/*
 * (C) Copyright 2014 Leo C. <erbl259-lmu@yahoo.de>
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#include "common.h"
#include <util/atomic.h>

#include "background.h"
#include "serial.h"
#include "z80-if.h"
#include "debug.h"
#include "z180-serv.h"

/*--------------------------------------------------------------------------*/


uint8_t z80_get_byte(uint32_t adr)
{
	uint8_t data;

	z80_bus_cmd(Request);
	data = z80_read(adr);
	z80_bus_cmd(Release);

	return data;
}


/*--------------------------------------------------------------------------*/

struct msg_item {
	uint8_t fct;
	uint8_t sub_min, sub_max;
	void (*func)(uint8_t, int, uint8_t *);
};

uint32_t msg_to_addr(uint8_t *msg)
{
	union {
		uint32_t as32;
		uint8_t as8[4];
	} addr;

	addr.as8[0] = msg[0];
	addr.as8[1] = msg[1];
	addr.as8[2] = msg[2];
	addr.as8[3] = 0;

	return addr.as32;
}


void do_msg_ini_memfifo(uint8_t subf, int len, uint8_t * msg)
{
	(void)len;

	z80_memfifo_init(subf, msg_to_addr(msg));
}


void do_msg_char_out(uint8_t subf, int len, uint8_t * msg)
{
	(void)subf;

	while (len--)
		putchar(*msg++);
}


const FLASH struct msg_item z80_messages[] =
{
	{ 0,			/* fct nr. */
	  1, 3,			/* sub fct nr. from, to */
	  do_msg_ini_memfifo},
	{ 1,
	  1, 1,
	  do_msg_char_out},
	{ 0xff,				/* end mark */
	  0, 0,
	  0},

};




void do_message(int len, uint8_t *msg)
{
	uint8_t fct, sub_fct;
	int_fast8_t i = 0;

	if (len >= 2) {
		fct = *msg++;
		sub_fct = *msg++;
		len -= 2;

		while (fct != z80_messages[i].fct) {
			if (z80_messages[i].fct == 0xff) {
				DBG_P(1, "do_message: Unknown function: %i, %i\n",
						fct, sub_fct);
				return; /* TODO: unknown message # */
			}

			++i;
		}

		while (fct == z80_messages[i].fct) {
			if (sub_fct >= z80_messages[i].sub_min &&
					sub_fct <= z80_messages[i].sub_max )
				break;
			++i;
		}

		if (z80_messages[i].fct != fct) {
			DBG_P(1, "do_message: Unknown sub function: %i, %i\n",
					fct, sub_fct);
			return; /* TODO: unknown message sub# */
		}

		(z80_messages[i].func)(sub_fct, len, msg);


	} else {
		/* TODO: error */
		DBG_P(1, "do_message: to few arguments (%i); this shouldn't happen!\n", len);
	}
}



#define CTRBUF_LEN 256

void check_msg_fifo(void)
{
	int ch;
	static int_fast8_t state;
	static int msglen,idx;
	static uint8_t buffer[CTRBUF_LEN];

	while ((ch = z80_memfifo_getc(fifo_msgin)) >= 0) {
		switch (state) {
		case 0:		/* wait for start of message */
			if (ch == 0xAE)	{ /* TODO: magic number */
				msglen = 0;
				idx = 0;
				state = 1;
			}
			break;
		case 1:		/* get msg len */
			if (ch > 0 && ch <= CTRBUF_LEN) {
				msglen = ch;
				state = 2;
			} else
				state = 0;
			break;
		case 2: 	/* get message */
			buffer[idx++] = ch;
			if (idx == msglen) {
				do_message(msglen, buffer);
				state = 0;
			}
			break;
		}
	}
}


int msg_handling(int state)
{
	uint8_t pending;

