/* Copyright (C) 2001-2019 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied,
   modified or distributed except as expressly authorized under the terms
   of the license contained in the file LICENSE in this distribution.

   Refer to licensing information at http://www.artifex.com or contact
   Artifex Software, Inc.,  1305 Grant Avenue - Suite 200, Novato,
   CA 94945, U.S.A., +1(415)492-9861, for further information.
*/


/* Internal matrix routines for Ghostscript library */

#ifndef gxmatrix_INCLUDED
#  define gxmatrix_INCLUDED

#include "gsmatrix.h"
#include "gxfixed.h"

/* The following switch is for developmenty purpose only.
   PRECISE_CURRENTPOINT 0 must not go to production due to no clamping. */
#define PRECISE_CURRENTPOINT 1 /* Old code compatible with dropped clamping = 0, new code = 1 */

/*
 * Define a matrix with a cached fixed-point copy of the translation.
 * This is only used by a few routines in gscoord.c; they are responsible
 * for ensuring the validity of the cache.  Note that the floating point
 * tx/ty values may be too large to fit in a fixed values; txy_fixed_valid
 * is false if this is the case, and true otherwise.
 */
struct gs_matrix_fixed_s {
    _matrix_body;
    fixed tx_fixed, ty_fixed;
    bool txy_fixed_valid;
};

typedef struct gs_matrix_fixed_s gs_matrix_fixed;

/* Make a gs_matrix_fixed from a gs_matrix. */
int gs_matrix_fixed_from_matrix(gs_matrix_fixed *, const gs_matrix *);

/* Coordinate transformations to fixed point. */
int gs_point_transform2fixed(const gs_matrix_fixed *, double, double,
                             gs_fixed_point *);
int gs_distance_transform2fixed(const gs_matrix_fixed *, double, double,
                                gs_fixed_point *);
#if PRECISE_CURRENTPOINT
int gs_point_transform2fixed_rounding(const gs_matrix_fixed * pmat,
                         double x, double y, gs_fixed_point * ppt);
#endif

/*
 * Define the fixed-point coefficient structure for avoiding
 * floating point in coordinate transformations.
 * Currently this is used only by the Type 1 font interpreter.
 * The setup is in gscoord.c.
 */
typedef struct {
    long xx, xy, yx, yy;
    int skewed;
    int shift;			/* see m_fixed */
    int max_bits;		/* max bits of coefficient */
    fixed round;		/* ditto */
} fixed_coeff;

/*
 * Multiply a fixed point value by a coefficient.  The coefficient has two
 * parts: a value (long) and a shift factor (int), The result is (fixed *
 * coef_value + round_value) >> (shift + _fixed_shift)) where the shift
 * factor and the round value are picked from the fixed_coeff structure, and
 * the coefficient value (from one of the coeff1 members) is passed
 * explicitly.  The last parameter specifies the number of bits available to
 * prevent overflow for integer arithmetic.  (This is a very custom
 * routine.)  The intermediate value may exceed the size of a long integer.
 */
fixed fixed_coeff_mult(fixed, long, const fixed_coeff *, int);

/*
 * Multiply a fixed whose integer part usually does not exceed max_bits
 * in magnitude by a coefficient from a fixed_coeff.
 * We can use a faster algorithm if the fixed is an integer within
 * a range that doesn't cause the multiplication to overflow an int.
 */
#define m_fixed(v, c, fc, maxb)\
  (((v) + (fixed_1 << (maxb - 1))) &\
    ((-fixed_1 << maxb) | _fixed_fraction_v) ?	/* out of range, or has fraction */\
    fixed_coeff_mult((v), (fc).c, &(fc), maxb) : \
   arith_rshift(fixed2int_var(v) * (fc).c + (fc).round, (fc).shift))

#endif /* gxmatrix_INCLUDED */
