282 lines
6.3 KiB
ArmAsm
282 lines
6.3 KiB
ArmAsm
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/* Copyright (C) 2008-2021 Free Software Foundation, Inc.
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Contributor: Joern Rennecke <joern.rennecke@embecosm.com>
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on behalf of Synopsys Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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/*
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- calculate 15..18 bit inverse using a table of approximating polynoms.
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precision is higher for polynoms used to evaluate input with larger
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value.
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- do one newton-raphson iteration step to double the precision,
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then multiply this with the divisor
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-> more time to decide if dividend is subnormal
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- the worst error propagation is on the side of the value range
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with the least initial defect, thus giving us about 30 bits precision.
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*/
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#include "arc-ieee-754.h"
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#if 0 /* DEBUG */
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.global __divsf3
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FUNC(__divsf3)
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.balign 4
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__divsf3:
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push_s blink
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push_s r1
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bl.d __divsf3_c
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push_s r0
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ld_s r1,[sp,4]
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st_s r0,[sp,4]
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bl.d __divsf3_asm
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pop_s r0
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pop_s r1
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pop_s blink
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cmp r0,r1
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#if 1
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bne abort
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jeq_s [blink]
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b abort
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#else
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bne abort
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j_s [blink]
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#endif
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ENDFUNC(__divsf3)
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#define __divsf3 __divsf3_asm
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#endif /* DEBUG */
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FUNC(__divsf3)
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.balign 4
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.L7f800000:
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.long 0x7f800000
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.Ldivtab:
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.long 0xfc0ffff0
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.long 0xf46ffefd
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.long 0xed1ffd2a
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.long 0xe627fa8e
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.long 0xdf7ff73b
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.long 0xd917f33b
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.long 0xd2f7eea3
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.long 0xcd1fe986
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.long 0xc77fe3e7
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.long 0xc21fdddb
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.long 0xbcefd760
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.long 0xb7f7d08c
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.long 0xb32fc960
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.long 0xae97c1ea
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.long 0xaa27ba26
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.long 0xa5e7b22e
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.long 0xa1cfa9fe
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.long 0x9ddfa1a0
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.long 0x9a0f990c
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.long 0x9667905d
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.long 0x92df878a
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.long 0x8f6f7e84
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.long 0x8c27757e
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.long 0x88f76c54
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.long 0x85df630c
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.long 0x82e759c5
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.long 0x8007506d
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.long 0x7d3f470a
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.long 0x7a8f3da2
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.long 0x77ef341e
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.long 0x756f2abe
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.long 0x72f7212d
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.long 0x709717ad
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.long 0x6e4f0e44
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.long 0x6c1704d6
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.long 0x69e6fb44
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.long 0x67cef1d7
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.long 0x65c6e872
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.long 0x63cedf18
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.long 0x61e6d5cd
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.long 0x6006cc6d
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.long 0x5e36c323
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.long 0x5c76b9f3
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.long 0x5abeb0b7
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.long 0x5916a79b
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.long 0x57769e77
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.long 0x55de954d
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.long 0x54568c4e
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.long 0x52d6834d
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.long 0x51667a7f
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.long 0x4ffe71b5
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.long 0x4e9e68f1
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.long 0x4d466035
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.long 0x4bf65784
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.long 0x4aae4ede
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.long 0x496e4646
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.long 0x48363dbd
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.long 0x47063547
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.long 0x45de2ce5
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.long 0x44be2498
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.long 0x43a61c64
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.long 0x4296144a
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.long 0x41860c0e
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.long 0x407e03ee
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__divsf3_support: /* This label makes debugger output saner. */
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.Ldenorm_fp1:
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bclr r6,r6,31
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norm.f r12,r6 ; flag for x/0 -> Inf check
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add r6,r6,r6
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rsub r5,r12,16
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ror r5,r1,r5
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asl r6,r6,r12
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bmsk r5,r5,5
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ld.as r5,[r3,r5]
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add r4,r6,r6
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; load latency
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MPYHU r7,r5,r4
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bic.ne.f 0, \
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0x60000000,r0 ; large number / denorm -> Inf
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beq_s .Linf_NaN
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asl r5,r5,13
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; wb stall
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; slow track
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sub r7,r5,r7
