124 lines
3.6 KiB
C++
124 lines
3.6 KiB
C++
--- src/trace/potrace/inkscape-potrace.cpp.orig Sat Jun 24 22:46:26 2006
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+++ src/trace/potrace/inkscape-potrace.cpp Sun Jun 25 01:29:20 2006
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@@ -54,6 +54,121 @@ static void potraceStatusCallback(double
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// (Inkscape::Trace::Potrace::PotraceTracingEngine *)userData;
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}
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+#ifndef log2
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+static const double
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+ln2 = 0.6931471805599452862268,
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+two54 = 1.80143985094819840000e+16, /* 43500000 00000000 */
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+Lg1 = 6.666666666666735130e-01, /* 3FE55555 55555593 */
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+Lg2 = 3.999999999940941908e-01, /* 3FD99999 9997FA04 */
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+Lg3 = 2.857142874366239149e-01, /* 3FD24924 94229359 */
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+Lg4 = 2.222219843214978396e-01, /* 3FCC71C5 1D8E78AF */
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+Lg5 = 1.818357216161805012e-01, /* 3FC74664 96CB03DE */
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+Lg6 = 1.531383769920937332e-01, /* 3FC39A09 D078C69F */
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+Lg7 = 1.479819860511658591e-01; /* 3FC2F112 DF3E5244 */
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+
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+static const double zero = 0.0;
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+
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+#if BYTE_ORDER == BIG_ENDIAN
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+
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+typedef union
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+{
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+ double value;
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+ struct
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+ {
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+ u_int32_t msw;
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+ u_int32_t lsw;
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+ } parts;
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+} ieee_double_shape_type;
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+
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+#endif
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+
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+#if BYTE_ORDER == LITTLE_ENDIAN
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+
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+typedef union
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+{
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+ double value;
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+ struct
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+ {
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+ u_int32_t lsw;
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+ u_int32_t msw;
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+ } parts;
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+} ieee_double_shape_type;
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+
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+#endif
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+
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+#define EXTRACT_WORDS(ix0,ix1,d) \
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+ do { \
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+ ieee_double_shape_type ew_u; \
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+ ew_u.value = (d); \
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+ (ix0) = ew_u.parts.msw; \
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+ (ix1) = ew_u.parts.lsw; \
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+ } while (0)
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+
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+#define GET_HIGH_WORD(i,d) \
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+ do { \
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+ ieee_double_shape_type gh_u; \
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+ gh_u.value = (d); \
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+ (i) = gh_u.parts.msw; \
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+ } while (0)
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+
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+#define SET_HIGH_WORD(d,v) \
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+ do { \
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+ ieee_double_shape_type sh_u; \
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+ sh_u.value = (d); \
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+ sh_u.parts.msw = (v); \
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+ (d) = sh_u.value; \
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+ } while (0)
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+
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+static double
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+_log2(double x)
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+{
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+ double hfsq,f,s,z,R,w,t1,t2,dk;
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+ int32_t k,hx,i,j;
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+ u_int32_t lx;
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+
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+ EXTRACT_WORDS(hx,lx,x);
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+
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+ k=0;
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+ if (hx < 0x00100000) { /* x < 2**-1022 */
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+ if (((hx&0x7fffffff)|lx)==0)
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+ return -two54/zero; /* log(+-0)=-inf */
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+ if (hx<0) return (x-x)/zero; /* log(-#) = NaN */
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+ k -= 54; x *= two54; /* subnormal number, scale up x */
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+ GET_HIGH_WORD(hx,x);
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+ }
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+ if (hx >= 0x7ff00000) return x+x;
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+ k += (hx>>20)-1023;
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+ hx &= 0x000fffff;
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+ i = (hx+0x95f64)&0x100000;
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+ SET_HIGH_WORD(x,hx|(i^0x3ff00000)); /* normalize x or x/2 */
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+ k += (i>>20);
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+ f = x-1.0;
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+ dk = (double)k;
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+ if((0x000fffff&(2+hx))<3) { /* |f| < 2**-20 */
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+ if (f==zero)
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+ return (dk);
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+ R = f*f*(0.5-0.33333333333333333*f);
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+ return (dk-(R-f)/ln2);
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+ }
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+ s = f/(2.0+f);
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+ z = s*s;
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+ i = hx-0x6147a;
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+ w = z*z;
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+ j = 0x6b851-hx;
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+ t1= w*(Lg2+w*(Lg4+w*Lg6));
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+ t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7)));
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+ i |= j;
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+ R = t2+t1;
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+ if(i>0) {
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+ hfsq=0.5*f*f;
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+ return (dk-(hfsq-s*(hfsq+R)-f)/ln2);
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+ } else
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+ return (dk-((s*(f-R))-f)/ln2);
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+}
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+
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+#define log2(x) _log2(x)
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+#endif
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+
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