186 lines
2.5 KiB
C
186 lines
2.5 KiB
C
#include "os.h"
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#include <mp.h>
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#include "dat.h"
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static mpdigit _mptwodata[1] = { 2 };
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static mpint _mptwo =
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{
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1,
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1,
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1,
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_mptwodata,
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MPstatic
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};
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mpint *mptwo = &_mptwo;
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static mpdigit _mponedata[1] = { 1 };
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static mpint _mpone =
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{
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1,
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1,
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1,
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_mponedata,
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MPstatic
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};
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mpint *mpone = &_mpone;
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static mpdigit _mpzerodata[1] = { 0 };
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static mpint _mpzero =
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{
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1,
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1,
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0,
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_mpzerodata,
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MPstatic
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};
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mpint *mpzero = &_mpzero;
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static int mpmindigits = 33;
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// set minimum digit allocation
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void
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mpsetminbits(int n)
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{
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if(n == 0)
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n = 1;
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mpmindigits = DIGITS(n);
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}
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// allocate an n bit 0'd number
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mpint*
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mpnew(int n)
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{
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mpint *b;
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b = mallocz(sizeof(mpint), 1);
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if(b == nil)
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sysfatal("mpnew: %r");
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n = DIGITS(n);
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if(n < mpmindigits)
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n = mpmindigits;
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n = n;
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b->p = (mpdigit*)mallocz(n*Dbytes, 1);
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if(b->p == nil)
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sysfatal("mpnew: %r");
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b->size = n;
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b->sign = 1;
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return b;
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}
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// guarantee at least n significant bits
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void
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mpbits(mpint *b, int m)
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{
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int n;
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n = DIGITS(m);
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if(b->size >= n){
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if(b->top >= n)
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return;
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memset(&b->p[b->top], 0, Dbytes*(n - b->top));
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b->top = n;
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return;
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}
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b->p = (mpdigit*)realloc(b->p, n*Dbytes);
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if(b->p == nil)
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sysfatal("mpbits: %r");
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memset(&b->p[b->top], 0, Dbytes*(n - b->top));
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b->size = n;
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b->top = n;
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}
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void
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mpfree(mpint *b)
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{
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if(b == nil)
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return;
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if(b->flags & MPstatic)
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sysfatal("freeing mp constant");
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memset(b->p, 0, b->top*Dbytes); // information hiding
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free(b->p);
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free(b);
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}
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void
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mpnorm(mpint *b)
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{
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int i;
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for(i = b->top-1; i >= 0; i--)
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if(b->p[i] != 0)
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break;
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b->top = i+1;
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if(b->top == 0)
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b->sign = 1;
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}
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mpint*
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mpcopy(mpint *old)
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{
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mpint *new;
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new = mpnew(Dbits*old->size);
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new->top = old->top;
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new->sign = old->sign;
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memmove(new->p, old->p, Dbytes*old->top);
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return new;
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}
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void
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mpassign(mpint *old, mpint *new)
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{
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mpbits(new, Dbits*old->top);
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new->sign = old->sign;
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new->top = old->top;
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memmove(new->p, old->p, Dbytes*old->top);
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}
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// number of significant bits in mantissa
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int
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mpsignif(mpint *n)
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{
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int i, j;
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mpdigit d;
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if(n->top == 0)
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return 0;
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for(i = n->top-1; i >= 0; i--){
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d = n->p[i];
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for(j = Dbits-1; j >= 0; j--){
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if(d & (((mpdigit)1)<<j))
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return i*Dbits + j + 1;
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}
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}
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return 0;
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}
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// k, where n = 2**k * q for odd q
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int
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mplowbits0(mpint *n)
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{
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int k, bit, digit;
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mpdigit d;
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if(n->top==0)
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return 0;
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k = 0;
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bit = 0;
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digit = 0;
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d = n->p[0];
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for(;;){
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if(d & (1<<bit))
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break;
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k++;
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bit++;
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if(bit==Dbits){
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if(++digit >= n->top)
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return 0;
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d = n->p[digit];
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bit = 0;
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}
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}
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return k;
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}
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