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comparison src/video/e_log.h @ 1662:782fd950bd46 SDL-1.3

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Revamp of the video system in progress - adding support for multiple displays, multiple windows, and a full video mode selection API. WARNING: None of the video drivers have been updated for the new API yet! The API is still under design and very fluid. The code is now run through a consistent indent format: indent -i4 -nut -nsc -br -ce The headers are being converted to automatically generate doxygen documentation.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 28 May 2006 13:04:16 +0000
parents 450721ad5436
children 4da1ee79c9af
comparison
equal deleted inserted replaced
1661:281d3f4870e5 1662:782fd950bd46
71 #ifdef __STDC__ 71 #ifdef __STDC__
72 static const double 72 static const double
73 #else 73 #else
74 static double 74 static double
75 #endif 75 #endif
76 ln2_hi = 6.93147180369123816490e-01, /* 3fe62e42 fee00000 */ 76 ln2_hi = 6.93147180369123816490e-01, /* 3fe62e42 fee00000 */
77 ln2_lo = 1.90821492927058770002e-10, /* 3dea39ef 35793c76 */ 77 ln2_lo = 1.90821492927058770002e-10, /* 3dea39ef 35793c76 */
78 Lg1 = 6.666666666666735130e-01, /* 3FE55555 55555593 */ 78 Lg1 = 6.666666666666735130e-01, /* 3FE55555 55555593 */
79 Lg2 = 3.999999999940941908e-01, /* 3FD99999 9997FA04 */ 79 Lg2 = 3.999999999940941908e-01, /* 3FD99999 9997FA04 */
80 Lg3 = 2.857142874366239149e-01, /* 3FD24924 94229359 */ 80 Lg3 = 2.857142874366239149e-01, /* 3FD24924 94229359 */
81 Lg4 = 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */ 81 Lg4 = 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */
82 Lg5 = 1.818357216161805012e-01, /* 3FC74664 96CB03DE */ 82 Lg5 = 1.818357216161805012e-01, /* 3FC74664 96CB03DE */
83 Lg6 = 1.531383769920937332e-01, /* 3FC39A09 D078C69F */ 83 Lg6 = 1.531383769920937332e-01, /* 3FC39A09 D078C69F */
84 Lg7 = 1.479819860511658591e-01; /* 3FC2F112 DF3E5244 */ 84 Lg7 = 1.479819860511658591e-01; /* 3FC2F112 DF3E5244 */
85 85
86 #ifdef __STDC__ 86 #ifdef __STDC__
87 double __ieee754_log(double x) 87 double
88 __ieee754_log (double x)
88 #else 89 #else
89 double __ieee754_log(x) 90 double
90 double x; 91 __ieee754_log (x)
92 double x;
91 #endif 93 #endif
92 { 94 {
93 double hfsq,f,s,z,R,w,t1,t2,dk; 95 double hfsq, f, s, z, R, w, t1, t2, dk;
94 int32_t k,hx,i,j; 96 int32_t k, hx, i, j;
95 u_int32_t lx; 97 u_int32_t lx;
96 98
97 EXTRACT_WORDS(hx,lx,x); 99 EXTRACT_WORDS (hx, lx, x);
98 100
99 k=0; 101 k = 0;
100 if (hx < 0x00100000) { /* x < 2**-1022 */ 102 if (hx < 0x00100000) { /* x < 2**-1022 */
101 if (((hx&0x7fffffff)|lx)==0) 103 if (((hx & 0x7fffffff) | lx) == 0)
102 return -two54/zero; /* log(+-0)=-inf */ 104 return -two54 / zero; /* log(+-0)=-inf */
103 if (hx<0) return (x-x)/zero; /* log(-#) = NaN */ 105 if (hx < 0)
104 k -= 54; x *= two54; /* subnormal number, scale up x */ 106 return (x - x) / zero; /* log(-#) = NaN */
105 GET_HIGH_WORD(hx,x); 107 k -= 54;
106 } 108 x *= two54; /* subnormal number, scale up x */
107 if (hx >= 0x7ff00000) return x+x; 109 GET_HIGH_WORD (hx, x);
108 k += (hx>>20)-1023; 110 }
109 hx &= 0x000fffff; 111 if (hx >= 0x7ff00000)
110 i = (hx+0x95f64)&0x100000; 112 return x + x;
111 SET_HIGH_WORD(x,hx|(i^0x3ff00000)); /* normalize x or x/2 */ 113 k += (hx >> 20) - 1023;
112 k += (i>>20); 114 hx &= 0x000fffff;
113 f = x-1.0; 115 i = (hx + 0x95f64) & 0x100000;
114 if((0x000fffff&(2+hx))<3) { /* |f| < 2**-20 */ 116 SET_HIGH_WORD (x, hx | (i ^ 0x3ff00000)); /* normalize x or x/2 */
115 if(f==zero) {if(k==0) return zero; else {dk=(double)k; 117 k += (i >> 20);
116 return dk*ln2_hi+dk*ln2_lo;} 118 f = x - 1.0;
117 } 119 if ((0x000fffff & (2 + hx)) < 3) { /* |f| < 2**-20 */
118 R = f*f*(0.5-0.33333333333333333*f); 120 if (f == zero) {
119 if(k==0) return f-R; else {dk=(double)k; 121 if (k == 0)
120 return dk*ln2_hi-((R-dk*ln2_lo)-f);} 122 return zero;
121 } 123 else {
122 s = f/(2.0+f); 124 dk = (double) k;
123 dk = (double)k; 125 return dk * ln2_hi + dk * ln2_lo;
124 z = s*s; 126 }
125 i = hx-0x6147a; 127 }
126 w = z*z; 128 R = f * f * (0.5 - 0.33333333333333333 * f);
127 j = 0x6b851-hx; 129 if (k == 0)
128 t1= w*(Lg2+w*(Lg4+w*Lg6)); 130 return f - R;
129 t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7))); 131 else {
130 i |= j; 132 dk = (double) k;
131 R = t2+t1; 133 return dk * ln2_hi - ((R - dk * ln2_lo) - f);
132 if(i>0) { 134 }
133 hfsq=0.5*f*f; 135 }
134 if(k==0) return f-(hfsq-s*(hfsq+R)); else 136 s = f / (2.0 + f);
135 return dk*ln2_hi-((hfsq-(s*(hfsq+R)+dk*ln2_lo))-f); 137 dk = (double) k;
136 } else { 138 z = s * s;
137 if(k==0) return f-s*(f-R); else 139 i = hx - 0x6147a;
138 return dk*ln2_hi-((s*(f-R)-dk*ln2_lo)-f); 140 w = z * z;
139 } 141 j = 0x6b851 - hx;
142 t1 = w * (Lg2 + w * (Lg4 + w * Lg6));
143 t2 = z * (Lg1 + w * (Lg3 + w * (Lg5 + w * Lg7)));
144 i |= j;
145 R = t2 + t1;
146 if (i > 0) {
147 hfsq = 0.5 * f * f;
148 if (k == 0)
149 return f - (hfsq - s * (hfsq + R));
150 else
151 return dk * ln2_hi - ((hfsq - (s * (hfsq + R) + dk * ln2_lo)) -
152 f);
153 } else {
154 if (k == 0)
155 return f - s * (f - R);
156 else
157 return dk * ln2_hi - ((s * (f - R) - dk * ln2_lo) - f);
158 }
140 } 159 }
160
161 /* vi: set ts=4 sw=4 expandtab: */