mpaux.c (2667B)
1 #include "os.h" 2 #include <mp.h> 3 #include "dat.h" 4 5 static mpdigit _mptwodata[1] = { 2 }; 6 static mpint _mptwo = 7 { 8 1, 9 1, 10 1, 11 _mptwodata, 12 MPstatic 13 }; 14 mpint *mptwo = &_mptwo; 15 16 static mpdigit _mponedata[1] = { 1 }; 17 static mpint _mpone = 18 { 19 1, 20 1, 21 1, 22 _mponedata, 23 MPstatic 24 }; 25 mpint *mpone = &_mpone; 26 27 static mpdigit _mpzerodata[1] = { 0 }; 28 static mpint _mpzero = 29 { 30 1, 31 1, 32 0, 33 _mpzerodata, 34 MPstatic 35 }; 36 mpint *mpzero = &_mpzero; 37 38 static int mpmindigits = 33; 39 40 /* set minimum digit allocation */ 41 void 42 mpsetminbits(int n) 43 { 44 if(n < 0) 45 sysfatal("mpsetminbits: n < 0"); 46 if(n == 0) 47 n = 1; 48 mpmindigits = DIGITS(n); 49 } 50 51 /* allocate an n bit 0'd number */ 52 mpint* 53 mpnew(int n) 54 { 55 mpint *b; 56 57 if(n < 0) 58 sysfatal("mpsetminbits: n < 0"); 59 60 b = mallocz(sizeof(mpint), 1); 61 if(b == nil) 62 sysfatal("mpnew: %r"); 63 n = DIGITS(n); 64 if(n < mpmindigits) 65 n = mpmindigits; 66 b->p = (mpdigit*)mallocz(n*Dbytes, 1); 67 if(b->p == nil) 68 sysfatal("mpnew: %r"); 69 b->size = n; 70 b->sign = 1; 71 72 return b; 73 } 74 75 /* guarantee at least n significant bits */ 76 void 77 mpbits(mpint *b, int m) 78 { 79 int n; 80 81 n = DIGITS(m); 82 if(b->size >= n){ 83 if(b->top >= n) 84 return; 85 memset(&b->p[b->top], 0, Dbytes*(n - b->top)); 86 b->top = n; 87 return; 88 } 89 b->p = (mpdigit*)realloc(b->p, n*Dbytes); 90 if(b->p == nil) 91 sysfatal("mpbits: %r"); 92 memset(&b->p[b->top], 0, Dbytes*(n - b->top)); 93 b->size = n; 94 b->top = n; 95 } 96 97 void 98 mpfree(mpint *b) 99 { 100 if(b == nil) 101 return; 102 if(b->flags & MPstatic) 103 sysfatal("freeing mp constant"); 104 memset(b->p, 0, b->size*Dbytes); /* information hiding */ 105 free(b->p); 106 free(b); 107 } 108 109 void 110 mpnorm(mpint *b) 111 { 112 int i; 113 114 for(i = b->top-1; i >= 0; i--) 115 if(b->p[i] != 0) 116 break; 117 b->top = i+1; 118 if(b->top == 0) 119 b->sign = 1; 120 } 121 122 mpint* 123 mpcopy(mpint *old) 124 { 125 mpint *new; 126 127 new = mpnew(Dbits*old->size); 128 new->top = old->top; 129 new->sign = old->sign; 130 memmove(new->p, old->p, Dbytes*old->top); 131 return new; 132 } 133 134 void 135 mpassign(mpint *old, mpint *new) 136 { 137 mpbits(new, Dbits*old->top); 138 new->sign = old->sign; 139 new->top = old->top; 140 memmove(new->p, old->p, Dbytes*old->top); 141 } 142 143 /* number of significant bits in mantissa */ 144 int 145 mpsignif(mpint *n) 146 { 147 int i, j; 148 mpdigit d; 149 150 if(n->top == 0) 151 return 0; 152 for(i = n->top-1; i >= 0; i--){ 153 d = n->p[i]; 154 for(j = Dbits-1; j >= 0; j--){ 155 if(d & (((mpdigit)1)<<j)) 156 return i*Dbits + j + 1; 157 } 158 } 159 return 0; 160 } 161 162 /* k, where n = 2**k * q for odd q */ 163 int 164 mplowbits0(mpint *n) 165 { 166 int k, bit, digit; 167 mpdigit d; 168 169 if(n->top==0) 170 return 0; 171 k = 0; 172 bit = 0; 173 digit = 0; 174 d = n->p[0]; 175 for(;;){ 176 if(d & (1<<bit)) 177 break; 178 k++; 179 bit++; 180 if(bit==Dbits){ 181 if(++digit >= n->top) 182 return 0; 183 d = n->p[digit]; 184 bit = 0; 185 } 186 } 187 return k; 188 }