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author | Franklin Wei <git@fwei.tk> | 2017-01-21 15:18:31 -0500 |
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committer | Franklin Wei <git@fwei.tk> | 2017-12-23 21:01:26 -0500 |
commit | a855d6202536ff28e5aae4f22a0f31d8f5b325d0 (patch) | |
tree | 8c75f224dd64ed360505afa8843d016b0d75000b /apps/plugins/sdl/src/video/e_log.h | |
parent | 01c6dcf6c7b9bb1ad2fa0450f99bacc5f3d3e04b (diff) | |
download | rockbox-a855d6202536ff28e5aae4f22a0f31d8f5b325d0.tar.gz rockbox-a855d6202536ff28e5aae4f22a0f31d8f5b325d0.zip |
Port of Duke Nukem 3D
This ports Fabien Sanglard's Chocolate Duke to run on a version of SDL
for Rockbox.
Change-Id: I8f2c4c78af19de10c1633ed7bb7a997b43256dd9
Diffstat (limited to 'apps/plugins/sdl/src/video/e_log.h')
-rw-r--r-- | apps/plugins/sdl/src/video/e_log.h | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/apps/plugins/sdl/src/video/e_log.h b/apps/plugins/sdl/src/video/e_log.h new file mode 100644 index 0000000000..7f8bf71614 --- /dev/null +++ b/apps/plugins/sdl/src/video/e_log.h | |||
@@ -0,0 +1,140 @@ | |||
1 | /* @(#)e_log.c 5.1 93/09/24 */ | ||
2 | /* | ||
3 | * ==================================================== | ||
4 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. | ||
5 | * | ||
6 | * Developed at SunPro, a Sun Microsystems, Inc. business. | ||
7 | * Permission to use, copy, modify, and distribute this | ||
8 | * software is freely granted, provided that this notice | ||
9 | * is preserved. | ||
10 | * ==================================================== | ||
11 | */ | ||
12 | |||
13 | #if defined(LIBM_SCCS) && !defined(lint) | ||
14 | static char rcsid[] = "$NetBSD: e_log.c,v 1.8 1995/05/10 20:45:49 jtc Exp $"; | ||
15 | #endif | ||
16 | |||
17 | /* __ieee754_log(x) | ||
18 | * Return the logrithm of x | ||
19 | * | ||
20 | * Method : | ||
21 | * 1. Argument Reduction: find k and f such that | ||
22 | * x = 2^k * (1+f), | ||
23 | * where sqrt(2)/2 < 1+f < sqrt(2) . | ||
24 | * | ||
25 | * 2. Approximation of log(1+f). | ||
26 | * Let s = f/(2+f) ; based on log(1+f) = log(1+s) - log(1-s) | ||
27 | * = 2s + 2/3 s**3 + 2/5 s**5 + ....., | ||
28 | * = 2s + s*R | ||
29 | * We use a special Reme algorithm on [0,0.1716] to generate | ||
30 | * a polynomial of degree 14 to approximate R The maximum error | ||
31 | * of this polynomial approximation is bounded by 2**-58.45. In | ||
32 | * other words, | ||
33 | * 2 4 6 8 10 12 14 | ||
34 | * R(z) ~ Lg1*s +Lg2*s +Lg3*s +Lg4*s +Lg5*s +Lg6*s +Lg7*s | ||
35 | * (the values of Lg1 to Lg7 are listed in the program) | ||
36 | * and | ||
37 | * | 2 14 | -58.45 | ||
38 | * | Lg1*s +...+Lg7*s - R(z) | <= 2 | ||
39 | * | | | ||
40 | * Note that 2s = f - s*f = f - hfsq + s*hfsq, where hfsq = f*f/2. | ||
41 | * In order to guarantee error in log below 1ulp, we compute log | ||
42 | * by | ||
43 | * log(1+f) = f - s*(f - R) (if f is not too large) | ||
44 | * log(1+f) = f - (hfsq - s*(hfsq+R)). (better accuracy) | ||
45 | * | ||
46 | * 3. Finally, log(x) = k*ln2 + log(1+f). | ||
47 | * = k*ln2_hi+(f-(hfsq-(s*(hfsq+R)+k*ln2_lo))) | ||
48 | * Here ln2 is split into two floating point number: | ||
49 | * ln2_hi + ln2_lo, | ||
50 | * where n*ln2_hi is always exact for |n| < 2000. | ||
51 | * | ||
52 | * Special cases: | ||
