266 lines
5.7 KiB
Text
266 lines
5.7 KiB
Text
/**
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* PANDA 3D SOFTWARE
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* Copyright (c) Carnegie Mellon University. All rights reserved.
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*
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* All use of this software is subject to the terms of the revised BSD
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* license. You should have received a copy of this license along
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* with this source code in a file named "LICENSE."
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*
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* @file pbitops.I
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* @author drose
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* @date 2008-05-10
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*/
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/**
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* Returns the number of 1 bits in the indicated word.
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*/
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INLINE int
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count_bits_in_word(uint16_t x) {
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return (int)num_bits_on[x];
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}
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/**
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* Returns the number of 1 bits in the indicated word.
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*/
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INLINE int
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count_bits_in_word(uint32_t x) {
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#if defined(__GNUC__) && defined(__POPCNT__)
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return __builtin_popcount((unsigned int) x);
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#else
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return (int)num_bits_on[x & 0xffff] + (int)num_bits_on[(x >> 16) & 0xffff];
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#endif
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}
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/**
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* Returns the number of 1 bits in the indicated word.
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*/
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INLINE int
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count_bits_in_word(uint64_t x) {
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#if defined(__GNUC__) && defined(__POPCNT__)
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return __builtin_popcountll((unsigned long long) x);
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#else
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return count_bits_in_word((uint32_t)x) + count_bits_in_word((uint32_t)(x >> 32));
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#endif
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}
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/**
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* Returns a value such that every bit at or below the highest bit in x is 1.
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*/
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INLINE uint16_t
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flood_bits_down(uint16_t x) {
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x |= (x >> 1);
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x |= (x >> 2);
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x |= (x >> 4);
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x |= (x >> 8);
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return x;
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}
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/**
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* Returns a value such that every bit at or below the highest bit in x is 1.
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*/
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INLINE uint32_t
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flood_bits_down(uint32_t x) {
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x |= (x >> 1);
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x |= (x >> 2);
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x |= (x >> 4);
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x |= (x >> 8);
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x |= (x >> 16);
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return x;
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}
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/**
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* Returns a value such that every bit at or below the highest bit in x is 1.
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*/
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INLINE uint64_t
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flood_bits_down(uint64_t x) {
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x |= (x >> 1);
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x |= (x >> 2);
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x |= (x >> 4);
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x |= (x >> 8);
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x |= (x >> 16);
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x |= (x >> 32);
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return x;
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}
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/**
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* Returns a value such that every bit at or above the highest bit in x is 1.
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*/
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INLINE uint16_t
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flood_bits_up(uint16_t x) {
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x |= (x << 1);
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x |= (x << 2);
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x |= (x << 4);
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x |= (x << 8);
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return x;
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}
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/**
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* Returns a value such that every bit at or above the highest bit in x is 1.
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*/
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INLINE uint32_t
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flood_bits_up(uint32_t x) {
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x |= (x << 1);
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x |= (x << 2);
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x |= (x << 4);
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x |= (x << 8);
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x |= (x << 16);
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return x;
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}
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/**
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* Returns a value such that every bit at or above the highest bit in x is 1.
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*/
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INLINE uint64_t
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flood_bits_up(uint64_t x) {
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x |= (x << 1);
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x |= (x << 2);
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x |= (x << 4);
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x |= (x << 8);
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x |= (x << 16);
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x |= (x << 32);
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return x;
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}
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/**
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* Returns the index of the lowest 1 bit in the word. Returns -1 if there are
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* no 1 bits.
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*/
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INLINE int
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get_lowest_on_bit(uint16_t x) {
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#if defined(_MSC_VER)
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unsigned long result;
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return (_BitScanForward(&result, (unsigned long) x) == 0) ? -1 : result;
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#elif defined(__GNUC__)
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return __builtin_ffs((int) x) - 1;
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#else
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if (x == 0) {
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return -1;
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}
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uint16_t w = (x & (~x + 1));
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return (int)num_bits_on[w - 1];
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#endif
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}
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/**
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* Returns the index of the lowest 1 bit in the word. Returns -1 if there are
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* no 1 bits.
