/*
 * (C) Copyright 2015,2016 Leo C. <erbl259-lmu@yahoo.de>
 *
 * SPDX-License-Identifier:	GPL-2.0
 */

/*
 * See CP/M 3 System Manual, Appendix D: CPM3.SYS File Format
 */

#include "common.h"
#include <ctype.h>
#include <string.h>
#include <stdbool.h>

#include "command.h"
#include "env.h"
#include "ff.h"
#include "eval_arg.h"
#include "con-utils.h"
#include "z80-if.h"
#include "debug.h"


#define RS		128		/* CP/M record size */

#define FSIZE_t DWORD

/*
 *	Load Routine
 *
 *	Input:  addr = Page Address of load top
 *		 	len  = Length in pages of module to read
 *
 */
int load(FIL *File, uint32_t addr, uint8_t len)
{
	uint8_t buffer[RS];
	unsigned int br;					/* bytes read */
	int res;

	len *= 2;		/* length in records of module */
	//debug("## load: addr: 0x%.4X, records: 0x%.4X, (%u)\n", addr, len, len);

	for (; len; len--) {
		addr -= RS;
		res = f_read(File, buffer, RS, &br);
		if (res || br != RS) {
			return 1;
		}

		if (!(z80_bus_cmd(Request) & ZST_ACQUIRED)) {
			my_puts_P(PSTR("Bus timeout\n"));
			return 2;
		}
		z80_write_block(buffer, addr, RS);
		z80_bus_cmd(Release);
		//debug("## written: 0x%.4X\n", addr);
	}

	return 0;
}

#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"

command_ret_t do_loadcpm3(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
	uint16_t mem_top;
	uint8_t res_len;
	uint16_t bank_top;
	uint8_t bank_len;
	uint16_t osentry_addr = 0;
	uint32_t common_base = 0;
	uint32_t banked_base;
	char *fname;
	FIL File;
	char default_fname[] = CONFIG_CPM3_SYSFILE;
	unsigned int br;					/* bytes read */
	uint8_t buffer[RS];
	int res;

	(void) cmdtp; (void) flag;


	//common_base = getenv_ulong(PSTR(ENV_CPM3_COMMON_BASE), 16,
	//					CONFIG_CPM3_COMMON_BASE);
	banked_base = getenv_ulong(PSTR(ENV_CPM3_BANKED_BASE), 16,
						CONFIG_CPM3_BANKED_BASE);

	if (argc > 3)
		banked_base = eval_arg(argv[3], NULL);
	if (argc > 2)
		common_base = eval_arg(argv[2], NULL);

	fname = getenv_str(PSTR(ENV_CPM3_SYSFILE));
	if (argc > 1) {
		fname = argv[1];
	}
	if (fname == NULL || *fname == '\0')
		fname = default_fname;

	res = f_open(&File, fname, FA_READ );
	if (res) {
		printf_P(PSTR("Error: failed to open '%s'\n"), fname);
		return CMD_RET_FAILURE;
	}

	printf_P(PSTR("Loading: '%s'...\n"), fname);

	/* read the load record */
	res = f_read(&File, buffer, RS, &br);
	if (res || br != RS)
		goto out;

	mem_top = buffer[0] << 8;
	res_len = buffer[1];
	bank_top = buffer[2] << 8;
	bank_len = buffer[3];
	osentry_addr = buffer[4] + (buffer[5] << 8);

	/* read display info */
	res = f_read(&File, buffer, RS, &br);
	if (res || br != RS)
		goto out;

	/* print the info */
	buffer[RS-1] = '$';
	uint8_t *p = memchr(buffer, '$', RS);
	*p = '\0';
	my_puts((char *)buffer);

	if (common_base == 0) {
		/* read common base
		 * http://www.seasip.info/Cpm/scb.html
		 */
		FSIZE_t common_base_ofs = ((res_len - 6) << 8)  + 2*RS + RS-7;
		FSIZE_t cur_pos = f_tell(&File);
		if ((res = f_lseek(&File, common_base_ofs)) ||
				(res = f_read(&File, buffer, 2, &br)) ||
				(br != 2) ||
				(res = f_lseek(&File, cur_pos)))
			goto out;
		common_base = (uint16_t) buffer[0] + (buffer[1] << 8);
		setenv_hex(PSTR(ENV_CPM3_COMMON_BASE), common_base);
	}

	setenv_hex(PSTR(ENV_CPM3_SCB), mem_top - ((res_len - (6 - 1)) << 8) + common_base);

	/* Main System Load	*/

	/* Load Common Portion of System */
	if ((res = load(&File, common_base + mem_top, res_len)) != 0)
		goto out;

	/* Load Banked Portion of System */
	res = load(&File, banked_base + bank_top, bank_len);

out:
	f_close(&File);

	if (res) {
		printf_P(PSTR("Error: failed to read '%s'\n"), fname);
		return CMD_RET_FAILURE;
	} else {
		if (res_len != 0) {
			if (osentry_addr + common_base > 0xffff) {
				z80_bus_cmd(Request);
				if (z80_read(osentry_addr + common_base) == 0xc3) {
					osentry_addr = z80_read(osentry_addr+common_base+1) +
							(z80_read(osentry_addr + common_base+2) << 8);
				}
				z80_bus_cmd(Release);
				if (banked_base + osentry_addr > 0xffff)
					osentry_addr = 0;
			}
			setenv_hex(PSTR(ENV_STARTADDRESS), osentry_addr);
		}
		printf_P(PSTR("Loaded: Resident: "));
		if (res_len != 0)
			printf_P(PSTR("0x%.5lX-0x%.5lX, "),
				(common_base + mem_top) - res_len*256,
				(common_base + mem_top) - 1);
		else
			printf_P(PSTR(" -  "));
		printf_P(PSTR("Banked: "));
		if (bank_len != 0)
			printf_P(PSTR("0x%.5lX-0x%.5lX\n"),
			(banked_base + bank_top) - bank_len*256,
			(banked_base + bank_top) - 1);
		else
			printf_P(PSTR(" -  \n"));

		return CMD_RET_SUCCESS;
	}
}