1/* Half-float conversion routines. 2 3 Copyright (C) 2008-2015 Free Software Foundation, Inc. 4 Contributed by CodeSourcery. 5 6 This file is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License as published by the 8 Free Software Foundation; either version 3, or (at your option) any 9 later version. 10 11 This file is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 Under Section 7 of GPL version 3, you are granted additional 17 permissions described in the GCC Runtime Library Exception, version 18 3.1, as published by the Free Software Foundation. 19 20 You should have received a copy of the GNU General Public License and 21 a copy of the GCC Runtime Library Exception along with this program; 22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 <http://www.gnu.org/licenses/>. */ 24 25static inline unsigned short 26__gnu_f2h_internal(unsigned int a, int ieee) 27{ 28 unsigned short sign = (a >> 16) & 0x8000; 29 int aexp = (a >> 23) & 0xff; 30 unsigned int mantissa = a & 0x007fffff; 31 unsigned int mask; 32 unsigned int increment; 33 34 if (aexp == 0xff) 35 { 36 if (!ieee) 37 return sign; 38 return sign | 0x7e00 | (mantissa >> 13); 39 } 40 41 if (aexp == 0 && mantissa == 0) 42 return sign; 43 44 aexp -= 127; 45 46 /* Decimal point between bits 22 and 23. */ 47 mantissa |= 0x00800000; 48 if (aexp < -14) 49 { 50 mask = 0x00ffffff; 51 if (aexp >= -25) 52 mask >>= 25 + aexp; 53 } 54 else 55 mask = 0x00001fff; 56 57 /* Round. */ 58 if (mantissa & mask) 59 { 60 increment = (mask + 1) >> 1; 61 if ((mantissa & mask) == increment) 62 increment = mantissa & (increment << 1); 63 mantissa += increment; 64 if (mantissa >= 0x01000000) 65 { 66 mantissa >>= 1; 67 aexp++; 68 } 69 } 70 71 if (ieee) 72 { 73 if (aexp > 15) 74 return sign | 0x7c00; 75 } 76 else 77 { 78 if (aexp > 16) 79 return sign | 0x7fff; 80 } 81 82 if (aexp < -24) 83 return sign; 84 85 if (aexp < -14) 86 { 87 mantissa >>= -14 - aexp; 88 aexp = -14; 89 } 90 91 /* We leave the leading 1 in the mantissa, and subtract one 92 from the exponent bias to compensate. */ 93 return sign | (((aexp + 14) << 10) + (mantissa >> 13)); 94} 95 96unsigned int 97__gnu_h2f_internal(unsigned short a, int ieee) 98{ 99 unsigned int sign = (unsigned int)(a & 0x8000) << 16; 100 int aexp = (a >> 10) & 0x1f; 101 unsigned int mantissa = a & 0x3ff; 102 103 if (aexp == 0x1f && ieee) 104 return sign | 0x7f800000 | (mantissa << 13); 105 106 if (aexp == 0) 107 { 108 int shift; 109 110 if (mantissa == 0) 111 return sign; 112 113 shift = __builtin_clz(mantissa) - 21; 114 mantissa <<= shift; 115 aexp = -shift; 116 } 117 118 return sign | (((aexp + 0x70) << 23) + (mantissa << 13)); 119} 120 121unsigned short 122__gnu_f2h_ieee(unsigned int a) 123{ 124 return __gnu_f2h_internal(a, 1); 125} 126 127unsigned int 128__gnu_h2f_ieee(unsigned short a) 129{ 130 return __gnu_h2f_internal(a, 1); 131} 132 133unsigned short 134__gnu_f2h_alternative(unsigned int x) 135{ 136 return __gnu_f2h_internal(x, 0); 137} 138 139unsigned int 140__gnu_h2f_alternative(unsigned short a) 141{ 142 return __gnu_h2f_internal(a, 0); 143} 144