/***************************************************************
       crc's            _ _      ___ _         __
        _ __ ___  _   _| | |_   / (_) | ___   / /_  __
       | '_ ` _ \| | | | | __| / /| | |/ _ \ / /\ \/ /
       | | | | | | |_| | | |_ / / | | | (_) / /  >  <
       |_| |_| |_|\__,_|_|\__/_/  |_|_|\___/_/  /_/\_\
                     (c) charles childers

 This is a special implementation of my ilo computer, with
 multiple copies of ilo running under a single host process.
 Using this you can quickly switch between ilo instances.

 User Interface

 This implementation runs on X11 and provides a visual display
 of the terminal with a set of buttons below the display. These
 can be used to switch between ilo instances. Closing the window
 will terminate the system.

 Keyboard Shortcuts

 +--------+-----------------------------+
 | CTRL+n | Switch to the next ilo      |
 | CTRL+p | Switch to the previous ilo  |
 | CTRL+c | Restart the current ilo     |
 | CTRL+a | Shut down the system        |
 +--------+-----------------------------+

 Additional Functionality

 This implementation supports the basic Graphica (Level 0) and
 pointer extensions. These are assigned to I/O devices 12 & 13.

 Notes

 - `bye` will act like `restart` on the current computer
 - switching can only be done when the system is waiting for
   input

 Building

 I use this to build it:

   cc -O2 -s `pkg-config --cflags --libs x11` mix.c -o mix

 It'll probably also work with -O3 and might be slightly faster

 **************************************************************/

/* Configuration ============================================ */

#define BLOCKS  "ilo.blocks" /* default data storage    */
#define ROM     "ilo.rom"    /* default ilo rom         */
#define FONT    "ilo.fnt"    /* default font            */

#define FONT_H  16           /* font height             */
#define FONT_W  8            /* font width              */

                             /* colors are 0xRRGGBB     */
#define FG      0xFFC000     /* foreground color, amber */
#define BG      0x000000     /* background color, black */
#define CURSOR  0x663999     /* cursor color, purple    */

#define FW      640          /* terminal width          */
#define FH      384          /* terminal height         */

#define BUTTON_HEIGHT 30     /* height for button row   */

#define CENTER_WINDOW        /* center window on start */

#define ILOS 3               /* number of instances     */
char *ButtonLabels[ILOS] = {"Instance 0", "Instance 1",
                            "Instance 2"};

/* ========================================================== */

#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>

#define V void
#define I int
#define C char

#define DS v->ds    /* data stack                       */
#define AS v->as    /* address stack pointer            */
#define SP v->sp    /* data stack pointer               */
#define RP v->rp    /* address ("return") stack pointer */
#define IP v->ip    /* instruction pointer              */
#define M  v->m     /* memory                           */
#define T DS[SP]    /* top of data stack                */
#define N DS[SP-1]  /* next on data stack               */
#define R AS[RP]    /* top of address stack             */
#define A  v->a     /* internal use by instructions     */
#define B  v->b     /* internal use by instructions     */
#define S  v->s     /* internal use by instructions     */
#define D  v->d     /* internal use by instructions     */
#define L  v->l     /* internal use by instructions     */
#define F  v->f     /* used to track block file pointer */
#define RESTART iof(v) /* restart ilo instance on error */
#define OK v->ok    /* ok to process further instructions? */

#define FAILED if (F == -1)

#define CTRL_A 1    /* CTRL+a, shut down mult/ilo/x     */
#define CTRL_C 3    /* CTRL+c, restart instance         */
#define CTRL_N 14   /* CTRL+n, switch to next instance  */
#define CTRL_P 16   /* CTRL+p, switch to prior instance */

