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/*
 * This file is part of the Black Magic Debug project.
 *
 * Copyright (C) 2011  Black Sphere Technologies Ltd.
 * Written by Gareth McMullin <gareth@blacksphere.co.nz>
 *
 * 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/>.
 */

/* This file implements the low-level SW-DP interface. */

#include <stdio.h>

#include "general.h"

#include "swdptap.h"

#include "gdb_packet.h"

static void swdptap_turnaround(uint8_t dir)
{
	static uint8_t olddir = 0;

	DEBUG("%s", dir ? "\n-> ":"\n<- ");

	/* Don't turnaround if direction not changing */
	if(dir == olddir) return;
	olddir = dir;

	uint8_t cmd[6];
	int i = 0;

	if(dir) {
		cmd[i++] = DEV2_OP_DIR_IN;
		cmd[i++] = SWDIO_PIN;
	}
	cmd[i++] = DEV2_OP_OUT_SET;
	cmd[i++] = SWCLK_PIN;
	cmd[i++] = DEV2_OP_OUT_RESET;
	cmd[i++] = SWCLK_PIN;
	if(!dir)
	{
		cmd[i++] = DEV2_OP_DIR_OUT;
		cmd[i++] = SWDIO_PIN;
	}
	platform_buffer_write(cmd, i);
}


int swdptap_init(void)
{
	/* This must be investigated in more detail.
	 * As described in STM32 Reference Manual... */
	swdptap_reset();
	swdptap_seq_out(0xE79E, 16); /* 0b0111100111100111 */ 
	swdptap_reset();
	swdptap_seq_out(0, 16); 

	return 0;
}


static uint64_t swdptap_seq_in_64(int ticks)
{
	int i;
	uint64_t ret = 0;

	swdptap_turnaround(1);

	uint8_t cmd[] = {
		DEV2_OP_SERIAL_IN, SWDIO_PIN, SWCLK_PIN, ticks,
	};
	platform_buffer_write(cmd, sizeof(cmd));
	uint8_t rep[8];
	int bytes = (ticks + 7) / 8;
	platform_buffer_read(rep, bytes);

	for(i = 0; i < bytes; i++)
		ret |= (uint64_t) rep[i] << (8 * i);

	DEBUG("(0x%0*llx,%d)", (ticks + 3) / 4, ret, ticks);

	return ret;
}


uint32_t swdptap_seq_in(int ticks)
{
	return swdptap_seq_in_64(ticks);
}


uint8_t swdptap_seq_in_parity(uint32_t *ret, int ticks)
{
	uint64_t tmp;
	uint8_t parity = 0;
	int i;

	tmp = swdptap_seq_in_64(ticks + 1);

	for(i = 0; i < ticks + 1; i++)
	{
		if(tmp & (1ull << i))
			parity ^= 1;
	}

	*ret = tmp & ((1ull << ticks) - 1);
	return parity;
}


static void swdptap_seq_out_64(uint64_t MS, int ticks)
{
	swdptap_turnaround(0);

	DEBUG("(0x%0*llx,%d)", (ticks + 3) / 4, MS, ticks);

	uint8_t cmd[12];
	int i = 0;
	cmd[i++] = DEV2_OP_SERIAL_OUT;
	cmd[i++] = SWDIO_PIN;
	cmd[i++] = SWCLK_PIN;
	cmd[i++] = ticks;
	for(; ticks > 0; ticks -= 8)
	{
		cmd[i++] = MS & 0xff;
		MS >>= 8;
	}
	platform_buffer_write(cmd, i);
}


void swdptap_seq_out(uint32_t MS, int ticks)
{
	swdptap_seq_out_64(MS, ticks);
}


void swdptap_seq_out_parity(uint32_t MS, int ticks)
{
	uint8_t parity = 0;
	uint64_t tmp;
	int i;

	for(i = 0; i < ticks; i++)
	{
		if(MS & (1 << i))
			parity ^= 1;
	}
	tmp = MS;
	if(parity)
		tmp |= 1ull << ticks;

	swdptap_seq_out_64(tmp, ticks + 1);
}


void swdptap_reset(void)
{
	/* 50 clocks with TMS high */
	swdptap_seq_out_64((1ull << 50) - 1, 50);
}