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Diffstat (limited to 'gfx/cairo/cairo/src/cairo-fixed-private.h')
| -rw-r--r-- | gfx/cairo/cairo/src/cairo-fixed-private.h | 358 |
1 files changed, 358 insertions, 0 deletions
diff --git a/gfx/cairo/cairo/src/cairo-fixed-private.h b/gfx/cairo/cairo/src/cairo-fixed-private.h new file mode 100644 index 000000000..9478d7d4f --- /dev/null +++ b/gfx/cairo/cairo/src/cairo-fixed-private.h @@ -0,0 +1,358 @@ +/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */ +/* Cairo - a vector graphics library with display and print output + * + * Copyright © 2007 Mozilla Corporation + * + * This library is free software; you can redistribute it and/or + * modify it either under the terms of the GNU Lesser General Public + * License version 2.1 as published by the Free Software Foundation + * (the "LGPL") or, at your option, under the terms of the Mozilla + * Public License Version 1.1 (the "MPL"). If you do not alter this + * notice, a recipient may use your version of this file under either + * the MPL or the LGPL. + * + * You should have received a copy of the LGPL along with this library + * in the file COPYING-LGPL-2.1; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA + * You should have received a copy of the MPL along with this library + * in the file COPYING-MPL-1.1 + * + * The contents of this file are subject to the Mozilla Public License + * Version 1.1 (the "License"); you may not use this file except in + * compliance with the License. You may obtain a copy of the License at + * http://www.mozilla.org/MPL/ + * + * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY + * OF ANY KIND, either express or implied. See the LGPL or the MPL for + * the specific language governing rights and limitations. + * + * The Original Code is the cairo graphics library. + * + * The Initial Developer of the Original Code is Mozilla Foundation + * + * Contributor(s): + * Vladimir Vukicevic <vladimir@pobox.com> + */ + +#ifndef CAIRO_FIXED_PRIVATE_H +#define CAIRO_FIXED_PRIVATE_H + +#include "cairo-fixed-type-private.h" + +#include "cairo-wideint-private.h" + +/* Implementation */ + +#if (CAIRO_FIXED_BITS != 32) +# error CAIRO_FIXED_BITS must be 32, and the type must be a 32-bit type. +# error To remove this limitation, you will have to fix the tesselator. +#endif + +#define CAIRO_FIXED_ONE ((cairo_fixed_t)(1 << CAIRO_FIXED_FRAC_BITS)) +#define CAIRO_FIXED_ONE_DOUBLE ((double)(1 << CAIRO_FIXED_FRAC_BITS)) +#define CAIRO_FIXED_ONE_FLOAT ((float)(1 << CAIRO_FIXED_FRAC_BITS)) +#define CAIRO_FIXED_EPSILON ((cairo_fixed_t)(1)) + +#define CAIRO_FIXED_FRAC_MASK ((cairo_fixed_t)(((cairo_fixed_unsigned_t)(-1)) >> (CAIRO_FIXED_BITS - CAIRO_FIXED_FRAC_BITS))) +#define CAIRO_FIXED_WHOLE_MASK (~CAIRO_FIXED_FRAC_MASK) + +static inline cairo_fixed_t +_cairo_fixed_from_int (int i) +{ + return i << CAIRO_FIXED_FRAC_BITS; +} + +/* This is the "magic number" approach to converting a double into fixed + * point as described here: + * + * http://www.stereopsis.com/sree/fpu2006.html (an overview) + * http://www.d6.com/users/checker/pdfs/gdmfp.pdf (in detail) + * + * The basic idea is to add a large enough number to the double that the + * literal floating point is moved up to the extent that it forces the + * double's value to be shifted down to the bottom of the mantissa (to make + * room for the large number being added in). Since the mantissa