c434782e3a
Use a shorter/simpler license convention, stops the header taking so much space. Follow the SPDX license specification: https://spdx.org/licenses - C/C++/objc/objc++ - Python - Shell Scripts - CMake, GNUmakefile While most of the source tree has been included - `./extern/` was left out. - `./intern/cycles` & `./intern/atomic` are also excluded because they use different header conventions. doc/license/SPDX-license-identifiers.txt has been added to list SPDX all used identifiers. See P2788 for the script that automated these edits. Reviewed By: brecht, mont29, sergey Ref D14069
119 lines
2.4 KiB
C++
119 lines
2.4 KiB
C++
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/** \file
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* \ingroup freestyle
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* \brief Pseudo-random number generator
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*/
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#include "RandGen.h"
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namespace Freestyle {
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//
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// Macro definitions
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//
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///////////////////////////////////////////////////////////////////////////////
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#define N 16
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#define MASK ((unsigned)(1 << (N - 1)) + (1 << (N - 1)) - 1)
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#define X0 0x330E
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#define X1 0xABCD
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#define X2 0x1234
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#define A0 0xE66D
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#define A1 0xDEEC
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#define A2 0x5
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#define C 0xB
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#if 0 // XXX Unused
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# define HI_BIT (1L << (2 * N - 1))
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#endif
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#define LOW(x) ((unsigned)(x)&MASK)
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#define HIGH(x) LOW((x) >> N)
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#define MUL(x, y, z) \
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{ \
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long l = (long)(x) * (long)(y); \
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(z)[0] = LOW(l); \
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(z)[1] = HIGH(l); \
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} \
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((void)0)
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#define CARRY(x, y) ((unsigned long)((long)(x) + (long)(y)) > MASK)
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#define ADDEQU(x, y, z) (z = CARRY(x, (y)), x = LOW(x + (y)))
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#define SET3(x, x0, x1, x2) ((x)[0] = (x0), (x)[1] = (x1), (x)[2] = (x2))
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#if 0 // XXX, unused
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# define SETLOW(x, y, n) SET3(x, LOW((y)[n]), LOW((y)[(n) + 1]), LOW((y)[(n) + 2]))
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#endif
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#define SEED(x0, x1, x2) (SET3(x, x0, x1, x2), SET3(a, A0, A1, A2), c = C)
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#if 0 // XXX, unused
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# define REST(v) \
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for (i = 0; i < 3; i++) { \
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xsubi[i] = x[i]; \
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x[i] = temp[i]; \
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} \
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return (v); \
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(void)0
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# define NEST(TYPE, f, F) \
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TYPE f(unsigned short *xsubi) \
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{ \
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int i; \
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TYPE v; \
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unsigned temp[3]; \
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for (i = 0; i < 3; i++) { \
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temp[i] = x[i]; \
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x[i] = LOW(xsubi[i]); \
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} \
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v = F(); \
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REST(v); \
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}
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#endif
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static unsigned x[3] = {
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X0,
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X1,
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X2,
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};
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static unsigned a[3] = {
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A0,
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A1,
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A2,
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};
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static unsigned c = C;
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//
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// Methods implementation
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//
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///////////////////////////////////////////////////////////////////////////////
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real RandGen::drand48()
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{
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static real two16m = 1.0 / (1L << N);
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next();
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return (two16m * (two16m * (two16m * x[0] + x[1]) + x[2]));
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}
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void RandGen::srand48(long seedval)
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{
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SEED(X0, LOW(seedval), HIGH(seedval));
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}
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void RandGen::next()
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{
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unsigned p[2], q[2], r[2], carry0, carry1;
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MUL(a[0], x[0], p);
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ADDEQU(p[0], c, carry0);
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ADDEQU(p[1], carry0, carry1);
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MUL(a[0], x[1], q);
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ADDEQU(p[1], q[0], carry0);
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MUL(a[1], x[0], r);
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x[2] = LOW(carry0 + carry1 + CARRY(p[1], r[0]) + q[1] + r[1] + a[0] * x[2] + a[1] * x[1] +
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a[2] * x[0]);
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x[1] = LOW(p[1] + r[0]);
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x[0] = LOW(p[0]);
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}
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} /* namespace Freestyle */
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