//                               -*- Mode: C -*- 
// 
// Cforall Version 1.0.0 Copyright (C) 2020 University of Waterloo
// 
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// bitmanip.hfa -- 
// 
// Author           : Peter A. Buhr
// Created On       : Sat Mar 14 18:12:27 2020
// Last Modified By : Peter A. Buhr
// Last Modified On : Mon Apr  6 22:17:19 2020
// Update Count     : 78
// 

#pragma once

// Reference: Bit Twiddling Hacks: http://graphics.stanford.edu/%7Eseander/bithacks.html#CountBitsSetNaive

// Bits are numbered 1-N.

#include <assert.h>

#define __bitsizeof( n ) (sizeof(n) * __CHAR_BIT__)

static inline {
    // Count leading 0 bits.
    unsigned int leading0s( unsigned char n ) { return n != 0 ? __builtin_clz( n ) - (__bitsizeof(unsigned int) - __bitsizeof(n)) : __bitsizeof(n); }
    unsigned int leading0s( unsigned short int n ) { return n != 0 ? __builtin_clz( n ) - (__bitsizeof(unsigned int) - __bitsizeof(n)) : __bitsizeof(n); }
    unsigned int leading0s( unsigned int n ) { return n != 0 ? __builtin_clz( n ) : __bitsizeof(n); }
    unsigned int leading0s( unsigned long int n ) { return n != 0 ? __builtin_clzl( n ) : __bitsizeof(n); }
    unsigned int leading0s( unsigned long long int n ) { return n != 0 ? __builtin_clzll( n ) : __bitsizeof(n); }

    // Count trailing 0 bits.
    unsigned int trailing0s( unsigned char n ) { return n != 0 ? __builtin_ctz( n ) : __bitsizeof(n); }
    unsigned int trailing0s( unsigned short int n ) { return n != 0 ? __builtin_ctz( n ) : __bitsizeof(n); }
    unsigned int trailing0s( unsigned int n ) { return n != 0 ? __builtin_ctz( n ) : __bitsizeof(n); }
    unsigned int trailing0s( unsigned long int n ) { return n != 0 ? __builtin_ctzl( n ) : __bitsizeof(n); }
    unsigned int trailing0s( unsigned long long int n ) { return n != 0 ? __builtin_ctzll( n ) : __bitsizeof(n); }

    // Count all 1 bits.
    unsigned int all1s( unsigned char n ) { return __builtin_popcount( n ); }
    unsigned int all1s( unsigned short int n ) { return __builtin_popcount( n ); }
    unsigned int all1s( unsigned int n ) { return __builtin_popcount( n ); }
    unsigned int all1s( unsigned long int n ) { return __builtin_popcountl( n ); }
    unsigned int all1s( unsigned long long int n ) { return __builtin_popcountll( n ); }

    // Count all 0 bits.
    unsigned int all0s( unsigned char n ) { return __bitsizeof(n) - __builtin_popcount( n ); }
    unsigned int all0s( unsigned short int n ) { return __bitsizeof(n) - __builtin_popcount( n ); }
    unsigned int all0s( unsigned int n ) { return __bitsizeof(n) - __builtin_popcount( n ); }
    unsigned int all0s( unsigned long int n ) { return __bitsizeof(n) - __builtin_popcountl( n ); }
    unsigned int all0s( unsigned long long int n ) { return __bitsizeof(n) - __builtin_popcountll( n ); }

    // Find least significiant zero bit. (ffs)
    unsigned int low0( unsigned char n ) { return __builtin_ffs( (typeof(n))~n ); }
    unsigned int low0( unsigned short int n ) { return __builtin_ffs( (typeof(n))~n ); }
    unsigned int low0( unsigned int n ) { return __builtin_ffs( ~n ); }
    unsigned int low0( unsigned long int n ) { return __builtin_ffsl( ~n ); }
    unsigned int low0( unsigned long long int n ) { return __builtin_ffsll( ~n ); }

    // Find least significiant one bit.
    unsigned int low1( unsigned int n ) { return __builtin_ffs( n ); }
    unsigned int low1( unsigned long int n ) { return __builtin_ffsl( n ); }
    unsigned int low1( unsigned long long int n ) { return __builtin_ffsll( n ); }

    // Find most significiant zero bit.
    unsigned int high0( unsigned char n ) { return n != (typeof(n))-1 ? __bitsizeof(unsigned int) - __builtin_clz( (typeof(n))~n ) : 0; }
    unsigned int high0( unsigned short int n ) { return n != (typeof(n))-1 ? __bitsizeof(unsigned int) - __builtin_clz( (typeof(n))~n ) : 0; }
    unsigned int high0( unsigned int n ) { return n != -1 ? __bitsizeof(n) - __builtin_clz( ~n ) : 0; }
    unsigned int high0( unsigned long int n ) { return n != -1 ? __bitsizeof(n) - __builtin_clzl( ~n ) : 0; }
    unsigned int high0( unsigned long long int n ) { return n != -1 ? __bitsizeof(n) - __builtin_clzll( ~n ) : 0; }

    // Find most significiant one bit.
    unsigned int high1( unsigned char n ) { return n != 0 ? __bitsizeof(unsigned int) - __builtin_clz( n ) : 0; }
    unsigned int high1( unsigned short int n ) { return n != 0 ? __bitsizeof(unsigned int) - __builtin_clz( n ) : 0; }
    unsigned int high1( unsigned int n ) { return n != 0 ? __bitsizeof(n) - __builtin_clz( n ) : 0; }
    unsigned int high1( unsigned long int n ) { return n != 0 ? __bitsizeof(n) - __builtin_clzl( n ) : 0; }
    unsigned int high1( unsigned long long int n ) { return n != 0 ? __bitsizeof(n) - __builtin_clzll( n ) : 0; }

    // Check for power of 2, clears bits below value, rounding down to the next lower multiple of value.
    bool is_pow2( int value ) { return (value & (value - 1)) == 0; }
    bool is_pow2( unsigned long long int value ) { return (value & (value - 1)) == 0; }

    // Returns value aligned at the floor of align, clear bits above or equal to align, giving value % align.
    unsigned int floor2( unsigned int value, unsigned int align ) { assert( is_pow2( align ) ); return value & -align; }
    unsigned long long int floor2( unsigned long long int value, unsigned long long int align ) { assert( is_pow2( align ) ); return value & -align; }

    unsigned int floor( unsigned int value, unsigned int align ) { return value / align * align; }
    unsigned long long int floor( unsigned long long int value, unsigned long long int align ) { return value / align * align; }

    // Returns value aligned at the ceiling of align, negate, round down, negate is the same as round up.
    unsigned int ceiling2( unsigned int value, unsigned int align ) { assert( is_pow2( align ) ); return -floor2( -value, align ); }
    unsigned long long int ceiling2( unsigned long long int value, unsigned long long int align ) { assert( is_pow2( align ) ); return -floor2( -value, align ); }

    unsigned int ceiling( unsigned int value, unsigned int align ) { return (value + (align - 1)) / align; }
    unsigned long long int ceiling( unsigned long long int value, unsigned long long int align ) { return (value + (align - 1)) / align; }
} // distribution

// Local Variables: //
// tab-width: 4 //
// End: //