/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the files COPYING and Copyright.html.  COPYING can be found at the root   *
 * of the source code distribution tree; Copyright.html can be found at the  *
 * root level of an installed copy of the electronic HDF5 document set and   *
 * is linked from the top-level documents page.  It can also be found at     *
 * http://hdfgroup.org/HDF5/doc/Copyright.html.  If you do not have          *
 * access to either file, you may request a copy from help@hdfgroup.org.     *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 * Module Info: This module contains the functionality for setting & querying
 *      the datatype precision for the H5T interface.
 */

#include "H5Tmodule.h"          /* This source code file is part of the H5T module */


#include "H5private.h"		/* Generic Functions			*/
#include "H5Eprivate.h"		/* Error handling		  	*/
#include "H5Iprivate.h"		/* IDs			  		*/
#include "H5Tpkg.h"		/* Datatypes				*/

/* Static local functions */
static herr_t H5T_set_precision(const H5T_t *dt, size_t prec);



/*-------------------------------------------------------------------------
 * Function:	H5Tget_precision
 *
 * Purpose:	Gets the precision of a datatype.  The precision is
 *		the number of significant bits which, unless padding is
 *		present, is 8 times larger than the value returned by
 *		H5Tget_size().
 *
 * Return:	Success:	Number of significant bits
 *
 *		Failure:	0 (all atomic types have at least one
 *				significant bit)
 *
 * Programmer:	Robb Matzke
 *		Wednesday, January  7, 1998
 *
 * Modifications:
 * 	Robb Matzke, 22 Dec 1998
 *	Also works for derived datatypes.
 *
 *-------------------------------------------------------------------------
 */
size_t
H5Tget_precision(hid_t type_id)
{
    H5T_t	*dt;
    size_t	ret_value;

    FUNC_ENTER_API(0)
    H5TRACE1("z", "i", type_id);

    /* Check args */
    if (NULL == (dt = (H5T_t *)H5I_object_verify(type_id,H5I_DATATYPE)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "not a datatype")

    /* Get precision */
    if((ret_value = H5T_get_precision(dt)) == 0)
        HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, 0, "cant't get precision for specified datatype")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Tget_precision() */


/*-------------------------------------------------------------------------
 * Function:	H5T_get_precision
 *
 * Purpose:	Gets the precision of a datatype.  The precision is
 *		the number of significant bits which, unless padding is
 *		present, is 8 times larger than the value returned by
 *		H5Tget_size().
 *
 * Return:	Success:	Number of significant bits
 *		Failure:	0 (all atomic types have at least one
 *				significant bit)
 *
 * Programmer:	Quincey Koziol
 *		Wednesday, October 17, 2007
 *
 *-------------------------------------------------------------------------
 */
size_t
H5T_get_precision(const H5T_t *dt)
{
    size_t	ret_value = 0;          /* Return value */

    FUNC_ENTER_NOAPI(0)

    /* Defer to parent*/
    while(dt->shared->parent)
        dt = dt->shared->parent;
    if(!H5T_IS_ATOMIC(dt->shared))
	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, 0, "operation not defined for specified datatype")

    /* Precision */
    ret_value = dt->shared->u.atomic.prec;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5T_get_precision() */


/*-------------------------------------------------------------------------
 * Function:	H5Tset_precision
 *
 * Purpose:	Sets the precision of a datatype.  The precision is
 *		the number of significant bits which, unless padding is
 *		present, is 8 times larger than the value returned by
 *		H5Tget_size().
 *
 *		If the precision is increased then the offset is decreased
 *		and then the size is increased to insure that significant
 *		bits do not "hang over" the edge of the datatype.
 *
 *		The precision property of strings is read-only.
 *
 *		When decreasing the precision of a floating point type, set
 *		the locations and sizes of the sign, mantissa, and exponent
 *		fields first.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		Wednesday, January  7, 1998
 *
 * Modifications:
 * 	Robb Matzke, 22 Dec 1998
 *	Moved real work to a private function.
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Tset_precision(hid_t type_id, size_t prec)
{
    H5T_t	*dt = NULL;
    herr_t      ret_value=SUCCEED;       /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE2("e", "iz", type_id, prec);

