Thomas Gleixner | 9d5a634 | 2019-05-31 01:09:55 -0700 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | /* IEEE754 floating point arithmetic |
| 3 | * double precision: common utilities |
| 4 | */ |
| 5 | /* |
| 6 | * MIPS floating point support |
| 7 | * Copyright (C) 1994-2000 Algorithmics Ltd. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 8 | */ |
| 9 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 10 | #include "ieee754dp.h" |
| 11 | |
Ralf Baechle | 2209bcb | 2014-04-16 01:31:11 +0200 | [diff] [blame] | 12 | union ieee754dp ieee754dp_div(union ieee754dp x, union ieee754dp y) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 13 | { |
Ralf Baechle | 3f7cac4 | 2014-04-26 01:49:14 +0200 | [diff] [blame] | 14 | u64 rm; |
| 15 | int re; |
| 16 | u64 bm; |
| 17 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 18 | COMPXDP; |
| 19 | COMPYDP; |
| 20 | |
| 21 | EXPLODEXDP; |
| 22 | EXPLODEYDP; |
| 23 | |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 24 | ieee754_clearcx(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | |
| 26 | FLUSHXDP; |
| 27 | FLUSHYDP; |
| 28 | |
| 29 | switch (CLPAIR(xc, yc)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 30 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN): |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN): |
| 32 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN): |
| 33 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN): |
| 34 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN): |
Maciej W. Rozycki | d5afa7e | 2015-04-03 23:25:34 +0100 | [diff] [blame] | 35 | return ieee754dp_nanxcpt(y); |
| 36 | |
| 37 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN): |
| 38 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN): |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 39 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO): |
| 40 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM): |
| 41 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM): |
| 42 | case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF): |
Maciej W. Rozycki | d5afa7e | 2015-04-03 23:25:34 +0100 | [diff] [blame] | 43 | return ieee754dp_nanxcpt(x); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 44 | |
| 45 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN): |
| 46 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN): |
| 47 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN): |
| 48 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN): |
| 49 | return y; |
| 50 | |
| 51 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN): |
| 52 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO): |
| 53 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM): |
| 54 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM): |
| 55 | case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF): |
| 56 | return x; |
| 57 | |
| 58 | |
Ralf Baechle | 3f7cac4 | 2014-04-26 01:49:14 +0200 | [diff] [blame] | 59 | /* |
| 60 | * Infinity handling |
| 61 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 62 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF): |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 63 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
Ralf Baechle | 90efba3 | 2014-04-25 03:19:57 +0200 | [diff] [blame] | 64 | return ieee754dp_indef(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 65 | |
| 66 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF): |
| 67 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF): |
| 68 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF): |
| 69 | return ieee754dp_zero(xs ^ ys); |
| 70 | |
| 71 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO): |
| 72 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM): |
| 73 | case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM): |
| 74 | return ieee754dp_inf(xs ^ ys); |
| 75 | |
Ralf Baechle | 3f7cac4 | 2014-04-26 01:49:14 +0200 | [diff] [blame] | 76 | /* |
| 77 | * Zero handling |
| 78 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 79 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO): |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 80 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
Ralf Baechle | 90efba3 | 2014-04-25 03:19:57 +0200 | [diff] [blame] | 81 | return ieee754dp_indef(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 82 | |
| 83 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO): |
| 84 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO): |
Ralf Baechle | 9e8bad1 | 2014-04-19 00:36:32 +0200 | [diff] [blame] | 85 | ieee754_setcx(IEEE754_ZERO_DIVIDE); |
Ralf Baechle | 90efba3 | 2014-04-25 03:19:57 +0200 | [diff] [blame] | 86 | return ieee754dp_inf(xs ^ ys); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 87 | |
| 88 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM): |
| 89 | case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM): |
| 90 | return ieee754dp_zero(xs == ys ? 0 : 1); |
| 91 | |
| 92 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM): |
| 93 | DPDNORMX; |
Liangliang Huang | c9b0299 | 2020-05-04 16:51:29 +0800 | [diff] [blame] | 94 | fallthrough; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 95 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM): |
| 96 | DPDNORMY; |
| 97 | break; |
| 98 | |
| 99 | case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM): |
| 100 | DPDNORMX; |
| 101 | break; |
| 102 | |
| 103 | case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM): |
| 104 | break; |
| 105 | } |
| 106 | assert(xm & DP_HIDDEN_BIT); |
| 107 | assert(ym & DP_HIDDEN_BIT); |
| 108 | |
| 109 | /* provide rounding space */ |
| 110 | xm <<= 3; |
| 111 | ym <<= 3; |
| 112 | |
Ralf Baechle | 3f7cac4 | 2014-04-26 01:49:14 +0200 | [diff] [blame] | 113 | /* now the dirty work */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | |
Ralf Baechle | 3f7cac4 | 2014-04-26 01:49:14 +0200 | [diff] [blame] | 115 | rm = 0; |
| 116 | re = xe - ye; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 117 | |
Ralf Baechle | 3f7cac4 | 2014-04-26 01:49:14 +0200 | [diff] [blame] | 118 | for (bm = DP_MBIT(DP_FBITS + 2); bm; bm >>= 1) { |
| 119 | if (xm >= ym) { |
| 120 | xm -= ym; |
| 121 | rm |= bm; |
| 122 | if (xm == 0) |
| 123 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 124 | } |
Ralf Baechle | 3f7cac4 | 2014-04-26 01:49:14 +0200 | [diff] [blame] | 125 | xm <<= 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 126 | } |
Ralf Baechle | 3f7cac4 | 2014-04-26 01:49:14 +0200 | [diff] [blame] | 127 | |
| 128 | rm <<= 1; |
| 129 | if (xm) |
| 130 | rm |= 1; /* have remainder, set sticky */ |
| 131 | |
| 132 | assert(rm); |
| 133 | |
| 134 | /* |
| 135 | * Normalise rm to rounding precision ? |
| 136 | */ |
| 137 | while ((rm >> (DP_FBITS + 3)) == 0) { |
| 138 | rm <<= 1; |
| 139 | re--; |
| 140 | } |
| 141 | |
| 142 | return ieee754dp_format(xs == ys ? 0 : 1, re, rm); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 143 | } |