66adedbd78
This patch optimizes `IndexMask::from_bits` by making use of the fact that many bits can be processed at once and one does not have to look at every bit individual in many cases. Bits are stored as array of `BitInt` (aka `uint64_t`). So we can process at least 64 bits at a time. On some platforms we can also make use of SIMD and process up to 128 bits at once. This can significantly improve performance if all bits are set/unset. As a byproduct, this patch also optimizes `IndexMask::from_bools` which is now implemented in terms of `IndexMask::from_bits`. The conversion from bools to bits has been optimized significantly too by using SIMD intrinsics. Pull Request: https://projects.blender.org/blender/blender/pulls/126888
186 lines
3.5 KiB
C
186 lines
3.5 KiB
C
/* SPDX-FileCopyrightText: 2023 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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/** \file
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* \ingroup bli
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*/
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#ifndef __MATH_BITS_INLINE_C__
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#define __MATH_BITS_INLINE_C__
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#ifdef _MSC_VER
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# include <intrin.h>
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#endif
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#include "BLI_math_bits.h"
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MINLINE unsigned int bitscan_forward_uint(unsigned int a)
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{
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BLI_assert(a != 0);
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#ifdef _MSC_VER
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unsigned long ctz;
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_BitScanForward(&ctz, a);
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return ctz;
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#else
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return (unsigned int)__builtin_ctz(a);
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#endif
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}
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MINLINE unsigned int bitscan_forward_uint64(unsigned long long a)
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{
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BLI_assert(a != 0);
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#ifdef _MSC_VER
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unsigned long ctz;
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_BitScanForward64(&ctz, a);
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return ctz;
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#else
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return (unsigned int)__builtin_ctzll(a);
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#endif
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}
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MINLINE int bitscan_forward_i(int a)
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{
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return (int)bitscan_forward_uint((unsigned int)a);
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}
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MINLINE unsigned int bitscan_forward_clear_uint(unsigned int *a)
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{
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unsigned int i = bitscan_forward_uint(*a);
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*a &= (*a) - 1;
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return i;
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}
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MINLINE int bitscan_forward_clear_i(int *a)
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{
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return (int)bitscan_forward_clear_uint((unsigned int *)a);
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}
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MINLINE unsigned int bitscan_reverse_uint(unsigned int a)
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{
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BLI_assert(a != 0);
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#ifdef _MSC_VER
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unsigned long clz;
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_BitScanReverse(&clz, a);
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return 31 - clz;
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#else
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return (unsigned int)__builtin_clz(a);
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#endif
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}
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MINLINE unsigned int bitscan_reverse_uint64(unsigned long long a)
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{
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BLI_assert(a != 0);
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#ifdef _MSC_VER
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unsigned long clz;
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_BitScanReverse64(&clz, a);
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return 31 - clz;
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#else
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return (unsigned int)__builtin_clzll(a);
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#endif
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}
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MINLINE int bitscan_reverse_i(int a)
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{
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return (int)bitscan_reverse_uint((unsigned int)a);
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}
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MINLINE unsigned int bitscan_reverse_clear_uint(unsigned int *a)
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{
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unsigned int i = bitscan_reverse_uint(*a);
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*a &= ~(0x80000000 >> i);
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return i;
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}
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MINLINE int bitscan_reverse_clear_i(int *a)
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{
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return (int)bitscan_reverse_clear_uint((unsigned int *)a);
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}
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MINLINE unsigned int highest_order_bit_uint(unsigned int n)
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{
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if (n == 0) {
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return 0;
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}
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return 1 << (sizeof(unsigned int) * 8 - bitscan_reverse_uint(n));
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}
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MINLINE unsigned short highest_order_bit_s(unsigned short n)
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{
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n |= (unsigned short)(n >> 1);
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n |= (unsigned short)(n >> 2);
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n |= (unsigned short)(n >> 4);
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n |= (unsigned short)(n >> 8);
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return (unsigned short)(n - (n >> 1));
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}
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#if !(COMPILER_GCC || COMPILER_CLANG || COMPILER_MSVC)
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MINLINE int count_bits_i(unsigned int i)
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{
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/* variable-precision SWAR algorithm. */
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i = i - ((i >> 1) & 0x55555555);
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i = (i & 0x33333333) + ((i >> 2) & 0x33333333);
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return (((i + (i >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24;
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}
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MINLINE int count_bits_uint64(const uint64_t a)
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{
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return count_bits_i((uint32_t)a) + count_bits_i((uint32_t)(a >> 32));
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}
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#endif
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MINLINE int float_as_int(float f)
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{
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union {
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int i;
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float f;
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} u;
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u.f = f;
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return u.i;
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}
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MINLINE unsigned int float_as_uint(float f)
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{
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union {
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unsigned int i;
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float f;
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} u;
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u.f = f;
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return u.i;
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}
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MINLINE float int_as_float(int i)
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{
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union {
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int i;
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float f;
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} u;
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u.i = i;
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return u.f;
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}
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MINLINE float uint_as_float(unsigned int i)
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{
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union {
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unsigned int i;
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float f;
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} u;
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u.i = i;
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return u.f;
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}
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MINLINE float xor_fl(float x, int y)
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{
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return int_as_float(float_as_int(x) ^ y);
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}
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MINLINE float half_to_float(ushort h)
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{
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const uint sign = (h & 0x8000);
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const uint exponent = (h & 0x7c00) + 0x1C000;
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const uint mantissa = (h & 0x03FF);
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const uint x = (sign << 16) | (exponent << 13) | (mantissa << 13);
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return uint_as_float(x);
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}
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#endif /* __MATH_BITS_INLINE_C__ */
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