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129 lines
3.1 KiB
C
129 lines
3.1 KiB
C
/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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* from: @(#)fdlibm.h 5.1 93/09/24
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* $Id: math_private.h,v 1.3 2004/02/09 07:10:38 andersen Exp $
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*/
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#ifndef _MATH_PRIVATE_H_
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#define _MATH_PRIVATE_H_
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#include <endian.h>
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#include <sys/types.h>
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/* The original fdlibm code used statements like:
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n0 = ((*(int*)&one)>>29)^1; * index of high word *
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ix0 = *(n0+(int*)&x); * high word of x *
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ix1 = *((1-n0)+(int*)&x); * low word of x *
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to dig two 32 bit words out of the 64 bit IEEE floating point
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value. That is non-ANSI, and, moreover, the gcc instruction
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scheduler gets it wrong. We instead use the following macros.
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Unlike the original code, we determine the endianness at compile
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time, not at run time; I don't see much benefit to selecting
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endianness at run time. */
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/* A union which permits us to convert between a double and two 32 bit
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ints. */
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/*
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* Math on arm is special:
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* For FPA, float words are always big-endian.
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* For VFP, floats words follow the memory system mode.
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*/
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#if (__BYTE_ORDER == __BIG_ENDIAN) || \
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(!defined(__VFP_FP__) && (defined(__arm__) || defined(__thumb__)))
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typedef union
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{
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double value;
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struct
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{
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u_int32_t msw;
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u_int32_t lsw;
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} parts;
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} ieee_double_shape_type;
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#else
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typedef union
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{
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double value;
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struct
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{
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u_int32_t lsw;
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u_int32_t msw;
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} parts;
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} ieee_double_shape_type;
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#endif
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/* Get two 32 bit ints from a double. */
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#define EXTRACT_WORDS(ix0,ix1,d) \
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do { \
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ieee_double_shape_type ew_u; \
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ew_u.value = (d); \
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(ix0) = ew_u.parts.msw; \
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(ix1) = ew_u.parts.lsw; \
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} while (0)
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/* Get the more significant 32 bit int from a double. */
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#define GET_HIGH_WORD(i,d) \
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do { \
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ieee_double_shape_type gh_u; \
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gh_u.value = (d); \
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(i) = gh_u.parts.msw; \
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} while (0)
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/* Get the less significant 32 bit int from a double. */
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#define GET_LOW_WORD(i,d) \
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do { \
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ieee_double_shape_type gl_u; \
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gl_u.value = (d); \
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(i) = gl_u.parts.lsw; \
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} while (0)
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/* Set a double from two 32 bit ints. */
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#define INSERT_WORDS(d,ix0,ix1) \
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do { \
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ieee_double_shape_type iw_u; \
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iw_u.parts.msw = (ix0); \
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iw_u.parts.lsw = (ix1); \
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(d) = iw_u.value; \
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} while (0)
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/* Set the more significant 32 bits of a double from an int. */
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#define SET_HIGH_WORD(d,v) \
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do { \
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ieee_double_shape_type sh_u; \
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sh_u.value = (d); \
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sh_u.parts.msw = (v); \
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(d) = sh_u.value; \
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} while (0)
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/* Set the less significant 32 bits of a double from an int. */
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#define SET_LOW_WORD(d,v) \
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do { \
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ieee_double_shape_type sl_u; \
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sl_u.value = (d); \
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sl_u.parts.lsw = (v); \
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(d) = sl_u.value; \
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} while (0)
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#endif /* _MATH_PRIVATE_H_ */
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