/***************************************************************************/
/*									   */
/* SUPRA CORP. Hard Disk Format drivers for the Atari 520 ST	           */
/*									   */
/* 15 April 1986							   */
/*									   */
/*	This file containes the routines that are necessary to access	   */
/*	  a DMA bus device on the Atari 520ST.  These examples are	   */
/*	  intended ONLY to be used as examples on how to read and write	   */
/*	  to the DMA bus.  They were written in MEGAMAX C.		   */
/*	NOTE:								   */
/*	  The 'asm' command in the 'FIFO_RD()' procedure may be required   */
/*	  if your compiler uses a 'CLR' to zero a memory location.  The	   */
/*	  two lines must store a LONG 0 into 'FIFO'.  A 'CLR' (what	   */
/*	  Megamax compiles the commented out line to) will NOT WORK.	   */
/*									   */
/*	Supra Corp. assumes no responsibility or liability for the use of  */
/*	  these routines.  This information is correct for the current     */
/*	  version (11/20/1985) of TOS in ROM, and is compatible with	   */
/*	  Atari's hard disk drive.					   */
/*	If you have questions or comments please use either Compuserve 	   */
/*	  or call the Supra Support BBS.  We are not able to answer	   */
/*	  questions over the phone about this information.  We do hope	   */
/*	  that this information will help answer the questions on the use  */
/*	  of the powerful and fast Atari 520ST DMA bus.			   */
/*									   */
/*	Tech Support Department						   */
/*	CIS 76004,565							   */
/*	SUPRA CORPORATION						   */
/*	1133 Commercial Way						   */
/*	Albany, OR  97321						   */
/*	(503) 967-9075							   */
/*	Supra Support BBS  (503) 926-1980				   */
/*									   */
/***************************************************************************/

/***************************************************************************/

WORD	*flock      = 0x43eL;
BYTE	*gpip       = 0xfffa01L;
WORD	*diskctl_w  = 0xff8604L;
LONG	*diskctl_l  = 0xff8604L;
WORD	*fifo       = 0xff8606L;
BYTE	*dmahigh    = 0xff8609L;
BYTE	*dmamid     = 0xff860bL;
BYTE	*dmalow     = 0xff860dL;

LONG	save_ssp;

#define	LONG_DELAY	690000
#define SHORT_DELAY	23000
#define	FLOCK_ON	-1
#define	FLOCK_OFF	0

/***************************************************************************/

VOID
sup_on()
{
	save_ssp = Super(0L);
}

VOID
sup_off()
{
	Super(save_ssp);
}

WORD
wait(time)
LONG	time;
{

	while(time--) {
		if( (*gpip & 0x20) == 0)
			return(0);
	}		
	return(-1);
}

VOID
fifo_rd(count)
WORD	count;
{

	*fifo = 0x90;
	*fifo = 0x190;
	*fifo = 0x90;
	*diskctl_w = count;
	*fifo = 0x8a;
/*	*diskctl_l = 0x0L;    DONT use this -- compiler does it WRONG */
	asm{
	move.l	#0x00ff8604,A0
	move.l	#0x00000000,(A0)
	}
}

VOID
fifo_wrt(count)
WORD	count;
{

	*fifo = 0x90;
	*fifo = 0x190;
	*diskctl_w = count;
	*fifo = 0x18a;
	*diskctl_l = 0x100L;
}

WORD
get_status(mode)
WORD	mode;
{
	WORD	err;

	err = wait(LONG_DELAY);
	if( !err ) {
		*fifo = mode;
		err = *diskctl_w & 0xff;
	}
	return(err);
}

VOID
end_hd()
{
	WORD	dummy;

	*fifo = 0x80;
	dummy = *diskctl_w;
	*flock	= FLOCK_OFF;
}

VOID
set_dma(buf)
LONG	buf;
{

	*dmalow = (BYTE) (buf & 0xff);
	*dmamid = (BYTE) ((buf >> 8) & 0xff);
	*dmahigh = (BYTE) ((buf >> 16) & 0xff);
}

WORD
select_sector(command,sectno,count,buf,dma)
LONG	command,sectno;
WORD	count;
LONG	buf;
WORD	dma;
{
	WORD	err;

	*flock = FLOCK_ON;
	if ( buf )
		set_dma(buf);
	*fifo = 0x88;
	*diskctl_l = ( (LONG) dma << 21) | command;
	err = wait(SHORT_DELAY);
	if( !err ) {
		*diskctl_l  = ( (LONG) dma << 21) | (sectno & 0x1f0000) | 0x8a;
		err = wait(SHORT_DELAY);
		if( !err ) {
			*diskctl_l = (sectno & 0xff00) << 8 | 0x8a;
			err = wait(SHORT_DELAY);
			if( !err ) {
				*diskctl_l = (sectno & 0xff) << 16 | 0x8a;
				err = wait(SHORT_DELAY);
				if( !err ) {
					*diskctl_l = (LONG) (count & 0xff) <<
						      16 | 0x8a;
					err = wait(SHORT_DELAY);
				}
			}
		}
	}
	return(err;
}

WORD
hd_read(sectno,count,buf,dma)
LONG	sectno;
WORD	count;
LONG	buf;
WORD	dma;
{
	WORD	err;

	sup_on();
	err = select_sector(READ,sectno,count,buf,dma);
	if( err == 0 )
		fifo_rd(count);
		err = get_status(0x8a);
	end_hd();
	sup_off();
	return(err);
}

WORD
hd_write(sectno,count,buf,dma)
LONG	sectno;
WORD	count;
LONG	buf;
WORD	dma;
{
	WORD	err;

	sup_on();
	err = select_sector(WRITE,sectno,count,buf,dma);
	if( err == 0 )
		fifo_wrt(count);
		err = get_status(0x18a);
	end_hd();
	sup_off();
	return(err);
}
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