fcnvuf.c

Go to the documentation of this file.

/*
 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
 *
 * Floating-point emulation code
 *  Copyright (C) 2001 Hewlett-Packard (Paul Bame) <[email protected]>
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2, or (at your option)
 *    any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
/*
 * BEGIN_DESC
 *
 *  File:
 *  @(#)    pa/spmath/fcnvuf.c      $Revision: 1.1 $
 *
 *  Purpose:
 *  Fixed point to Floating-point Converts
 *
 *  External Interfaces:
 *  dbl_to_dbl_fcnvuf(srcptr,nullptr,dstptr,status)
 *  dbl_to_sgl_fcnvuf(srcptr,nullptr,dstptr,status)
 *  sgl_to_dbl_fcnvuf(srcptr,nullptr,dstptr,status)
 *  sgl_to_sgl_fcnvuf(srcptr,nullptr,dstptr,status)
 *
 *  Internal Interfaces:
 *
 *  Theory:
 *  <<please update with a overview of the operation of this file>>
 *
 * END_DESC
*/


#include "float.h"
#include "sgl_float.h"
#include "dbl_float.h"
#include "cnv_float.h"

/************************************************************************
 *  Fixed point to Floating-point Converts              *
 ************************************************************************/

/*
 *  Convert Single Unsigned Fixed to Single Floating-point format
 */

int
sgl_to_sgl_fcnvuf(
            unsigned int *srcptr,
            unsigned int *nullptr,
            sgl_floating_point *dstptr,
            unsigned int *status)
{
    register unsigned int src, result = 0;
    register int dst_exponent;

    src = *srcptr;

    /* Check for zero */ 
    if (src == 0) { 
            Sgl_setzero(result); 
        *dstptr = result;
            return(NOEXCEPTION); 
    } 
    /*
     * Generate exponent and normalized mantissa
     */
    dst_exponent = 16;    /* initialize for normalization */
    /*
     * Check word for most significant bit set.  Returns
     * a value in dst_exponent indicating the bit position,
     * between -1 and 30.
     */
    Find_ms_one_bit(src,dst_exponent);
    /*  left justify source, with msb at bit position 0  */
    src <<= dst_exponent+1;
    Sgl_set_mantissa(result, src >> SGL_EXP_LENGTH);
    Sgl_set_exponent(result, 30+SGL_BIAS - dst_exponent);

    /* check for inexact */
    if (Suint_isinexact_to_sgl(src)) {
        switch (Rounding_mode()) {
            case ROUNDPLUS: 
                Sgl_increment(result);
                break;
            case ROUNDMINUS: /* never negative */
                break;
            case ROUNDNEAREST:
                Sgl_roundnearest_from_suint(src,result);
                break;
        }
        if (Is_inexacttrap_enabled()) {
            *dstptr = result;
            return(INEXACTEXCEPTION);
        }
        else Set_inexactflag();
    }
    *dstptr = result;
    return(NOEXCEPTION);
}

/*
 *  Single Unsigned Fixed to Double Floating-point 
 */

int
sgl_to_dbl_fcnvuf(
            unsigned int *srcptr,
            unsigned int *nullptr,
            dbl_floating_point *dstptr,
            unsigned int *status)
{
    register int dst_exponent;
    register unsigned int src, resultp1 = 0, resultp2 = 0;

    src = *srcptr;

    /* Check for zero */
    if (src == 0) {
            Dbl_setzero(resultp1,resultp2);
            Dbl_copytoptr(resultp1,resultp2,dstptr);
            return(NOEXCEPTION);
    }
    /*
     * Generate exponent and normalized mantissa
     */
    dst_exponent = 16;    /* initialize for normalization */
    /*
     * Check word for most significant bit set.  Returns
     * a value in dst_exponent indicating the bit position,
     * between -1 and 30.
     */
    Find_ms_one_bit(src,dst_exponent);
    /*  left justify source, with msb at bit position 0  */
    src <<= dst_exponent+1;
    Dbl_set_mantissap1(resultp1, src >> DBL_EXP_LENGTH);
    Dbl_set_mantissap2(resultp2, src << (32-DBL_EXP_LENGTH));
    Dbl_set_exponent(resultp1, (30+DBL_BIAS) - dst_exponent);
    Dbl_copytoptr(resultp1,resultp2,dstptr);
    return(NOEXCEPTION);
}

/*
 *  Double Unsigned Fixed to Single Floating-point 
 */

int
dbl_to_sgl_fcnvuf(
            dbl_unsigned *srcptr,
            unsigned int *nullptr,
            sgl_floating_point *dstptr,
            unsigned int *status)
{
    int dst_exponent;
    unsigned int srcp1, srcp2, result = 0;

    Duint_copyfromptr(srcptr,srcp1,srcp2);