	ATOMIC_BLOCK(ATOMIC_FORCEON) {
		pending = (Stat & S_MSG_PENDING) != 0;
		Stat &= ~S_MSG_PENDING;
	}

	if (pending) {
		switch (state) {
		case 0:
			z80_bus_cmd(Request);
			uint32_t addr = z80_read(0x40) +
				((uint16_t) z80_read(0x41) << 8) +
				((uint32_t) z80_read(0x42) << 16);
			z80_bus_cmd(Release);
			if (addr != 0) {
				z80_memfifo_init(fifo_msgin, addr);
				state = 1;
			}
			break;
		case 1:
			check_msg_fifo();
			break;
		}
	}

	return state;
}


static int handle_msg_handling;

void setup_z180_serv(void)
{

	handle_msg_handling = bg_register(msg_handling, 0);
}

void restart_z180_serv(void)
{
	z80_bus_cmd(Request);
	z80_write(0x40, 0);
	z80_write(0x41, 0);
	z80_write(0x42, 0);
	z80_bus_cmd(Release);

	for (int i = 0; i < NUM_FIFOS; i++)
		z80_memfifo_init(i, 0);
	bg_setstat(handle_msg_handling, 0);
}

/*--------------------------------------------------------------------------*/

const FLASH uint8_t iniprog[] = {
	0xAF,			// xor     a
	0xED, 0x39, 0x36,	// out0    (rcr),a         ;disable  DRAM refresh
	0x3E, 0x30,		// ld      a,030h
	0xED, 0x39, 0x32	//out0    (dcntl),a       ;0 mem, max i/0 wait states
};

const FLASH uint8_t sertest[] = {
	0xAF,              //  	xor	a
	0xED, 0x39, 0x36,  //  	out0	(rcr),a		;disable  DRAM refresh
	0x3E, 0x30,        //  	ld	a,030h
	0xED, 0x39, 0x32,  //  	out0	(dcntl),a	;0 mem, max i/0 wait states
	0x3E, 0x80,        //  	ld	a,M_MPBT		;no MP, PS=10, DR=16, SS=0
	0xED, 0x39, 0x03,  //  	out0	(cntlb1),a
	0x3E, 0x64,        //  	ld	a,M_RE + M_TE + M_MOD2	;
	0xED, 0x39, 0x01,  //  	out0	(cntla1),a
	0x3E, 0x00,        //  	ld	a,0
	0xED, 0x39, 0x05,  //  	out0	(stat1),a	;Enable rx interrupts
	0xED, 0x38, 0x05,  //l0:in0	a,(stat1)
	0xE6, 0x80,        //  	and	80h
	0x28, 0xF9,        //  	jr	z,l0
	0xED, 0x00, 0x09,  //  	in0	b,(rdr1)
	0xED, 0x38, 0x05,  //l1:in0	a,(stat1)
	0xE6, 0x02,        //  	and	02h
	0x28, 0xF9,        //  	jr	z,l1
	0xED, 0x01, 0x07,  //  	out0	(tdr1),b
	0x18, 0xEA,        //  	jr	l0
};

const FLASH uint8_t test1[] = {
	0xAF,              //	xor	a
	0xED, 0x39, 0x36,  //	out0	(rcr),a		;disable  DRAM refresh
	0x3E, 0x30,        //	ld	a,030h
	0xED, 0x39, 0x32,  //	out0	(dcntl),a	;0 mem, max i/0 wait states
	0x21, 0x1E, 0x00,  // 	ld	hl,dmclrt	;load DMA registers
	0x06, 0x08,        //	ld	b,dmct_e-dmclrt
	0x0E, 0x20,        //	ld	c,sar0l
	0xED, 0x93,        //	otimr
	0x3E, 0xC3,        //	ld	a,0c3h		;dst +1, src +1, burst
	0xED, 0x39, 0x31,  //	out0	(dmode),a	;
	0x3E, 0x62,        //	ld	a,062h		;enable dma0,
	0xED, 0x39, 0x30,  //cl_1:	out0	(dstat),a	;copy 64k
	0x18, 0xFB,        //	jr	cl_1		;
	0x00, 0x00,        //dmclrt:	dw	0		;src (inc)
	0x00,              //	db 	0		;src
	0x00, 0x00,        //	dw	0		;dst (inc),
	0x00,              //	db	0		;dst
	0x00, 0x00,        //	dw 	0		;count (64k)
};