#ifndef __buf_h__
#define __buf_h__

#include "common.h"

/*
 * Note that all of these constants should be powers of two or
 * their corresponding AND-masks in order for the code to work
 * as intended, and that certain ratios must be preservered
 * for example, produce size must be at least as great as
 * consume size
 */

#define BUF_SIZE   16384        // external SRAM size
#define BUF_MASK   0x3FFF       // buffer size mask for fast modulus
//#define BUF_ADDR 0x0260       // for 8515 (with 512b internal RAM)
#define BUF_ADDR   0x1000       // for mega103 (with 4kb internal RAM)

char * buf = BUF_ADDR;

WORD producer = 0;
WORD consumer = 0;


// circular buffer functions

/*

These routines have been replaced by the macros below for speed.

char canProduce();

char canConsume();

void produce(char c);

char consume();
*/

void clear();

// high-efficiency alternative to byte-level is a block-level model

#define BUF_BLOCK_SIZE 2048     // buffer block size (sector size is a good choice)

//is it safe to read from the buffer and play some data
#define SAFE_TO_PRODUCE (((producer + BUF_BLOCK_SIZE) & BUF_MASK) != consumer)

//is it safe to read some data from the buf and output it to the STA013?
#define SAFE_TO_CONSUME (producer != consumer)

//indicate that some data has been read from the CDROM
#define MULTI_PRODUCE   producer = ((producer + BUF_BLOCK_SIZE) & BUF_MASK)

//indicate that some data has been written to the STA013 
#define MULTI_CONSUME   consumer = ((consumer + BUF_BLOCK_SIZE) & BUF_MASK)

#endif