1/* Copyright (C) 2008-2019 Free Software Foundation, Inc.
2   Contributor: Joern Rennecke <joern.rennecke@embecosm.com>
3		on behalf of Synopsys Inc.
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify it under
8the terms of the GNU General Public License as published by the Free
9Software Foundation; either version 3, or (at your option) any later
10version.
11
12GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13WARRANTY; without even the implied warranty of MERCHANTABILITY or
14FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
15for more details.
16
17Under Section 7 of GPL version 3, you are granted additional
18permissions described in the GCC Runtime Library Exception, version
193.1, as published by the Free Software Foundation.
20
21You should have received a copy of the GNU General Public License and
22a copy of the GCC Runtime Library Exception along with this program;
23see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
24<http://www.gnu.org/licenses/>.  */
25
26/*
27   - calculate 15..18 bit inverse using a table of approximating polynoms.
28     precision is higher for polynoms used to evaluate input with larger
29     value.
30   - do one newton-raphson iteration step to double the precision,
31     then multiply this with the divisor
32	-> more time to decide if dividend is subnormal
33     - the worst error propagation is on the side of the value range
34       with the least initial defect, thus giving us about 30 bits precision.
35 */
36#include "arc-ieee-754.h"
37
38#if 0 /* DEBUG */
39	.global __divsf3
40	FUNC(__divsf3)
41	.balign 4
42__divsf3:
43	push_s blink
44	push_s r1
45	bl.d __divsf3_c
46	push_s r0
47	ld_s r1,[sp,4]
48	st_s r0,[sp,4]
49	bl.d __divsf3_asm
50	pop_s r0
51	pop_s r1
52	pop_s blink
53	cmp r0,r1
54#if 1
55	bne abort
56	jeq_s [blink]
57	b abort
58#else
59	bne abort
60	j_s [blink]
61#endif
62	ENDFUNC(__divsf3)
63#define __divsf3 __divsf3_asm
64#endif /* DEBUG */
65
66	FUNC(__divsf3)
67	.balign 4
68.L7f800000:
69	.long 0x7f800000
70.Ldivtab:
71	.long 0xfc0ffff0
72	.long 0xf46ffefd
73	.long 0xed1ffd2a
74	.long 0xe627fa8e
75	.long 0xdf7ff73b
76	.long 0xd917f33b
77	.long 0xd2f7eea3
78	.long 0xcd1fe986
79	.long 0xc77fe3e7
80	.long 0xc21fdddb
81	.long 0xbcefd760
82	.long 0xb7f7d08c
83	.long 0xb32fc960
84	.long 0xae97c1ea
85	.long 0xaa27ba26
86	.long 0xa5e7b22e
87	.long 0xa1cfa9fe
88	.long 0x9ddfa1a0
89	.long 0x9a0f990c
90	.long 0x9667905d
91	.long 0x92df878a
92	.long 0x8f6f7e84
93	.long 0x8c27757e
94	.long 0x88f76c54
95	.long 0x85df630c
96	.long 0x82e759c5
97	.long 0x8007506d
98	.long 0x7d3f470a
99	.long 0x7a8f3da2
100	.long 0x77ef341e
101	.long 0x756f2abe
102	.long 0x72f7212d
103	.long 0x709717ad
104	.long 0x6e4f0e44
105	.long 0x6c1704d6
106	.long 0x69e6fb44
107	.long 0x67cef1d7
108	.long 0x65c6e872
109	.long 0x63cedf18
110	.long 0x61e6d5cd
111	.long 0x6006cc6d
112	.long 0x5e36c323
113	.long 0x5c76b9f3
114	.long 0x5abeb0b7
115	.long 0x5916a79b
116	.long 0x57769e77
117	.long 0x55de954d
118	.long 0x54568c4e
119	.long 0x52d6834d
120	.long 0x51667a7f
121	.long 0x4ffe71b5
122	.long 0x4e9e68f1
123	.long 0x4d466035
124	.long 0x4bf65784
125	.long 0x4aae4ede
126	.long 0x496e4646
127	.long 0x48363dbd
128	.long 0x47063547
129	.long 0x45de2ce5
130	.long 0x44be2498
131	.long 0x43a61c64
132	.long 0x4296144a
133	.long 0x41860c0e
134	.long 0x407e03ee
135__divsf3_support: /* This label makes debugger output saner.  */
136.Ldenorm_fp1:
137	bclr r6,r6,31
138	norm.f r12,r6 ; flag for x/0 -> Inf check
139	add r6,r6,r6
140	rsub r5,r12,16
141	ror r5,r1,r5
