| /* |
| * ==================================================== |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| * |
| * Developed at SunPro, a Sun Microsystems, Inc. business. |
| * Permission to use, copy, modify, and distribute this |
| * software is freely granted, provided that this notice |
| * is preserved. |
| * ==================================================== |
| */ |
| |
| /* |
| * __ieee754_fmodf(x,y) |
| * Return x mod y in exact arithmetic |
| * Method: shift and subtract |
| */ |
| |
| #include "bsd_privatef.h" |
| |
| float bsd__ieee754_fmodf(float x, float y) |
| { |
| int32_t n,hx,hy,hz,ix,iy,sx,i; |
| |
| GET_FLOAT_WORD(hx,x); |
| GET_FLOAT_WORD(hy,y); |
| sx = hx&0x80000000; /* sign of x */ |
| hx ^=sx; /* |x| */ |
| hy &= 0x7fffffff; /* |y| */ |
| |
| /* purge off exception values */ |
| if(hy==0||(hx>=0x7f800000)|| /* y=0,or x not finite */ |
| (hy>0x7f800000)) /* or y is NaN */ |
| return (x*y)/(x*y); |
| if(hx<hy) return x; /* |x|<|y| return x */ |
| if(hx==hy) |
| return Zero[(u_int32_t)sx>>31]; /* |x|=|y| return x*0*/ |
| |
| /* determine ix = ilogb(x) */ |
| if(hx<0x00800000) { /* subnormal x */ |
| for (ix = -126,i=(hx<<8); i>0; i<<=1) ix -=1; |
| } else ix = (hx>>23)-127; |
| |
| /* determine iy = ilogb(y) */ |
| if(hy<0x00800000) { /* subnormal y */ |
| for (iy = -126,i=(hy<<8); i>=0; i<<=1) iy -=1; |
| } else iy = (hy>>23)-127; |
| |
| /* set up {hx,lx}, {hy,ly} and align y to x */ |
| if(ix >= -126) |
| hx = 0x00800000|(0x007fffff&hx); |
| else { /* subnormal x, shift x to normal */ |
| n = -126-ix; |
| hx = hx<<n; |
| } |
| if(iy >= -126) |
| hy = 0x00800000|(0x007fffff&hy); |
| else { /* subnormal y, shift y to normal */ |
| n = -126-iy; |
| hy = hy<<n; |
| } |
| |
| /* fix point fmod */ |
| n = ix - iy; |
| while(n--) { |
| hz=hx-hy; |
| if(hz<0){hx = hx+hx;} |
| else { |
| if(hz==0) /* return sign(x)*0 */ |
| return Zero[(u_int32_t)sx>>31]; |
| hx = hz+hz; |
| } |
| } |
| hz=hx-hy; |
| if(hz>=0) {hx=hz;} |
| |
| /* convert back to floating value and restore the sign */ |
| if(hx==0) /* return sign(x)*0 */ |
| return Zero[(u_int32_t)sx>>31]; |
| while(hx<0x00800000) { /* normalize x */ |
| hx = hx+hx; |
| iy -= 1; |
| } |
| if(iy>= -126) { /* normalize output */ |
| hx = ((hx-0x00800000)|((iy+127)<<23)); |
| SET_FLOAT_WORD(x,hx|sx); |
| } else { /* subnormal output */ |
| n = -126 - iy; |
| hx >>= n; |
| SET_FLOAT_WORD(x,hx|sx); |
| x *= one; /* create necessary signal */ |
| } |
| return x; /* exact output */ |
| } |
