// (C) 2022 by Folkert van Heusden
// Released under Apache License v2.0
#include <errno.h>
#include <string.h>

#include "bus.h"
#include "cpu.h"
#include "error.h"
#include "gen.h"
#include "log.h"
#include "rl02.h"
#include "utils.h"


constexpr int sectors_per_track = 40;
constexpr int bytes_per_sector  = 256;

static const char * const regnames[] = { 
	"control status",
	"bus address   ",
	"disk address  ",
	"multipurpose  "
	};

rl02::rl02(const std::vector<disk_backend *> & files, bus *const b, std::atomic_bool *const disk_read_acitivity, std::atomic_bool *const disk_write_acitivity) :
	b(b),
	disk_read_acitivity(disk_read_acitivity),
	disk_write_acitivity(disk_write_acitivity)
{
	memset(registers, 0x00, sizeof registers);
	memset(xfer_buffer, 0x00, sizeof xfer_buffer);

	fhs = files;
}

rl02::~rl02()
{
	for(auto fh : fhs)
		delete fh;
}

uint8_t rl02::readByte(const uint16_t addr)
{
	uint16_t v = readWord(addr & ~1);

	if (addr & 1)
		return v >> 8;

	return v;
}

uint16_t rl02::readWord(const uint16_t addr)
{
	const int reg = (addr - RL02_BASE) / 2;

	if (addr == RL02_CSR) {  // control status
		setBit(registers[reg], 0, true);  // drive ready (DRDY)
		setBit(registers[reg], 7, true);  // controller ready (CRDY)
	}

	uint16_t value = registers[reg];

	// TODO

	DOLOG(debug, true, "RL02 read %s/%o: %06o", regnames[reg], addr, value);

	return value;
}

void rl02::writeByte(const uint16_t addr, const uint8_t v)
{
	uint16_t vtemp = registers[(addr - RL02_BASE) / 2];

	if (addr & 1) {
		vtemp &= ~0xff00;
		vtemp |= v << 8;
	}
	else {
		vtemp &= ~0x00ff;
		vtemp |= v;
	}

	writeWord(addr, vtemp);
}

uint32_t rl02::calcOffset(const uint16_t da)
{
	int           sector            = da & 63;
	int           track             = (da >> 6) & 1023;

	uint32_t      offset            = (sectors_per_track * track + sector) * bytes_per_sector;

	return offset;
}

void rl02::writeWord(const uint16_t addr, uint16_t v)
{
#if defined(ESP32)
	digitalWrite(LED_BUILTIN, LOW);
#endif

	DOLOG(debug, true, "RL02 write %06o: %06o", addr, v);

	const int reg = (addr - RL02_BASE) / 2;

        registers[reg] = v;

	if (addr == RL02_CSR) {  // control status
		const uint8_t command = (v >> 1) & 7;

		const bool    do_exec = !(v & 128);

		DOLOG(debug, true, "RL02 set command %d, exec: %d", command, do_exec);

		uint32_t disk_offset = calcOffset(registers[(RL02_DAR - RL02_BASE) / 2] & ~1);
		int      device      = 0;  // TODO

		if (command == 2) {  // get status
			registers[(RL02_MPR - RL02_BASE) / 2] = 0;
		}
		else if (command == 6 || command == 7) {  // read data / read data without header check
			*disk_read_acitivity = true;

			bool proceed = true;

			uint32_t temp_disk_offset = disk_offset;

			uint32_t memory_address = registers[(RL02_BAR - RL02_BASE) / 2];

			uint32_t count          = (65536 - registers[(RL02_MPR - RL02_BASE) / 2]) * 2;

			DOLOG(debug, true, "RL02 read %d bytes (dec) from %d (dec) to %06o (oct)", count, disk_offset, memory_address);

			uint32_t p    = memory_address;
			while(proceed && count > 0) {
				uint32_t cur = std::min(uint32_t(sizeof xfer_buffer), count);

				if (!fhs.at(device)->read(temp_disk_offset, cur, xfer_buffer)) {
					DOLOG(ll_error, true, "RL02 read error %s", strerror(errno));
					break;
				}

				for(uint32_t i=0; i<cur; i++, p++)
					b->writeByte(p, xfer_buffer[i]);

				temp_disk_offset += cur;

				count -= cur;
			}

			if (registers[(RL02_CSR - RL02_BASE) / 2] & 64) {  // interrupt enable?
				DOLOG(debug, true, "RL02 triggering interrupt");

				b->getCpu()->queue_interrupt(5, 0254);
			}

			*disk_read_acitivity = false;
		}
	}

#if defined(ESP32)
	digitalWrite(LED_BUILTIN, HIGH);
#endif
}