/*
 * JR-IDE Project
 * - (c) 2017 Alan Hightower
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "pimount.h"
#include "jride.h"

#pragma data_seg("_TEXT", "CODE");
#pragma code_seg("_TEXT", "CODE");


volatile uint16_t far *ide_sector;
volatile  uint8_t far *ide_window;


extern void _xfer_in (uint16_t far *dst, uint16_t words);
#pragma aux _xfer_in = \
	"push ds" \
	"lds si, dword ptr ide_sector" \
	"cld" \
	"rep movsw" \
	"pop ds" \
	parm [di es] [cx] \
	modify [si es di cx];

extern void _xfer_out (uint16_t far *src, uint16_t words);
#pragma aux _xfer_out = \
	"les di, dword ptr ide_sector" \
	"push ds" \
     "mov ds, dx" \
	"cld" \
	"rep movsw" \
	"pop ds" \
	parm [si dx] [cx] \
	modify [si es di cx];

extern uint16_t get_ds (void);
#pragma aux get_ds = \
    "mov ax,ds" \
    value [ax];


/*
 * Due to issues in the FIFO code atm, partial sector transfers
 * are not working.  So always transfer-in a full sector and
 * trasfer out of the scratch buffer as needed
 */

int _redir_pull (uint8_t subcmd)
{
	ide_window[IDE_REG_SEC_COUNT] = 1;
	ide_window[IDE_REG_FEATURE]   = subcmd;
	ide_window[IDE_REG_COMMAND]   = IDE_CMD_REDIRECTOR;

	while (ide_window[IDE_REG_STATUS] & 0x80); // busy

	if (ide_window[IDE_REG_STATUS] & 1) // error bit
		return -1;

	while (!(ide_window[IDE_REG_STATUS] & 0x08));

	_xfer_in (MK_FP(get_ds(), &ctx.scratch), 256);

	ctx.prev_pull = subcmd;

	return 0;
}

int _redir_push (uint8_t subcmd)
{
	ide_window[IDE_REG_SEC_COUNT] = 1;
	ide_window[IDE_REG_FEATURE]   = subcmd;
	ide_window[IDE_REG_COMMAND]   = IDE_CMD_REDIRECTOR;

	while (ide_window[IDE_REG_STATUS] & 0x80); // busy

	if (ide_window[IDE_REG_STATUS] & 1) // error bit
		return -1;

	while (!(ide_window[IDE_REG_STATUS] & 0x08));

	_xfer_out (MK_FP(get_ds(), &ctx.scratch), 256);

	// On OUT transfers, wait for data to be consumed by Pi

	while (!(ide_window[IDE_REG_STATUS] & 0x40)); // ready

	return 0;
}