为什么这个while（cnt>7）的循环不进去呢？

#include

***it ADDR0 = P1^0;
***it ADDR1 = P1^1;
***it ADDR2 = P1^2;
***it ADDR3 = P1^3;
***it ENLED = P1^4;

void main()
{
unsigned int i;
unsigned char cnt = 0;

ADDR0 = 0;
ENLED = 0;
ADDR1 = 1;
ADDR2 = 1;
ADDR3 = 1;

while (1)
{
P0 = ~(0x01 << cnt);
for (i=1; i<30000; i++);
cnt++;
if (cnt > 7)
{
cnt = 0;
while (cnt > 7)
{
P0 = ~(0x80 >> cnt);
for (i=1; i<30000; i++);
cnt++;
}
cnt = 0;
}
}
}
  这个while（cnt>7）的循环怎么不进去啊？
  这是一个流水灯，左边流完，又往右边流