| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 1 | /* |
| 2 | * ==================================================== |
| 3 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| 4 | * |
| 5 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
| 6 | * Permission to use, copy, modify, and distribute this |
| 7 | * software is freely granted, provided that this notice |
| 8 | * is preserved. |
| 9 | * ==================================================== |
| 10 | */ |
| 11 | |
| 12 | /* __ieee754_remainder(x,p) |
| 13 | * Return : |
| 14 | * returns x REM p = x - [x/p]*p as if in infinite |
| 15 | * precise arithmetic, where [x/p] is the (infinite bit) |
| 16 | * integer nearest x/p (in half way case choose the even one). |
| 17 | * Method : |
| 18 | * Based on fmod() return x-[x/p]chopped*p exactlp. |
| 19 | */ |
| 20 | |
| 21 | #include "math.h" |
| 22 | #include "math_private.h" |
| 23 | |
| 24 | static const double zero = 0.0; |
| 25 | |
| 26 | double attribute_hidden __ieee754_remainder(double x, double p) |
| 27 | { |
| 28 | int32_t hx,hp; |
| 29 | u_int32_t sx,lx,lp; |
| 30 | double p_half; |
| 31 | |
| 32 | EXTRACT_WORDS(hx,lx,x); |
| 33 | EXTRACT_WORDS(hp,lp,p); |
| 34 | sx = hx&0x80000000; |
| 35 | hp &= 0x7fffffff; |
| 36 | hx &= 0x7fffffff; |
| 37 | |
| 38 | /* purge off exception values */ |
| 39 | if((hp|lp)==0) return (x*p)/(x*p); /* p = 0 */ |
| 40 | if((hx>=0x7ff00000)|| /* x not finite */ |
| 41 | ((hp>=0x7ff00000)&& /* p is NaN */ |
| 42 | (((hp-0x7ff00000)|lp)!=0))) |
| 43 | return (x*p)/(x*p); |
| 44 | |
| 45 | |
| 46 | if (hp<=0x7fdfffff) x = __ieee754_fmod(x,p+p); /* now x < 2p */ |
| 47 | if (((hx-hp)|(lx-lp))==0) return zero*x; |
| 48 | x = fabs(x); |
| 49 | p = fabs(p); |
| 50 | if (hp<0x00200000) { |
| 51 | if(x+x>p) { |
| 52 | x-=p; |
| 53 | if(x+x>=p) x -= p; |
| 54 | } |
| 55 | } else { |
| 56 | p_half = 0.5*p; |
| 57 | if(x>p_half) { |
| 58 | x-=p; |
| 59 | if(x>=p_half) x -= p; |
| 60 | } |
| 61 | } |
| 62 | GET_HIGH_WORD(hx,x); |
| 63 | SET_HIGH_WORD(x,hx^sx); |
| 64 | return x; |
| 65 | } |
| 66 | |
| 67 | /* |
| 68 | * wrapper remainder(x,p) |
| 69 | */ |
| 70 | #ifndef _IEEE_LIBM |
| 71 | double remainder(double x, double y) |
| 72 | { |
| 73 | double z = __ieee754_remainder(x, y); |
| 74 | if (_LIB_VERSION == _IEEE_ || isnan(y)) |
| 75 | return z; |
| 76 | if (y == 0.0) |
| 77 | return __kernel_standard(x, y, 28); /* remainder(x,0) */ |
| 78 | return z; |
| 79 | } |
| 80 | strong_alias(remainder, drem) |
| 81 | #else |
| 82 | strong_alias(__ieee754_remainder, remainder) |
| 83 | strong_alias(__ieee754_remainder, drem) |
| 84 | #endif |
| 85 | libm_hidden_def(remainder) |