/* ReC98
 * -----
 * MDRV2 functions
 */

#pragma option -Z-

#include <fcntl.h>
#include <io.h>
#include <malloc.h>
#include <string.h>
#include "platform.h"
#include "x86real.h"
extern "C" {
#include "th01/snd/mdrv2.h"
}

typedef enum {
	MDRV2_MPLAY = 0x00,
	MDRV2_MFADE_OUT_BLOCK = 0x01,
	MDRV2_MFADE_OUT_NONBLOCK = 0x02,
	MDRV2_MSTOP = 0x03,
	MDRV2_EPLAY = 0x04,
	MDRV2_MSET = 0x06,
	MDRV2_ESET = 0x07,
	MDRV2_CHECK_BOARD = 0x09,
	MDRV2_MFADE_IN = 0x0F,
} mdrv2_func_t;

static const uint8_t MDRV2 = 0xF2;

inline uint16_t mdrv2_call(mdrv2_func_t func) {
	_AH = func;
	geninterrupt(MDRV2);
	return _AX;
}

extern char mdrv2_have_board;
struct hack { char x[12]; }; // XXX
extern const struct hack mdrv2_magic;

bool16 mdrv2_resident(void)
{
	char s1[sizeof(mdrv2_magic)];
	const struct hack s2 = mdrv2_magic;
	char far *magicp = (char far *)(
		((long)peek(0, MDRV2 * 4 + 2) << 16) + 0x102
	);
	int i;

	for(i = 0; i < sizeof(s1); i++) {
		s1[i] = magicp[i];
	}
	if(strcmp(s1, s2.x) != 0) {
		return false;
	}
	return true;
}

void near pascal mdrv2_load(const char *fn, char func)
{
	if(mdrv2_have_board) {
		int handle = open(fn, (O_BINARY | O_RDONLY));	// opens a DOS handle
		int length = filelength(handle);
		seg_t sgm;
		int ofs;
		void far *block;

		block = farmalloc(length);
		sgm = FP_SEG(block);
		ofs = FP_OFF(block);

		_asm {
			push	ds
			mov	ax, 0x3F00
			mov	bx, handle
			mov	cx, length
			mov	ds, sgm
			mov	dx, ofs
		}
		geninterrupt(0x21);
		_asm { pop	ds; }

		close(handle);
		_asm {
			push	ds
			mov	ah, func
			mov	ds, sgm
			mov	si, ofs
		}
		geninterrupt(MDRV2);
		_asm { pop	ds; }

		farfree(block);
	}
}

void mdrv2_bgm_load(const char *fn)
{
	mdrv2_load(fn, MDRV2_MSET);
}

void mdrv2_se_load(const char *fn)
{
	mdrv2_load(fn, MDRV2_ESET);
}

void mdrv2_bgm_play(void)
{
	if(mdrv2_have_board) {
		mdrv2_call(MDRV2_MPLAY);
	}
}

void mdrv2_bgm_stop(void)
{
	if(mdrv2_have_board) {
		mdrv2_call(MDRV2_MSTOP);
	}
}

void mdrv2_bgm_fade_out_nonblock(void)
{
	if(mdrv2_have_board) {
		mdrv2_call(MDRV2_MFADE_OUT_NONBLOCK);
	}
}

void mdrv2_bgm_fade_out_block(void)
{
	if(mdrv2_have_board) {
		mdrv2_call(MDRV2_MFADE_OUT_BLOCK);
	}
}

void mdrv2_bgm_fade_in(void)
{
	if(mdrv2_have_board) {
		mdrv2_call(MDRV2_MFADE_IN);
	}
}

int mdrv2_check_board(void)
{
	mdrv2_have_board = mdrv2_call(MDRV2_CHECK_BOARD);
	return mdrv2_have_board;
}

void mdrv2_se_play(int se)
{
	if(se && mdrv2_have_board) {
		se += (MDRV2_EPLAY << 8);
		_asm { mov	ax, se; } // Prevent [se] from being put into a register
		geninterrupt(MDRV2);
	}
}