a

libmp/mpaux.c

@@ -0,0 +1,185 @@
+#include "os.h"
+#include <mp.h>
+#include "dat.h"
+
+static mpdigit _mptwodata[1] = { 2 };
+static mpint _mptwo =
+{
+	1,
+	1,
+	1,
+	_mptwodata,
+	MPstatic
+};
+mpint *mptwo = &_mptwo;
+
+static mpdigit _mponedata[1] = { 1 };
+static mpint _mpone =
+{
+	1,
+	1,
+	1,
+	_mponedata,
+	MPstatic
+};
+mpint *mpone = &_mpone;
+
+static mpdigit _mpzerodata[1] = { 0 };
+static mpint _mpzero =
+{
+	1,
+	1,
+	0,
+	_mpzerodata,
+	MPstatic
+};
+mpint *mpzero = &_mpzero;
+
+static int mpmindigits = 33;
+
+// set minimum digit allocation
+void
+mpsetminbits(int n)
+{
+	if(n == 0)
+		n = 1;
+	mpmindigits = DIGITS(n);
+}
+
+// allocate an n bit 0'd number 
+mpint*
+mpnew(int n)
+{
+	mpint *b;
+
+	b = mallocz(sizeof(mpint), 1);
+	if(b == nil)
+		sysfatal("mpnew: %r");
+	n = DIGITS(n);
+	if(n < mpmindigits)
+		n = mpmindigits;
+	n = n;
+	b->p = (mpdigit*)mallocz(n*Dbytes, 1);
+	if(b->p == nil)
+		sysfatal("mpnew: %r");
+	b->size = n;
+	b->sign = 1;
+
+	return b;
+}
+
+// guarantee at least n significant bits
+void
+mpbits(mpint *b, int m)
+{
+	int n;
+
+	n = DIGITS(m);
+	if(b->size >= n){
+		if(b->top >= n)
+			return;
+		memset(&b->p[b->top], 0, Dbytes*(n - b->top));
+		b->top = n;
+		return;
+	}
+	b->p = (mpdigit*)realloc(b->p, n*Dbytes);
+	if(b->p == nil)
+		sysfatal("mpbits: %r");
+	memset(&b->p[b->top], 0, Dbytes*(n - b->top));
+	b->size = n;
+	b->top = n;
+}
+
+void
+mpfree(mpint *b)
+{
+	if(b == nil)
+		return;
+	if(b->flags & MPstatic)
+		sysfatal("freeing mp constant");
+	memset(b->p, 0, b->top*Dbytes);	// information hiding
+	free(b->p);
+	free(b);
+}
+
+void
+mpnorm(mpint *b)
+{
+	int i;
+
+	for(i = b->top-1; i >= 0; i--)
+		if(b->p[i] != 0)
+			break;
+	b->top = i+1;
+	if(b->top == 0)
+		b->sign = 1;
+}
+
+mpint*
+mpcopy(mpint *old)
+{
+	mpint *new;
+
+	new = mpnew(Dbits*old->size);
+	new->top = old->top;
+	new->sign = old->sign;
+	memmove(new->p, old->p, Dbytes*old->top);
+	return new;
+}
+
+void
+mpassign(mpint *old, mpint *new)
+{
+	mpbits(new, Dbits*old->top);
+	new->sign = old->sign;
+	new->top = old->top;
+	memmove(new->p, old->p, Dbytes*old->top);
+}
+
+// number of significant bits in mantissa
+int
+mpsignif(mpint *n)
+{
+	int i, j;
+	mpdigit d;
+
+	if(n->top == 0)
+		return 0;
+	for(i = n->top-1; i >= 0; i--){
+		d = n->p[i];
+		for(j = Dbits-1; j >= 0; j--){
+			if(d & (((mpdigit)1)<<j))
+				return i*Dbits + j + 1;
+		}
+	}
+	return 0;
+}
+
+// k, where n = 2**k * q for odd q
+int
+mplowbits0(mpint *n)
+{
+	int k, bit, digit;
+	mpdigit d;
+
+	if(n->top==0)
+		return 0;
+	k = 0;
+	bit = 0;
+	digit = 0;
+	d = n->p[0];
+	for(;;){
+		if(d & (1<<bit))
+			break;
+		k++;
+		bit++;
+		if(bit==Dbits){
+			if(++digit >= n->top)
+				return 0;
+			d = n->p[digit];
+			bit = 0;
+		}
+	}
+	return k;
+}
+