsr/%fpiar,USER_FPCR(%a6)
49
50|
51| Check if trap enabled
52|
53	btstb		#snan_bit,FPCR_ENABLE(%a6)
54	bnes		ena		|If enabled, then branch
55
56	bsrl		move_out	|else SNAN disabled
57|
58| It is possible to have an inex1 exception with the
59| snan.  If the inex enable bit is set in the FPCR, and either
60| inex2 or inex1 occurred, we must clean up and branch to the
61| real inex handler.
62|
63ck_inex:
64	moveb	FPCR_ENABLE(%a6),%d0
65	andb	FPSR_EXCEPT(%a6),%d0
66	andib	#0x3,%d0
67	beq	end_snan
68|
69| Inexact enabled and reported, and we must take an inexact exception.
70|
71take_inex:
72	moveb		#INEX_VEC,EXC_VEC+1(%a6)
73	moveml		USER_DA(%a6),%d0-%d1/%a0-%a1
74	fmovemx	USER_FP0(%a6),%fp0-%fp3
75	fmoveml	USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
76	frestore	(%a7)+
77	unlk		%a6
78	bral		real_inex
79|
80| SNAN is enabled.  Check if inst is move_out.
81| Make any corrections to the 040 output as necessary.
82|
83ena:
84	btstb		#5,CMDREG1B(%a6) |if set, inst is move out
85	beq		not_out
86
87	bsrl		move_out
88
89report_snan:
90	moveb		(%a7),VER_TMP(%a6)
91	cmpib		#VER_40,(%a7)	|test for orig unimp frame
92	bnes		ck_rev
93	moveql		#13,%d0		|need to zero 14 lwords
94	bras		rep_con
95ck_rev:
96	moveql		#11,%d0		|need to zero 12 lwords
97rep_con:
98	clrl		(%a7)
99loop1:
100	clrl		-(%a7)		|clear and dec a7
101	dbra		%d0,loop1
102	moveb		VER_TMP(%a6),(%a7) |format a busy frame
103	moveb		#BUSY_SIZE-4,1(%a7)
104	movel		USER_FPSR(%a6),FPSR_SHADOW(%a6)
105	orl		#sx_mask,E_BYTE(%a6)
106	moveml		USER_DA(%a6),%d0-%d1/%a0-%a1
107	fmovemx	USER_FP0(%a6),%fp0-%fp3
108	fmoveml	USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
109	frestore	(%a7)+
110	unlk		%a6
111	bral		real_snan
112|
113| Exit snan handler by expanding the unimp frame into a busy frame
114|
115end_snan:
116	bclrb		#E1,E_BYTE(%a6)
117
118	moveb		(%a7),VER_TMP(%a6)
119	cmpib		#VER_40,(%a7)	|test for orig unimp frame
120	bnes		ck_rev2
121	moveql		#13,%d0		|need to zero 14 lwords
122	bras		rep_con2
123ck_rev2:
124	moveql		#11,%d0		|need to zero 12 lwords
125rep_con2:
126	clrl		(%a7)
127loop2:
128	clrl		-(%a7)		|clear and dec a7
129	dbra		%d0,loop2
130	moveb		VER_TMP(%a6),(%a7) |format a busy frame
131	moveb		#BUSY_SIZE-4,1(%a7) |write busy size
132	movel		USER_FPSR(%a6),FPSR_SHADOW(%a6)
133	orl		#sx_mask,E_BYTE(%a6)
134	moveml		USER_DA(%a6),%d0-%d1/%a0-%a1
135	fmovemx	USER_FP0(%a6),%fp0-%fp3
136	fmoveml	USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
137	frestore	(%a7)+
138	unlk		%a6
139	bral		fpsp_done
140
141|
142| Move_out
143|
144move_out:
145	movel		EXC_EA(%a6),%a0	|get <ea> from exc frame
146
147	bfextu		CMDREG1B(%a6){#3:#3},%d0 |move rx field to d0{2:0}
148	cmpil		#0,%d0		|check for long
149	beqs		sto_long	|branch if move_out long
150
151	cmpil		#4,%d0		|check for word
152	beqs		sto_word	|branch if move_out word
153
154	cmpil		#6,%d0		|check for byte
155	beqs		sto_byte	|branch if move_out byte
156
157|
158| Not byte, word or long
159|
160	rts
161|
