Differential D52429 Diff 161904 lib/libc/gen/rand48.h

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lib/libc/gen/rand48.h

	/*			/*
	* Copyright (c) 1993 Martin Birgmeier			* Copyright (c) 1993 Martin Birgmeier
	* All rights reserved.			* All rights reserved.
	*			*
	* You may redistribute unmodified or modified versions of this source			* You may redistribute unmodified or modified versions of this source
	* code provided that the above copyright notice and this and the			* code provided that the above copyright notice and this and the
	* following conditions are retained.			* following conditions are retained.
	*			*
	* This software is provided ``as is'', and comes with no warranties			* This software is provided ``as is'', and comes with no warranties
	* of any kind. I shall in no event be liable for anything that happens			* of any kind. I shall in no event be liable for anything that happens
	* to anyone/anything when using this software.			* to anyone/anything when using this software.
	*/			*/

	#ifndef _RAND48_H_			#ifndef _RAND48_H_
	#define _RAND48_H_			#define _RAND48_H_

				#include <sys/types.h>
	#include <math.h>			#include <math.h>
	#include <stdlib.h>			#include <stdlib.h>

	void _dorand48(unsigned short[3]);			#include "fpmath.h"

	#define RAND48_SEED_0 (0x330e)			#define RAND48_SEED_0 (0x330e)
	#define RAND48_SEED_1 (0xabcd)			#define RAND48_SEED_1 (0xabcd)
	#define RAND48_SEED_2 (0x1234)			#define RAND48_SEED_2 (0x1234)
	#define RAND48_MULT_0 (0xe66d)			#define RAND48_MULT_0 (0xe66d)
	#define RAND48_MULT_1 (0xdeec)			#define RAND48_MULT_1 (0xdeec)
	#define RAND48_MULT_2 (0x0005)			#define RAND48_MULT_2 (0x0005)
	#define RAND48_ADD (0x000b)			#define RAND48_ADD (0x000b)

				typedef uint64_t uint48;

				extern uint48 _rand48_seed;
				extern uint48 _rand48_mult;
				extern uint48 _rand48_add;

				#define TOUINT48(x, y, z) \
				((uint48)(x) + (((uint48)(y)) << 16) + (((uint48)(z)) << 32))

				#define RAND48_SEED TOUINT48(RAND48_SEED_0, RAND48_SEED_1, RAND48_SEED_2)
				#define RAND48_MULT TOUINT48(RAND48_MULT_0, RAND48_MULT_1, RAND48_MULT_2)

				#define LOADRAND48(l, x) do { \
				(l) = TOUINT48((x)[0], (x)[1], (x)[2]); \
				} while (0)

				#define STORERAND48(l, x) do { \
				(x)[0] = (unsigned short)(l); \
				(x)[1] = (unsigned short)((l) >> 16); \
				(x)[2] = (unsigned short)((l) >> 32); \
				} while (0)

				#define _DORAND48(l) do { \
				(l) = (l) * _rand48_mult + _rand48_add; \
				} while (0)

				#define DORAND48(l, x) do { \
				LOADRAND48(l, x); \
				_DORAND48(l); \
				STORERAND48(l, x); \
				} while (0)

				#define ERAND48_BEGIN \
				union { \
				union IEEEd2bits ieee; \
				uint64_t u64; \
				} u; \
				int s

				/*
				* Optimization for speed: assume doubles are IEEE 754 and use bit fiddling
				* rather than converting to double. Specifically, clamp the result to 48 bits
				* and convert to a double in [0.0, 1.0) via division by 2^48. Normalize by
				* shifting the most significant bit into the implicit one position and
				* adjusting the exponent accordingly. The store to the exponent field
				* overwrites the implicit one.
				*/
				#define ERAND48_END(x) do { \
				u.u64 = ((x) & 0xffffffffffffULL); \
				if (u.u64 == 0) \
				return (0.0); \
				u.u64 <<= 5; \
				for (s = 0; !(u.u64 & (1LL << 52)); s++, u.u64 <<= 1) \
				; \
				u.ieee.bits.exp = 1022 - s; \
				return (u.ieee.d); \
				} while (0)

	#endif /* _RAND48_H_ */			#endif /* _RAND48_H_ */