#define ROWS ((FH/FONT_H) - 1)
#define COLS ((FW/FONT_W) - 1)

typedef struct ilo ilo;
struct ilo {
  I  ip,            /* instruction pointer              */
     sp,            /* data stack pointer               */
     rp,            /* address stack pointer            */
     ds[33],        /* data stack                       */
     as[257],       /* address stack                    */
     m[65536];      /* memory                           */
  C *blocks,        /* name of block file (ilo.blocks)  */
    *rom;           /* name of image (ilo.rom)          */
  I  a, b, f, s, d, l, ok;
  C  i[1];
};
struct ilo systems[ILOS]; /* ilo session data           */
I cur;              /* track current session            */

#define BUTTON_WIDTH  (FW / ILOS)
#define WINDOW_HEIGHT (FH + BUTTON_HEIGHT)
#define WINDOW_WIDTH  (FW)

I frame[(FW * FH)/32];    /* frame buffer for display */
I font[4096];             /* font bitmap              */
I tx, ty;                 /* text cursor location     */

/* variables for Arland's DEC subset                  */
I acc[32], acc_i = 0, ground = 0, on = 0;

/* variables for X11 stuff                            */
Display *disp;
Window win;
GC gc;
XEvent event;
Window Buttons[ILOS];

V update_labels() {
  unsigned long white;
  white = WhitePixel(disp, DefaultScreen(disp));
  XSetForeground(disp, gc, white);
  for (I i = 0; i < ILOS; i++) {
    XClearWindow(disp, Buttons[i]);
    XDrawString(disp, Buttons[i], gc, 20, 20, ButtonLabels[i],
                strlen(ButtonLabels[i]));
    if (cur == i) {
      XDrawString(disp, Buttons[i], gc, 10, 20, "*", 1);
    }
//    XSetForeground(disp, gc, white);
    XDrawLine(disp, Buttons[i], gc, 0, 0, FW, 0);
  }
}

V dputc(I);
V term_putc(I c);
V redraw();

V iof(ilo *);

V p(C *s) { while(*s) dputc(*s++); }
V e(ilo *v, C *s) { p("E:"); p(s); p("\n"); OK = 1; RESTART; }
V dso(ilo *v) { if ((SP + 1) > 32)      { e(v, "DSO"); } }
V dsu(ilo *v) { if ((SP - 1) < 0)       { e(v, "DSU"); } }
V rso(ilo *v) { if ((RP + 1) > 256)     { e(v, "RSO"); } }
V rsu(ilo *v) { if ((RP - 1) < 0)       { e(v, "RSU"); } }
V dbz(ilo *v) { if (T == 0)             { e(v, "DBZ"); } }
V mem(ilo *v) { if (T < 0 || T > 65535) { e(v, "MEM"); } }
V uli(ilo *v) { e(v, "ULI"); }
V ulf(ilo *v) { e(v, "ULF"); }
V usi(ilo *v) { e(v, "URI"); }
V urb(ilo *v) { e(v, "URB"); }
V uwb(ilo *v) { e(v, "UWB"); }

V push(ilo *v, I n) { dso(v); DS[SP + 1] = n; SP += 1; }
I pop(ilo *v) { dsu(v); SP -= 1; return DS[SP + 1]; }

/* display & terminal emulation ============================= */

V add_buttons() {
  for (I i = 0; i < ILOS; i++) {
    Buttons[i] = XCreateSimpleWindow(disp, win, i*BUTTON_WIDTH,
                                     FH, BUTTON_WIDTH,
                                     BUTTON_HEIGHT, 1, 0, 0);
    XSelectInput(disp, Buttons[i],
                 ButtonPressMask | ExposureMask);
    XMapWindow(disp, Buttons[i]);
  }
}

V initialize_display() {
  disp = XOpenDisplay(NULL);
  win = XCreateSimpleWindow(disp, RootWindow(disp, 0),
                            0, 0, WINDOW_WIDTH, WINDOW_HEIGHT,
                            0, 0x0, 0x0);
  XSelectInput(disp, win, ExposureMask | KeyPressMask |
                          ButtonPressMask | ButtonReleaseMask);
  XStoreName(disp, win, "mult/ilo");
  gc = DefaultGC(disp, DefaultScreen(disp));
  add_buttons();
  XMapWindow(disp, win);
  XFlush(disp);
}

