在32位应用程序中提供错误输出的64位算法

我不明白为什么下面相同的操作报告两个不同的输出。当我的num被声明为负值,并且我将num添加到baseAddr时,我看到我的addr超过了32位范围。另一方面,如果我将num声明为正值并进行减法运算,我确实看到了正确的结果。即准确地报告了我的结果输出。有人能解释一下下面的计算出了什么问题吗?

/* Architecture is powerpc. Program cross-compiled for powerpc. Gcc Version- 4.6.2 */
#include <stdio.h>
typedef unsigned long long u_int64;
typedef unsigned long u_int32;

int main() {
   u_int64 baseAddr = 0x8e008128;
   u_int32 num = -360;
   u_int64 addr = baseAddr + num;
   printf("\nAddr 1st step = 0x%llx\n", addr);

   /* Same operation, but slightly different */
   num = 360;
   addr = baseAddr - num;
   printf("\nAddr 2nd step = 0x%llx\n", addr);
   return 0;
}

/* Output:
Addr printed is 0x18e007fc0, but I need just 0x8e007fc0
/diagsk10copy/bin # ./e500GPR

Addr 1st step = 0x18e007fc0 //Wrong
Addr 2nd step = 0x8e007fc0
*/