is, at a + * given moment in time, a fixed point integer itself, one can convert a + * float to various fixed point representations by moving around the point + * of a floating point number through arithmetic operations. This behavior + * is reliable on most modern platforms as it is mandated by the IEEE-754 + * standard for floating point arithmetic. + * + * For our purposes, a "magic number" must be carefully selected that is + * both large enough to produce the desired point-shifting effect, and also + * has no lower bits in its representation that would interfere with our + * value at the bottom of the mantissa. The magic number is calculated as + * follows: + * + * (2 ^ (MANTISSA_SIZE - FRACTIONAL_SIZE)) * 1.5 + * + * where in our case: + * - MANTISSA_SIZE for 64-bit doubles is 52 + * - FRACTIONAL_SIZE for 16.16 fixed point is 16 + * + * Although this approach provides a very large speedup of this function + * on a wide-array of systems, it does come with two caveats: + * + * 1) It uses banker's rounding as opposed to arithmetic rounding. + * 2) It doesn't function properly if the FPU is in single-precision + * mode. + */ + +/* The 16.16 number must always be available */ +#define CAIRO_MAGIC_NUMBER_FIXED_16_16 (103079215104.0) + +#if CAIRO_FIXED_BITS <= 32 +#define CAIRO_MAGIC_NUMBER_FIXED ((1LL << (52 - CAIRO_FIXED_FRAC_BITS)) * 1.5) + +/* For 32-bit fixed point numbers */ +static inline cairo_fixed_t +_cairo_fixed_from_double (double d) +{ + union { + double d; + int32_t i[2]; + } u; + + u.d = d + CAIRO_MAGIC_NUMBER_FIXED; +#ifdef FLOAT_WORDS_BIGENDIAN + return u.i[1]; +#else + return u.i[0]; +#endif +} + +#else +# error Please define a magic number for your fixed point type! +# error See cairo-fixed-private.h for details. +#endif + +static inline cairo_fixed_t +_cairo_fixed_from_26_6 (uint32_t i) +{ +#if CAIRO_FIXED_FRAC_BITS > 6 + return i << (CAIRO_FIXED_FRAC_BITS - 6); +#else + return i >> (6 - CAIRO_FIXED_FRAC_BITS); +#endif +} + +static inline cairo_fixed_t +_cairo_fixed_from_16_16 (uint32_t i) +{ +#if CAIRO_FIXED_FRAC_BITS > 16 + return i << (CAIRO_FIXED_FRAC_BITS - 16); +#else + return i >> (16 - CAIRO_FIXED_FRAC_BITS); +#endif +} + +static inline double +_cairo_fixed_to_double (cairo_fixed_t f) +{ + return ((double) f) / CAIRO_FIXED_ONE_DOUBLE; +} + +static inline float +_cairo_fixed_to_float (cairo_fixed_t f) +{ + return ((float) f) / CAIRO_FIXED_ONE_FLOAT; +} + +static inline int +_cairo_fixed_is_integer (cairo_fixed_t f) +{ + return (f & CAIRO_FIXED_FRAC_MASK) == 0; +} + +static inline cairo_fixed_t +_cairo_fixed_floor (cairo_fixed_t f) +{ + return f & ~CAIRO_FIXED_FRAC_MASK; +} + +static inline cairo_fixed_t +_cairo_fixed_round (cairo_fixed_t f) +{ + return _cairo_fixed_floor (f + (CAIRO_FIXED_FRAC_MASK+1)/2); +} + +static inline cairo_fixed_t +_cairo_fixed_round_down (cairo_fixed_t f) +{ + return _cairo_fixed_floor (f + CAIRO_FIXED_FRAC_MASK/2); +} + +static inline int +_cairo_fixed_integer_part (cairo_fixed_t f) +{ + return f >> CAIRO_FIXED_FRAC_BITS; +} + +static inline int +_cairo_fixed_integer_round (cairo_fixed_t f) +{ + return _cairo_fixed_integer_part (f + (CAIRO_FIXED_FRAC_MASK+1)/2); +} + +static inline int +_cairo_fixed_integer_round_down (cairo_fixed_t f) +{ + return _cairo_fixed_integer_part (f + CAIRO_FIXED_FRAC_MASK/2); +} + +static inline int +_cairo_fixed_fractional_part (cairo_fixed_t f) +{ + return f & CAIRO_FIXED_FRAC_MASK; +} + +static inline int +_cairo_fixed_integer_floor (cairo_fixed_t f) +{ + if (f >= 0) + return f >> CAIRO_FIXED_FRAC_BITS; + else + return -((-f - 1) >> CAIRO_FIXED_FRAC_BITS) - 1; +} + +static inline int +_cairo_fixed_integer_ceil (cairo_fixed_t f) +{ + if (f > 0) + return ((f - 1)>>CAIRO_FIXED_FRAC_BITS) + 1; + else + return - (-f >> CAIRO_FIXED_FRAC_BITS); +} + +/* A bunch of explicit 16.16 operators; we need these + * to interface with pixman and other backends that require + * 16.16 fixed point types. + */ +static inline cairo_fixed_16_16_t +_cairo_fixed_to_16_16 (cairo_fixed_t f) +{ +#if (CAIRO_FIXED_FRAC_BITS == 16) && (CAIRO_FIXED_BITS == 32) + return f; +#elif CAIRO_FIXED_FRAC_BITS > 16 + /* We're just dropping the low bits, so we won't ever got over/underflow here */ + return f >> (CAIRO_FIXED_FRAC_BITS - 16); +#else + cairo_fixed_16_16_t x; + + /* Handle overflow/underflow by clamping to the lowest/highest + * value representable as 16.16 + */ + if ((f >> CAIRO_FIXED_FRAC_BITS) < INT16_MIN) { + x = INT32_MIN; + } else if ((f >> CAIRO_FIXED_FRAC_BITS) > INT16_MAX) { + x = INT32_MAX; + } else { + x = f << (16 - CAIRO_FIXED_FRAC_BITS); + } + + return x; +#endif +} + +static inline cairo_fixed_16_16_t +_cairo_fixed_16_16_from_double (double d) +{ + union { + double d; + int32_t i[2]; + } u; + + u.d = d + CAIRO_MAGIC_NUMBER_FIXED_16_16; +#ifdef FLOAT_WORDS_BIGENDIAN + return u.i[1]; +#else + return u.i[0]; +#endif +} + +static inline int +_cairo_fixed_16_16_floor (cairo_fixed_16_16_t f) +{ + if (f >= 0) + return f >> 16; + else + return -((-f - 1) >> 16) - 1; +} + +static inline double +_cairo_fixed_16_16_to_double (cairo_fixed_16_16_t f) +{ + return ((double) f) / (double) (1 << 16); +} + +#if CAIRO_FIXED_BITS == 32 + +static inline cairo_fixed_t +_cairo_fixed_mul (cairo_fixed_t a, cairo_fixed_t b) +{ + cairo_int64_t temp = _cairo_int32x32_64_mul (a, b); + return _cairo_int64_to_int32(_cairo_int64_rsl (temp, CAIRO_FIXED_FRAC_BITS)); +} + +/* computes round (a * b / c) */ +static inline cairo_fixed_t +_cairo_fixed_mul_div (cairo_fixed_t a, cairo_fixed_t b, cairo_fixed_t c) +{ + cairo_int64_t ab = _cairo_int32x32_64_mul (a, b); + cairo_int64_t c64 = _cairo_int32_to_int64 (c); + return _cairo_int64_to_int32 (_cairo_int64_divrem (ab, c64).quo); +} + +/* computes floor (a * b / c) */ +static inline cairo_fixed_t +_cairo_fixed_mul_div_floor (cairo_fixed_t a, cairo_fixed_t b, cairo_fixed_t c) +{ + return _cairo_int64_32_div (_cairo_int32x32_64_mul (a, b), c); +} + + +static inline cairo_fixed_t +_cairo_edge_compute_intersection_y_for_x (const cairo_point_t *p1, + const cairo_point_t *p2, + cairo_fixed_t x) +{ + cairo_fixed_t y, dx; + + if (x == p1->x) + return p1->y; + if (x == p2->x) + return p2->y; + + y = p1->y; + dx = p2->x - p1->x; + if (dx != 0) + y += _cairo_fixed_mul_div_floor (x - p1->x, p2->y - p1->y, dx); + + return y; +} + +static inline cairo_fixed_t +_cairo_edge_compute_intersection_x_for_y (const cairo_point_t *p1, + const cairo_point_t *p2, + cairo_fixed_t y) +{ + cairo_fixed_t x, dy; + + if (y == p1->y) + return p1->x; + if (y == p2->y) + return p2->x; + + x = p1->x; + dy = p2->y - p1->y; + if (dy != 0) + x += _cairo_fixed_mul_div_floor (y - p1->y, p2->x - p1->x, dy); + + return x; +} + +#else +# error Please define multiplication and other operands for your fixed-point type size +#endif + +#endif /* CAIRO_FIXED_PRIVATE_H */ |