common/ringbuffer.h

   1 #ifndef RINGBUFFER_H_
   2 #define RINGBUFFER_H_
   3
   4 #define RINGBUFFER(name, size) uint8_t name[(size)+4] = { (size)+1, 0, 0 }
   5
   6 static inline uint8_t ringbuffer_size(const uint8_t *buffer)
   7 {
   8         return buffer[0]-1;
   9 }
  10
  11 static inline uint8_t ringbuffer_fill(const uint8_t *buffer)
  12 {
  13         const uint8_t size = buffer[0];
  14         uint8_t head = buffer[1];
  15         uint8_t tail = buffer[2];
  16         if(head<tail)
  17                 head += size;
  18         return head-tail;
  19 }
  20
  21 static inline uint8_t ringbuffer_space(const uint8_t *buffer)
  22 {
  23         return ringbuffer_size(buffer)-ringbuffer_fill(buffer);
  24 }
  25
  26 static inline void ringbuffer_push(uint8_t *buffer, uint8_t value)
  27 {
  28         const uint8_t size = buffer[0];
  29         uint8_t head = buffer[1];
  30         buffer[3+head] = value;
  31         ++head;
  32         if(head>=size)
  33                 head -= size;
  34         buffer[1] = head;
  35 }
  36
  37 static inline void ringbuffer_blocking_push(uint8_t *buffer, uint8_t value)
  38 {
  39         const uint8_t size = buffer[0];
  40         uint8_t next_head = buffer[1]+1;
  41         if(next_head>=size)
  42                 next_head -= size;
  43         const volatile uint8_t *tail = buffer+2;
  44         while(next_head==*tail) ;
  45         ringbuffer_push(buffer, value);
  46 }
  47
  48 static inline uint8_t ringbuffer_pop(uint8_t *buffer)
  49 {
  50         const uint8_t size = buffer[0];
  51         uint8_t tail = buffer[2];
  52         uint8_t value = buffer[3+tail];
  53         ++tail;
  54         if(tail>=size)
  55                 tail -= size;
  56         buffer[2] = tail;
  57         return value;
  58 }
  59
  60 static inline uint8_t ringbuffer_blocking_pop(uint8_t *buffer)
  61 {
  62         const volatile uint8_t *head = buffer+1;
  63         uint8_t tail = buffer[2];
  64         while(*head==tail) ;
  65         return ringbuffer_pop(buffer);
  66 }
  67
  68 #endif