[C++-sig] problem about conertting c++ method to python

[sam wang]

hi, there,

I want to convert a little c++ method to python. it just retrieves the length of some unsigned
values from a vector according to some rules.

one of them seems work while another one didn't work, could you please let me know what's wrong
and how I should correct it?

any hint will great appreciate!
Sammy

the following is the source code of the method:

*****************c++ function and converted python which seems work****************

c++:
int getint(uchar *&p)
{
   int c = *((char *)p);
   p++;
   if(c==-128) { int n = *p++; n |= *((char *)p)<<8; p++; return n;}
   else if(c==-127) { int n = *p++; n |= *p++<<8; n |= *p++<<16; return n|(*p++<<24); }
   else return c;
};

python:
   def __getint(this):
       if this.p[0]==-128:
           return this.p[1] | (this.p[1]<<8), 3
       elif this.p[0] == -127:
           return this.p[1] | (this.p[2] <<8) | (this.p[3] << 16) | (this.p[4]), 5
       else:
           return this.p[0], 1



************another c++ method and converted python which didn't work*******************

c++:
int getuint(uchar *&p)
{
   int n = *p++;
   if(n & 0x80)
   {
       n += (*p++ << 7) - 0x80;
       if(n & (1<<14)) n += (*p++ << 14) - (1<<14);
       if(n & (1<<21)) n += (*p++ << 21) - (1<<21);
       if(n & (1<<28)) n |= 0xF0000000;
   };
   return n;
};

python:
   def __getuint(this):
       n = this.p[0]
       s = 1
       if (n & 0x80):
           n += (this.p[0] << 7) - 0x80;
           s += 1
           if (n & (1<<14)):
                n += (this.p[1] << 14) - (1<<14);
                s += 1
           if (n & (1<<21)):
                n += (this.p[2] << 21) - (1<<21);
                s += 1
           if (n & (1<<28)): n |= 0xF0000000;
       return n, s

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