1/* 2 * Copyright © 2014 Intel Corporation 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining a 5 * copy of this software and associated documentation files (the "Software"), 6 * to deal in the Software without restriction, including without limitation 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 8 * and/or sell copies of the Software, and to permit persons to whom the 9 * Software is furnished to do so, subject to the following conditions: 10 * 11 * The above copyright notice and this permission notice (including the next 12 * paragraph) shall be included in all copies or substantial portions of the 13 * Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 21 * IN THE SOFTWARE. 22 */ 23#include "brw_reg.h" 24 25union fu { 26 float f; 27 unsigned u; 28 struct { 29 unsigned mantissa:23; 30 unsigned exponent:8; 31 unsigned sign:1; 32 } s; 33}; 34 35int 36brw_float_to_vf(float f) 37{ 38 union fu fu = { .f = f }; 39 40 /* ±0.0f is special cased. */ 41 if (f == 0.0f) 42 return fu.s.sign << 7; 43 44 unsigned mantissa = fu.s.mantissa >> (23 - 4); 45 unsigned exponent = fu.s.exponent - (127 - 3); 46 unsigned vf = (fu.s.sign << 7) | (exponent << 4) | mantissa; 47 48 /* 0.125 would have had the same representation as 0.0, so reject it. */ 49 if ((vf & 0x7f) == 0) 50 return -1; 51 52 /* Make sure the mantissa fits in 4-bits and the exponent in 3-bits. */ 53 if (fu.u & 0x7ffff || exponent > 7) 54 return -1; 55 56 return vf; 57} 58 59float 60brw_vf_to_float(unsigned char vf) 61{ 62 union fu fu; 63 64 /* ±0.0f is special cased. */ 65 if (vf == 0x00 || vf == 0x80) { 66 fu.u = vf << 24; 67 return fu.f; 68 } 69 70 fu.s.sign = vf >> 7; 71 fu.s.exponent = ((vf & 0x70) >> 4) + (127 - 3); 72 fu.s.mantissa = (vf & 0xf) << (23 - 4); 73 74 return fu.f; 75} 76