V cleanup_display() {
  XUnmapWindow(disp, win);
  XDestroyWindow(disp, win);
  XCloseDisplay(disp);
}

V cursor() {
  XSetForeground(disp, gc, CURSOR);
  XFillRectangle(disp, win, gc, tx, ty, FONT_W, FONT_H);
  XFlush(disp);
}

V sel(I n) { cur = n; }

I handle_keypress() {
  C text[255];
  KeySym key = XLookupKeysym(&event.xkey, 0);
  XLookupString(&event.xkey, text, 255, &key, 0);
  if (text[0] == 13) text[0] = 10;
  if (text[0] != 0)  return (I) text[0];
  return 0;
}

V handle_expose() { redraw(); update_labels(); cursor(); }

I handle_button() {
  for (I i = 0; i < ILOS; i++) {
    if (event.xbutton.window == Buttons[i]) { sel(i); }
  }
  update_labels();
  return 32;
}

I wait_key() {
  I k = 0;
  while (k == 0) {
    XNextEvent(disp, &event);
    if (event.type == KeyPress)    { k = handle_keypress(); }
    if (event.type == Expose)      {     handle_expose();   }
    if (event.type == ButtonPress) { k = handle_button();   }
  }
  return k;
}

V load_font(ilo *v) {
  F = open(FONT, O_RDONLY, 0666); FAILED { ulf(v); return; }
  read(F, &font, 4096);
  close(F);
}

V pixel(I x, I y, I c) {
  I index = y * FW + x;
  if (c == 0) {
    frame[(index / 32)] &= ~(1 << (31 - index % 32));
    XSetForeground(disp, gc, BG);
  } else {
    frame[(index / 32)] |= 1 << (31 - index % 32);
    XSetForeground(disp, gc, FG);
  }
  XDrawPoint(disp, win, gc, x, y);
}

I get_pixel(I x, I y) {
  I index = y * FW + x;
  I bit_pos = 31 - index % 32;
  I mask = 1 << bit_pos;
  return (frame[(index / 32)] & mask) >> bit_pos;
}

V redraw() {
  for (I x = 0; x < FW; x++) {
    for (I y = 0; y < FH; y++) {
      XSetForeground(disp, gc, get_pixel(x, y) ? FG : BG);
      XDrawPoint(disp, win, gc, x, y);
    }
  }
}

V scroll() {
  I memsize = (FH * FW) / 32;
  I last_row = (FW * FONT_H) / 32;
  for (I i = 0; i < memsize - last_row; i++) {
    frame[i] = frame[i + last_row];
  }
  for (I i = memsize - last_row; i < memsize; i++) {
    frame[i] = 0;
  }
  redraw();
}

unsigned C reverse(unsigned C b) {
  b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
  b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
  b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
  return b;
}

V special_backspace() {
  if (tx - FONT_W >= 0) {
    tx -= FONT_W ; dputc(' '); tx -= FONT_W;
  }
}

V special_tab() {
  I ts = tx / FONT_W;
  for (I i = ts; i < ((ts + 7) / 8) * 8; i++) { dputc(' '); }
}

V special_crlf() { ty += FONT_H; tx = 0; }

V handle_special_character(I c) {
  switch (c) {
    case 8:
    case 127: special_backspace(); break;
    case 9:   special_tab();       break;
    case 10:
    case 13:  special_crlf();      break;
  }
}

V handle_regular_character(C *bitmap) {
  I x, y, set;
  for (x = 0; x < FONT_H; x++) {
    for (y = 0; y < FONT_W; y++) {
      set = reverse(bitmap[x]) & 1 << y;
      pixel(tx + y, ty + x, set ? 1 : 0);
    }
  }
  tx += FONT_W;
}

V advance_cursor_and_scroll() {
  if (tx >= FW) { tx = 0; ty += FONT_H; }
  if (ty > (FH - FONT_H)) { ty -= FONT_H; scroll(); }
}

#define NORMAL !(c < 32 || c == 127)

