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/* Copyright (C) 2008-2021 Free Software Foundation, Inc.
Contributor: Joern Rennecke <>
on behalf of Synopsys Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<>. */
- calculate 15..18 bit inverse using a table of approximating polynoms.
precision is higher for polynoms used to evaluate input with larger
- do one newton-raphson iteration step to double the precision,
then multiply this with the divisor
-> more time to decide if dividend is subnormal
- the worst error propagation is on the side of the value range
with the least initial defect, thus giving us about 30 bits precision.
#include "arc-ieee-754.h"
#if 0 /* DEBUG */
.global __divsf3
.balign 4
push_s blink
push_s r1
bl.d __divsf3_c
push_s r0
ld_s r1,[sp,4]
st_s r0,[sp,4]
bl.d __divsf3_asm
pop_s r0
pop_s r1
pop_s blink
cmp r0,r1
#if 1
bne abort
jeq_s [blink]
b abort
bne abort
j_s [blink]
#define __divsf3 __divsf3_asm
#endif /* DEBUG */
.balign 4
.long 0x7f800000
.long 0xfc0ffff0
.long 0xf46ffefd
.long 0xed1ffd2a
.long 0xe627fa8e
.long 0xdf7ff73b
.long 0xd917f33b
.long 0xd2f7eea3
.long 0xcd1fe986
.long 0xc77fe3e7
.long 0xc21fdddb
.long 0xbcefd760
.long 0xb7f7d08c
.long 0xb32fc960
.long 0xae97c1ea
.long 0xaa27ba26
.long 0xa5e7b22e
.long 0xa1cfa9fe
.long 0x9ddfa1a0
.long 0x9a0f990c
.long 0x9667905d
.long 0x92df878a
.long 0x8f6f7e84
.long 0x8c27757e
.long 0x88f76c54
.long 0x85df630c
.long 0x82e759c5
.long 0x8007506d
.long 0x7d3f470a
.long 0x7a8f3da2
.long 0x77ef341e
.long 0x756f2abe
.long 0x72f7212d
.long 0x709717ad
.long 0x6e4f0e44
.long 0x6c1704d6
.long 0x69e6fb44
.long 0x67cef1d7
.long 0x65c6e872
.long 0x63cedf18
.long 0x61e6d5cd
.long 0x6006cc6d
.long 0x5e36c323
.long 0x5c76b9f3
.long 0x5abeb0b7
.long 0x5916a79b
.long 0x57769e77
.long 0x55de954d
.long 0x54568c4e
.long 0x52d6834d
.long 0x51667a7f
.long 0x4ffe71b5
.long 0x4e9e68f1
.long 0x4d466035
.long 0x4bf65784
.long 0x4aae4ede
.long 0x496e4646
.long 0x48363dbd
.long 0x47063547
.long 0x45de2ce5
.long 0x44be2498
.long 0x43a61c64
.long 0x4296144a
.long 0x41860c0e
.long 0x407e03ee
__divsf3_support: /* This label makes debugger output saner. */
bclr r6,r6,31
norm.f r12,r6 ; flag for x/0 -> Inf check
add r6,r6,r6
rsub r5,r12,16
ror r5,r1,r5
asl r6,r6,r12
bmsk r5,r5,5 r5,[r3,r5]
add r4,r6,r6
; load latency
MPYHU r7,r5,r4 0, \
0x60000000,r0 ; large number / denorm -> Inf
beq_s .Linf_NaN
asl r5,r5,13
; wb stall
; slow track
sub r7,r5,r7
MPYHU r8,r7,r6
asl_s r12,r12,23
and.f r2,r0,r9
add r2,r2,r12
asl r12,r0,8
; wb stall
bne.d .Lpast_denorm_fp1
MPYHU r8,r8,r7
bclr r12,r12,31
norm.f r3,r12 ; flag for 0/x -> 0 check 0,0x60000000,r1 ; denorm/large number -> 0
beq_s .Lret0
asl_s r12,r12,r3
asl_s r3,r3,23
add_s r12,r12,r12
add r11,r11,r3
b.d .Lpast_denorm_fp0
mov_s r3,r12
.balign 4
bclr.f 0,r0,31 ; 0/0 -> NaN
xor_s r0,r0,r1
bmsk r1,r0,30
bic_s r0,r0,r1
sub.eq r0,r0,1
j_s.d [blink]
or r0,r0,r9
xor_s r0,r0,r1
bmsk r1,r0,30
j_s.d [blink]
bic_s r0,r0,r1
lsr_s r0,r0,31
bmsk.f 0,r1,22
asl_s r0,r0,31
bne_s 0f ; inf/inf -> nan
brne r2,r9,.Lsigned0 ; x/inf -> 0, but x/nan -> nan
0: j_s.d [blink]
mov r0,-1
tst_s r1,r1
j_s.d [blink]
bxor.mi r0,r0,31
.balign 4
.global __divsf3
/* N.B. the spacing between divtab and the sub3 to get its address must
be a multiple of 8. */
lsr r2,r1,17
sub3 r3,pcl,55;(.-.Ldivtab) >> 3
bmsk_s r2,r2,5 r5,[r3,r2]
asl r4,r1,9 r9,[pcl,-114]; [pcl,(-((.-.L7f800000) >> 2))] ; 0x7f800000
MPYHU r7,r5,r4
asl r6,r1,8
and.f r11,r1,r9
bset r6,r6,31
asl r5,r5,13
; wb stall
beq .Ldenorm_fp1
sub r7,r5,r7
MPYHU r8,r7,r6
breq.d r11,r9,.Linf_nan_fp1
and.f r2,r0,r9
beq.d .Ldenorm_fp0
asl r12,r0,8
; wb stall
breq r2,r9,.Linf_nan_fp0
MPYHU r8,r8,r7
bset r3,r12,31
cmp_s r3,r6 r3,r3,1
add_s r2,r2, /* wait for immediate */ \
/* wb stall */ \
sub r7,r7,r8 ; u1.31 inverse, about 30 bit
MPYHU r3,r3,r7
sbc r2,r2,r11
xor.f 0,r0,r1
and r0,r2,r9
bxor.mi r0,r0,31
brhs r2, /* wb stall / wait for immediate */ \
add_s r3,r3,0x22 ; round to nearest or higher
tst r3,0x3c ; check if rounding was unsafe
lsr r3,r3,6
jne.d [blink] ; return if rounding was safe.
add_s r0,r0,r3
/* work out exact rounding if we fall through here. */
/* We know that the exact result cannot be represented in single
precision. Find the mid-point between the two nearest
representable values, multiply with the divisor, and check if
the result is larger than the dividend. */
add_s r3,r3,r3
sub_s r3,r3,1
mpyu r3,r3,r6
asr.f 0,r0,1 ; for round-to-even in case this is a denorm
rsub r2,r9,25
asl_s r12,r12,r2
; wb stall
; slow track
sub.f 0,r12,r3
j_s.d [blink]
sub.mi r0,r0,1
/* For denormal results, it is possible that an exact result needs
rounding, and thus the round-to-even rule has to come into play. */
brlo r2,0xc0000000,.Linf
asr_s r2,r2,23
bic r0,r0,r9
neg r9,r2
brlo.d r9,25,.Lpast_denorm
lsr r3,r3,r9
/* Fall through: return +- 0 */
j_s [blink]
j_s.d [blink]
or r0,r0,r9