| 0,0 → 1,75 |
|---|
| /* |
| * Copyright © 2014 Intel Corporation |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a |
| * copy of this software and associated documentation files (the "Software"), |
| * to deal in the Software without restriction, including without limitation |
| * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
| * and/or sell copies of the Software, and to permit persons to whom the |
| * Software is furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice (including the next |
| * paragraph) shall be included in all copies or substantial portions of the |
| * Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
| * IN THE SOFTWARE. |
| */ |
| #include "brw_reg.h" |
| |
| union fu { |
| float f; |
| unsigned u; |
| struct { |
| unsigned mantissa:23; |
| unsigned exponent:8; |
| unsigned sign:1; |
| } s; |
| }; |
| |
| int |
| brw_float_to_vf(float f) |
| { |
| union fu fu = { .f = f }; |
| |
| /* ±0.0f is special cased. */ |
| if (f == 0.0f) |
| return fu.s.sign << 7; |
| |
| unsigned mantissa = fu.s.mantissa >> (23 - 4); |
| unsigned exponent = fu.s.exponent - (127 - 3); |
| unsigned vf = (fu.s.sign << 7) | (exponent << 4) | mantissa; |
| |
| /* 0.125 would have had the same representation as 0.0, so reject it. */ |
| if ((vf & 0x7f) == 0) |
| return -1; |
| |
| /* Make sure the mantissa fits in 4-bits and the exponent in 3-bits. */ |
| if (fu.u & 0x7ffff || exponent > 7) |
| return -1; |
| |
| return vf; |
| } |
| |
| float |
| brw_vf_to_float(unsigned char vf) |
| { |
| union fu fu; |
| |
| /* ±0.0f is special cased. */ |
| if (vf == 0x00 || vf == 0x80) { |
| fu.u = vf << 24; |
| return fu.f; |
| } |
| |
| fu.s.sign = vf >> 7; |
| fu.s.exponent = ((vf & 0x70) >> 4) + (127 - 3); |
| fu.s.mantissa = (vf & 0xf) << (23 - 4); |
| |
| return fu.f; |
| } |