V dputc(I c) {
  C *bitmap = (C *)font + (c * ((FONT_H * FONT_W) / 8));
  handle_special_character(c);
  if (NORMAL) { handle_regular_character(bitmap); }
  advance_cursor_and_scroll();
}

I acc_pop() {
  I k = acc_i;
  if (acc_i > 0) {
    acc_i -= 1;
    if (acc_i == -1) {
      acc_i = 0;
    }
  }
  return acc[k];
}

V acc_reset() {
  for (I x = 0; x < 32; x++) { acc[x] = 0; }
  ground = on = 0;
}

V gt_up(I n)       { ty -= FONT_H; if (ty < 0) ty = 0;  }
V gt_down(I n)     { ty += FONT_H; if (ty > ROWS * FONT_H) ty = ROWS * FONT_H; }
V gt_left(I n)     { tx -= FONT_W; if (tx < 0) tx = 0; }
V gt_right(I n)    { tx += FONT_W; if (tx > COLS * FONT_W) ty = COLS * FONT_W; }
V gt_move_cursor() {
  if (acc_i >= 1) {
    I a = (acc_pop() - 1) * FONT_W;
    I b = (acc_pop() - 1) * FONT_H;
    ty = b; if (ty < 0) ty = 0; if (ty > FONT_H * ROWS) ty = FONT_H * ROWS;
    tx = a; if (tx < 0) tx = 0; if (tx > FONT_W * COLS) tx = FONT_W * COLS;
    acc_reset();
    return;
  }
  /* home */
  tx = 0; ty = 0;
  acc_reset();
}

V gt_reset()       { acc_reset(); }
V gt_next()        { acc_i += 1; acc[acc_i] = 0; }
V gt_clear() {
  acc_reset();
  for (I x = 0; x < (FW * FH) / 32; x++) frame[x] = 0;
  tx = ty = 0;
  redraw();
}
V gt_set_attr()    { acc_reset(); }

V term_putc(I c) {
  if (c == 27) { on = -2; return; }
  switch (on) {
    case 0:
      dputc(c);
      return;
    case -2:
      if (c == '[') {
        on = -1;
        return;
      }
      on = 0;
      dputc(c);
      return;
  }
  if (c >= '0' && c <= '9') {
    acc[acc_i] *= 10;
    acc[acc_i] += c - 48;
    if (c == '3') {
      ground = 0;
    }
    if (c == '4') {
      ground = 1;
    }
  } else {
    switch (c) {
      case 'A': gt_up(acc_pop());    break;
      case 'B': gt_down(acc_pop());  break;
      case 'C': gt_left(acc_pop());  break;
      case 'D': gt_right(acc_pop()); break;
      case 'm': gt_set_attr();       break;
      case ';': gt_next();           break;
      case 'H': gt_move_cursor();    break;
      case 'J': gt_clear();          break;
      default: on = 0;
               dputc(c);
    }
  }
}

/* graphica, level 0 ======================================== */

I p0, p0x, p0y, pcolor = FG;
I px(I p) { return p >> 16;   }
I py(I p) { return p & 65535; }

V gra0(ilo *v) { push(v, 0); }
V gra1(ilo *v) { push(v, 2); }
V gra2(ilo *v) { push(v, FONT_H); push(v, FONT_W); }
V gra3(ilo *v) { push(v, FH);     push(v, FW);     }
V gra4(ilo *v) { pcolor = (pop(v) != 0) ? FG : BG; }
V gra5(ilo *v) { p0 = pop(v); p0x = px(p0); p0y = py(p0);
                 pixel(p0x, p0y, pcolor); }
V gra6(ilo *v) { p0 = pop(v); p0x = px(p0); p0y = py(p0);
                 push(v, get_pixel(p0x, p0y)); }
V gra(ilo *v) {
  switch (pop(v)) {
    case 0: gra0(v); break;  case 1: gra1(v); break;
    case 2: gra2(v); break;  case 3: gra3(v); break;
    case 4: gra4(v); break;  case 5: gra5(v); break;
    case 6: gra6(v); break;
  }
}

