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authorMatt A. Tobin <email@mattatobin.com>2021-11-19 05:13:01 -0500
committerMatt A. Tobin <email@mattatobin.com>2021-11-19 05:13:01 -0500
commitf8796cf0a4259b4b24b3be8ece0e0c26e2c017d5 (patch)
tree763b1085175be05e2f3183facb7db9e9494105da /libs/cairo/src/cairo-fixed-private.h
parente1b02c50457a45eb26108cd318ea833d4608da9b (diff)
downloadaura-central-f8796cf0a4259b4b24b3be8ece0e0c26e2c017d5.tar.gz
Issue %3003 - Move cairo up one level
- This also rewrites the moz.build file to be not insane from years of script manipulation - This also eliminates the remaining mac/uikit quartz shit as well as the BeOS junk.
Diffstat (limited to 'libs/cairo/src/cairo-fixed-private.h')
-rw-r--r--libs/cairo/src/cairo-fixed-private.h326
1 files changed, 326 insertions, 0 deletions
diff --git a/libs/cairo/src/cairo-fixed-private.h b/libs/cairo/src/cairo-fixed-private.h
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#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 */