www.pudn.com > MyPlayerbylqh.rar > Ring.cpp

 
 
 
#include "ring.h" 
 
 
 
#define RING_SIZE   98000 
 
char                ring[RING_SIZE]; 
unsigned int        read_pos; 
unsigned int        write_pos; 
 
 
void ring_init() 
{ 
  read_pos  = 0; 
  write_pos = 0; 
} 
 
void ring_read(char *data, int size) 
{ 
  if(write_pos <= read_pos) { 
     
    if(read_pos + size < RING_SIZE) { 
      memcpy(data, ring + read_pos, size); 
      read_pos += size; 
    } 
    else { 
      if(read_pos + size < RING_SIZE + write_pos) { 
	 
	unsigned int before, after; 
	 
	before = (RING_SIZE - 1) - read_pos; 
	after = size - before; 
	 
	memcpy(data, ring + read_pos, before); 
	memcpy(data + before, ring, after); 
	 
	read_pos = after; 
      } 
      else { 
	  } 
    } 
  } 
  else { 
    if(read_pos + size <= write_pos) { 
      memcpy(data, ring + read_pos, size); 
      read_pos += size; 
    } 
    else { 
    } 
  }  
} 
 
void ring_write(char *data, int size) 
{ 
  if(write_pos >= read_pos) { 
     
    if(write_pos + size < RING_SIZE) { 
      memcpy(ring + write_pos, data, size); 
      write_pos += size; 
    } 
    else { 
      if(write_pos + size < RING_SIZE + read_pos) { 
	 
	unsigned int before, after; 
 
	before = (RING_SIZE - 1) - write_pos; 
	after = size - before; 
 
	memcpy(ring + write_pos, data, before); 
	memcpy(ring, data + before, after); 
 
 
	write_pos = after; 
      } 
    } 
  } 
  else { 
    if(write_pos + size <= read_pos) { 
      memcpy(ring + write_pos, data, size); 
      write_pos += size; 
    } 
 
    return; 
  } 
} 
 
int ring_full(int size) 
{ 
  if(write_pos == read_pos) 
    return 0; 
 
  if(write_pos > read_pos) { 
 
    if(write_pos + size < read_pos + RING_SIZE) 
      return 0; 
 
    return 1; 
  } 
  else { 
    if(write_pos + size < read_pos) 
      return 0; 
 
    return 1; 
  } 
}