10b57cec5SDimitry Andric //===-- popcountdi2.c - Implement __popcountdi2 ---------------------------===// 20b57cec5SDimitry Andric // 30b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 40b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 50b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 60b57cec5SDimitry Andric // 70b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 80b57cec5SDimitry Andric // 90b57cec5SDimitry Andric // This file implements __popcountdi2 for the compiler_rt library. 100b57cec5SDimitry Andric // 110b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 120b57cec5SDimitry Andric 130b57cec5SDimitry Andric #include "int_lib.h" 140b57cec5SDimitry Andric 150b57cec5SDimitry Andric // Returns: count of 1 bits 160b57cec5SDimitry Andric __popcountdi2(di_int a)17*5ffd83dbSDimitry AndricCOMPILER_RT_ABI int __popcountdi2(di_int a) { 180b57cec5SDimitry Andric du_int x2 = (du_int)a; 190b57cec5SDimitry Andric x2 = x2 - ((x2 >> 1) & 0x5555555555555555uLL); 200b57cec5SDimitry Andric // Every 2 bits holds the sum of every pair of bits (32) 210b57cec5SDimitry Andric x2 = ((x2 >> 2) & 0x3333333333333333uLL) + (x2 & 0x3333333333333333uLL); 220b57cec5SDimitry Andric // Every 4 bits holds the sum of every 4-set of bits (3 significant bits) (16) 230b57cec5SDimitry Andric x2 = (x2 + (x2 >> 4)) & 0x0F0F0F0F0F0F0F0FuLL; 240b57cec5SDimitry Andric // Every 8 bits holds the sum of every 8-set of bits (4 significant bits) (8) 250b57cec5SDimitry Andric su_int x = (su_int)(x2 + (x2 >> 32)); 260b57cec5SDimitry Andric // The lower 32 bits hold four 16 bit sums (5 significant bits). 270b57cec5SDimitry Andric // Upper 32 bits are garbage 280b57cec5SDimitry Andric x = x + (x >> 16); 290b57cec5SDimitry Andric // The lower 16 bits hold two 32 bit sums (6 significant bits). 300b57cec5SDimitry Andric // Upper 16 bits are garbage 310b57cec5SDimitry Andric return (x + (x >> 8)) & 0x0000007F; // (7 significant bits) 320b57cec5SDimitry Andric } 33