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118 lines
2.2 KiB
118 lines
2.2 KiB
//========================================================================
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//
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// FixedPoint.cc
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//
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// Fixed point type, with C++ operators.
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//
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// Copyright 2004 Glyph & Cog, LLC
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//
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//========================================================================
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#include <aconf.h>
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#if USE_FIXEDPOINT
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#ifdef USE_GCC_PRAGMAS
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#pragma implementation
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#endif
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#include "FixedPoint.h"
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#define ln2 ((FixedPoint)0.69314718)
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FixedPoint FixedPoint::sqrt(FixedPoint x) {
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FixedPoint y0, y1, z;
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if (x.val <= 0) {
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y1.val = 0;
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} else {
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y1.val = x.val == 1 ? 2 : x.val >> 1;
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do {
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y0.val = y1.val;
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z = x / y0;
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y1.val = (y0.val + z.val) >> 1;
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} while (::abs(y0.val - y1.val) > 1);
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}
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return y1;
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}
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FixedPoint FixedPoint::pow(FixedPoint x, FixedPoint y) {
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FixedPoint t, t2, lnx0, lnx, z0, z;
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int d, n, i;
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if (y.val <= 0) {
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z.val = 0;
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} else {
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// y * ln(x)
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t = (x - 1) / (x + 1);
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t2 = t * t;
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d = 1;
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lnx = 0;
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do {
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lnx0 = lnx;
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lnx += t / d;
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t *= t2;
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d += 2;
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} while (::abs(lnx.val - lnx0.val) > 2);
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lnx.val <<= 1;
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t = y * lnx;
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// exp(y * ln(x))
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n = floor(t / ln2);
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t -= ln2 * n;
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t2 = t;
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d = 1;
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i = 1;
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z = 1;
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do {
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z0 = z;
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z += t2 / d;
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t2 *= t;
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++i;
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d *= i;
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} while (::abs(z.val - z0.val) > 2 && d < (1 << fixptShift));
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if (n >= 0) {
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z.val <<= n;
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} else if (n < 0) {
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z.val >>= -n;
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}
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}
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return z;
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}
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int FixedPoint::mul(int x, int y) {
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#if 1 //~tmp
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return ((FixPtInt64)x * y) >> fixptShift;
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#else
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int ah0, ah, bh, al, bl;
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ah0 = x & fixptMaskH;
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ah = x >> fixptShift;
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al = x - ah0;
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bh = y >> fixptShift;
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bl = y - (bh << fixptShift);
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return ah0 * bh + ah * bl + al * bh + ((al * bl) >> fixptShift);
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#endif
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}
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int FixedPoint::div(int x, int y) {
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#if 1 //~tmp
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return ((FixPtInt64)x << fixptShift) / y;
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#else
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#endif
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}
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GBool FixedPoint::divCheck(FixedPoint x, FixedPoint y, FixedPoint *result) {
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#if 1 //~tmp
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FixPtInt64 z;
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z = ((FixPtInt64)x.val << fixptShift) / y.val;
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if ((z == 0 && x != 0) ||
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z >= ((FixPtInt64)1 << 31) || z < -((FixPtInt64)1 << 31)) {
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return gFalse;
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}
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result->val = z;
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return gTrue;
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#else
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#endif
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}
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#endif // USE_FIXEDPOINT
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