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/*
*
* Copyright (C) 2015 Valve 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 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.
*
* Author: Chia-I Wu <olvaffe@gmail.com>
*
*/
#include "icd-utils.h"
/* stolen from Mesa */
uint16_t u_float_to_half(float f)
{
union fi {
float f;
uint32_t ui;
};
uint32_t sign_mask = 0x80000000;
uint32_t round_mask = ~0xfff;
uint32_t f32inf = 0xff << 23;
uint32_t f16inf = 0x1f << 23;
uint32_t sign;
union fi magic;
union fi f32;
uint16_t f16;
magic.ui = 0xf << 23;
f32.f = f;
/* Sign */
sign = f32.ui & sign_mask;
f32.ui ^= sign;
if (f32.ui == f32inf) {
/* Inf */
f16 = 0x7c00;
} else if (f32.ui > f32inf) {
/* NaN */
f16 = 0x7e00;
} else {
/* Number */
f32.ui &= round_mask;
f32.f *= magic.f;
f32.ui -= round_mask;
/*
* Clamp to max finite value if overflowed.
* OpenGL has completely undefined rounding behavior for float to
* half-float conversions, and this matches what is mandated for float
* to fp11/fp10, which recommend round-to-nearest-finite too.
* (d3d10 is deeply unhappy about flushing such values to infinity, and
* while it also mandates round-to-zero it doesn't care nearly as much
* about that.)
*/
if (f32.ui > f16inf)
f32.ui = f16inf - 1;
f16 = f32.ui >> 13;
}
/* Sign */
f16 |= sign >> 16;
return f16;
}
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