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/**************************************************************************

 *

 * Copyright 2008 Tungsten Graphics, Inc., Cedar Park, Texas.

 * All Rights Reserved.

 *

 **************************************************************************/

/**

 * Code to implement GL_OES_query_matrix.  See the spec at:

 * http://www.khronos.org/registry/gles/extensions/OES/OES_query_matrix.txt

 */

#include 

#include 

#include "GLES/gl.h"

#include "GLES/glext.h"

/**

 * This is from the GL_OES_query_matrix extension specification:

 *

 *  GLbitfield glQueryMatrixxOES( GLfixed mantissa[16],

 *                                GLint   exponent[16] )

 *  mantissa[16] contains the contents of the current matrix in GLfixed

 *  format.  exponent[16] contains the unbiased exponents applied to the

 *  matrix components, so that the internal representation of component i

 *  is close to mantissa[i] * 2^exponent[i].  The function returns a status

 *  word which is zero if all the components are valid. If

 *  status & (1<

 *  The implementations are not required to keep track of overflows.  In

 *  that case, the invalid bits are never set.

 */

#define INT_TO_FIXED(x) ((GLfixed) ((x) << 16))

#define FLOAT_TO_FIXED(x) ((GLfixed) ((x) * 65536.0))

#if defined(_MSC_VER)

/* Oddly, the fpclassify() function doesn't exist in such a form

 * on MSVC.  This is an implementation using slightly different

 * lower-level Windows functions.

 */

#include 

enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}

fpclassify(double x)

{

    switch(_fpclass(x)) {

        case _FPCLASS_SNAN: /* signaling NaN */

        case _FPCLASS_QNAN: /* quiet NaN */

            return FP_NAN;

        case _FPCLASS_NINF: /* negative infinity */

        case _FPCLASS_PINF: /* positive infinity */

            return FP_INFINITE;

        case _FPCLASS_NN:   /* negative normal */

        case _FPCLASS_PN:   /* positive normal */

            return FP_NORMAL;

        case _FPCLASS_ND:   /* negative denormalized */

        case _FPCLASS_PD:   /* positive denormalized */

            return FP_SUBNORMAL;

        case _FPCLASS_NZ:   /* negative zero */

        case _FPCLASS_PZ:   /* positive zero */

            return FP_ZERO;

        default:

            /* Should never get here; but if we do, this will guarantee

             * that the pattern is not treated like a number.

             */

            return FP_NAN;

    }

}

#elif defined(__APPLE__) || defined(__CYGWIN__) || defined(__FreeBSD__) || \

     defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__) || \

     (defined(__sun) && defined(__C99FEATURES__)) || defined(__MINGW32__) || \

     (defined(__sun) && defined(__GNUC__))

/* fpclassify is available. */

#elif !defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 600

enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}

fpclassify(double x)

{

   /* XXX do something better someday */

   return FP_NORMAL;

}

#endif

extern GLbitfield GL_APIENTRY _es_QueryMatrixxOES(GLfixed mantissa[16], GLint exponent[16]);

/* The Mesa functions we'll need */

extern void GL_APIENTRY _mesa_GetIntegerv(GLenum pname, GLint *params);

extern void GL_APIENTRY _mesa_GetFloatv(GLenum pname, GLfloat *params);

GLbitfield GL_APIENTRY _es_QueryMatrixxOES(GLfixed mantissa[16], GLint exponent[16])

{

    GLfloat matrix[16];

    GLint tmp;

    GLenum currentMode = GL_FALSE;

    GLenum desiredMatrix = GL_FALSE;

    /* The bitfield returns 1 for each component that is invalid (i.e.

     * NaN or Inf).  In case of error, everything is invalid.

     */

    GLbitfield rv;

    register unsigned int i;

    unsigned int bit;

    /* This data structure defines the mapping between the current matrix

     * mode and the desired matrix identifier.

     */

    static struct {

        GLenum currentMode;

        GLenum desiredMatrix;

    } modes[] = {

        {GL_MODELVIEW, GL_MODELVIEW_MATRIX},

        {GL_PROJECTION, GL_PROJECTION_MATRIX},

        {GL_TEXTURE, GL_TEXTURE_MATRIX},

    };

    /* Call Mesa to get the current matrix in floating-point form.  First,

     * we have to figure out what the current matrix mode is.

     */

    _mesa_GetIntegerv(GL_MATRIX_MODE, &tmp);

    currentMode = (GLenum) tmp;

    /* The mode is either GL_FALSE, if for some reason we failed to query

     * the mode, or a given mode from the above table.  Search for the

     * returned mode to get the desired matrix; if we don't find it,

     * we can return immediately, as _mesa_GetInteger() will have

     * logged the necessary error already.

     */

    for (i = 0; i < sizeof(modes)/sizeof(modes[0]); i++) {

        if (modes[i].currentMode == currentMode) {

            desiredMatrix = modes[i].desiredMatrix;

            break;

        }

    }

    if (desiredMatrix == GL_FALSE) {

        /* Early error means all values are invalid. */

        return 0xffff;

    }

    /* Now pull the matrix itself. */

    _mesa_GetFloatv(desiredMatrix, matrix);

    rv = 0;

    for (i = 0, bit = 1; i < 16; i++, bit<<=1) {

        float normalizedFraction;

        int exp;

        switch (fpclassify(matrix[i])) {

            /* A "subnormal" or denormalized number is too small to be

             * represented in normal format; but despite that it's a

             * valid floating point number.  FP_ZERO and FP_NORMAL

             * are both valid as well.  We should be fine treating

             * these three cases as legitimate floating-point numbers.

             */

            case FP_SUBNORMAL:

            case FP_NORMAL:

            case FP_ZERO:

                normalizedFraction = (GLfloat)frexp(matrix[i], &exp);

                mantissa[i] = FLOAT_TO_FIXED(normalizedFraction);

                exponent[i] = (GLint) exp;

                break;

            /* If the entry is not-a-number or an infinity, then the

             * matrix component is invalid.  The invalid flag for

             * the component is already set; might as well set the

             * other return values to known values.  We'll set

             * distinct values so that a savvy end user could determine

             * whether the matrix component was a NaN or an infinity,

             * but this is more useful for debugging than anything else

             * since the standard doesn't specify any such magic

             * values to return.

             */

            case FP_NAN:

                mantissa[i] = INT_TO_FIXED(0);

                exponent[i] = (GLint) 0;

                rv |= bit;

                break;

            case FP_INFINITE:

                /* Return +/- 1 based on whether it's a positive or

                 * negative infinity.

                 */

                if (matrix[i] > 0) {

                    mantissa[i] = INT_TO_FIXED(1);

                }

                else {

                    mantissa[i] = -INT_TO_FIXED(1);

                }

                exponent[i] = (GLint) 0;

                rv |= bit;

                break;

            /* We should never get here; but here's a catching case

             * in case fpclassify() is returnings something unexpected.

             */

            default:

                mantissa[i] = INT_TO_FIXED(2);

                exponent[i] = (GLint) 0;

                rv |= bit;

                break;

        }

    } /* for each component */

    /* All done */

    return rv;

}