// (C) 2018-2023 by Folkert van Heusden
// Released under MIT license

#include <errno.h>
#include <string.h>

#include "bus.h"
#include "cpu.h"
#include "error.h"
#include "gen.h"
#include "log.h"
#include "rk05.h"
#include "utils.h"


static const char * const regnames[] = { 
	"RK05_DS drivestatus",
	"RK05_ERROR        ",
	"RK05_CS ctrlstatus",
	"RK05_WC word count",
	"RK05_BA busaddress",
	"RK05_DA disk addrs",
	"RK05_DATABUF      "
	};

rk05::rk05(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);

	fhs = files;
}

rk05::~rk05()
{
	for(auto fh : fhs)
		delete fh;
}

uint8_t rk05::readByte(const uint16_t addr)
{
	uint16_t v = readWord(addr & ~1);

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

	return v;
}

uint16_t rk05::readWord(const uint16_t addr)
{
	const int reg = (addr - RK05_BASE) / 2;

	if (addr == RK05_DS) {		// 0177400
		setBit(registers[reg], 11, true); // disk on-line
		setBit(registers[reg], 8, true); // sector ok
		setBit(registers[reg], 7, true); // drive ready
		setBit(registers[reg], 6, true); // seek ready
		setBit(registers[reg], 4, true); // heads in position
	}
	else if (addr == RK05_ERROR)	// 0177402
		registers[reg] = 0;
	else if (addr == RK05_CS) {	// 0177404
		setBit(registers[reg], 15, false); // clear error
		setBit(registers[reg], 14, false); // clear hard error
		setBit(registers[reg], 7, true); // controller ready
	}

	uint16_t vtemp = registers[reg];

	if (addr == RK05_CS)
		setBit(registers[reg], 0, false); // clear go

	DOLOG(debug, true, "RK05 read %s/%o: %06o", reg[regnames], addr, vtemp);

	return vtemp;
}

void rk05::writeByte(const uint16_t addr, const uint8_t v)
{
	uint16_t vtemp = registers[(addr - RK05_BASE) / 2];

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

	writeWord(addr, vtemp);
}

void rk05::writeWord(const uint16_t addr, uint16_t v)
{
	const int reg = (addr - RK05_BASE) / 2;

	registers[reg] = v;

	if (addr == RK05_CS) {
		if (v & 1) { // GO
			const int    func   = (v >> 1) & 7; // FUNCTION
			int16_t      wc     = registers[(RK05_WC - RK05_BASE) / 2];
			const size_t reclen = wc < 0 ? (-wc * 2) : wc * 2;

			uint16_t temp     = registers[(RK05_DA - RK05_BASE) / 2];
			uint8_t  sector   = temp & 0b1111;
			uint8_t  surface  = (temp >> 4) & 1;
			int      track    = (temp >> 4) & 511;
			uint16_t cylinder = (temp >> 5) & 255;
			uint16_t device   = temp >> 13;

			const uint32_t diskoff = track * 12 + sector;

			const uint32_t diskoffb = diskoff * 512l; // RK05 is high density
			const uint16_t memoff = registers[(RK05_BA - RK05_BASE) / 2];

			registers[(RK05_CS - RK05_BASE) / 2] &= ~(1 << 13); // reset search complete

			if (func == 0) { // controller reset
				DOLOG(debug, true, "RK05 invoke %d (controller reset)", func);
			}
			else if (func == 1) { // write
				*disk_write_acitivity = true;

				DOLOG(debug, true, "RK05 drive %d position sec %d surf %d cyl %d, reclen %zo, WRITE to %o, mem: %o", device, sector, surface, cylinder, reclen, diskoffb, memoff);

				uint8_t *xfer_buffer = new uint8_t[reclen];

				uint32_t p = reclen;
				for(size_t i=0; i<reclen; i++)
					xfer_buffer[i] = b->readUnibusByte(memoff + i);

				if (!fhs.at(device)->write(diskoffb, reclen, xfer_buffer))
					DOLOG(ll_error, true, "RK05(%d) write error %s", device, strerror(errno));

				if (v & 2048)
					DOLOG(debug, true, "RK05 inhibit BA increase");
				else
					registers[(RK05_BA - RK05_BASE) / 2] += p;

				if (++sector >= 12) {
					sector = 0;
					if (++surface >= 2) {
						surface = 0;
						cylinder++;
					}
				}

				registers[(RK05_DA - RK05_BASE) / 2] = sector | (surface << 4) | (cylinder << 5);

				delete [] xfer_buffer;

				*disk_write_acitivity = false;
			}
			else if (func == 2) { // read
				*disk_read_acitivity = true;

				DOLOG(debug, true, "RK05 drive %d position sec %d surf %d cyl %d, reclen %zo, READ from %o, mem: %o", device, sector, surface, cylinder, reclen, diskoffb, memoff);

				uint8_t xfer_buffer[512];

				uint32_t temp_diskoffb = diskoffb;

				uint32_t temp = reclen;
				uint32_t p = memoff;
				while(temp > 0) {
					uint32_t cur = std::min(uint32_t(sizeof xfer_buffer), temp);

					if (!fhs.at(device)->read(temp_diskoffb, cur, xfer_buffer)) {
						DOLOG(ll_error, true, "RK05 read error %s", strerror(errno));
						break;
					}

					temp_diskoffb += cur;

					for(uint32_t i=0; i<cur; i++) {
						if (p >= 0160000)
							break;

						b->writeUnibusByte(p++, xfer_buffer[i]);
					}

					temp -= cur;
				}

				if (v & 2048)
					DOLOG(debug, true, "RK05 inhibit BA increase");
				else
					registers[(RK05_BA - RK05_BASE) / 2] += p;

				if (++sector >= 12) {
					sector = 0;
					if (++surface >= 2) {
						surface = 0;
						cylinder++;
					}
				}

				registers[(RK05_DA - RK05_BASE) / 2] = sector | (surface << 4) | (cylinder << 5);

				*disk_read_acitivity = false;
			}
			else if (func == 4) {
				DOLOG(debug, true, "RK05 invoke %d (seek) to %o", func, diskoffb);

				registers[(RK05_CS - RK05_BASE) / 2] |= 1 << 13; // search complete
			}
			else if (func == 7) {
				DOLOG(debug, true, "RK05 invoke %d (write lock)", func);
			}
			else {
				DOLOG(debug, true, "RK05 command %d UNHANDLED", func);
			}

			registers[(RK05_WC - RK05_BASE) / 2] = 0;

			registers[(RK05_DS - RK05_BASE) / 2] |= 64;  // drive ready
			registers[(RK05_CS - RK05_BASE) / 2] |= 128;  // control ready

			// bit 6, invoke interrupt when done vector address 220, see http://www.pdp-11.nl/peripherals/disk/rk05-info.html
			if (v & 64) {
				registers[(RK05_DS - RK05_BASE) / 2] &= ~(7l << 13);  // store id of the device that caused the interrupt
				registers[(RK05_DS - RK05_BASE) / 2] |= device << 13;

				b->getCpu()->queue_interrupt(5, 0220);
			}
		}
	}
}