/* pointer device =========================================== */
/* returns x, y, button state                                 */

V ptr(ilo *v) {
  I x, y, wx, wy;
  unsigned I mask;
  Window w;
  XQueryPointer(disp, win, &w, &w, &x, &y, &wx, &wy, &mask);
  push(v, x);
  push(v, y);
  if (mask & Button1Mask) push(v, -1); else push(v, 0);
}

/* the ilo cpu ============================================== */

V load_image(ilo *v) {
  F = open(v->rom, O_RDONLY, 0666); FAILED { uli(v); return; }
  read(F, &M, 65536 * 4);
  close(F);
  IP = SP = RP = 0;
}

V save_image(ilo *v) {
  F = open(v->rom, O_WRONLY, 0666); FAILED { usi(v); return; }
  write(F, &M, 65536 * 4);
  close(F);
}

V block_common(ilo *v) {
  B = pop(v); /* block buffer */
  A = pop(v); /* block number */
  lseek(F, 4096 * A, SEEK_SET);
}

V read_block(ilo *v) {
  F = open(v->blocks, O_RDONLY, 0666); FAILED { urb(v); return; }
  block_common(v);
  read(F, M + B, 4096);
  close(F);
}

V write_block(ilo *v) {
  F = open(v->blocks, O_WRONLY, 0666); FAILED { uwb(v); return; }
  block_common(v);
  write(F, M + B, 4096);
  close(F);
}

V save_ip(ilo *v) { RP += 1; R = IP; }
V symmetric(ilo *v) { if (B >= 0 && N < 0) { T += 1; N -= B; } }

V li(ilo *v) { IP += 1; push(v, M[IP]); }
V du(ilo *v) { push(v, T); }
V dr(ilo *v) { DS[SP] = 0; SP -= 1; }
V sw(ilo *v) { A = T; T = N; N = A; }
V pu(ilo *v) { RP += 1; R = pop(v); }
V po(ilo *v) { push(v, R); RP -= 1; }
V ju(ilo *v) { IP = pop(v) - 1; }
V ca(ilo *v) { save_ip(v); IP = pop(v) - 1; }
V cc(ilo *v) { A = pop(v);
               if (pop(v)) { save_ip(v);
                             IP = A - 1; } }
V cj(ilo *v) { A = pop(v);
               if (pop(v)) { IP = A - 1; } }
V re(ilo *v) { IP = R; RP -= 1; }
V eq(ilo *v) { N = (N == T) ? -1 : 0; SP -= 1; }
V ne(ilo *v) { N = (N != T) ? -1 : 0; SP -= 1; }
V lt(ilo *v) { N = (N <  T) ? -1 : 0; SP -= 1; }
V gt(ilo *v) { N = (N >  T) ? -1 : 0; SP -= 1; }
V fe(ilo *v) { T = M[T]; }
V st(ilo *v) { M[T] = N; SP -= 2; }
V ad(ilo *v) { N += T; SP -= 1; }
V su(ilo *v) { N -= T; SP -= 1; }
V mu(ilo *v) { N *= T; SP -= 1; }
V di(ilo *v) { A = T; B = N;
               if (A == 0) { dbz(v); OK = 1; RESTART; return; }
               T = B / A; N = B % A;
               symmetric(v); }
V an(ilo *v) { N = T & N; SP -= 1; }
V or(ilo *v) { N = T | N; SP -= 1; }
V xo(ilo *v) { N = T ^ N; SP -= 1; }
V sl(ilo *v) { N = N << T; SP -= 1; }
V sr(ilo *v) { N = N >> T; SP -= 1; }
V cp(ilo *v) { L = pop(v); D = pop(v); S = T; T = -1;
               while (L) {
                 if (M[D] != M[S]) { T = 0; }
                 L -= 1; S += 1; D += 1; } }
V cy(ilo *v) { L = pop(v); D = pop(v); S = pop(v);
               while (L) {
                 M[D] = M[S];
                 L -= 1; S += 1; D += 1; } }

