text: /******************************************************************************
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  #include "bid_internal.h"
  
  #define MAX_FORMAT_DIGITS     16
  #define DECIMAL_EXPONENT_BIAS 398
  #define MAX_DECIMAL_EXPONENT  767
  
  BID_TYPE0_FUNCTION_ARGTYPE1_OTHER_ARGTYPE2(BID_UINT64, bid64_scalbn, BID_UINT64, x, int, n)
    BID_UINT64 sign_x, coefficient_x, res;
    BID_SINT64 exp64;
    int exponent_x, rmode;
  
    // unpack arguments, check for NaN or Infinity
    if (!unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x)) {
      // x is Inf. or NaN or 0
  #ifdef BID_SET_STATUS_FLAGS
      if ((x & SNAN_MASK64) == SNAN_MASK64)	// y is sNaN
        __set_status_flags (pfpsf, BID_INVALID_EXCEPTION);
  #endif
      if (coefficient_x)
        res = coefficient_x & QUIET_MASK64;
  	else {
         exp64 = (BID_SINT64) exponent_x + (BID_SINT64) n;
  	   if(exp64<0) exp64=0;
  	   if(exp64>MAX_DECIMAL_EXPONENT) exp64=MAX_DECIMAL_EXPONENT;
         exponent_x = exp64;
        res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);	// 0
  	}
      BID_RETURN (res);
    }
  
    exp64 = (BID_SINT64) exponent_x + (BID_SINT64) n;
    exponent_x = exp64;
  
    if ((BID_UINT32) exponent_x <= MAX_DECIMAL_EXPONENT) {
      res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);
      BID_RETURN (res);
    }
    // check for overflow
    if (exp64 > MAX_DECIMAL_EXPONENT) {
      // try to normalize coefficient
      while ((coefficient_x < 1000000000000000ull)
  	   && (exp64 > MAX_DECIMAL_EXPONENT)) {
        // coefficient_x < 10^15, scale by 10
        coefficient_x = (coefficient_x << 1) + (coefficient_x << 3);
        exponent_x--;
        exp64--;
      }
      if (exp64 <= MAX_DECIMAL_EXPONENT) {
        res = very_fast_get_BID64 (sign_x, exponent_x, coefficient_x);
        BID_RETURN (res);
      } else
        exponent_x = 0x7fffffff;	// overflow
    }
    // exponent < 0
    // the BID pack routine will round the coefficient
    rmode = rnd_mode;
    res = get_BID64 (sign_x, exponent_x, coefficient_x, rmode, pfpsf);
    BID_RETURN (res);
  
  }
  