| The Android Open Source Project | 1dc9e47 | 2009-03-03 19:28:35 -0800 | [diff] [blame] | 1 | /* e_hypotf.c -- float version of e_hypot.c. |
| 2 | * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. |
| 3 | */ |
| 4 | |
| 5 | /* |
| 6 | * ==================================================== |
| 7 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| 8 | * |
| 9 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
| 10 | * Permission to use, copy, modify, and distribute this |
| 11 | * software is freely granted, provided that this notice |
| 12 | * is preserved. |
| 13 | * ==================================================== |
| 14 | */ |
| 15 | |
| 16 | #ifndef lint |
| 17 | static char rcsid[] = "$FreeBSD: src/lib/msun/src/e_hypotf.c,v 1.9 2002/05/28 18:15:03 alfred Exp $"; |
| 18 | #endif |
| 19 | |
| 20 | #include "math.h" |
| 21 | #include "math_private.h" |
| 22 | |
| 23 | float |
| 24 | __ieee754_hypotf(float x, float y) |
| 25 | { |
| 26 | float a=x,b=y,t1,t2,y1,y2,w; |
| 27 | int32_t j,k,ha,hb; |
| 28 | |
| 29 | GET_FLOAT_WORD(ha,x); |
| 30 | ha &= 0x7fffffff; |
| 31 | GET_FLOAT_WORD(hb,y); |
| 32 | hb &= 0x7fffffff; |
| 33 | if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;} |
| 34 | SET_FLOAT_WORD(a,ha); /* a <- |a| */ |
| 35 | SET_FLOAT_WORD(b,hb); /* b <- |b| */ |
| 36 | if((ha-hb)>0xf000000) {return a+b;} /* x/y > 2**30 */ |
| 37 | k=0; |
| 38 | if(ha > 0x58800000) { /* a>2**50 */ |
| 39 | if(ha >= 0x7f800000) { /* Inf or NaN */ |
| 40 | w = a+b; /* for sNaN */ |
| 41 | if(ha == 0x7f800000) w = a; |
| 42 | if(hb == 0x7f800000) w = b; |
| 43 | return w; |
| 44 | } |
| 45 | /* scale a and b by 2**-68 */ |
| 46 | ha -= 0x22000000; hb -= 0x22000000; k += 68; |
| 47 | SET_FLOAT_WORD(a,ha); |
| 48 | SET_FLOAT_WORD(b,hb); |
| 49 | } |
| 50 | if(hb < 0x26800000) { /* b < 2**-50 */ |
| 51 | if(hb <= 0x007fffff) { /* subnormal b or 0 */ |
| 52 | if(hb==0) return a; |
| 53 | SET_FLOAT_WORD(t1,0x7e800000); /* t1=2^126 */ |
| 54 | b *= t1; |
| 55 | a *= t1; |
| 56 | k -= 126; |
| 57 | } else { /* scale a and b by 2^68 */ |
| 58 | ha += 0x22000000; /* a *= 2^68 */ |
| 59 | hb += 0x22000000; /* b *= 2^68 */ |
| 60 | k -= 68; |
| 61 | SET_FLOAT_WORD(a,ha); |
| 62 | SET_FLOAT_WORD(b,hb); |
| 63 | } |
| 64 | } |
| 65 | /* medium size a and b */ |
| 66 | w = a-b; |
| 67 | if (w>b) { |
| 68 | SET_FLOAT_WORD(t1,ha&0xfffff000); |
| 69 | t2 = a-t1; |
| 70 | w = __ieee754_sqrtf(t1*t1-(b*(-b)-t2*(a+t1))); |
| 71 | } else { |
| 72 | a = a+a; |
| 73 | SET_FLOAT_WORD(y1,hb&0xfffff000); |
| 74 | y2 = b - y1; |
| 75 | SET_FLOAT_WORD(t1,ha+0x00800000); |
| 76 | t2 = a - t1; |
| 77 | w = __ieee754_sqrtf(t1*y1-(w*(-w)-(t1*y2+t2*b))); |
| 78 | } |
| 79 | if(k!=0) { |
| 80 | SET_FLOAT_WORD(t1,0x3f800000+(k<<23)); |
| 81 | return t1*w; |
| 82 | } else return w; |
| 83 | } |