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62 lines
1.5 KiB
C++

/*
* Project 25 IMBE Encoder/Decoder Fixed-Point implementation
* Developed by Pavel Yazev E-mail: pyazev@gmail.com
* Version 1.0 (c) Copyright 2009
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* The software is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this; see the file COPYING. If not, write to the Free
* Software Foundation, Inc., 51 Franklin Street, Boston, MA
* 02110-1301, USA.
*/
#include "typedef.h"
#include "basic_op.h"
static UWord32 seed = 1;
//-----------------------------------------------------------------------------
// PURPOSE:
// Generate pseudo-random numbers in range -1...1
//
//
// INPUT:
// None
//
// OUTPUT:
// None
//
// RETURN:
// Pseudo-random number in signed Q1.16 format
//
//-----------------------------------------------------------------------------
Word16 rand_gen(void)
{
UWord32 hi, lo;
lo = 16807 * (seed & 0xFFFF);
hi = 16807 * (seed >> 16);
lo += (Word32)(hi & 0x7FFF) << 16;
lo += (hi >> 15);
if(lo > 0x7FFFFFFF)
lo -= 0x7FFFFFFF;
seed = lo;
return (Word16)lo;
}