    /* Check for zero */
    if (srcp1 == 0 && srcp2 == 0) {
            Sgl_setzero(result);
            *dstptr = result;
            return(NOEXCEPTION);
    }
    /*
     * Generate exponent and normalized mantissa
     */
    dst_exponent = 16;    /* initialize for normalization */
    if (srcp1 == 0) {
        /*
         * Check word for most significant bit set.  Returns
         * a value in dst_exponent indicating the bit position,
         * between -1 and 30.
         */
        Find_ms_one_bit(srcp2,dst_exponent);
        /*  left justify source, with msb at bit position 0  */
        srcp1 = srcp2 << dst_exponent+1;    
        srcp2 = 0;
        /*
         *  since msb set is in second word, need to 
         *  adjust bit position count
         */
        dst_exponent += 32;
    }
    else {
        /*
         * Check word for most significant bit set.  Returns
         * a value in dst_exponent indicating the bit position,
         * between -1 and 30.
         *
         */
        Find_ms_one_bit(srcp1,dst_exponent);
        /*  left justify source, with msb at bit position 0  */
        if (dst_exponent >= 0) {
            Variable_shift_double(srcp1,srcp2,(31-dst_exponent),
             srcp1); 
            srcp2 <<= dst_exponent+1;
        }
    }
    Sgl_set_mantissa(result, srcp1 >> SGL_EXP_LENGTH);
    Sgl_set_exponent(result, (62+SGL_BIAS) - dst_exponent);

    /* check for inexact */
    if (Duint_isinexact_to_sgl(srcp1,srcp2)) {
        switch (Rounding_mode()) {
            case ROUNDPLUS: 
                Sgl_increment(result);
                break;
            case ROUNDMINUS: /* never negative */
                break;
            case ROUNDNEAREST:
                Sgl_roundnearest_from_duint(srcp1,srcp2,result);
                break;
        }
        if (Is_inexacttrap_enabled()) {
            *dstptr = result;
            return(INEXACTEXCEPTION);
        }
        else Set_inexactflag();
    }
    *dstptr = result;
    return(NOEXCEPTION);
}

/*
 *  Double Unsigned Fixed to Double Floating-point 
 */

int
dbl_to_dbl_fcnvuf(
            dbl_unsigned *srcptr,
            unsigned int *nullptr,
            dbl_floating_point *dstptr,
            unsigned int *status)
{
    register int dst_exponent;
    register unsigned int srcp1, srcp2, resultp1 = 0, resultp2 = 0;

    Duint_copyfromptr(srcptr,srcp1,srcp2);

    /* Check for zero */
    if (srcp1 == 0 && srcp2 ==0) {
            Dbl_setzero(resultp1,resultp2);
            Dbl_copytoptr(resultp1,resultp2,dstptr);
            return(NOEXCEPTION);
    }
    /*
     * Generate exponent and normalized mantissa
     */
    dst_exponent = 16;    /* initialize for normalization */
    if (srcp1 == 0) {
        /*
         * Check word for most significant bit set.  Returns
         * a value in dst_exponent indicating the bit position,
         * between -1 and 30.
         */
        Find_ms_one_bit(srcp2,dst_exponent);
        /*  left justify source, with msb at bit position 0  */
        srcp1 = srcp2 << dst_exponent+1;
        srcp2 = 0;
        /*
         *  since msb set is in second word, need to 
         *  adjust bit position count
         */
        dst_exponent += 32;
    }
    else {
        /*
         * Check word for most significant bit set.  Returns
         * a value in dst_exponent indicating the bit position,
         * between -1 and 30.
         */
        Find_ms_one_bit(srcp1,dst_exponent);
        /*  left justify source, with msb at bit position 0  */
        if (dst_exponent >= 0) {
            Variable_shift_double(srcp1,srcp2,(31-dst_exponent),
             srcp1); 
            srcp2 <<= dst_exponent+1;
        }
    }
    Dbl_set_mantissap1(resultp1, srcp1 >> DBL_EXP_LENGTH);
    Shiftdouble(srcp1,srcp2,DBL_EXP_LENGTH,resultp2);
    Dbl_set_exponent(resultp1, (62+DBL_BIAS) - dst_exponent);

    /* check for inexact */
    if (Duint_isinexact_to_dbl(srcp2)) {
        switch (Rounding_mode()) {
            case ROUNDPLUS: 
                Dbl_increment(resultp1,resultp2);
                break;
            case ROUNDMINUS: /* never negative */
                break;
            case ROUNDNEAREST:
                Dbl_roundnearest_from_duint(srcp2,resultp1,
                resultp2);
                break;
        }
        if (Is_inexacttrap_enabled()) {
            Dbl_copytoptr(resultp1,resultp2,dstptr);
            return(INEXACTEXCEPTION);
        }
        else Set_inexactflag();
    }
    Dbl_copytoptr(resultp1,resultp2,dstptr);
    return(NOEXCEPTION);
}