/*
*cfout.c - Encode interface for C

*    Copyright (c) 19xx-1991, Microsoft Corporation.  All rights reserved.

*Purpose:

*Revision History:
*   07-20-91        GDP     Ported to C from assembly
*   04-30-92        GDP     Added _dtold routine (moved here from ldtod.c)
*   05-14-92        GDP     NDIGITS is now 17 (instead of 16)
*   05-26-92       GWK     Windbg srcs

*/


#include <string.h>
#include "mathsup.h"




#define NDIGITS 17

void __dtold(_ULDOUBLE *pld, UDOUBLE *px);


#ifndef MTHREAD
static struct _strflt ret;
static FOS fos;
#endif

#ifdef MTHREAD
STRFLT _fltout2(UDOUBLE x, STRFLT flt, char *resultstr)
{
    _ULDOUBLE ld;
    FOS autofos;

    __dtold(&ld, &x);
    flt->flag =  $I10_OUTPUT(ld,NDIGITS,0,&autofos);
    flt->sign = autofos.sign;
    flt->decpt = autofos.exp;
    strcpy(resultstr,autofos.man);
    flt->mantissa = resultstr;

    return flt;
}

#else

STRFLT _fltout(UDOUBLE x)
{
    _ULDOUBLE ld;

    __dtold(&ld, &x);
    ret.flag = $I10_OUTPUT(ld,NDIGITS,0,&fos);
    ret.sign = fos.sign;
    ret.decpt = fos.exp;
    ret.mantissa = fos.man;

    return &ret;
}

#endif




/*
* __dtold -    convert a double into a _ULDOUBLE

*Purpose:  Use together with i10_output() to get string conversion
*   for double

*Entry: double *px

*Exit: the corresponding _ULDOUBLE value is returned in *pld

*Exceptions:

*/

void __dtold(_ULDOUBLE *pld, UDOUBLE *px)
{
    u_short exp;
    u_short sign;
    u_long manhi, manlo;
    u_long msb = MSB_ULONG;
    u_short ldexp = 0;

    exp = (*U_SHORT4_D(px) & (u_short)0x7ff0) >> 4;
    sign = *U_SHORT4_D(px) & (u_short)0x8000;
    manhi = *UL_HI_D(px) & 0xfffff;
    manlo = *UL_LO_D(px);

    switch (exp) {
    case D_MAXEXP:
    ldexp = LD_MAXEXP;
    break;
    case 0:
    /* check for zero */
    if (manhi == 0 && manlo == 0) {
        *UL_MANHI_LD(pld) = 0;
        *UL_MANLO_LD(pld) = 0;
        *U_EXP_LD(pld) = 0;
        return;
    }
    /* we have a denormal -- we'll normalize later */
    ldexp = (u_short) ((s_short)exp - D_BIAS + LD_BIAS + 1);
    msb = 0;
    break;
    default:
    exp -= D_BIAS;
    ldexp = (u_short) ((s_short)exp + LD_BIAS);
    break;
    }

    *UL_MANHI_LD(pld) = msb | manhi << 11 | manlo >> 21;
    *UL_MANLO_LD(pld) = manlo << 11;

    /* normalize if necessary */
    while ((*UL_MANHI_LD(pld) & MSB_ULONG) == 0) {
    /* shift left */
    *UL_MANHI_LD(pld) = *UL_MANHI_LD(pld) << 1 |
                (MSB_ULONG & *UL_MANLO_LD(pld) ? 1: 0);
    (*UL_MANLO_LD(pld)) <<= 1;
    ldexp --;
    }

    *U_EXP_LD(pld) = sign | ldexp;

}