From ed4673952ba5ec554d3a045cfeced013644919e7 Mon Sep 17 00:00:00 2001
From: Ezequiel <ezequielinfo@yahoo.com.ar>
Date: Wed, 5 Oct 2005 01:33:30 +0000
Subject: [PATCH] resta corregida + un par de asserts

---
 src/number.h     | 41 +++++++++++++++++-------------
 tests/number.cpp | 66 +++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 77 insertions(+), 30 deletions(-)

diff --git a/src/number.h b/src/number.h
index 71705cc..27d19a8 100644
--- a/src/number.h
+++ b/src/number.h
@@ -132,19 +132,18 @@ struct number
 	// borrow)
 	void borrow(size_type i)
 	{
-		if (chunk.size() >= i)
+		// para poder pedir prestado debo tener uno a la izquierda
+		assert (chunk.size() >= i);
+		
+		if (chunk[i] == 0)
 		{
-			if (chunk[i] == 0)
-			{
-				borrow(i+1); // Overflow, pido prestado
-				chunk[i] = ~((N)0); //quedo con el valor máximo
-			}
-			else
-			{
-				--chunk[i]; //tengo para dar, pero pierdo uno yo
-			}
+			borrow(i+1); // Overflow, pido prestado
+			chunk[i] = ~((N)0); //quedo con el valor máximo
+		}
+		else
+		{
+			--chunk[i]; //tengo para dar, pero pierdo uno yo
 		}
-		//else ERROR, están haciendo a-b con a>b
 	}
 	// Verifica si es un número par
 	bool es_impar() const
@@ -326,11 +325,17 @@ number< N, E >& number< N, E >::operator-= (const number< N, E >& n)
 		// si no alcanza para restar pido prestado
 		if ((minuend.chunk[i] < subtrahend.chunk[i]))
 		{
-			minuend.borrow(i);
+			// no puedo pedir si soy el más significativo ...
+			assert (i != fin);
+
+			// le pido uno al que me sigue
+			minuend.borrow(i+1);
 		}
 		
-		// resto el chunk i-ésimo
-		minuend.chunk[i] -= subtrahend.chunk[i];
+		// es como hacer 24-5: el 4 pide prestado al 2 (borrow(i+1)) y después
+		// se hace 4 + (9-5) + 1
+
+		minuend.chunk[i] += (~((N)0) - subtrahend.chunk[i]) + 1; 
 	}
 
 	//retorno el minuendo ya restado
@@ -397,17 +402,17 @@ number< N, E > operator<< (const number< N, E >& n, typename number< N, E >::siz
 	return tmp;
 }
 
-template < typename N, typename E >
-std::ostream& operator<< (std::ostream& os, const number< N, E >& n)
+template < typename NN, typename EE >
+std::ostream& operator<< (std::ostream& os, const number< NN, EE >& n)
 {
 	// FIXME sacar una salida bonita en ASCII =)
 	if (n.sign == positive)
 		os << "+ ";
 	else
 		os << "- ";
-	for (typename number< N, E >::const_reverse_iterator i = n.chunk.rbegin();
+	for (typename number< NN, EE >::const_reverse_iterator i = n.chunk.rbegin();
 			i != n.chunk.rend(); ++i)
-		os << std::setfill('0') << std::setw(sizeof(N) * 2) << std::hex
+		os << std::setfill('0') << std::setw(sizeof(NN) * 2) << std::hex
 			<< *i << " ";
 	return os;
 }
diff --git a/tests/number.cpp b/tests/number.cpp
index fc74c55..3b9d1b5 100644
--- a/tests/number.cpp
+++ b/tests/number.cpp
@@ -4,7 +4,7 @@
 int main()
 {
 #if 0
-	unsigned buf[5] = { 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0 };
+	unsigned long buf[5] = { 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0 };
 	//unsigned buf[3] = { 0xffffffff, 0x1, 0 };
 	number<> nu(buf, 4);
 	//number< unsigned > nu2(nu);
@@ -18,18 +18,25 @@ int main()
 
 #if 0
 	number< unsigned > nu = 0xffffffff;
-	std::cout << "nu = " << nu << "\n\n";
+	std::cout << "nu = " << nu ;
 
 	nu << 5;
-	std::cout << "nu = " << nu << "\n\n";
+	std::cout << "nu = " << nu ;
 
-	number<> n1 = 0x00000000;
-	number<> n2 = 0x00000000;
+	number<> n1 = 0xFFFFFFFF;
+	number<> n2 = 0xFFFFFFFF;
 
-	n2 += 1;
+	n1 += 1;
 
-	n1 <<= 1;
-	n2 <<= 1;
+/*	for (int k = 0; k < 100; k++)
+	{
+		n1 += (unsigned) rand() * k;
+		n2 += (unsigned) rand() * k;
+	}
+*/
+	
+//	n1 <<= 1;
+//	n2 <<= 1;
 
 	if (n1 < n2)
 		std::cout << "n1 es menor que n2\n";
@@ -54,12 +61,47 @@ int main()
 	std::cout << "n1-n2: " << n1 ;
 #endif
 
+#if 1
 	uint32_t buf[] = { 0x00000040, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000 };
-	number<> nu(buf, 8);
+	number<> nu(buf, 8, negative);
 	number<> nu2 = 0x2;
-	std::cout << "nu = " << nu << "\n\n";
-	std::cout << "nu2 = " << nu2 << "\n\n";
-	std::cout << "nu * nu2 = "  << naif(nu, nu2) << "\n\n";
+	std::cout << "nu = " << nu ;
+	std::cout << "\n";
+	std::cout << "nu2 = " << nu2 ;
+	std::cout << "\n";
+	std::cout << "nu * nu2 = "  << naif(nu, nu2) ;
+	std::cout << "\n";
+	std::cout << "nu + nu2 = "  << nu + nu2 ;
+	std::cout << "\n";
+	std::cout << "nu - nu2 = "  << nu - nu2 ;
+
+#endif
+
+	number<> h = 0x10000000;
+	h<<=1;
+	h += 0xfffffffc;
+	h<<=1;
+	h += 0xffffffff;
+	h<<=1;
+	h += 0x00000002;
+	number<> d = 0;
+	number<> m = 0xfffffffe;
+	m<<=1;
+	m += 0xffffffff;
+	m<<=1;
+	m += 0x00000001;
+
+	std::cout << "h: " << h ;
+	std::cout << "\n";
+	std::cout << "d: " << d ;
+	std::cout << "\n";
+	std::cout << "m: " << m ;
+	std::cout << "\n";
+
+	number<> a = h - d - m;
+
+	std::cout << "h-d-m: " << a ;
+
 
 	return 0;
 }
-- 
2.43.0