142	asl r6,r6,r12
143	bmsk r5,r5,5
144	ld.as r5,[r3,r5]
145	add r4,r6,r6
146	; load latency
147	MPYHU r7,r5,r4
148	bic.ne.f 0, \
149		0x60000000,r0 ; large number / denorm -> Inf
150	beq_s .Linf_NaN
151	asl r5,r5,13
152	; wb stall
153	; slow track
154	sub r7,r5,r7
155	MPYHU r8,r7,r6
156	asl_s r12,r12,23
157	and.f r2,r0,r9
158	add r2,r2,r12
159	asl r12,r0,8
160	; wb stall
161	bne.d .Lpast_denorm_fp1
162.Ldenorm_fp0:
163	MPYHU r8,r8,r7
164	bclr r12,r12,31
165	norm.f r3,r12 ; flag for 0/x -> 0 check
166	bic.ne.f 0,0x60000000,r1 ; denorm/large number -> 0
167	beq_s .Lret0
168	asl_s r12,r12,r3
169	asl_s r3,r3,23
170	add_s r12,r12,r12
171	add r11,r11,r3
172	b.d .Lpast_denorm_fp0
173	mov_s r3,r12
174	.balign 4
175.Linf_NaN:
176	bclr.f 0,r0,31 ; 0/0 -> NaN
177	xor_s r0,r0,r1
178	bmsk r1,r0,30
179	bic_s r0,r0,r1
180	sub.eq r0,r0,1
181	j_s.d [blink]
182	or r0,r0,r9
183.Lret0:
184	xor_s r0,r0,r1
185	bmsk r1,r0,30
186	j_s.d [blink]
187	bic_s r0,r0,r1
188.Linf_nan_fp1:
189	lsr_s r0,r0,31
190	bmsk.f 0,r1,22
191	asl_s r0,r0,31
192	bne_s 0f ; inf/inf -> nan
193	brne r2,r9,.Lsigned0 ; x/inf -> 0, but x/nan -> nan
1940:	j_s.d [blink]
195	mov r0,-1
196.Lsigned0:
197.Linf_nan_fp0:
198	tst_s r1,r1
199	j_s.d [blink]
200	bxor.mi r0,r0,31
201	.balign 4
202	.global __divsf3
203/* N.B. the spacing between divtab and the sub3 to get its address must
204   be a multiple of 8.  */
205__divsf3:
206	lsr r2,r1,17
207	sub3 r3,pcl,55;(.-.Ldivtab) >> 3
208	bmsk_s r2,r2,5
209	ld.as r5,[r3,r2]
210	asl r4,r1,9
211	ld.as r9,[pcl,-114]; [pcl,(-((.-.L7f800000) >> 2))] ; 0x7f800000
212	MPYHU r7,r5,r4
213	asl r6,r1,8
214	and.f r11,r1,r9
215	bset r6,r6,31
216	asl r5,r5,13
217	; wb stall
218	beq .Ldenorm_fp1
219	sub r7,r5,r7
220	MPYHU r8,r7,r6
221	breq.d r11,r9,.Linf_nan_fp1
222	and.f r2,r0,r9
223	beq.d .Ldenorm_fp0
224	asl r12,r0,8
225	; wb stall
226	breq r2,r9,.Linf_nan_fp0
227	MPYHU r8,r8,r7
228.Lpast_denorm_fp1:
229	bset r3,r12,31
230.Lpast_denorm_fp0:
231	cmp_s r3,r6
232	lsr.cc r3,r3,1
233	add_s r2,r2, /* wait for immediate */ \
234	/* wb stall */ \
235		0x3f000000
236	sub r7,r7,r8 ; u1.31 inverse, about 30 bit
237	MPYHU r3,r3,r7
238	sbc r2,r2,r11
239	xor.f 0,r0,r1
240	and r0,r2,r9
241	bxor.mi r0,r0,31
242	brhs r2, /* wb stall / wait for immediate */ \
243		0x7f000000,.Linf_denorm
244.Lpast_denorm:
245	add_s r3,r3,0x22 ; round to nearest or higher
246	tst r3,0x3c ; check if rounding was unsafe
247	lsr r3,r3,6
248	jne.d [blink] ; return if rounding was safe.
249	add_s r0,r0,r3
250        /* work out exact rounding if we fall through here.  */
251        /* We know that the exact result cannot be represented in single
252           precision.  Find the mid-point between the two nearest
253           representable values, multiply with the divisor, and check if
254           the result is larger than the dividend.  */
255        add_s r3,r3,r3
256        sub_s r3,r3,1
257        mpyu r3,r3,r6
258	asr.f 0,r0,1 ; for round-to-even in case this is a denorm
259	rsub r2,r9,25
260        asl_s r12,r12,r2
261	; wb stall
262	; slow track
263        sub.f 0,r12,r3
264        j_s.d [blink]
265        sub.mi r0,r0,1
266/* For denormal results, it is possible that an exact result needs
267   rounding, and thus the round-to-even rule has to come into play.  */
268.Linf_denorm:
269	brlo r2,0xc0000000,.Linf
270.Ldenorm:
271	asr_s r2,r2,23
272	bic r0,r0,r9
273	neg r9,r2
274	brlo.d r9,25,.Lpast_denorm
275	lsr r3,r3,r9
276	/* Fall through: return +- 0 */
277	j_s [blink]
278.Linf:
279	j_s.d [blink]
280	or r0,r0,r9
281	ENDFUNC(__divsf3)
282