/*
 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
 *
 * Floating-point emulation code
 *  Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
 *
 *    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/fcnvxf.c              $Revision: 1.1 $
 *
 *  Purpose:
 *      Single Fixed-point to Single Floating-point
 *      Single Fixed-point to Double Floating-point 
 *      Double Fixed-point to Single Floating-point 
 *      Double Fixed-point to Double Floating-point 
 *
 *  External Interfaces:
 *      dbl_to_dbl_fcnvxf(srcptr,nullptr,dstptr,status)
 *      dbl_to_sgl_fcnvxf(srcptr,nullptr,dstptr,status)
 *      sgl_to_dbl_fcnvxf(srcptr,nullptr,dstptr,status)
 *      sgl_to_sgl_fcnvxf(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"

/*
 *  Convert single fixed-point to single floating-point format
 */

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

        src = *srcptr;
        /* 
         * set sign bit of result and get magnitude of source 
         */
        if (src < 0) {
                Sgl_setone_sign(result);  
                Int_negate(src);
        }
        else {
                Sgl_setzero_sign(result);
                /* 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 1  */
        if (dst_exponent >= 0) src <<= dst_exponent;
        else src = 1 << 30;
        Sgl_set_mantissa(result, src >> (SGL_EXP_LENGTH-1));
        Sgl_set_exponent(result, 30+SGL_BIAS - dst_exponent);

        /* check for inexact */
        if (Int_isinexact_to_sgl(src)) {
                switch (Rounding_mode()) {
                        case ROUNDPLUS: 
                                if (Sgl_iszero_sign(result)) 
                                        Sgl_increment(result);
                                break;
                        case ROUNDMINUS: 
                                if (Sgl_isone_sign(result)) 
                                        Sgl_increment(result);
                                break;
                        case ROUNDNEAREST:
                                Sgl_roundnearest_from_int(src,result);
                }
                if (Is_inexacttrap_enabled()) {
                        *dstptr = result;
                        return(INEXACTEXCEPTION);
                }
                else Set_inexactflag();
        }
        *dstptr = result;
        return(NOEXCEPTION);
}

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

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

        src = *srcptr;
        /* 
         * set sign bit of result and get magnitude of source 
         */
        if (src < 0) {
                Dbl_setone_sign(resultp1);  
                Int_negate(src);
        }
        else {
                Dbl_setzero_sign(resultp1);
                /* 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 1  */
        if (dst_exponent >= 0) src <<= dst_exponent;
        else src = 1 << 30;
        Dbl_set_mantissap1(resultp1, src >> DBL_EXP_LENGTH - 1);
        Dbl_set_mantissap2(resultp2, src << (33-DBL_EXP_LENGTH));
        Dbl_set_exponent(resultp1, (30+DBL_BIAS) - dst_exponent);
        Dbl_copytoptr(resultp1,resultp2,dstptr);
        return(NOEXCEPTION);
}

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

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

        Dint_copyfromptr(srcptr,srcp1,srcp2);
        /* 
         * set sign bit of result and get magnitude of source 
         */
        if (srcp1 < 0) {
                Sgl_setone_sign(result);  
                Dint_negate(srcp1,srcp2);
        }
        else {
                Sgl_setzero_sign(result);
                /* 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 1  */
                if (dst_exponent >= 0) {
                        srcp1 = srcp2 << dst_exponent;    
                        srcp2 = 0;
                }
                else {
                        srcp1 = srcp2 >> 1;
                        srcp2 <<= 31; 
                }
                /*
                 *  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 1  */
                if (dst_exponent > 0) {
                        Variable_shift_double(srcp1,srcp2,(32-dst_exponent),
                         srcp1); 
                        srcp2 <<= dst_exponent;
                }
                /*
                 * If dst_exponent = 0, we don't need to shift anything.
                 * If dst_exponent = -1, src = - 2**63 so we won't need to 
                 * shift srcp2.
                 */
                else srcp1 >>= -(dst_exponent);
        }
        Sgl_set_mantissa(result, srcp1 >> SGL_EXP_LENGTH - 1);
        Sgl_set_exponent(result, (62+SGL_BIAS) - dst_exponent);

        /* check for inexact */
        if (Dint_isinexact_to_sgl(srcp1,srcp2)) {
                switch (Rounding_mode()) {
                        case ROUNDPLUS: 
                                if (Sgl_iszero_sign(result)) 
                                        Sgl_increment(result);
                                break;
                        case ROUNDMINUS: 
                                if (Sgl_isone_sign(result)) 
                                        Sgl_increment(result);
                                break;
                        case ROUNDNEAREST:
                                Sgl_roundnearest_from_dint(srcp1,srcp2,result);
                }
                if (Is_inexacttrap_enabled()) {
                        *dstptr = result;
                        return(INEXACTEXCEPTION);
                }
                else Set_inexactflag();
        }
        *dstptr = result;
        return(NOEXCEPTION);
}

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

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

        Dint_copyfromptr(srcptr,srcp1,srcp2);
        /* 
         * set sign bit of result and get magnitude of source 
         */
        if (srcp1 < 0) {
                Dbl_setone_sign(resultp1);
                Dint_negate(srcp1,srcp2);
        }
        else {
                Dbl_setzero_sign(resultp1);
                /* 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 1  */
                if (dst_exponent >= 0) {
                        srcp1 = srcp2 << dst_exponent;    
                        srcp2 = 0;
                }
                else {
                        srcp1 = srcp2 >> 1;
                        srcp2 <<= 31;
                }
                /*
                 *  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 1  */
                if (dst_exponent > 0) {
                        Variable_shift_double(srcp1,srcp2,(32-dst_exponent),
                         srcp1); 
                        srcp2 <<= dst_exponent;
                }
                /*
                 * If dst_exponent = 0, we don't need to shift anything.
                 * If dst_exponent = -1, src = - 2**63 so we won't need to 
                 * shift srcp2.
                 */
                else srcp1 >>= -(dst_exponent);
        }
        Dbl_set_mantissap1(resultp1, srcp1 >> (DBL_EXP_LENGTH-1));
        Shiftdouble(srcp1,srcp2,DBL_EXP_LENGTH-1,resultp2);
        Dbl_set_exponent(resultp1, (62+DBL_BIAS) - dst_exponent);

        /* check for inexact */
        if (Dint_isinexact_to_dbl(srcp2)) {
                switch (Rounding_mode()) {
                        case ROUNDPLUS: 
                                if (Dbl_iszero_sign(resultp1)) {
                                        Dbl_increment(resultp1,resultp2);
                                }
                                break;
                        case ROUNDMINUS: 
                                if (Dbl_isone_sign(resultp1)) {
                                        Dbl_increment(resultp1,resultp2);
                                }
                                break;
                        case ROUNDNEAREST:
                                Dbl_roundnearest_from_dint(srcp2,resultp1,
                                resultp2);
                }
                if (Is_inexacttrap_enabled()) {
                        Dbl_copytoptr(resultp1,resultp2,dstptr);
                        return(INEXACTEXCEPTION);
                }
                else Set_inexactflag();
        }
        Dbl_copytoptr(resultp1,resultp2,dstptr);
        return(NOEXCEPTION);
}