circular_buffer.h

00001 #ifndef MBED_CIRC_BUFFER_H
00002 #define MBED_CIRC_BUFFER_H
00003 
00004 #include "mbed.h"
00005 
00006 #define OVERWRITE_ENABLE    1
00007 #define SEEK_ENABLE         2
00008 
00009 /** Classes circular_buffer_f and circular_buffer_c
00010 *
00011 *   Example use:-
00012 * @code
00013 * #include "mbed.h"
00014 * #include "circular_buffer.h"
00015 *  Serial pc(USBTX, USBRX); // Comms to Tera Term on pc
00016 *  Serial gizmo(p28, p27); //  Serial port for gizmo on pins 27, 28
00017 *  circular_buffer_c   chatter;   //  create  instance of circular_buffer_c for chars
00018 *
00019 * void    Rx_divert (void)  {          //  Gets attached to Serial::RxIrq interrupt handler
00020 *    while   (gizmo.readable())         //  diverting rec'd chars into purpose provided,
00021 *        chatter.write(gizmo.getc()); //  sufficiently sized, circular buffer
00022 * }
00023 *
00024 *   main    ()  {
00025 *   char buff[BUF_SIZE];           //  allocate memory for circular buffer_c
00026 *   char x;
00027 *       //  Use init function to initialise (no constructor functions here)
00028 *   chatter.init(BUF_SIZE, buff, SEEK_ENABLE | OVERWRITE_ENABLE);
00029 *
00030 *   gizmo.attach   (Rx_divert, Serial::RxIrq); //  gizmo rx now diverted to circ buff
00031 *   //  serial_in buffer now ready to use
00032 *   while   (1) {
00033 *       if  (chatter.readable())    {
00034 *           chatter.read(&x);
00035 *           pc.putc(x);
00036 *       }
00037 *   }
00038 *  }
00039 * @endcode
00040 */
00041 class circular_buffer_f   {     //  Circular buffer of floats
00042     float   *buffbase, *Onbuff, *Offbuff, *buffend;
00043     int     buffsize;
00044     bool    emptyf, fullf,      // Buffer full and empty flags
00045             overwrite_enable,   // To allow new data to overwrite old, unread data
00046             seek_enable;        // To allow read pointer repositioning 'n' behind current newest
00047     public:
00048 
00049 /** Returns true if stuff is in buffer to be read
00050 *
00051 */
00052     bool    readable    ()  {return !emptyf;}
00053 
00054 /** Returns true if space exists in buffer to write more
00055 *
00056 */
00057     bool    writeable   ()  {return !fullf;}
00058     
00059 /** Use init to setup buffer size, buffer mem address, and OVERWRITE_ENABLE and SEEK_ENABLE flags
00060 *  If OVERWRITE_ENABLE is set, allows new data to overwrite old, unread data.
00061 *  If OVERWRITE_ENABLE is clear, writes to a full buffer return false and new data is lost
00062 */
00063     void    init    (int size, float *buffstart, int flags);  // Size and address of buffer to work with
00064 
00065 /** If SEEK_ENABLE flag set, sets read pointer to some distance_back in prep for multiple read using get_samps
00066 *
00067 */
00068     bool    seek    (int distance_back) ;   // Assumes at least that much has been written to buff beforehand
00069 
00070 /** Write places one sample into buffer. Returns false if buffer already full, true otherwise
00071 *
00072 */
00073     bool    write   (float a)  ;     // Put value into circular buffer
00074 
00075 /** Read one sample out from buffer. Returns false if nothing to be read, true otherwise
00076 *
00077 */
00078     bool    read    (float *rd)  ;
00079 
00080 
00081 /** get_samps reads len samples from buffer into destination array
00082 *
00083 */
00084     bool    get_samps (float *dest, int len) ;
00085 }  ; // end of class circular_buffer_f
00086 
00087 
00088 
00089 class circular_buffer_c   {     //  Circular buffer of char
00090     char *buffbase, *Onbuff, *Offbuff, *buffend;
00091     int buffsize;
00092     bool    emptyf, fullf,      // Buffer full and empty flags
00093             overwrite_enable,   // To allow new data to overwrite old, unread data
00094             seek_enable;        // To allow read pointer repositioning 'n' behind current newest
00095     public:
00096     bool    readable    ()  {return !emptyf;}
00097     bool    writeable   ()  {return !fullf;}
00098     
00099     void    init    (int size, char *buffstart, int flags);  // Size and address of buffer to work with
00100     bool    seek    (int distance_back) ;   // Assumes at least that much has been written to buff beforehand
00101     bool    write   (char a)  ;     // Put value into circular buffer
00102     bool    read    (char *rd)  ;
00103     bool    get_samps (char *dest, int len) ;
00104 }  ; // end of class circular_buffer_c
00105 
00106 #endif