53 | * log(x) is NaN with signal if x < 0 (including -INF) ; | ||
54 | * log(+INF) is +INF; log(0) is -INF with signal; | ||
55 | * log(NaN) is that NaN with no signal. | ||
56 | * | ||
57 | * Accuracy: | ||
58 | * according to an error analysis, the error is always less than | ||
59 | * 1 ulp (unit in the last place). | ||
60 | * | ||
61 | * Constants: | ||
62 | * The hexadecimal values are the intended ones for the following | ||
63 | * constants. The decimal values may be used, provided that the | ||
64 | * compiler will convert from decimal to binary accurately enough | ||
65 | * to produce the hexadecimal values shown. | ||
66 | */ | ||
67 | |||
68 | /*#include "math.h"*/ | ||
69 | #include "math_private.h" | ||
70 | |||
71 | #ifdef __STDC__ | ||
72 | static const double | ||
73 | #else | ||
74 | static double | ||
75 | #endif | ||
76 | ln2_hi = 6.93147180369123816490e-01, /* 3fe62e42 fee00000 */ | ||
77 | ln2_lo = 1.90821492927058770002e-10, /* 3dea39ef 35793c76 */ | ||
78 | Lg1 = 6.666666666666735130e-01, /* 3FE55555 55555593 */ | ||
79 | Lg2 = 3.999999999940941908e-01, /* 3FD99999 9997FA04 */ | ||
80 | Lg3 = 2.857142874366239149e-01, /* 3FD24924 94229359 */ | ||
81 | Lg4 = 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */ | ||
82 | Lg5 = 1.818357216161805012e-01, /* 3FC74664 96CB03DE */ | ||
83 | Lg6 = 1.531383769920937332e-01, /* 3FC39A09 D078C69F */ | ||
84 | Lg7 = 1.479819860511658591e-01; /* 3FC2F112 DF3E5244 */ | ||
85 | |||
86 | #ifdef __STDC__ | ||
87 | double __ieee754_log(double x) | ||
88 | #else | ||
89 | double __ieee754_log(x) | ||
90 | double x; | ||
91 | #endif | ||
92 | { | ||
93 | double hfsq,f,s,z,R,w,t1,t2,dk; | ||
94 | int32_t k,hx,i,j; | ||
95 | u_int32_t lx; | ||
96 | |||
97 | EXTRACT_WORDS(hx,lx,x); | ||
98 | |||
99 | k=0; | ||
100 | if (hx < 0x00100000) { /* x < 2**-1022 */ | ||
101 | if (((hx&0x7fffffff)|lx)==0) | ||
102 | return -two54/zero; /* log(+-0)=-inf */ | ||
103 | if (hx<0) return (x-x)/zero; /* log(-#) = NaN */ | ||
104 | k -= 54; x *= two54; /* subnormal number, scale up x */ | ||
105 | GET_HIGH_WORD(hx,x); | ||
106 | } | ||
107 | if (hx >= 0x7ff00000) return x+x; | ||
108 | k += (hx>>20)-1023; | ||
109 | hx &= 0x000fffff; | ||
110 | i = (hx+0x95f64)&0x100000; | ||
111 | SET_HIGH_WORD(x,hx|(i^0x3ff00000)); /* normalize x or x/2 */ | ||
112 | k += (i>>20); | ||
113 | f = x-1.0; | ||
114 | if((0x000fffff&(2+hx))<3) { /* |f| < 2**-20 */ | ||
115 | if(f==zero) {if(k==0) return zero; else {dk=(double)k; | ||
116 | return dk*ln2_hi+dk*ln2_lo;} | ||
117 | } | ||
118 | R = f*f*(0.5-0.33333333333333333*f); | ||
119 | if(k==0) return f-R; else {dk=(double)k; | ||
120 | return dk*ln2_hi-((R-dk*ln2_lo)-f);} | ||
121 | } | ||
122 | s = f/(2.0+f); | ||
123 | dk = (double)k; | ||
124 | z = s*s; | ||
125 | i = hx-0x6147a; | ||
126 | w = z*z; | ||
127 | j = 0x6b851-hx; | ||
128 | t1= w*(Lg2+w*(Lg4+w*Lg6)); | ||
129 | t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7))); | ||
130 | i |= j; | ||
131 | R = t2+t1; | ||
132 | if(i>0) { | ||
133 | hfsq=0.5*f*f; | ||
134 | if(k==0) return f-(hfsq-s*(hfsq+R)); else | ||
135 | return dk*ln2_hi-((hfsq-(s*(hfsq+R)+dk*ln2_lo))-f); | ||
136 | } else { | ||
137 | if(k==0) return f-s*(f-R); else | ||
138 | return dk*ln2_hi-((s*(f-R)-dk*ln2_lo)-f); | ||
139 | } | ||
140 | } | ||