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*/
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INLINE int
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get_lowest_on_bit(uint32_t x) {
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#if defined(_MSC_VER)
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unsigned long result;
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return (_BitScanForward(&result, (unsigned long) x) == 0) ? -1 : result;
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#elif defined(__GNUC__)
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return __builtin_ffs((int) x) - 1;
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#else
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if (x == 0) {
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return -1;
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}
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uint32_t w = (x & (~x + 1));
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return count_bits_in_word(w - 1);
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#endif
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}
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/**
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* Returns the index of the lowest 1 bit in the word. Returns -1 if there are
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* no 1 bits.
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*/
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INLINE int
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get_lowest_on_bit(uint64_t x) {
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#if defined(_MSC_VER) && defined(_M_X64)
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unsigned long result;
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return (_BitScanForward64(&result, (unsigned __int64) x) == 0) ? -1 : result;
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#elif defined(__GNUC__)
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return __builtin_ffsll((long long) x) - 1;
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#else
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if (x == 0) {
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return -1;
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}
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uint64_t w = (x & (~x + 1));
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return count_bits_in_word(w - 1);
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#endif
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}
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/**
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* Returns the index of the highest 1 bit in the word. Returns -1 if there
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* are no 1 bits.
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*/
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INLINE int
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get_highest_on_bit(uint16_t x) {
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#if defined(_MSC_VER)
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unsigned long result;
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return (_BitScanReverse(&result, (unsigned long) x) == 0) ? -1 : result;
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#elif defined(__GNUC__)
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return (x == 0) ? -1 : 31 - __builtin_clz((unsigned int) x);
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#else
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uint16_t w = flood_bits_down(x);
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return count_bits_in_word(w) - 1;
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#endif
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}
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/**
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* Returns the index of the highest 1 bit in the word. Returns -1 if there
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* are no 1 bits.
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*/
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INLINE int
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get_highest_on_bit(uint32_t x) {
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#if defined(_MSC_VER)
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unsigned long result;
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return (_BitScanReverse(&result, (unsigned long) x) == 0) ? -1 : result;
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#elif defined(__GNUC__)
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return (x == 0) ? -1 : 31 - __builtin_clz((unsigned int) x);
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#else
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uint32_t w = flood_bits_down(x);
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return count_bits_in_word(w) - 1;
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#endif
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}
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/**
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* Returns the index of the highest 1 bit in the word. Returns -1 if there
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* are no 1 bits.
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*/
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INLINE int
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get_highest_on_bit(uint64_t x) {
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#if defined(_MSC_VER) && defined(_M_X64)
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unsigned long result;
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return (_BitScanReverse64(&result, (unsigned __int64) x) == 0) ? -1 : result;
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#elif defined(__GNUC__)
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return (x == 0) ? -1 : 63 - __builtin_clzll((unsigned long long) x);
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#else
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uint64_t w = flood_bits_down(x);
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return count_bits_in_word(w) - 1;
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#endif
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}
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/**
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* Returns the smallest power of 2 greater than x.
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*
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* Returns the smallest number n such that (1 << n) is larger than x.
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*/
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INLINE int
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get_next_higher_bit(uint16_t x) {
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return get_highest_on_bit(x) + 1;
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}
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/**
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* Returns the smallest power of 2 greater than x.
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*
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* Returns the smallest number n such that (1 << n) is larger than x.
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*/
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INLINE int
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get_next_higher_bit(uint32_t x) {
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return get_highest_on_bit(x) + 1;
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}
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/**
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* Returns the smallest power of 2 greater than x.
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*
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* Returns the smallest number n such that (1 << n) is larger than x.
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*/
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INLINE int
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get_next_higher_bit(uint64_t x) {
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return get_highest_on_bit(x) + 1;
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}
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