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83 lines
2.6 KiB
C
83 lines
2.6 KiB
C
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// normrnd.c
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// functions to generate gaussian distributed numbers
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//
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// (c) 2016 - Nico Palermo, IV3NWV - Microtelecom Srl, Italy
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//
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// Credits to Andrea Montefusco - IW0HDV for his help on adapting the sources
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// to OSs other than MS Windows
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//
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// ------------------------------------------------------------------------------
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// This file is part of the qracodes project, a Forward Error Control
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// encoding/decoding package based on Q-ary RA (Repeat and Accumulate) LDPC codes.
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//
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// qracodes is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// qracodes is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with qracodes source distribution.
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// If not, see <http://www.gnu.org/licenses/>.
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#include "normrnd.h"
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#if _WIN32 // note the underscore: without it, it's not msdn official!
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// Windows (x64 and x86)
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#include <windows.h> // required only for GetTickCount(...)
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#define K_RAND_MAX UINT_MAX
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#elif _SVID_SOURCE || _XOPEN_SOURCE || __unix__ || (defined (__APPLE__) && defined(__MACH__)) /* POSIX or Unix or Apple */
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#include <stdlib.h>
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#define rand_s(x) (*x)=(unsigned int)lrand48() // returns unsigned integers in the range 0..0x7FFFFFFF
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#define K_RAND_MAX 0x7FFFFFFF // that's the max number
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// generated by lrand48
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#else
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#error "No good quality PRNG found"
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#endif
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// use MS rand_s(...) function
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void normrnd_s(float *dst, int nitems, float mean, float stdev)
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{
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unsigned int r;
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float phi=0, u=0;
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int set = 0;
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while (nitems--)
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if (set==1) {
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*dst++ = (float)sin(phi)*u*stdev+mean;
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set = 0;
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}
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else {
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rand_s((unsigned int*)&r); phi = (M_2PI/(1.0f+K_RAND_MAX))*r;
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rand_s((unsigned int*)&r); u = (float)sqrt(-2.0f* log( (1.0f/(1.0f+K_RAND_MAX))*(1.0f+r) ) );
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*dst++ = (float)cos(phi)*u*stdev+mean;
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set=1;
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}
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}
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/* NOT USED
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// use MS rand() function
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void normrnd(float *dst, int nitems, float mean, float stdev)
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{
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float phi=0, u=0;
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int set = 0;
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while (nitems--)
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if (set==1) {
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*dst++ = (float)sin(phi)*u*stdev+mean;
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set = 0;
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}
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else {
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phi = (M_2PI/(1.0f+RAND_MAX))*rand();
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u = (float)sqrt(-2.0f* log( (1.0f/(1.0f+RAND_MAX))*(1.0f+rand()) ) );
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*dst++ = (float)cos(phi)*u*stdev+mean;
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set=1;
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}
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}
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*/
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