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