V pre(V) { cur -= 1; if (cur < 0) cur = ILOS - 1; update_labels(); }
V nxt(V) { cur += 1; if (cur > (ILOS - 1)) cur = 0; update_labels(); }

V ioa(ilo *v) { term_putc(pop(v)); }
V iob(ilo *v) { redraw(); cursor();
                v->i[0] = wait_key(); push(v, v->i[0]); term_putc(T);
                if (v->i[0] == CTRL_N) { T = 32; nxt(); }
                if (v->i[0] == CTRL_P) { T = 32; pre(); }
                if (v->i[0] == CTRL_C) { T = 32; RESTART;
                                         OK = 1; }
                if (v->i[0] == CTRL_A) { T = 32; exit(0); } }
V ioc(ilo *v) { read_block(v); }
V iod(ilo *v) { write_block(v); }
V ioe(ilo *v) { save_image(v); }
V iof(ilo *v) { load_image(v); IP = -1; }
V iog(ilo *v) { RESTART; }
V ioh(ilo *v) { push(v, SP); push(v, RP); }

V io(ilo *v) {
  switch (pop(v)) {
    case  0: ioa(v); break;  case  1: iob(v); break;
    case  2: ioc(v); break;  case  3: iod(v); break;
    case  4: ioe(v); break;  case  5: iof(v); break;
    case  6: iog(v); break;  case  7: ioh(v); break;
    /* optional extensions after this point */
    case 12: gra(v); break;  case 13: ptr(v); break;
    default: break;
  }
}

V process(ilo *v, I o) {
  switch (o) {
    case  0:        break;   case  1: li(v); break;
    case  2: du(v); break;   case  3: dr(v); break;
    case  4: sw(v); break;   case  5: pu(v); break;
    case  6: po(v); break;   case  7: ju(v); break;
    case  8: ca(v); break;   case  9: cc(v); break;
    case 10: cj(v); break;   case 11: re(v); break;
    case 12: eq(v); break;   case 13: ne(v); break;
    case 14: lt(v); break;   case 15: gt(v); break;
    case 16: fe(v); break;   case 17: st(v); break;
    case 18: ad(v); break;   case 19: su(v); break;
    case 20: mu(v); break;   case 21: di(v); break;
    case 22: an(v); break;   case 23: or(v); break;
    case 24: xo(v); break;   case 25: sl(v); break;
    case 26: sr(v); break;   case 27: cp(v); break;
    case 28: cy(v); break;   case 29: io(v); break;
    default: break;
  }
}

/* This is used to help skip processing NOP operations and */
/* abort on errors                                         */

#define VALID(n) (OK == 0) && ((opcode >> n) & 0xFF)

V execute() {
  I opcode;
  ilo *v = &systems[cur];
  while (IP < 65536) {
    opcode = M[IP];
    OK = 0;
    if (VALID(0))   process(v, opcode & 0xFF);
    if (VALID(8))   process(v, (opcode >> 8) & 0xFF);
    if (VALID(16))  process(v, (opcode >> 16) & 0xFF);
    if (VALID(24))  process(v, (opcode >> 24) & 0xFF);
    IP += 1;
    v = &systems[cur];
  }
}

/* main entry point ========================================= */

I main(I argc, C **argv) {
  ilo *v;
  I i;

  /* setup each session */
  for (i = 0; i < ILOS; i++) {
    v = &systems[i];
    v->blocks = (argc > 1) ? argv[1] : BLOCKS;
    v->rom    = (argc > 2) ? argv[2] : ROM;
    load_image(v);
  }

  /* load the font data */
  load_font(&systems[0]);
  initialize_display();

#ifdef CENTER_WINDOW
  XMoveWindow(disp, win, (DisplayWidth(disp, DefaultScreen(disp)) - FW) / 2,
                         (DisplayHeight(disp, DefaultScreen(disp)) - FH - BUTTON_HEIGHT) / 2);
#endif

  cur = 0;
  execute();

  cleanup_display();
  return 0;
}