| #include "SDL_internal.h" |
| /* |
| * ==================================================== |
| * 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_fmod(x,y) |
| * Return x mod y in exact arithmetic |
| * Method: shift and subtract |
| */ |
| |
| #include "math_libm.h" |
| #include "math_private.h" |
| |
| static const double one = 1.0, Zero[] = {0.0, -0.0,}; |
| |
| double attribute_hidden __ieee754_fmod(double x, double y) |
| { |
| int32_t n,hx,hy,hz,ix,iy,sx,i; |
| u_int32_t lx,ly,lz; |
| |
| EXTRACT_WORDS(hx,lx,x); |
| EXTRACT_WORDS(hy,ly,y); |
| sx = hx&0x80000000; /* sign of x */ |
| hx ^=sx; /* |x| */ |
| hy &= 0x7fffffff; /* |y| */ |
| |
| /* purge off exception values */ |
| if((hy|ly)==0||(hx>=0x7ff00000)|| /* y=0,or x not finite */ |
| ((hy|((ly|-(int32_t)ly)>>31))>0x7ff00000)) /* or y is NaN */ |
| return (x*y)/(x*y); |
| if(hx<=hy) { |
| if((hx<hy)||(lx<ly)) return x; /* |x|<|y| return x */ |
| if(lx==ly) |
| return Zero[(u_int32_t)sx>>31]; /* |x|=|y| return x*0*/ |
| } |
| |
| /* determine ix = ilogb(x) */ |
| if(hx<0x00100000) { /* subnormal x */ |
| if(hx==0) { |
| for (ix = -1043, i=lx; i>0; i<<=1) ix -=1; |
| } else { |
| for (ix = -1022,i=(hx<<11); i>0; i<<=1) ix -=1; |
| } |
| } else ix = (hx>>20)-1023; |
| |
| /* determine iy = ilogb(y) */ |
| if(hy<0x00100000) { /* subnormal y */ |
| if(hy==0) { |
| for (iy = -1043, i=ly; i>0; i<<=1) iy -=1; |
| } else { |
| for (iy = -1022,i=(hy<<11); i>0; i<<=1) iy -=1; |
| } |
| } else iy = (hy>>20)-1023; |
| |
| /* set up {hx,lx}, {hy,ly} and align y to x */ |
| if(ix >= -1022) |
| hx = 0x00100000|(0x000fffff&hx); |
| else { /* subnormal x, shift x to normal */ |
| n = -1022-ix; |
| if(n<=31) { |
| hx = (hx<<n)|(lx>>(32-n)); |
| lx <<= n; |
| } else { |
| hx = lx<<(n-32); |
| lx = 0; |
| } |
| } |
| if(iy >= -1022) |
| hy = 0x00100000|(0x000fffff&hy); |
| else { /* subnormal y, shift y to normal */ |
| n = -1022-iy; |
| if(n<=31) { |
| hy = (hy<<n)|(ly>>(32-n)); |
| ly <<= n; |
| } else { |
| hy = ly<<(n-32); |
| ly = 0; |
| } |
| } |
| |
| /* fix point fmod */ |
| n = ix - iy; |
| while(n--) { |
| hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1; |
| if(hz<0){hx = hx+hx+(lx>>31); lx = lx+lx;} |
| else { |
| if((hz|lz)==0) /* return sign(x)*0 */ |
| return Zero[(u_int32_t)sx>>31]; |
| hx = hz+hz+(lz>>31); lx = lz+lz; |
| } |
| } |
| hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1; |
| if(hz>=0) {hx=hz;lx=lz;} |
| |
| /* convert back to floating value and restore the sign */ |
| if((hx|lx)==0) /* return sign(x)*0 */ |
| return Zero[(u_int32_t)sx>>31]; |
| while(hx<0x00100000) { /* normalize x */ |
| hx = hx+hx+(lx>>31); lx = lx+lx; |
| iy -= 1; |
| } |
| if(iy>= -1022) { /* normalize output */ |
| hx = ((hx-0x00100000)|((iy+1023)<<20)); |
| INSERT_WORDS(x,hx|sx,lx); |
| } else { /* subnormal output */ |
| n = -1022 - iy; |
| if(n<=20) { |
| lx = (lx>>n)|((u_int32_t)hx<<(32-n)); |
| hx >>= n; |
| } else if (n<=31) { |
| lx = (hx<<(32-n))|(lx>>n); hx = sx; |
| } else { |
| lx = hx>>(n-32); hx = sx; |
| } |
| INSERT_WORDS(x,hx|sx,lx); |
| x *= one; /* create necessary signal */ |
| } |
| return x; /* exact output */ |
| } |
| |
| /* |
| * wrapper fmod(x,y) |
| */ |
| #ifndef _IEEE_LIBM |
| double fmod(double x, double y) |
| { |
| double z = __ieee754_fmod(x, y); |
| if (_LIB_VERSION == _IEEE_ || isnan(y) || isnan(x)) |
| return z; |
| if (y == 0.0) |
| return __kernel_standard(x, y, 27); /* fmod(x,0) */ |
| return z; |
| } |
| #else |
| strong_alias(__ieee754_fmod, fmod) |
| #endif |
| libm_hidden_def(fmod) |