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https://github.com/kmc-jp/n64-emu.git
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78 lines
2.4 KiB
C
78 lines
2.4 KiB
C
/* Copyright (c) 2020 Themaister
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#ifndef CLAMPING_H_
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#define CLAMPING_H_
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#if SMALL_TYPES && 0
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// This path is buggy on RADV LLVM, disable for time being.
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i16x4 clamp_9bit_notrunc(i16x4 color)
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{
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// [-129, -256] should clamp to 0xff, subtracting by 0x80 will underflow back to positive numbers.
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// [-128, -1] should clamp to 0.
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color -= I16_C(0x80);
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// Sign-extend to 9-bit.
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color <<= I16_C(7);
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color >>= I16_C(7);
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color += I16_C(0x80);
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return clamp(color, i16x4(0), i16x4(0xff));
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}
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#else
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i16x4 clamp_9bit_notrunc(ivec4 color)
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{
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// [-129, -256] should clamp to 0xff, subtracting by 0x80 will underflow back to positive numbers.
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// [-128, -1] should clamp to 0.
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color -= 0x80;
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// Sign-extend to 9-bit.
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color = bitfieldExtract(color, 0, 9);
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color += 0x80;
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return i16x4(clamp(color, ivec4(0), ivec4(0xff)));
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}
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#endif
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u8x4 clamp_9bit(i16x4 color)
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{
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return u8x4(clamp_9bit_notrunc(color));
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}
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int clamp_9bit(int color)
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{
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return clamp(bitfieldExtract(color - 0x80, 0, 9) + 0x80, 0, 0xff);
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}
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// Returns 18-bit UNORM depth.
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int clamp_z(int z)
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{
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// Similar to RGBA, we reserve an extra bit to deal with overflow and underflow.
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z -= (1 << 17);
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z <<= (31 - 18);
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z >>= (31 - 18);
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z += (1 << 17);
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// [0x00000, 0x3ffff] maps to self.
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// [0x40000, 0x5ffff] maps to 0x3ffff.
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// [0x60000, 0x7ffff] maps to 0.
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return clamp(z, 0, 0x3ffff);
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}
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#endif
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