libgcc/config/arc/ieee-754/arc600-dsp/divsf3.S

   1 /* Copyright (C) 2008-2016 Free Software Foundation, Inc.
   2    Contributor: Joern Rennecke <joern.rennecke@embecosm.com>
   3                 on behalf of Synopsys Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see 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 #define mlo acc2
  38 #define mhi acc1
  39 #define mul64(b,c) mullw 0,b,c` machlw 0,b,c
  40 #define mulu64(b,c) mululw 0,b,c` machulw 0,b,c
  41
  42 #if 0 /* DEBUG */
  43         .global __divsf3
  44         FUNC(__divsf3)
  45         .balign 4
  46 __divsf3:
  47         push_s blink
  48         push_s r1
  49         bl.d __divsf3_c
  50         push_s r0
  51         ld_s r1,[sp,4]
  52         st_s r0,[sp,4]
  53         bl.d __divsf3_asm
  54         pop_s r0
  55         pop_s r1
  56         pop_s blink
  57         cmp r0,r1
  58 #if 1
  59         bne abort
  60         jeq_s [blink]
  61         b abort
  62 #else
  63         bne abort
  64         j_s [blink]
  65 #endif
  66         ENDFUNC(__divsf3)
  67 #define __divsf3 __divsf3_asm
  68 #endif /* DEBUG */
  69
  70         FUNC(__divsf3)
  71         .balign 4
  72 .Ldivtab:
  73         .long 0xfc0ffff0
  74         .long 0xf46ffefd
  75         .long 0xed1ffd2a
  76         .long 0xe627fa8e
  77         .long 0xdf7ff73b
  78         .long 0xd917f33b
  79         .long 0xd2f7eea3
  80         .long 0xcd1fe986
  81         .long 0xc77fe3e7
  82         .long 0xc21fdddb
  83         .long 0xbcefd760
  84         .long 0xb7f7d08c
  85         .long 0xb32fc960
  86         .long 0xae97c1ea
  87         .long 0xaa27ba26
  88         .long 0xa5e7b22e
  89         .long 0xa1cfa9fe
  90         .long 0x9ddfa1a0
  91         .long 0x9a0f990c
  92         .long 0x9667905d
  93         .long 0x92df878a
  94         .long 0x8f6f7e84
  95         .long 0x8c27757e
  96         .long 0x88f76c54
  97         .long 0x85df630c
  98         .long 0x82e759c5
  99         .long 0x8007506d
 100         .long 0x7d3f470a
 101         .long 0x7a8f3da2
 102         .long 0x77ef341e
 103         .long 0x756f2abe
 104         .long 0x72f7212d
 105         .long 0x709717ad
 106         .long 0x6e4f0e44
 107         .long 0x6c1704d6
 108         .long 0x69e6fb44
 109         .long 0x67cef1d7
 110         .long 0x65c6e872
 111         .long 0x63cedf18
 112         .long 0x61e6d5cd
 113         .long 0x6006cc6d
 114         .long 0x5e36c323
 115         .long 0x5c76b9f3
 116         .long 0x5abeb0b7
 117         .long 0x5916a79b
 118         .long 0x57769e77
 119         .long 0x55de954d
 120         .long 0x54568c4e
 121         .long 0x52d6834d
 122         .long 0x51667a7f
 123         .long 0x4ffe71b5
 124         .long 0x4e9e68f1
 125         .long 0x4d466035
 126         .long 0x4bf65784
 127         .long 0x4aae4ede
 128         .long 0x496e4646
 129         .long 0x48363dbd
 130         .long 0x47063547
 131         .long 0x45de2ce5
 132         .long 0x44be2498
 133         .long 0x43a61c64
 134         .long 0x4296144a
 135         .long 0x41860c0e
 136         .long 0x407e03ee
 137 .L7f800000:
 138         .long 0x7f800000
 139         .balign 4
 140         .global __divsf3_support
 141 __divsf3_support:
 142 .Linf_NaN:
 143         bclr.f 0,r0,31 ; 0/0 -> NaN
 144         xor_s r0,r0,r1
 145         bmsk r1,r0,30
 146         bic_s r0,r0,r1
 147         sub.eq r0,r0,1
 148         j_s.d [blink]
 149         or r0,r0,r9
 150 .Lret0:
 151         xor_s r0,r0,r1
 152         bmsk r1,r0,30
 153         j_s.d [blink]
 154         bic_s r0,r0,r1
 155 /* N.B. the spacing between divtab and the sub3 to get its address must
 156    be a multiple of 8.  */
 157 __divsf3:
 158         ld.as r9,[pcl,-9]; [pcl,(-((.-.L7f800000) >> 2))] ; 0x7f800000
 159         sub3 r3,pcl,37;(.-.Ldivtab) >> 3
