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sortix--sortix/libc/rand.cpp
Jonas 'Sortie' Termansen 1a3aa45c2c Add srand(3).
2013-12-17 14:30:28 +01:00

65 lines
1.6 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
This file is part of the Sortix C Library.
The Sortix C Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
The Sortix C Library 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
rand.cpp
Returns a random value.
*******************************************************************************/
#include <stdlib.h>
#if 1
static unsigned int m_w = 1337;
static unsigned int m_z = 37;
static unsigned int RandomUnsignedInt()
{
m_z = 36969 * (m_z & 65535) + (m_z >> 16);
m_w = 18000 * (m_w & 65535) + (m_w >> 16);
return (m_z << 16) + m_w; /* 32-bit result */
}
extern "C" int rand()
{
return RandomUnsignedInt() % 32768;
}
extern "C" void srand(unsigned int seed)
{
m_w = seed >> 16 & 0xFFFF;
m_z = seed >> 0 & 0xFFFF;
}
#else
static unsigned random_seed = 1337;
extern "C" int rand()
{
random_seed = random_seed + 37 * 1103515245 + 12345;
return random_seed >> 16;
}
extern "C" void srand(unsigned int seed)
{
random_seed = seed;
}
#endif