    /* Check args */
    if (NULL == (dt = (H5T_t *)H5I_object_verify(type_id,H5I_DATATYPE)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a datatype")
    if (H5T_STATE_TRANSIENT!=dt->shared->state)
        HGOTO_ERROR(H5E_ARGS, H5E_CANTSET, FAIL, "datatype is read-only")
    if (prec == 0)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "precision must be positive")
    if (H5T_ENUM==dt->shared->type && dt->shared->u.enumer.nmembs>0)
        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "operation not allowed after members are defined")
    if (H5T_STRING==dt->shared->type)
        HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "precision for this type is read-only")
    if (H5T_COMPOUND==dt->shared->type || H5T_OPAQUE==dt->shared->type)
        HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "operation not defined for specified datatype")

    /* Do the work */
    if (H5T_set_precision(dt, prec)<0)
        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "unable to set precision")

done:
    FUNC_LEAVE_API(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5T_set_precision
 *
 * Purpose:	Sets the precision of a datatype.  The precision is
 *		the number of significant bits which, unless padding is
 *		present, is 8 times larger than the value returned by
 *		H5Tget_size().
 *
 *		If the precision is increased then the offset is decreased
 *		and then the size is increased to insure that significant
 *		bits do not "hang over" the edge of the datatype.
 *
 *		The precision property of strings is read-only.
 *
 *		When decreasing the precision of a floating point type, set
 *		the locations and sizes of the sign, mantissa, and exponent
 *		fields first.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		Wednesday, January  7, 1998
 *
 * Modifications:
 * 	Robb Matzke, 22 Dec 1998
 *	Also works for derived datatypes.
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5T_set_precision(const H5T_t *dt, size_t prec)
{
    size_t	offset, size;
    herr_t      ret_value=SUCCEED;       /* Return value */

    FUNC_ENTER_NOAPI(FAIL)

    /* Check args */
    HDassert(dt);
    HDassert(prec>0);
    HDassert(H5T_OPAQUE!=dt->shared->type);
    HDassert(H5T_COMPOUND!=dt->shared->type);
    HDassert(H5T_STRING!=dt->shared->type);
    HDassert(!(H5T_ENUM==dt->shared->type && 0==dt->shared->u.enumer.nmembs));

    if (dt->shared->parent) {
	if (H5T_set_precision(dt->shared->parent, prec)<0)
	    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "unable to set precision for base type")

        /* Adjust size of datatype appropriately */
        if(dt->shared->type==H5T_ARRAY)
            dt->shared->size = dt->shared->parent->shared->size * dt->shared->u.array.nelem;
        else if(dt->shared->type!=H5T_VLEN)
            dt->shared->size = dt->shared->parent->shared->size;
    } else {
        if (H5T_IS_ATOMIC(dt->shared)) {
	    /* Adjust the offset and size */
	    offset = dt->shared->u.atomic.offset;
	    size = dt->shared->size;
	    if (prec > 8*size)
                offset = 0;
	    else if (offset+prec > 8 * size)
                offset = 8 * size - prec;
	    if (prec > 8*size)
                size = (prec+7) / 8;

	    /* Check that things are still kosher */
	    switch (dt->shared->type) {
                case H5T_INTEGER:
                case H5T_TIME:
                case H5T_BITFIELD:
                    /* nothing to check */
                    break;

                case H5T_FLOAT:
                    /*
                     * The sign, mantissa, and exponent fields should be adjusted
                     * first when decreasing the precision of a floating point
                     * type.
                     */
                    if (dt->shared->u.atomic.u.f.sign >= prec+offset ||
                            dt->shared->u.atomic.u.f.epos + dt->shared->u.atomic.u.f.esize > prec+offset ||
                            dt->shared->u.atomic.u.f.mpos + dt->shared->u.atomic.u.f.msize > prec+offset)
                        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "adjust sign, mantissa, and exponent fields first")
                    break;

                case H5T_NO_CLASS:
                case H5T_STRING:
                case H5T_OPAQUE:
                case H5T_COMPOUND:
                case H5T_REFERENCE:
                case H5T_ENUM:
                case H5T_VLEN:
                case H5T_ARRAY:
                case H5T_NCLASSES:
                default:
                    HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "operation not defined for datatype class")
	    } /* end switch */

	    /* Commit */
	    dt->shared->size = size;
            dt->shared->u.atomic.offset = offset;
            dt->shared->u.atomic.prec = prec;
	} /* end if */
        else
            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "operation not defined for specified datatype")
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
}

