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  1. /*
  2.  * Copyright (C) 2005 Josef Cejka
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #include <arch/fmath.h>
  30. #include <print.h>
  31.  
  32. #define FMATH_MANTISA_MASK ( 0x000fffffffffffffLL )
  33.  
  34. int fmath_is_negative(double num)
  35. {
  36.     fmath_ld_union_t fmath_ld_union;
  37.     fmath_ld_union.bf = num;
  38.     return ((fmath_ld_union.ldd[7])&0x80)==0x80; /*first bit is sign, IA32 is little endian -> 8th byte*/
  39.  
  40. }
  41.  
  42. signed short fmath_get_binary_exponent(double num)
  43. {
  44.     fmath_ld_union_t fmath_ld_union;
  45.     fmath_ld_union.bf = num;
  46.     return (signed short)((((fmath_ld_union.ldd[7])&0x7f)<<4) + (((fmath_ld_union.ldd[6])&0xf0)>>4)) -FMATH_EXPONENT_BIAS; /* exponent is 11 bits lenght, so sevent bits is in 8th byte and 4 bits in 7th */
  47. }
  48.  
  49. double fmath_get_decimal_exponent(double num)
  50. {
  51.     double value;
  52.     /* log10(2)*log2(x) => log10(x) */
  53.     __asm__ __volatile__ ( \
  54.     "fldlg2     #load log10(2)  \n\t"   \
  55.     "fxch %%st(1)       \n\t" \
  56.     "fyl2x      #count st(0)*log2(st(1))->st(1); pop st(0)  \n\t" \
  57.     : "=t" (value) : "0"(num) );
  58.     return value;
  59. }
  60.  
  61. __u64 fmath_get_binary_mantisa(double num)
  62. {
  63.     union { __u64 _u; double _d;} un = { _d : num };
  64.     un._u=un._u &(FMATH_MANTISA_MASK); /* mask 52 bits of mantisa*/
  65.     return un._u;
  66. }
  67.  
  68. double fmath_fint(double num, double *intp)
  69. {
  70.     fmath_ld_union_t fmath_ld_union_num;
  71.     fmath_ld_union_t fmath_ld_union_int;
  72.     signed short exp;
  73.     __u64 mask,mantisa;
  74.     int i;
  75.    
  76.     exp=fmath_get_binary_exponent(num);
  77.    
  78.     if (exp<0) {
  79.         *intp = 0.0;
  80.         *intp = fmath_set_sign(0.0L,fmath_is_negative(num));
  81.         return num;
  82.         }
  83.        
  84.  
  85.     if (exp>51) {
  86.         *intp=num;
  87.         num=0.0;
  88.         num= fmath_set_sign(0.0L,fmath_is_negative(*intp));
  89.         return num;
  90.     }
  91.    
  92.     fmath_ld_union_num.bf = num;
  93.    
  94.     mask = FMATH_MANTISA_MASK>>exp;
  95.     //mantisa = (fmath_get-binary_mantisa(num))&(~mask);
  96.    
  97.     for (i=0;i<7;i++) {
  98.         /* Ugly construction for obtain sign, exponent and integer part from num */
  99.         fmath_ld_union_int.ldd[i]=fmath_ld_union_num.ldd[i]&(((~mask)>>(i*8))&0xff);
  100.     }
  101.    
  102.     fmath_ld_union_int.ldd[6]|=((fmath_ld_union_num.ldd[6])&(0xf0));
  103.     fmath_ld_union_int.ldd[7]=fmath_ld_union_num.ldd[7];
  104.    
  105.     *intp=fmath_ld_union_int.bf;
  106.     return fmath_ld_union_num.bf-fmath_ld_union_int.bf;
  107. };
  108.    
  109. double fmath_set_sign(double num,__u8 sign)
  110. {
  111.     fmath_ld_union_t fmath_ld_union;
  112.     fmath_ld_union.bf = num;
  113.     fmath_ld_union.ldd[7]=((fmath_ld_union.ldd[7])&0x7f)|(sign<<7); /* change 64th bit (IA32 is a little endian)*/
  114.     return fmath_ld_union.bf;
  115. }
  116.  
  117. double fmath_abs(double num)
  118. {
  119.     return fmath_set_sign(num,0);
  120. }
  121.  
  122. double fmath_dpow(double base, double exponent)
  123. {
  124.     double value=1.0;
  125.     if (base<=0.0) return base;
  126.    
  127.     //2^(x*log2(10)) = 2^y = 10^x
  128.    
  129.     __asm__ __volatile__ (      \
  130.         "fyl2x # ST(1):=ST(1)*log2(ST(0)), pop st(0) \n\t "     \
  131.         "fld    %%st(0) \n\t"   \
  132.         "frndint \n\t"      \
  133.         "fxch %%st(1) \n\t"     \
  134.         "fsub %%st(1),%%st(0) \n\t" \
  135.         "f2xm1  # ST := 2^ST -1\n\t"            \
  136.         "fld1 \n\t"         \
  137.         "faddp %%st(0),%%st(1) \n\t"    \
  138.         "fscale #ST:=ST*2^(ST(1))\n\t"      \
  139.         "fstp %%st(1) \n\t"     \
  140.     "" : "=t" (value) :  "0" (base), "u" (exponent) );
  141.     return value;
  142. }
  143.  
  144.