src/integer/bitwise/cl_I_ash_I.cc

   1 // ash().
   2
   3 // General includes.
   4 #include "base/cl_sysdep.h"
   5
   6 // Specification.
   7 #include "cln/integer.h"
   8
   9
  10 // Implementation.
  11
  12 #include "integer/cl_I.h"
  13 #include "base/digitseq/cl_DS.h"
  14
  15 namespace cln {
  16
  17 const cl_I ash (const cl_I& x, const cl_I& y)
  18 {
  19     // Methode:
  20     // x = 0 -> 0 als Ergebnis
  21     // y = 0 -> x als Ergebnis
  22     // y > 0 -> y = intDsize*k + i, j=k+(1 falls i>0, 0 falls i=0).
  23     //          j Wörter mehr reservieren, k Nullwörter, dann übertragen,
  24     //          bei i>0: um i Bits links schieben (i=1 geht einfacher).
  25     // y < 0 -> y <= - intDsize * (Länge(A0) in Digits) -> Ergebnis = 0 oder -1.
  26     //          Sonst: -y = intDsize*k + i mit k<Länge(A0).
  27     //                  Übertrage die (Länge(A0)-k) MSDigits,
  28     //                  falls i>0: schiebe sie um i Bits nach rechts (i=1 geht einfacher).
  29         if (zerop(x))
  30                 return 0;               // x=0 -> 0 als Ergebnis
  31         if (zerop(y))
  32                 return x;               // y=0 -> x als Ergebnis
  33         CL_ALLOCA_STACK;
  34         if (!minusp(y)) {
  35                 // y>=0
  36                 var uintL i; // i = y mod intDsize, >=0, <intDsize
  37                 var uintC k; // k = y div intDsize, >=0, <2^intCsize
  38                 if (bignump(y)) {
  39                         #if (log2_intDsize+intCsize <= cl_value_len-1)
  40                         // y >= 2^(cl_value_len-1) >= intDsize*2^intCsize
  41                         throw ash_exception(y);
  42                         #else
  43                         // y >= 2^(cl_value_len-1)
  44                         // usable only if y < intDsize*2^intCsize
  45                         var cl_heap_bignum* bn = TheBignum(y);
  46                         var uintC len = bn->length;
  47                         if (len > ceiling(log2_intDsize+intCsize+1,intDsize))
  48                                 throw ash_exception(y);
  49                         // bn_minlength <= len <= ceiling(log2_intDsize+intCsize+1,intDsize).
  50                         if (bn_minlength == ceiling(log2_intDsize+intCsize+1,intDsize)
  51                             || len == ceiling(log2_intDsize+intCsize+1,intDsize))
  52                                 if (mspref(arrayMSDptr(bn->data,len),0) >= (uintD)bit((log2_intDsize+intCsize)%intDsize))
  53                                         throw ash_exception(y);
  54                         #if (log2_intDsize+intCsize > intDsize)
  55                         #define IF_LENGTH(i)  \
  56                           if (bn_minlength <= i && i <= ceiling(log2_intDsize+intCsize+1,intDsize) && (i == ceiling(log2_intDsize+intCsize+1,intDsize) || len == i))
  57                         IF_LENGTH(1)
  58                                 k = 0;
  59                         else IF_LENGTH(2)
  60                                 k = get_uint1D_Dptr(arrayLSDptr(bn->data,2) lspop 1);
  61                         else IF_LENGTH(3)
  62                                 k = get_uint2D_Dptr(arrayLSDptr(bn->data,3) lspop 1);
  63                         else IF_LENGTH(4)
  64                                 k = get_uint3D_Dptr(arrayLSDptr(bn->data,4) lspop 1);
  65                         else IF_LENGTH(5)
  66                                 k = get_uint4D_Dptr(arrayLSDptr(bn->data,5) lspop 1);
  67                         else
  68                                 throw runtime_exception();
  69                         #undef IF_LENGTH
  70                         k = k << (intDsize-log2_intDsize);
  71                         #else
  72                         // log2_intDsize+intCsize <= intDsize,
  73                         // implies len==1 or len==2 && lspref(arrayLSDptr(bn->data,len),1) == 0.
  74                         k = 0;
  75                         #endif
  76                         k |= lspref(arrayLSDptr(bn->data,len),0) >> log2_intDsize;
  77                         i = lspref(arrayLSDptr(bn->data,len),0) % intDsize;
  78                         #endif
  79                 } else {
  80                         var uintV y_ = FN_to_V(y); // Wert von y, >=0, <intDsize*2^intCsize
  81                         i = y_%intDsize;
  82                         k = floor(y_,intDsize);
  83                 }
  84                 var uintD* LSDptr;
  85                 var uintC len;
  86                 var const uintD* x_LSDptr;
  87                 I_to_NDS_nocopy(x, ,len=,x_LSDptr=,false,); // DS zu x bilden.
  88                 if (k >= (uintC)(~len)) // kann len+k+1 Überlauf geben?
  89                         { throw ash_exception(y); } // ja -> Fehler
  90                 num_stack_alloc_1(len+k,,LSDptr=);
  91                 LSDptr = clear_loop_lsp(LSDptr,k); // k Nulldigits
  92                 var uintD* MSDptr = copy_loop_lsp(x_LSDptr,LSDptr,len);
  93                 // Nun ist MSDptr/len/LSDptr die DS zu x.
