Function decShiftToMost

extern/decNumber/decNumber.c:6683–6724

------------------------------------------------------------------ */ decShiftToMost -- shift digits in array towards most significant */ / uar is the array */ digits is the count of digits in use in the array */ shift is the number of zeros to pad with (least significant); */ it must be zero or positive

/* be large enough to hold the result, after shifting).               */
/* ------------------------------------------------------------------ */
static Int decShiftToMost(Unit *uar, Int digits, Int shift) {
  Unit  *target, *source, *first;  // work
  Int   cut;                       // odd 0's to add
  uInt  next;                      // work

  if (shift==0) return digits;     // [fastpath] nothing to do
  if ((digits+shift)<=DECDPUN) {   // [fastpath] single-unit case
    *uar=(Unit)(*uar*powers[shift]);
    return digits+shift;
    }

  next=0;                          // all paths
  source=uar+D2U(digits)-1;        // where msu comes from
  target=source+D2U(shift);        // where upper part of first cut goes
  cut=DECDPUN-MSUDIGITS(shift);    // where to slice
  if (cut==0) {                    // unit-boundary case
    for (; source>=uar; source--, target--) *target=*source;
    }
   else {
    first=uar+D2U(digits+shift)-1; // where msu of source will end up
    for (; source>=uar; source--, target--) {
      // split the source Unit and accumulate remainder for next
      #if DECDPUN<=4
        uInt quot=QUOT10(*source, cut);
        uInt rem=*source-quot*powers[cut];
        next+=quot;
      #else
        uInt rem=*source%powers[cut];
        next+=*source/powers[cut];
      #endif
      if (target<=first) *target=(Unit)next;   // write to target iff valid
      next=rem*powers[DECDPUN-cut];            // save remainder for next Unit
      }
    } // shift-move

  // propagate any partial unit to one below and clear the rest
  for (; target>=uar; target--) {
    *target=(Unit)next;
    next=0;
    }
  return digits+shift;
  } // decShiftToMost

/* ------------------------------------------------------------------ */
/* decShiftToLeast -- shift digits in array towards least significant */