#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdarg.h>
#include <assert.h>
#include <unistd.h>
#include <fcntl.h>

#define nil NULL

void
panic(char *fmt, ...)
{
	va_list ap;
	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	fprintf(stderr, "\n");
	va_end(ap);
	exit(1);
}

FILE*
mustopen(const char *name, const char *mode)
{
	FILE *f;
	if(f = fopen(name, mode), f == nil)
		panic("couldn't open file: %s", name);
	return f;
}

int
hasinput(int fd)
{
	fd_set fds;
	struct timeval timeout;

	if(fd < 0) return 0;

	timeout.tv_sec = 0;
	timeout.tv_usec = 0;
	FD_ZERO(&fds);
	FD_SET(fd, &fds);
	return select(fd+1, &fds, NULL, NULL, &timeout) > 0;
}

typedef struct Flexowriter Flexowriter;
struct Flexowriter
{
	int in, out;
};

void
putfl(Flexowriter *fl, int c)
{
	char cc;
	cc = c & 077;
	write(fl->out, &cc, 1);
}
int
getfl(Flexowriter *fl)
{
	char c;
	read(fl->in, &c, 1);
	return c;
}

typedef uint32_t word;

typedef struct TX0 TX0;
#define MEMSZ 0200000
#define AMSK 0177777

struct TX0
{
	int ss;
	int ios;
	int pbs;
	int dev;
	int c;
	word ac;
	word lr;
	word mbr;
	word mar;
	word pc, prevpc;
	word ir;
	word core[MEMSZ];

	word tbr;
	word tac;

	Flexowriter *fl;
};

static void
pstate(TX0 *tx)
{
	printf("%06o: AC/%06o LR/%06o PC/%06o\n",
		tx->prevpc, tx->ac, tx->lr, tx->pc);
	printf("  01/%06o 02/%06o rsp/%06o psp/%06o\n",
		tx->core[01],
		tx->core[02],
		tx->core[057],
		tx->core[0117]);
/*
	printf("  10/%06o 11/%06o 12/%06o 13/%06o\n",
		tx->core[010],
		tx->core[011],
		tx->core[012],
		tx->core[013]);
*/
}

static word
readcore(TX0 *tx)
{
	tx->mbr = tx->core[tx->mar] & 0777777;
	return tx->mbr;
}

static void
writecore(TX0 *tx)
{
	tx->core[tx->mar] = tx->mbr & 0777777;
}

static void
step(TX0 *tx)
{
	word mbr_t;

	tx->mbr = 0;
	if(tx->c == 0){
		tx->prevpc = tx->mar;
		readcore(tx);
		tx->pc = 0;
		tx->ir = tx->mbr>>16;
		tx->pc = tx->mar+1 & AMSK;
		tx->mar = tx->mbr & AMSK;

		switch(tx->ir){
		case 0:
		case 1:
			tx->c = 1;
			break;
		case 2:
			if((tx->ac & 0400000) == 0)
				tx->c = 1;
			break;
		case 3:
			// opr
			// 0.8
			if(tx->mar & 0100000) tx->ac &= 0000777;
			if(tx->mar & 0040000) tx->ac &= 0777000;
			if((tx->mar & 0030000) == 0020000){
				// IO stop
				tx->ss = 0;
				tx->ios = 0;
				tx->dev = tx->mar>>9 & 7;
			}
			tx->c = 1;
			break;
		}
	}else{
		switch(tx->ir){
		case 0:
			// sto
			tx->mbr = tx->ac;
			writecore(tx);
			break;
		case 1:
			// add
			readcore(tx);
			tx->ac ^= tx->mbr;
			tx->ac += (~tx->ac & tx->mbr)<<1;
			if(tx->ac & 01000000) tx->ac += 1;
			tx->ac &= 0777777;
			break;
		case 2:
			// trn - branch not taken
			break;
		case 3:
			// opr
			// 1.1
			if((tx->mar & 0104) == 0004) tx->ac |= tx->tac;
			if((tx->mar & 0104) == 0100) ; // TODO: pen
			// 1.2
			if(tx->mar & 1) tx->mbr |= tx->mar & 2 ? tx->tbr : tx->ac;
			if(tx->mar & 040) tx->ac = ~tx->ac & 0777777;
			// 1.3
			mbr_t = tx->mbr;
			if((tx->mar & 3) == 2) tx->mbr = tx->lr;
			if((tx->mar & 0600) == 0200) tx->lr = mbr_t;
			// 1.4
			if(tx->mar & 020) tx->ac ^= tx->mbr;
			else if((tx->mar & 0600) == 0400)
				tx->ac = tx->ac>>1 | tx->ac&0400000;
			else if((tx->mar & 0600) == 0600)
				tx->ac = (tx->ac>>1 | tx->ac<<17) & 0777777;
			// 1.6
			if((tx->mar & 0030000) == 0030000)
				tx->pbs = 0;	// halt
			// 1.7
			if(tx->mar & 010){
				tx->ac += (~tx->ac & tx->mbr)<<1;
				if(tx->ac & 01000000) tx->ac += 1;
				tx->ac &= 0777777;
			}
			break;
		}
		tx->mar = tx->pc;
		tx->c = 0;
//		pstate(tx);
	}

