133 lines
2.5 KiB
C
133 lines
2.5 KiB
C
/*
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*cfout.c - Encode interface for C
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* Copyright (c) 19xx-1991, Microsoft Corporation. All rights reserved.
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*Purpose:
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*Revision History:
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* 07-20-91 GDP Ported to C from assembly
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* 04-30-92 GDP Added _dtold routine (moved here from ldtod.c)
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* 05-14-92 GDP NDIGITS is now 17 (instead of 16)
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* 05-26-92 GWK Windbg srcs
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*/
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#include <string.h>
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#include "mathsup.h"
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#define NDIGITS 17
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void __dtold(_ULDOUBLE *pld, UDOUBLE *px);
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#ifndef MTHREAD
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static struct _strflt ret;
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static FOS fos;
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#endif
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#ifdef MTHREAD
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STRFLT _fltout2(UDOUBLE x, STRFLT flt, char *resultstr)
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{
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_ULDOUBLE ld;
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FOS autofos;
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__dtold(&ld, &x);
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flt->flag = $I10_OUTPUT(ld,NDIGITS,0,&autofos);
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flt->sign = autofos.sign;
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flt->decpt = autofos.exp;
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strcpy(resultstr,autofos.man);
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flt->mantissa = resultstr;
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return flt;
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}
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#else
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STRFLT _fltout(UDOUBLE x)
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{
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_ULDOUBLE ld;
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__dtold(&ld, &x);
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ret.flag = $I10_OUTPUT(ld,NDIGITS,0,&fos);
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ret.sign = fos.sign;
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ret.decpt = fos.exp;
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ret.mantissa = fos.man;
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return &ret;
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}
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#endif
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/*
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* __dtold - convert a double into a _ULDOUBLE
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*Purpose: Use together with i10_output() to get string conversion
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* for double
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*Entry: double *px
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*Exit: the corresponding _ULDOUBLE value is returned in *pld
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*Exceptions:
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*/
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void __dtold(_ULDOUBLE *pld, UDOUBLE *px)
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{
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u_short exp;
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u_short sign;
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u_long manhi, manlo;
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u_long msb = MSB_ULONG;
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u_short ldexp = 0;
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exp = (*U_SHORT4_D(px) & (u_short)0x7ff0) >> 4;
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sign = *U_SHORT4_D(px) & (u_short)0x8000;
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manhi = *UL_HI_D(px) & 0xfffff;
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manlo = *UL_LO_D(px);
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switch (exp) {
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case D_MAXEXP:
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ldexp = LD_MAXEXP;
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break;
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case 0:
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/* check for zero */
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if (manhi == 0 && manlo == 0) {
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*UL_MANHI_LD(pld) = 0;
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*UL_MANLO_LD(pld) = 0;
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*U_EXP_LD(pld) = 0;
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return;
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}
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/* we have a denormal -- we'll normalize later */
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ldexp = (u_short) ((s_short)exp - D_BIAS + LD_BIAS + 1);
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msb = 0;
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break;
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default:
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exp -= D_BIAS;
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ldexp = (u_short) ((s_short)exp + LD_BIAS);
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break;
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}
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*UL_MANHI_LD(pld) = msb | manhi << 11 | manlo >> 21;
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*UL_MANLO_LD(pld) = manlo << 11;
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/* normalize if necessary */
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while ((*UL_MANHI_LD(pld) & MSB_ULONG) == 0) {
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/* shift left */
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*UL_MANHI_LD(pld) = *UL_MANHI_LD(pld) << 1 |
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(MSB_ULONG & *UL_MANLO_LD(pld) ? 1: 0);
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(*UL_MANLO_LD(pld)) <<= 1;
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ldexp --;
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}
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*U_EXP_LD(pld) = sign | ldexp;
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}
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