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MPYHU r8,r7,r6
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asl_s r12,r12,23
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and.f r2,r0,r9
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add r2,r2,r12
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asl r12,r0,8
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; wb stall
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bne.d .Lpast_denorm_fp1
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.Ldenorm_fp0:
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MPYHU r8,r8,r7
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bclr r12,r12,31
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norm.f r3,r12 ; flag for 0/x -> 0 check
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bic.ne.f 0,0x60000000,r1 ; denorm/large number -> 0
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beq_s .Lret0
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asl_s r12,r12,r3
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asl_s r3,r3,23
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add_s r12,r12,r12
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add r11,r11,r3
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b.d .Lpast_denorm_fp0
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mov_s r3,r12
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.balign 4
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.Linf_NaN:
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bclr.f 0,r0,31 ; 0/0 -> NaN
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xor_s r0,r0,r1
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bmsk r1,r0,30
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bic_s r0,r0,r1
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sub.eq r0,r0,1
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j_s.d [blink]
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or r0,r0,r9
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.Lret0:
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xor_s r0,r0,r1
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bmsk r1,r0,30
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j_s.d [blink]
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bic_s r0,r0,r1
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.Linf_nan_fp1:
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lsr_s r0,r0,31
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bmsk.f 0,r1,22
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asl_s r0,r0,31
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bne_s 0f ; inf/inf -> nan
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brne r2,r9,.Lsigned0 ; x/inf -> 0, but x/nan -> nan
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0: j_s.d [blink]
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mov r0,-1
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.Lsigned0:
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.Linf_nan_fp0:
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tst_s r1,r1
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j_s.d [blink]
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bxor.mi r0,r0,31
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.balign 4
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.global __divsf3
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/* N.B. the spacing between divtab and the sub3 to get its address must
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be a multiple of 8. */
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__divsf3:
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lsr r2,r1,17
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sub3 r3,pcl,55;(.-.Ldivtab) >> 3
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bmsk_s r2,r2,5
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ld.as r5,[r3,r2]
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asl r4,r1,9
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ld.as r9,[pcl,-114]; [pcl,(-((.-.L7f800000) >> 2))] ; 0x7f800000
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MPYHU r7,r5,r4
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asl r6,r1,8
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and.f r11,r1,r9
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bset r6,r6,31
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asl r5,r5,13
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; wb stall
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beq .Ldenorm_fp1
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sub r7,r5,r7
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MPYHU r8,r7,r6
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breq.d r11,r9,.Linf_nan_fp1
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and.f r2,r0,r9
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beq.d .Ldenorm_fp0
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asl r12,r0,8
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; wb stall
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breq r2,r9,.Linf_nan_fp0
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MPYHU r8,r8,r7
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.Lpast_denorm_fp1:
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bset r3,r12,31
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.Lpast_denorm_fp0:
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cmp_s r3,r6
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lsr.cc r3,r3,1
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add_s r2,r2, /* wait for immediate */ \
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/* wb stall */ \
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0x3f000000
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sub r7,r7,r8 ; u1.31 inverse, about 30 bit
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MPYHU r3,r3,r7
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sbc r2,r2,r11
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xor.f 0,r0,r1
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and r0,r2,r9
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bxor.mi r0,r0,31
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brhs r2, /* wb stall / wait for immediate */ \
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0x7f000000,.Linf_denorm
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.Lpast_denorm:
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add_s r3,r3,0x22 ; round to nearest or higher
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tst r3,0x3c ; check if rounding was unsafe
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lsr r3,r3,6
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jne.d [blink] ; return if rounding was safe.
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add_s r0,r0,r3
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/* work out exact rounding if we fall through here. */
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/* We know that the exact result cannot be represented in single
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precision. Find the mid-point between the two nearest
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representable values, multiply with the divisor, and check if
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the result is larger than the dividend. */
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add_s r3,r3,r3
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sub_s r3,r3,1
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mpyu r3,r3,r6
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asr.f 0,r0,1 ; for round-to-even in case this is a denorm
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rsub r2,r9,25
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asl_s r12,r12,r2
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; wb stall
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; slow track
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sub.f 0,r12,r3
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j_s.d [blink]
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sub.mi r0,r0,1
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/* For denormal results, it is possible that an exact result needs
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rounding, and thus the round-to-even rule has to come into play. */
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.Linf_denorm:
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brlo r2,0xc0000000,.Linf
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.Ldenorm:
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asr_s r2,r2,23
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bic r0,r0,r9
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neg r9,r2
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brlo.d r9,25,.Lpast_denorm
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lsr r3,r3,r9
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/* Fall through: return +- 0 */
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j_s [blink]
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.Linf:
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j_s.d [blink]
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or r0,r0,r9
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ENDFUNC(__divsf3)
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