1 /* ef_hypot.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 #include "fdlibm.h" 17 18 #ifdef __STDC__ __ieee754_hypotf(float x,float y)19 float __ieee754_hypotf(float x, float y) 20 #else 21 float __ieee754_hypotf(x,y) 22 float x, y; 23 #endif 24 { 25 float a=x,b=y,t1,t2,y1,y2,w; 26 __int32_t j,k,ha,hb; 27 28 GET_FLOAT_WORD(ha,x); 29 ha &= 0x7fffffffL; 30 GET_FLOAT_WORD(hb,y); 31 hb &= 0x7fffffffL; 32 if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;} 33 SET_FLOAT_WORD(a,ha); /* a <- |a| */ 34 SET_FLOAT_WORD(b,hb); /* b <- |b| */ 35 if((ha-hb)>0xf000000L) {return a+b;} /* x/y > 2**30 */ 36 k=0; 37 if(ha > 0x58800000L) { /* a>2**50 */ 38 if(!FLT_UWORD_IS_FINITE(ha)) { /* Inf or NaN */ 39 w = a+b; /* for sNaN */ 40 if(FLT_UWORD_IS_INFINITE(ha)) w = a; 41 if(FLT_UWORD_IS_INFINITE(hb)) w = b; 42 return w; 43 } 44 /* scale a and b by 2**-68 */ 45 ha -= 0x22000000L; hb -= 0x22000000L; k += 68; 46 SET_FLOAT_WORD(a,ha); 47 SET_FLOAT_WORD(b,hb); 48 } 49 if(hb < 0x26800000L) { /* b < 2**-50 */ 50 if(FLT_UWORD_IS_ZERO(hb)) { 51 return a; 52 } else if(FLT_UWORD_IS_SUBNORMAL(hb)) { 53 SET_FLOAT_WORD(t1,0x3f000000L); /* 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&0xfffff000L); 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&0xfffff000L); 74 y2 = b - y1; 75 SET_FLOAT_WORD(t1,ha+0x00800000L); 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(t1,0x3f800000L+(k<<23)); 81 return t1*w; 82 } else return w; 83 } 84