obs-studio/libobs/graphics/half.h
2023-05-20 01:31:18 -07:00

103 lines
3.4 KiB
C

/******************************************************************************
Copyright (C) 2023 by Lain Bailey <lain@obsproject.com>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
******************************************************************************/
/******************************************************************************
The MIT License (MIT)
Copyright (c) 2011-2019 Microsoft Corp
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.
******************************************************************************/
#pragma once
#include "math-defs.h"
#ifdef __cplusplus
extern "C" {
#endif
struct half {
uint16_t u;
};
/* adapted from DirectXMath XMConvertFloatToHalf */
static struct half half_from_float(float f)
{
uint32_t Result;
uint32_t IValue;
memcpy(&IValue, &f, sizeof(IValue));
uint32_t Sign = (IValue & 0x80000000U) >> 16U;
IValue = IValue & 0x7FFFFFFFU; // Hack off the sign
if (IValue > 0x477FE000U) {
// The number is too large to be represented as a half. Saturate to infinity.
if (((IValue & 0x7F800000) == 0x7F800000) &&
((IValue & 0x7FFFFF) != 0)) {
Result = 0x7FFF; // NAN
} else {
Result = 0x7C00U; // INF
}
} else if (!IValue) {
Result = 0;
} else {
if (IValue < 0x38800000U) {
// The number is too small to be represented as a normalized half.
// Convert it to a denormalized value.
uint32_t Shift = 113U - (IValue >> 23U);
IValue = (0x800000U | (IValue & 0x7FFFFFU)) >> Shift;
} else {
// Rebias the exponent to represent the value as a normalized half.
IValue += 0xC8000000U;
}
Result = ((IValue + 0x0FFFU + ((IValue >> 13U) & 1U)) >> 13U) &
0x7FFFU;
}
struct half h;
h.u = (uint16_t)(Result | Sign);
return h;
}
static struct half half_from_bits(uint16_t u)
{
struct half h;
h.u = u;
return h;
}
#ifdef __cplusplus
}
#endif