162| Get the 32 most significant bits of etemp mantissa
163|
164sto_long:
165	movel		ETEMP_HI(%a6),%d1
166	movel		#4,%d0		|load byte count
167|
168| Set signalling nan bit
169|
170	bsetl		#30,%d1
171|
172| Store to the users destination address
173|
174	tstl		%a0		|check if <ea> is 0
175	beqs		wrt_dn		|destination is a data register
176
177	movel		%d1,-(%a7)	|move the snan onto the stack
178	movel		%a0,%a1		|load dest addr into a1
179	movel		%a7,%a0		|load src addr of snan into a0
180	bsrl		mem_write	|write snan to user memory
181	movel		(%a7)+,%d1	|clear off stack
182	rts
183|
184| Get the 16 most significant bits of etemp mantissa
185|
186sto_word:
187	movel		ETEMP_HI(%a6),%d1
188	movel		#2,%d0		|load byte count
189|
190| Set signalling nan bit
191|
192	bsetl		#30,%d1
193|
194| Store to the users destination address
195|
196	tstl		%a0		|check if <ea> is 0
197	beqs		wrt_dn		|destination is a data register
198
199	movel		%d1,-(%a7)	|move the snan onto the stack
200	movel		%a0,%a1		|load dest addr into a1
201	movel		%a7,%a0		|point to low word
202	bsrl		mem_write	|write snan to user memory
203	movel		(%a7)+,%d1	|clear off stack
204	rts
205|
206| Get the 8 most significant bits of etemp mantissa
207|
208sto_byte:
209	movel		ETEMP_HI(%a6),%d1
210	movel		#1,%d0		|load byte count
211|
212| Set signalling nan bit
213|
214	bsetl		#30,%d1
215|
216| Store to the users destination address
217|
218	tstl		%a0		|check if <ea> is 0
219	beqs		wrt_dn		|destination is a data register
220	movel		%d1,-(%a7)	|move the snan onto the stack
221	movel		%a0,%a1		|load dest addr into a1
222	movel		%a7,%a0		|point to source byte
223	bsrl		mem_write	|write snan to user memory
224	movel		(%a7)+,%d1	|clear off stack
225	rts
226
227|
228|	wrt_dn --- write to a data register
229|
230|	We get here with D1 containing the data to write and D0 the
231|	number of bytes to write: 1=byte,2=word,4=long.
232|
233wrt_dn:
234	movel		%d1,L_SCR1(%a6)	|data
235	movel		%d0,-(%a7)	|size
236	bsrl		get_fline	|returns fline word in d0
237	movel		%d0,%d1
238	andil		#0x7,%d1		|d1 now holds register number
239	movel		(%sp)+,%d0	|get original size
240	cmpil		#4,%d0
241	beqs		wrt_long
242	cmpil		#2,%d0
243	bnes		wrt_byte
244wrt_word:
245	orl		#0x8,%d1
246	bral		reg_dest
247wrt_long:
248	orl		#0x10,%d1
249	bral		reg_dest
250wrt_byte:
251	bral		reg_dest
252|
253| Check if it is a src nan or dst nan
254|
255not_out:
256	movel		DTAG(%a6),%d0
257	bfextu		%d0{#0:#3},%d0	|isolate dtag in lsbs
258
259	cmpib		#3,%d0		|check for nan in destination
260	bnes		issrc		|destination nan has priority
261dst_nan:
262	btstb		#6,FPTEMP_HI(%a6) |check if dest nan is an snan
263	bnes		issrc		|no, so check source for snan
264	movew		FPTEMP_EX(%a6),%d0
265	bras		cont
266issrc:
267	movew		ETEMP_EX(%a6),%d0
268cont:
269	btstl		#15,%d0		|test for sign of snan
270	beqs		clr_neg
271	bsetb		#neg_bit,FPSR_CC(%a6)
272	bra		report_snan
273clr_neg:
274	bclrb		#neg_bit,FPSR_CC(%a6)
275	bra		report_snan
276
277	|end
278