1 /* mpn_popcount, mpn_hamdist -- mpn bit population count/hamming distance. 2 3 Copyright 1994, 1996, 2000, 2001, 2002, 2005, 2011, 2012 Free Software 4 Foundation, Inc. 5 6 This file is part of the GNU MP Library. 7 8 The GNU MP Library is free software; you can redistribute it and/or modify 9 it under the terms of the GNU Lesser General Public License as published by 10 the Free Software Foundation; either version 3 of the License, or (at your 11 option) any later version. 12 13 The GNU MP Library is distributed in the hope that it will be useful, but 14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 16 License for more details. 17 18 You should have received a copy of the GNU Lesser General Public License 19 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 20 21 #include "gmp.h" 22 #include "gmp-impl.h" 23 24 #if OPERATION_popcount 25 #define FNAME mpn_popcount 26 #define POPHAM(u,v) u 27 #endif 28 29 #if OPERATION_hamdist 30 #define FNAME mpn_hamdist 31 #define POPHAM(u,v) u ^ v 32 #endif 33 34 mp_bitcnt_t 35 FNAME (mp_srcptr up, 36 #if OPERATION_hamdist 37 mp_srcptr vp, 38 #endif 39 mp_size_t n) __GMP_NOTHROW 40 { 41 mp_bitcnt_t result = 0; 42 mp_limb_t p0, p1, p2, p3, x, p01, p23; 43 mp_size_t i; 44 45 ASSERT (n >= 1); /* Actually, this code handles any n, but some 46 assembly implementations do not. */ 47 48 for (i = n >> 2; i != 0; i--) 49 { 50 p0 = POPHAM (up[0], vp[0]); 51 p0 -= (p0 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */ 52 p0 = ((p0 >> 2) & MP_LIMB_T_MAX/5) + (p0 & MP_LIMB_T_MAX/5); /* 4 0-4 */ 53 54 p1 = POPHAM (up[1], vp[1]); 55 p1 -= (p1 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */ 56 p1 = ((p1 >> 2) & MP_LIMB_T_MAX/5) + (p1 & MP_LIMB_T_MAX/5); /* 4 0-4 */ 57 58 p01 = p0 + p1; /* 8 0-8 */ 59 p01 = ((p01 >> 4) & MP_LIMB_T_MAX/17) + (p01 & MP_LIMB_T_MAX/17); /* 8 0-16 */ 60 61 p2 = POPHAM (up[2], vp[2]); 62 p2 -= (p2 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */ 63 p2 = ((p2 >> 2) & MP_LIMB_T_MAX/5) + (p2 & MP_LIMB_T_MAX/5); /* 4 0-4 */ 64 65 p3 = POPHAM (up[3], vp[3]); 66 p3 -= (p3 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */ 67 p3 = ((p3 >> 2) & MP_LIMB_T_MAX/5) + (p3 & MP_LIMB_T_MAX/5); /* 4 0-4 */ 68 69 p23 = p2 + p3; /* 8 0-8 */ 70 p23 = ((p23 >> 4) & MP_LIMB_T_MAX/17) + (p23 & MP_LIMB_T_MAX/17); /* 8 0-16 */ 71 72 x = p01 + p23; /* 8 0-32 */ 73 x = (x >> 8) + x; /* 8 0-64 */ 74 x = (x >> 16) + x; /* 8 0-128 */ 75 #if GMP_LIMB_BITS > 32 76 x = ((x >> 32) & 0xff) + (x & 0xff); /* 8 0-256 */ 77 result += x; 78 #else 79 result += x & 0xff; 80 #endif 81 up += 4; 82 #if OPERATION_hamdist 83 vp += 4; 84 #endif 85 } 86 87 n &= 3; 88 if (n != 0) 89 { 90 x = 0; 91 do 92 { 93 p0 = POPHAM (up[0], vp[0]); 94 p0 -= (p0 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */ 95 p0 = ((p0 >> 2) & MP_LIMB_T_MAX/5) + (p0 & MP_LIMB_T_MAX/5); /* 4 0-4 */ 96 p0 = ((p0 >> 4) + p0) & MP_LIMB_T_MAX/17; /* 8 0-8 */ 97 98 x += p0; 99 up += 1; 100 #if OPERATION_hamdist 101 vp += 1; 102 #endif 103 } 104 while (--n); 105 106 x = (x >> 8) + x; 107 x = (x >> 16) + x; 108 #if GMP_LIMB_BITS > 32 109 x = (x >> 32) + x; 110 #endif 111 result += x & 0xff; 112 } 113 114 return result; 115 } 116