	if(tx->pbs == 0)
		tx->ss = 0;

	// handle IO
	if(tx->ss == 0){
		if(tx->ios == 0){
			int c;
			switch(tx->dev){
			case 0:
				break;
			case 1:
			case 2:
			case 3:
			case 4:	// pnt
				c = 0;
				if(tx->ac & 0000001) c |= 1;
				if(tx->ac & 0000010) c |= 2;
				if(tx->ac & 0000100) c |= 4;
				if(tx->ac & 0001000) c |= 010;
				if(tx->ac & 0010000) c |= 020;
				if(tx->ac & 0100000) c |= 040;
				putfl(tx->fl, c);
				tx->ios = 1;
				break;
			case 5:
			case 6:
			case 7:
				break;
			}

			if(tx->pbs == 0)
				tx->ss = 0;
		}else
			tx->ss = tx->pbs;
	}

//	sleep(1);
}

void
readmem(TX0 *tx, FILE *f)
{
	char buf[100], *s;
	word a, w;

	a = 0;
	while(s = fgets(buf, 100, f)){
		while(*s){
			if(*s == ';')
				break;
			else if('0' <= *s && *s <= '7'){
				w = strtol(s, &s, 8);
				if(*s == ':'){
					a = w;
					s++;
				}else if(a < MEMSZ)
					tx->core[a++] = w & 0777777;
			}else
				s++;
		}
	}
}

void
printmem(TX0 *tx)
{
	word a;
	for(a = 0; a < MEMSZ; a++)
		if(tx->core[a])
			printf("%06o/%06o\n", a, tx->core[a]);
}

TX0 tx0;
Flexowriter fl;

int
main()
{
	FILE *mf;

	memset(&fl, 0, sizeof(fl));
	fl.in = open("/tmp/fl", O_RDWR);
	if(fl.in < 0)
		panic("can't open /tmp/fl");
	fl.out = fl.in;

	memset(&tx0, 0, sizeof(tx0));
	tx0.pbs = 1;
	tx0.fl = &fl;
	tx0.mar = tx0.pc = 040;

	mf = mustopen("out.mem", "r");
	readmem(&tx0, mf);
	fclose(mf);

	printmem(&tx0);
	printf("\n\n");

	tx0.ss = 1;
	while(tx0.ss){
		step(&tx0);

		if(hasinput(tx0.fl->in)){
			int c;
			c = getfl(tx0.fl);
			tx0.lr = 0400000;
			if(c & 001) tx0.lr |= 0000001;
			if(c & 002) tx0.lr |= 0000010;
			if(c & 004) tx0.lr |= 0000100;
			if(c & 010) tx0.lr |= 0001000;
			if(c & 020) tx0.lr |= 0010000;
			if(c & 040) tx0.lr |= 0100000;
		}
	}

	printmem(&tx0);
	pstate(&tx0);

	return 0;
}