Searching for a substring in a ring queue

Question

I am implementing a function which searches through a ring queue for a given substring. The function returns true if the substring is found, otherwise false. There is a cell containing null between the tail and head to signify the end of string. Please give feedback on this implementation.

bool SoftwareSerial::contains(const char *substr){
 char *pBuffer =_receive_buffer + _receive_buffer_head; 
 char *pSubstr = substr;
 for(; *pBuffer != 0 && *pSubstr != 0; ++pBuffer ){
 if(pBuffer == (_receive_buffer + _SS_MAX_RX_BUFF)){
 pBuffer = _receive_buffer + _receive_buffer_head;
 }
 if(*pBuffer != *pSubstr){
 pSubstr = substr;
 continue;
 }
 ++pSubstr;
 }
 return (*pSubstr == 0);
}

Answer 1

There were few bugs in the function. 1. pStr should point to the start of the buffer once it reaches the end of the buffer. 2. A flag should be set when a character matches and unset the flag when next coming character doesn't match. Here the modified version that I believe is correct:

bool Buffer::contains(const char *pcSubstr){
const char *pcCurrentSubstr = pcSubstr;
const char *pStr = buffer + head;
bool seen = false;
for (; *pStr != 0 && *pcCurrentSubstr != 0; ++pStr){
 if(pStr == (buffer + MAX_BUFFER_SIZE)){
 pStr = buffer;
 }
 if(*pStr != *pcCurrentSubstr){
 pcCurrentSubstr = pcSubstr;
 if(seen){
 --pStr;
 }
 seen = false;
 continue;
 }
 seen = true;
 ++pcCurrentSubstr;
}
return (*pcCurrentSubstr == 0);
}