src/mp-binary.c

   1 #include "mp.h"
   2 #include "mp-internal.h"
   3 #include "calctool.h" // FIXME: Used for MAX_DIGITS
   4
   5 static char digits[] = "0123456789ABCDEF";
   6
   7 static int hex_to_int(char digit)
   8 {
   9     if (digit >= '0' && digit <= '9')
  10         return digit - '0';
  11     if (digit >= 'A' && digit <= 'F')
  12         return digit - 'A' + 10;
  13     if (digit >= 'a' && digit <= 'f')
  14         return digit - 'a' + 10;
  15     return 0;
  16 }
  17
  18
  19 static void
  20 mp_bitwise(const MPNumber *x, const MPNumber *y, int (*bitwise_operator)(int, int), MPNumber *z, int wordlen)
  21 {
  22     char text1[MAX_DIGITS], text2[MAX_DIGITS], text_out[MAX_DIGITS];
  23     int offset1, offset2, offset_out;
  24
  25     mp_cast_to_string(x, 16, 0, 0, text1, MAX_DIGITS);
  26     mp_cast_to_string(y, 16, 0, 0, text2, MAX_DIGITS);
  27     offset1 = strlen(text1) - 1;
  28     offset2 = strlen(text2) - 1;
  29     offset_out = wordlen / 4 - 1;
  30     if (offset_out <= 0) {
  31         offset_out = offset1 > offset2 ? offset1 : offset2;
  32     }
  33     if (offset_out > 0 && (offset_out < offset1 || offset_out < offset2)) {
  34         mperr("Overflow. Try a bigger word size");
  35         return;
  36     }
  37
  38     /* Perform bitwise operator on each character from right to left */
  39     for (text_out[offset_out+1] = '\0'; offset_out >= 0; offset_out--) {
  40         int v1 = 0, v2 = 0;
  41
  42         if (offset1 >= 0) {
  43             v1 = hex_to_int(text1[offset1]);
  44             offset1--;
  45         }
  46         if (offset2 >= 0) {
  47             v2 = hex_to_int(text2[offset2]);
  48             offset2--;
  49         }
  50         text_out[offset_out] = digits[bitwise_operator(v1, v2)];
  51     }
  52
  53     mp_set_from_string(text_out, 16, z);
  54 }
  55
  56
  57 static int mp_bitwise_and(int v1, int v2) { return v1 & v2; }
  58 static int mp_bitwise_or(int v1, int v2) { return v1 | v2; }
  59 static int mp_bitwise_xor(int v1, int v2) { return v1 ^ v2; }
  60 static int mp_bitwise_xnor(int v1, int v2) { return v1 ^ v2 ^ 0xF; }
  61 static int mp_bitwise_not(int v1, int dummy) { return v1 ^ 0xF; }
  62
  63
  64 int
  65 mp_is_overflow (const MPNumber *x, int wordlen)
  66 {
  67     MPNumber tmp1, tmp2;
  68     mp_set_from_integer(2, &tmp1);
  69     mp_pwr_integer(&tmp1, wordlen, &tmp2);
  70     return mp_is_greater_than (&tmp2, x);
  71 }
  72
  73
  74 void
  75 mp_and(const MPNumber *x, const MPNumber *y, MPNumber *z)
  76 {
  77     mp_bitwise(x, y, mp_bitwise_and, z, 0);
  78 }
  79
  80
  81 void
  82 mp_or(const MPNumber *x, const MPNumber *y, MPNumber *z)
  83 {
  84     mp_bitwise(x, y, mp_bitwise_or, z, 0);
  85 }
  86
  87
  88 void
  89 mp_xor(const MPNumber *x, const MPNumber *y, MPNumber *z)
  90 {
  91     mp_bitwise(x, y, mp_bitwise_xor, z, 0);
  92 }
  93
  94
  95 void
  96 mp_xnor(const MPNumber *x, const MPNumber *y, int wordlen, MPNumber *z)
  97 {
  98     mp_bitwise(x, y, mp_bitwise_xnor, z, wordlen);
  99 }
 100
 101
 102 void
 103 mp_not(const MPNumber *x, int wordlen, MPNumber *z)
 104 {
 105     MPNumber temp;
 106     mp_set_from_integer(0, &temp);
 107     mp_bitwise(x, &temp, mp_bitwise_not, z, wordlen);
 108 }
 109
 110
 111 void
 112 mp_mask(const MPNumber *x, int wordlen, MPNumber *z)
 113 {
 114     char text[MAX_DIGITS];
 115     size_t len, offset;
 116
 117     /* Convert to a hexadecimal string and use last characters */
 118     mp_cast_to_string(x, 16, 0, 0, text, MAX_DIGITS);
 119     len = strlen(text);
 120     offset = wordlen / 4;
 121     offset = len > offset ? len - offset: 0;
 122     mp_set_from_string(text + offset, 16, z);
 123 }
 124
 125
 126 void
 127 mp_shift(const MPNumber *x, int count, MPNumber *z)
 128 {
 129     int i, multiplier = 1;
 130
 131     if (count >= 0) {
 132         for (i = 0; i < count; i++)
 133             multiplier *= 2;
 134         mp_multiply_integer(x, multiplier, z);
 135     }
 136     else {
 137         MPNumber temp;
 138         for (i = 0; i < -count; i++)
 139             multiplier *= 2;
 140         mp_divide_integer(x, multiplier, &temp);
 141         mp_integer_component(&temp, z);
 142     }
 143 }
 144
 145
 146 void
 147 mp_1s_complement(const MPNumber *x, int wordlen, MPNumber *z)
 148 {
 149     MPNumber t;
 150     mp_set_from_integer(0, &t);
 151     mp_bitwise(x, &t, mp_bitwise_xnor, z, wordlen);
 152 }
 153
 154
 155 void
 156 mp_2s_complement(const MPNumber *x, int wordlen, MPNumber *z)
 157 {
 158     mp_1s_complement (x, wordlen, z);
 159     mp_add_integer (z, 1, z);
 160 }