  94                 // Oberhalb von ihr liegen k Nulldigits, unterhalb ist 1 Digit Platz.
  95                 // MSDptr/len+k/.. ist jetzt die Gesamt-DS.
  96                 // Noch um i Bits nach links schieben:
  97                 if (!(i==0)) // Bei i>0
  98                   { // noch ein weiteres Digit dazunehmen (Vorzeichen)
  99                     {var uintD sign = sign_of_sintD(mspref(MSDptr,0));
 100                      lsprefnext(MSDptr) = sign;
 101                      len++;
 102                     }
 103                     // Schiebeschleife: die unteren len Digits um i Bits schieben
 104                     if (i==1)
 105                       { shift1left_loop_lsp(LSDptr,len); }
 106                     else
 107                       { shiftleft_loop_lsp(LSDptr,len,i,0); }
 108                   }
 109                 return DS_to_I(MSDptr,len+k);
 110         } else {
 111                 // y<0
 112                 var uintL i; // i = (-y) mod intDsize, >=0, <intDsize
 113                 var uintC k; // k = (-y) div intDsize, >=0, <2^intCsize
 114                 if (bignump(y)) {
 115                         #if (log2_intDsize+intCsize <= cl_value_len-1)
 116                         // -y-1 >= 2^(cl_value_len-1) >= intDsize*2^intCsize
 117                         goto sign;
 118                         #else
 119                         // -y-1 >= 2^(cl_value_len-1)
 120                         // usable only if -y-1 < intDsize*2^intCsize
 121                         // We write -y-1 = lognot(y) = k*intDsize+i and then add 1.
 122                         var cl_heap_bignum* bn = TheBignum(y);
 123                         var uintC len = bn->length;
 124                         if (len > ceiling(log2_intDsize+intCsize+1,intDsize))
 125                                 goto sign;
 126                         // bn_minlength <= len <= ceiling(log2_intDsize+intCsize+1,intDsize).
 127                         if (bn_minlength == ceiling(log2_intDsize+intCsize+1,intDsize)
 128                             || len == ceiling(log2_intDsize+intCsize+1,intDsize))
 129                                 if (mspref(arrayMSDptr(bn->data,len),0) < (uintD)(-bit((log2_intDsize+intCsize)%intDsize)))
 130                                         goto sign;
 131                         #if (log2_intDsize+intCsize > intDsize)
 132                         #define IF_LENGTH(i)  \
 133                           if (bn_minlength <= i && i <= ceiling(log2_intDsize+intCsize+1,intDsize) && (i == ceiling(log2_intDsize+intCsize+1,intDsize) || len == i))
 134                         IF_LENGTH(1)
 135                                 k = 0;
 136                         else IF_LENGTH(2)
 137                                 k = ~get_sint1D_Dptr(arrayLSDptr(bn->data,2) lspop 1);
 138                         else IF_LENGTH(3)
 139                                 k = ~get_sint2D_Dptr(arrayLSDptr(bn->data,3) lspop 1);
 140                         else IF_LENGTH(4)
 141                                 k = ~get_sint3D_Dptr(arrayLSDptr(bn->data,4) lspop 1);
 142                         else IF_LENGTH(5)
 143                                 k = ~get_sint4D_Dptr(arrayLSDptr(bn->data,5) lspop 1);
 144                         else
 145                                 throw runtime_exception();
 146                         #undef IF_LENGTH
 147                         k = k << (intDsize-log2_intDsize);
 148                         #else
 149                         // log2_intDsize+intCsize <= intDsize,
 150                         // implies len==1 or len==2 && lspref(arrayLSDptr(bn->data,len),1) == ~0.
 151                         k = 0;
 152                         #endif
 153                         k |= (uintD)(~lspref(arrayLSDptr(bn->data,len),0)) >> log2_intDsize;
 154                         i = (uintD)(-lspref(arrayLSDptr(bn->data,len),0)) % intDsize;
 155                         if (i == 0)
 156                                 if (++k == 0)
 157                                         goto sign;
 158                         #endif
 159                 } else {
 160                         var uintV y_ = -FN_to_V(y); // Wert von -y, >0, <intDsize*2^intCsize
 161                         i = y_%intDsize;
 162                         k = floor(y_,intDsize);
 163                 }
 164                 // DS zu x bilden:
 165                 var uintD* MSDptr;
 166                 var uintC len;
 167                 I_to_NDS(x, MSDptr=,len=,); // DS zu x bilden.
 168                 if (k>=len) goto sign; // -y >= intDsize*len -> Vorzeichen von x zurück
 169                 len -= k; // rechte k Digits einfach streichen
 170                 // Noch ist len>0. Um i Bits nach rechts schieben:
 171                 if (!(i==0)) // Bei i>0:
 172                   { // Schiebe len Digits ab MSDptr um i Bits nach rechts:
 173                     if (i==1)
 174                       { shift1right_loop_msp(MSDptr,len,sign_of_sintD(mspref(MSDptr,0))); }
 175                       else
 176                       { shiftrightsigned_loop_msp(MSDptr,len,i); }
 177                   }
 178                 return DS_to_I(MSDptr,len);
 179         }
 180 sign:   // Ergebnis ist 0, falls x>=0, und -1, falls x<0:
 181         return (minusp(x) ? cl_I(-1) : cl_I(0));
 182 }
 183
 184 }  // namespace cln