/*
 * CHU - IO routines to CH375 from DOS
 * Copyright (C) 2024-2026 Javier S. Pedro
 *
 * 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 <https://www.gnu.org/licenses/>.
 */

#ifndef CH375DOS_H
#define CH375DOS_H

#include <stdint.h>
#include <stdbool.h>
#include <conio.h>
#include <ch375.h>

/* This file defines the routines that are used by ch375.h to actually IO
 * to the underlying device. */

struct ch375 {
	uint16_t io_base;
};

static inline uint8_t ch375_read_data(struct ch375 *dev)
{
	return inp(dev->io_base + CH375_PORT_DATA);
}

static inline void ch375_write_data(struct ch375 *dev, uint8_t data)
{
	outp(dev->io_base + CH375_PORT_DATA, data);
}

static inline void ch375_send_command(struct ch375 *dev, enum ch375_command cmd)
{
	outp(dev->io_base + CH375_PORT_CMD, cmd);
}

/// True if interrupt line is currently active (i.e. low)
static inline bool ch375_poll_interrupt(struct ch375 *dev)
{
	return !(inp(dev->io_base + CH375_PORT_CMD) & 0x80);
}


/** Reads one transfer block (64 bytes max). */
#if _M_IX86 >= 200
// Watcom does not seem able to synthesize rep ins/outs. Do it in 286+ mode.
static uint8_t ch375_read_data_block(struct ch375 *dev, uint8_t far *buffer);
#pragma aux ch375_read_data_block = \
	"mov dx, [bx]" \
	"in al, dx" \
	"movzx cx, al" \
	"rep ins byte ptr es:[di], dx" \
	__parm [bx] [es di] \
	__value [al] \
	__modify exact [cx dx di]
#else
static uint8_t ch375_read_data_block(struct ch375 *dev, uint8_t far *buffer)
{
	uint8_t i, n = ch375_read_data(dev);

	for (i = 0; i < n; i++) {
		buffer[i] = ch375_read_data(dev);
	}

	return n;
}
#endif

#if _M_IX86 >= 200
static void ch375_write_data_block(struct ch375 *dev, uint8_t far * buffer, uint8_t n);
#pragma aux ch375_write_data_block = \
	"mov dx, [bx]" \
	"out dx, al" \
	"movzx cx, al" \
	"rep outs dx, byte ptr es:[si]" \
	__parm [bx] [es si] [al] \
	__modify exact [cx dx si]
#else
static void ch375_write_data_block(struct ch375 *dev, uint8_t far * buffer, uint8_t n)
{
	uint8_t i;

	ch375_write_data(dev, n);

	for (i = 0; i < n; i++) {
		ch375_write_data(dev, buffer[i]);
	}
}
#endif

#endif // CH375DOS_H