a

libmp/strtomp.c

@@ -0,0 +1,205 @@
+#include "os.h"
+#include <mp.h>
+#include <libsec.h>
+#include "dat.h"
+
+static struct {
+	int	inited;
+
+	uchar	t64[256];
+	uchar	t32[256];
+	uchar	t16[256];
+	uchar	t10[256];
+} tab;
+
+enum {
+	INVAL=	255
+};
+
+static char set64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+static char set32[] = "23456789abcdefghijkmnpqrstuvwxyz";
+static char set16[] = "0123456789ABCDEF0123456789abcdef";
+static char set10[] = "0123456789";
+
+static void
+init(void)
+{
+	char *p;
+
+	memset(tab.t64, INVAL, sizeof(tab.t64));
+	memset(tab.t32, INVAL, sizeof(tab.t32));
+	memset(tab.t16, INVAL, sizeof(tab.t16));
+	memset(tab.t10, INVAL, sizeof(tab.t10));
+
+	for(p = set64; *p; p++)
+		tab.t64[*p] = p-set64;
+	for(p = set32; *p; p++)
+		tab.t32[*p] = p-set32;
+	for(p = set16; *p; p++)
+		tab.t16[*p] = (p-set16)%16;
+	for(p = set10; *p; p++)
+		tab.t10[*p] = (p-set10);
+
+	tab.inited = 1;
+}
+
+static char*
+from16(char *a, mpint *b)
+{
+	char *p, *next;
+	int i;
+	mpdigit x;
+
+	b->top = 0;
+	for(p = a; *p; p++)
+		if(tab.t16[*p] == INVAL)
+			break;
+	mpbits(b, (p-a)*4);
+	b->top = 0;
+	next = p;
+	while(p > a){
+		x = 0;
+		for(i = 0; i < Dbits; i += 4){
+			if(p <= a)
+				break;
+			x |= tab.t16[*--p]<<i;
+		}
+		b->p[b->top++] = x;
+	}
+	return next;
+}
+
+static ulong mppow10[] = {
+	1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000
+};
+
+static char*
+from10(char *a, mpint *b)
+{
+	ulong x, y;
+	mpint *pow, *r;
+	int i;
+
+	pow = mpnew(0);
+	r = mpnew(0);
+
+	b->top = 0;
+	for(;;){
+		// do a billion at a time in native arithmetic
+		x = 0;
+		for(i = 0; i < 9; i++){
+			y = tab.t10[*a];
+			if(y == INVAL)
+				break;
+			a++;
+			x *= 10;
+			x += y;
+		}
+		if(i == 0)
+			break;
+
+		// accumulate into mpint
+		uitomp(mppow10[i], pow);
+		uitomp(x, r);
+		mpmul(b, pow, b);
+		mpadd(b, r, b);
+		if(i != 9)
+			break;
+	}
+	mpfree(pow);
+	mpfree(r);
+	return a;
+}
+
+static char*
+from64(char *a, mpint *b)
+{
+	char *buf = a;
+	uchar *p;
+	int n, m;
+
+	for(; tab.t64[*a] != INVAL; a++)
+		;
+	n = a-buf;
+	mpbits(b, n*6);
+	p = malloc(n);
+	if(p == nil)
+		return a;
+	m = dec64(p, n, buf, n);
+	betomp(p, m, b);
+	free(p);
+	return a;
+}
+
+static char*
+from32(char *a, mpint *b)
+{
+	char *buf = a;
+	uchar *p;
+	int n, m;
+
+	for(; tab.t64[*a] != INVAL; a++)
+		;
+	n = a-buf;
+	mpbits(b, n*5);
+	p = malloc(n);
+	if(p == nil)
+		return a;
+	m = dec32(p, n, buf, n);
+	betomp(p, m, b);
+	free(p);
+	return a;
+}
+
+mpint*
+strtomp(char *a, char **pp, int base, mpint *b)
+{
+	int sign;
+	char *e;
+
+	if(b == nil)
+		b = mpnew(0);
+
+	if(tab.inited == 0)
+		init();
+
+	while(*a==' ' || *a=='\t')
+		a++;
+
+	sign = 1;
+	for(;; a++){
+		switch(*a){
+		case '-':
+			sign *= -1;
+			continue;
+		}
+		break;
+	}
+
+	switch(base){
+	case 10:
+		e = from10(a, b);
+		break;
+	default:
+	case 16:
+		e = from16(a, b);
+		break;
+	case 32:
+		e = from32(a, b);
+		break;
+	case 64:
+		e = from64(a, b);
+		break;
+	}
+
+	// if no characters parsed, there wasn't a number to convert
+	if(e == a)
+		return nil;
+
+	mpnorm(b);
+	b->sign = sign;
+	if(pp != nil)
+		*pp = e;
+
+	return b;
+}