// (C) 2018 by Folkert van Heusden
// Released under Apache License v2.0
#include <errno.h>
#include <string.h>

#include "tm-11.h"
#include "gen.h"
#include "memory.h"
#include "utils.h"

tm_11::tm_11(const std::string & file, memory *const m) : m(m)
{
	offset = 0;
	memset(registers, 0x00, sizeof registers);

	fh = fopen(file.c_str(), "rb");
}

tm_11::~tm_11()
{
	fclose(fh);
}

uint8_t tm_11::readByte(const uint16_t addr)
{
	uint16_t v = readWord(addr & ~1);

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

	return v;
}

uint16_t tm_11::readWord(const uint16_t addr)
{
	const int reg = (addr - TM_11_BASE) / 2;
	uint16_t vtemp = registers[reg];

	D(printf("TM-11 read addr %o: ", addr);)

	if (addr == TM_11_MTS) {
		setBit(vtemp, 15, false); // ILC
		setBit(vtemp, 14, false); // EOC
		setBit(vtemp, 13, false); // CRE
		setBit(vtemp, 12, false); // PAE
		setBit(vtemp, 11, false); // BGL
		setBit(vtemp, 10, false); // EOT
		setBit(vtemp,  9, false); // RLE
		setBit(vtemp,  8, false); // BTE
		setBit(vtemp,  7, false); // NXM
		setBit(vtemp,  6, true);  // SELR
		setBit(vtemp,  5, false); // BOT - beginning of tape
		setBit(vtemp,  4, false); // 7CH
		setBit(vtemp,  3, false); // SDWN
		setBit(vtemp,  2, false); // WRL - write lock
		setBit(vtemp,  1, false); // RWS
		setBit(vtemp,  0, true);  // TUR - tape unit ready
	}
	else if (addr == TM_11_MTC) {
		registers[reg] ^= 1 << 7; // CU RDY
	}
	else if (addr == TM_11_MTBRC) { // record length
		vtemp = 0;
	}

	D(printf("%o\n", vtemp);)

	return vtemp;
}

void tm_11::writeByte(const uint16_t addr, const uint8_t v)
{
	uint16_t vtemp = registers[(addr - TM_11_BASE) / 2];

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

	writeWord(addr, vtemp);
}

void tm_11::writeWord(const uint16_t addr, uint16_t v)
{
	D(printf("TM-11 write %o: %o\n", addr, v);)

	if (addr == TM_11_MTC) {
		if (v & 1) { // GO
			const int func = (v >> 1) & 7; // FUNCTION
			const int reclen = 512;

			D(printf("invoke %d\n", func);)

			if (func == 0) { // off-line
				v = 128; // TODO set error if error
			}
			else if (func == 1) { // read
				D(printf("reading %d bytes from offset %d\n", reclen, offset);)
				if (fread(xfer_buffer, 1, reclen, fh) != reclen)
					D(printf("failed: %s\n", strerror(errno));)
				for(int i=0; i<reclen; i++)
					m -> writeByte(registers[(TM_11_MTCMA - TM_11_BASE) / 2] + i, xfer_buffer[i]);
				offset += reclen;

				v = 128; // TODO set error if error
			}
			else if (func == 2) { // write
				for(int i=0; i<reclen; i++)
					xfer_buffer[i] = m -> readByte(registers[(TM_11_MTCMA - TM_11_BASE) / 2] + i);
				fwrite(xfer_buffer, 1, reclen, fh);
				offset += reclen;
				v = 128; // TODO
			}
			else if (func == 4) { // space forward
				offset += reclen;
				v = 128; // TODO
			}
			else if (func == 5) { // space backward
				if (offset >= reclen)
					offset -= reclen;
				v = 128; // TODO
			}
			else if (func == 7) { // rewind
				offset = 0;
				v = 128; // TODO set error if error
			}
		}
	}
	else if (addr == TM_11_MTCMA) {
		v &= ~1;
		D(printf("Set DMA address to %o\n", v);)
	}

	D(printf("set register %o to %o\n", addr, v);)
	registers[(addr - TM_11_BASE) / 2] = v;
}