 160         lsr r2,r1,17
 161         and.f r11,r1,r9
 162         bmsk r5,r2,5
 163         beq.d .Ldenorm_fp1
 164         asl r6,r1,8
 165         and.f r2,r0,r9
 166         ld.as r5,[r3,r5]
 167         asl r4,r1,9
 168         bset r6,r6,31
 169         breq.d r11,r9,.Linf_nan_fp1
 170 .Lpast_denorm_fp1:
 171         mululw 0,r5,r4
 172         machulw r8,r5,r4
 173         breq.d r2,r9,.Linf_nan_fp0
 174         asl r5,r5,13
 175         sub r7,r5,r8
 176         mululw 0,r7,r6
 177         machulw r8,r7,r6
 178         beq.d .Ldenorm_fp0
 179         asl r12,r0,8
 180         mulu64 (r8,r7)
 181         bset r3,r12,31
 182 .Lpast_denorm_fp0:
 183         cmp_s r3,r6
 184         lsr.cc r3,r3,1
 185         add_s r2,r2, /* wait for immediate */ \
 186                 0x3f000000
 187         sub r7,r7,mhi ; u1.31 inverse, about 30 bit
 188         mulu64 (r3,r7)
 189         sbc r2,r2,r11
 190         xor.f 0,r0,r1
 191         and r0,r2,r9
 192         bclr r3,r9,23 ; 0x7f000000
 193         brhs.d r2,r3,.Linf_denorm
 194         bxor.mi r0,r0,31
 195 .Lpast_denorm:
 196         add r3,mhi,0x22 ; round to nearest or higher
 197         tst r3,0x3c ; check if rounding was unsafe
 198         lsr r3,r3,6
 199         jne.d [blink] ; return if rounding was safe.
 200         add_s r0,r0,r3
 201         /* work out exact rounding if we fall through here.  */
 202         /* We know that the exact result cannot be represented in single
 203            precision.  Find the mid-point between the two nearest
 204            representable values, multiply with the divisor, and check if
 205            the result is larger than the dividend.  */
 206         add_s r3,r3,r3
 207         sub_s r3,r3,1
 208         mulu64 (r3,r6)
 209         asr.f 0,r0,1 ; for round-to-even in case this is a denorm
 210         rsub r2,r9,25
 211         asl_s r12,r12,r2
 212         sub.f 0,r12,mlo
 213         j_s.d [blink]
 214         sub.mi r0,r0,1
 215 .Linf_nan_fp1:
 216         lsr_s r0,r0,31
 217         bmsk.f 0,r1,22
 218         asl_s r0,r0,31
 219         bne_s 0f ; inf/inf -> nan
 220         brne r2,r9,.Lsigned0 ; x/inf -> 0, but x/nan -> nan
 221 0:      j_s.d [blink]
 222         mov r0,-1
 223 .Lsigned0:
 224 .Linf_nan_fp0:
 225         tst_s r1,r1
 226         j_s.d [blink]
 227         bxor.mi r0,r0,31
 228         .balign 4
 229         .global __divsf3
 230 /* For denormal results, it is possible that an exact result needs
 231    rounding, and thus the round-to-even rule has to come into play.  */
 232 .Linf_denorm:
 233         brlo r2,0xc0000000,.Linf
 234 .Ldenorm:
 235         asr_s r2,r2,23
 236         bic r0,r0,r9
 237         neg r9,r2
 238         brlo.d r9,25,.Lpast_denorm
 239         lsr r3,mlo,r9
 240         /* Fall through: return +- 0 */
 241         j_s [blink]
 242 .Linf:
 243         j_s.d [blink]
 244         or r0,r0,r9
 245         .balign 4
 246 .Ldenorm_fp1:
 247         norm.f r12,r6 ; flag for x/0 -> Inf check
 248         add r6,r6,r6
 249         rsub r5,r12,16
 250         ror r5,r1,r5
 251         bmsk r5,r5,5
 252         bic.ne.f 0, \
 253                 0x60000000,r0 ; large number / denorm -> Inf
 254         ld.as r5,[r3,r5]
 255         asl r6,r6,r12
 256         beq.d .Linf_NaN
 257         and.f r2,r0,r9
 258         add r4,r6,r6
 259         asl_s r12,r12,23
 260         bne.d .Lpast_denorm_fp1
 261         add_s r2,r2,r12
 262 .Ldenorm_fp0:
 263         mulu64 (r8,r7)
 264         bclr r12,r12,31
 265         norm.f r3,r12 ; flag for 0/x -> 0 check
 266         bic.ne.f 0,0x60000000,r1 ; denorm/large number -> 0
 267         beq_s .Lret0
 268         asl_s r12,r12,r3
 269         asl_s r3,r3,23
 270         add_s r12,r12,r12
 271         add r11,r11,r3
 272         b.d .Lpast_denorm_fp0
 273         mov_s r3,r12
 274         ENDFUNC(__divsf3)