Function decFloatFromBCD

extern/decNumber/decCommon.c:577–646

------------------------------------------------------------------ */ decFloatFromBCD -- set decFloat from exponent, BCD8, and sign */ / df is the target decFloat */ exp is the in-range unbiased exponent, q, or a special value in */ the form returned by decFloatGetExponent */ bcdar holds DECPMAX digits to set the coefficient fro

/* No error is possible, and no status will be set.                   */
/* ------------------------------------------------------------------ */
decFloat * decFloatFromBCD(decFloat *df, Int exp, const uByte *bcdar,
                           Int sig) {
  uInt encode, dpd;                     // work
  const uByte *ub;                      // ..

  if (EXPISSPECIAL(exp)) encode=exp|sig;// specials already encoded
   else {                               // is finite
    // encode the combination field and exponent continuation
    uInt uexp=(uInt)(exp+DECBIAS);      // biased exponent
    uInt code=(uexp>>DECECONL)<<4;      // top two bits of exp
    code+=bcdar[0];                     // add msd
    // look up the combination field and make high word
    encode=DECCOMBFROM[code]|sig;       // indexed by (0-2)*16+msd
    encode|=(uexp<<(32-6-DECECONL)) & 0x03ffffff; // exponent continuation
    }

  // private macro to extract a declet, n (where 0<=n<DECLETS and 0
  // refers to the declet from the least significant three digits)
  // and put the corresponding DPD code into dpd.
  // Use of a working pointer, uInt *ub, is assumed.

  #define getDPDb(dpd, n) ub=bcdar+DECPMAX-1-(3*(n))-2;     \
    dpd=BCD2DPD[(*ub*256)+(*(ub+1)*16)+*(ub+2)];

  // place the declets in the encoding words and copy to result (df),
  // according to endianness; in all cases complete the sign word
  // first
  #if DECPMAX==7
    getDPDb(dpd, 1);
    encode|=dpd<<10;
    getDPDb(dpd, 0);
    encode|=dpd;
    DFWORD(df, 0)=encode;     // just the one word

  #elif DECPMAX==16
    getDPDb(dpd, 4); encode|=dpd<<8;
    getDPDb(dpd, 3); encode|=dpd>>2;
    DFWORD(df, 0)=encode;
    encode=dpd<<30;
    getDPDb(dpd, 2); encode|=dpd<<20;
    getDPDb(dpd, 1); encode|=dpd<<10;
    getDPDb(dpd, 0); encode|=dpd;
    DFWORD(df, 1)=encode;

  #elif DECPMAX==34
    getDPDb(dpd,10); encode|=dpd<<4;
    getDPDb(dpd, 9); encode|=dpd>>6;
    DFWORD(df, 0)=encode;

    encode=dpd<<26;
    getDPDb(dpd, 8); encode|=dpd<<16;
    getDPDb(dpd, 7); encode|=dpd<<6;
    getDPDb(dpd, 6); encode|=dpd>>4;
    DFWORD(df, 1)=encode;

    encode=dpd<<28;
    getDPDb(dpd, 5); encode|=dpd<<18;
    getDPDb(dpd, 4); encode|=dpd<<8;