my pointers are not getting changed when passing into a function...

[C++ Newbie]

I have the following function that takes in 2 pointers, does copies and then returns. The problem I have is that when the function returns I want the pointers to have the modified values but they retain the original values. Can someone tell me why & how to fix it?

unsigned char *p_source_buf;// {I set this to a memory buffer which read in a file};
unsigned char *pInBuf = new char[200];
unsigned int num_bytes_to_insert;

void main(void){
  byte_copy(m_pInBuf, p_source_buf, num_bytes_to_insert);
}


const unsigned int BITMASK_FOR_LEAST_SIGNIFICANT_TWO_BITS = 0x3;
inline void byte_copy(unsigned char *p_in_buf, unsigned char *p_source_buf, unsigned int num_bytes_to_insert){
		//Transfer remaining bytes individually
		unsigned int remaining_bytes = static_cast<unsigned int>(num_bytes_to_insert & BITMASK_FOR_SIGNIFICANT_TWO_BITS);
		for(unsigned int i=0;i<remaining_bytes;i++)
			*p_in_buf++ = *p_source_buf++;
}