gcc/libdecnumber/decNumber.c

2666 /*     Exp =Exp +len(var1) -len(var2)                                 */
2703 /* long subtractions.  These are acc and var1 respectively.           */
2704 /* var1 is a copy of the lhs coefficient, var2 is the rhs coefficient.*/
2721   Unit varbuff[D2U (DECBUFFER * 2 + DECDPUN) * sizeof (Unit)];	/* buffer for var1 */
2722   Unit *var1 = varbuff;		/* -> var1 array for long subtraction */
2729   Int var1initpad = 0;		/* var1 initial padding (digits) */
2942       /* var1 is the padded LHS ready for subtractions. */
2944       /* The maximum units we need for var1 (long subtraction) is: */
2968 	  var1 = varalloc;	/* use the allocated space */
2972       /* is truly extended into the var1 buffer, with 0 padding, so we can */
2976       msu1 = var1 + var1units - 1;	/* msu of var1 */
2980       for (; target >= var1; target--)
2983       /* rhs (var2) is left-aligned with var1 at the start */
3005       /* number of leading zeros in var1 msu and subtract those in var2 msu. */
3015       /* var1 accumulator towards least if need be.  (It's much easier to */
3021 	  /* save the initial 'false' padding of var1, in digits */
3028 	  decShiftToLeast (var1, var1units, cut);
3059 	      for (; *msu1 == 0 && msu1 > var1; msu1--)
3063 		break;		/* var1 too low for subtract */
3078 		      if (pv1 == var1)
3083 		    break;	/* var1 too low to subtract */
3085 		    {		/* var1 == var2 */
3086 		      /* reach here if var1 and var2 are identical; subtraction */
3090 		      *var1 = 0;	/* set var1 to 0 */
3093 		    }		/* var1 == var2 */
3103 		  /* The var2 msu is one unit towards the lsu of the var1 msu, */
3111 	      /* subtraction needed; var1 is > var2 */
3113 	      /* subtract var1-var2, into var1; only the overlap needs */
3117 	      decDumpAr ('1', &var1[shift], var1units - shift);
3121 	      decUnitAddSub (&var1[shift], var1units - shift,
3122 			     var2, var2units, 0, &var1[shift], -mult);
3124 	      decDumpAr ('#', &var1[shift], var1units - shift);
3126 	      /* var1 now probably has leading zeros; these are removed at the */
3151 	  if (*var1 == 0 && var1units == 1)
3164 	  /* to get here, var1 is less than var2, so divide var2 by the per- */
3173       /*       var1     has any residue at the stopping point */
3189 	  if (*var1 != 0 || var1units > 1)
3238 	      /* [Here, the exponent will be 0, because we adjusted var1 */
3247 	      if (*var1 == 0 && var1units == 1)
3265 	      /* treat the residue, in var1, as the value to return, via acc */
3267 	      /*   var1 initial padding (saved above) */
3275 	      /* shift var1 the requested amount, and adjust its digits */
3276 	      var1units = decShiftToLeast (var1, var1units, postshift);
3277 	      accnext = var1;
3278 	      accdigits = decGetDigits (var1, var1units);
3295 		  /* calculate remainder*2 into the var1 buffer (which has */
3303 		  /* Here, accnext (var1) holds tarunits Units with twice the */
3362 		      /* safely use var1 for the working Units array. */