248 lines
7.8 KiB
C
248 lines
7.8 KiB
C
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//----------------------------------------------------------------------------
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// Anti-Grain Geometry - Version 2.2
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// Copyright (C) 2002-2004 Maxim Shemanarev (http://www.antigrain.com)
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//
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// Permission to copy, use, modify, sell and distribute this software
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// is granted provided this copyright notice appears in all copies.
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// This software is provided "as is" without express or implied
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// warranty, and with no claim as to its suitability for any purpose.
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//
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//----------------------------------------------------------------------------
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// Contact: mcseem@antigrain.com
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// mcseemagg@yahoo.com
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// http://www.antigrain.com
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//----------------------------------------------------------------------------
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#ifndef AGG_MATH_INCLUDED
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#define AGG_MATH_INCLUDED
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#include <math.h>
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#include "agg_basics.h"
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namespace agg
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{
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const double intersection_epsilon = 1.0e-8;
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//------------------------------------------------------calc_point_location
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inline double calc_point_location(double x1, double y1,
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double x2, double y2,
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double x, double y)
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{
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return (x - x2) * (y2 - y1) - (y - y2) * (x2 - x1);
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}
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//--------------------------------------------------------point_in_triangle
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inline bool point_in_triangle(double x1, double y1,
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double x2, double y2,
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double x3, double y3,
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double x, double y)
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{
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bool cp1 = calc_point_location(x1, y1, x2, y2, x, y) < 0.0;
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bool cp2 = calc_point_location(x2, y2, x3, y3, x, y) < 0.0;
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bool cp3 = calc_point_location(x3, y3, x1, y1, x, y) < 0.0;
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return cp1 == cp2 && cp2 == cp3 && cp3 == cp1;
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}
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//-----------------------------------------------------------calc_distance
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inline double calc_distance(double x1, double y1, double x2, double y2)
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{
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double dx = x2-x1;
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double dy = y2-y1;
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return sqrt(dx * dx + dy * dy);
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}
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//------------------------------------------------calc_point_line_distance
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inline double calc_point_line_distance(double x1, double y1,
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double x2, double y2,
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double x, double y)
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{
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double dx = x2-x1;
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double dy = y2-y1;
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return ((x - x2) * dy - (y - y2) * dx) / sqrt(dx * dx + dy * dy);
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}
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//-------------------------------------------------------calc_intersection
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inline bool calc_intersection(double ax, double ay, double bx, double by,
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double cx, double cy, double dx, double dy,
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double* x, double* y)
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{
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double num = (ay-cy) * (dx-cx) - (ax-cx) * (dy-cy);
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double den = (bx-ax) * (dy-cy) - (by-ay) * (dx-cx);
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if(fabs(den) < intersection_epsilon) return false;
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double r = num / den;
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*x = ax + r * (bx-ax);
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*y = ay + r * (by-ay);
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return true;
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}
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//--------------------------------------------------------calc_orthogonal
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inline void calc_orthogonal(double thickness,
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double x1, double y1,
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double x2, double y2,
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double* x, double* y)
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{
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double dx = x2 - x1;
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double dy = y2 - y1;
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double d = sqrt(dx*dx + dy*dy);
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*x = thickness * dy / d;
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*y = thickness * dx / d;
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}
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//--------------------------------------------------------dilate_triangle
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inline void dilate_triangle(double x1, double y1,
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double x2, double y2,
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double x3, double y3,
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double *x, double* y,
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double d)
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{
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double dx1=0.0;
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double dy1=0.0;
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double dx2=0.0;
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double dy2=0.0;
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double dx3=0.0;
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double dy3=0.0;
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double loc = calc_point_location(x1, y1, x2, y2, x3, y3);
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if(fabs(loc) > intersection_epsilon)
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{
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if(calc_point_location(x1, y1, x2, y2, x3, y3) > 0.0)
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{
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d = -d;
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}
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calc_orthogonal(d, x1, y1, x2, y2, &dx1, &dy1);
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calc_orthogonal(d, x2, y2, x3, y3, &dx2, &dy2);
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calc_orthogonal(d, x3, y3, x1, y1, &dx3, &dy3);
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}
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*x++ = x1 + dx1; *y++ = y1 - dy1;
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*x++ = x2 + dx1; *y++ = y2 - dy1;
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*x++ = x2 + dx2; *y++ = y2 - dy2;
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*x++ = x3 + dx2; *y++ = y3 - dy2;
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*x++ = x3 + dx3; *y++ = y3 - dy3;
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*x++ = x1 + dx3; *y++ = y1 - dy3;
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}
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//-------------------------------------------------------calc_polygon_area
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template<class Storage> double calc_polygon_area(const Storage& st)
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{
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unsigned i;
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double sum = 0.0;
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double x = st[0].x;
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double y = st[0].y;
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double xs = x;
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double ys = y;
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for(i = 1; i < st.size(); i++)
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{
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const typename Storage::value_type& v = st[i];
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sum += x * v.y - y * v.x;
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x = v.x;
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y = v.y;
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}
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return (sum + x * ys - y * xs) * 0.5;
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}
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//------------------------------------------------------------------------
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// Tables for fast sqrt
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extern int16u g_sqrt_table[1024];
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extern int8 g_elder_bit_table[256];
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//---------------------------------------------------------------fast_sqrt
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//Fast integer Sqrt - really fast: no cycles, divisions or multiplications
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#if defined(_MSC_VER)
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#pragma warning(push)
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#pragma warning(disable : 4035) //Disable warning "no return value"
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#endif
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inline unsigned fast_sqrt(unsigned val)
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{
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#if defined(_M_IX86) && defined(_MSC_VER) && !defined(AGG_NO_ASM)
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//For Ix86 family processors this assembler code is used.
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//The key command here is bsr - determination the number of the most
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//significant bit of the value. For other processors
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//(and maybe compilers) the pure C "#else" section is used.
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__asm
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{
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mov ebx, val
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mov edx, 11
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bsr ecx, ebx
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sub ecx, 9
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jle less_than_9_bits
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shr ecx, 1
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adc ecx, 0
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sub edx, ecx
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shl ecx, 1
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shr ebx, cl
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less_than_9_bits:
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xor eax, eax
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mov ax, g_sqrt_table[ebx*2]
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mov ecx, edx
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shr eax, cl
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}
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#else
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//This code is actually pure C and portable to most
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//arcitectures including 64bit ones.
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unsigned t = val;
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int bit=0;
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unsigned shift = 11;
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//The following piece of code is just an emulation of the
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//Ix86 assembler command "bsr" (see above). However on old
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//Intels (like Intel MMX 233MHz) this code is about twice
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//faster (sic!) then just one "bsr". On PIII and PIV the
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//bsr is optimized quite well.
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bit = t >> 24;
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if(bit)
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{
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bit = g_elder_bit_table[bit] + 24;
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}
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else
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{
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bit = (t >> 16) & 0xFF;
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if(bit)
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{
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bit = g_elder_bit_table[bit] + 16;
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}
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else
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{
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bit = (t >> 8) & 0xFF;
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if(bit)
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{
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bit = g_elder_bit_table[bit] + 8;
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}
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else
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{
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bit = g_elder_bit_table[t];
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}
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}
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}
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//This is calculation sqrt itself.
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bit -= 9;
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if(bit > 0)
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{
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bit = (bit >> 1) + (bit & 1);
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shift -= bit;
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val >>= (bit << 1);
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}
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return g_sqrt_table[val] >> shift;
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#endif
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}
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#if defined(_MSC_VER)
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#pragma warning(pop)
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#endif
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}
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#endif
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