circbuff.cpp

00001 #include "circbuff.h"
00002 
00003 CircBuff::CircBuff(uint16_t buffSize)
00004 {
00005     // set up the buffer with parsed size
00006     m_buffSize = buffSize;
00007     m_buf = new unsigned char [m_buffSize];
00008     for (int i = 0; i < m_buffSize; i++) {
00009         m_buf[i] = 0;
00010     }
00011 
00012     // init indexes
00013     m_start = 0;
00014     m_end   = 0;
00015 }
00016 
00017 CircBuff::~CircBuff()
00018 {
00019     delete m_buf;
00020 }
00021 
00022 void CircBuff::putc(unsigned char c)
00023 {
00024     // get the remaining space left in the buffer by checking end and start idx
00025     uint16_t remSize = remainingSize();
00026 
00027     // check we have enough room for the new array passed in
00028     if (remSize == 0) {
00029         return;
00030     }
00031 
00032     // else copy the byte in
00033     m_buf[m_end++] = c;
00034     if (m_end == m_buffSize) {
00035         m_end = 0;  // wrap around
00036     }
00037 
00038 }
00039 
00040 void CircBuff::add(unsigned char *s)
00041 {
00042     // check if can write? How to check if we have connected.
00043     uint16_t sSize = 0, i = 0, j = 0;
00044 
00045     // get the length of the passed array (it should be null terminated, but include max buffer size for caution)
00046     for (sSize = 0; (sSize < m_buffSize) && (s[sSize] != 0); sSize++);
00047 
00048     // get the remaining space left in the buffer by checking end and start idx
00049     uint16_t remSize = remainingSize();
00050 
00051     // check we have enough room for the new array passed in
00052     if (sSize > remSize) {
00053         return;
00054     }
00055 
00056     // copy the array in
00057     for (i = 0; i < sSize; i++) {
00058         m_buf[m_end++] = s[i];
00059         if (m_end == m_buffSize) {
00060             m_end = 0;  // wrap around
00061         }
00062     }
00063 }
00064 
00065 uint16_t CircBuff::remainingSize()
00066 {
00067     // get the remaining space left in the buffer by checking end and start idx
00068     uint16_t retval = 0;
00069     if (m_start == m_end) {
00070         retval = m_buffSize;
00071     }
00072     else if (m_start < m_end) {
00073         // the distance between the start and end point
00074         // subtract that from the total length of the buffer
00075         retval = m_buffSize - (m_end - m_start);
00076     }
00077     else {
00078         // the amount of space left is whatever is between the end point and the start point
00079         retval = m_start - m_end;
00080     }
00081     return retval;
00082 }
00083 
00084 uint16_t CircBuff::read(unsigned char *s, uint16_t len)
00085 {
00086     if (m_start == m_end) {
00087         return 0; // there is nothing stored in the circular buffer
00088     }
00089 
00090     // start copying the desired amount over
00091     for (int i = 0; i < len; i++) {
00092         s[i] = m_buf[m_start++];
00093         
00094         if (m_start == m_buffSize) {
00095             m_start = 0;    // wrap start pointer
00096         }
00097 
00098         if (m_start == m_end) {
00099             s[++i] = 0;
00100             return (i); // we have reached the end of the buffer
00101         }
00102     }
00103     return len;
00104 }
00105 
00106