summary refs log tree commit diff stats
path: root/TODO
blob: c3be20c72fddf9bd0c96f8db9361cb97e255e1eb (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
Console

   (X) #0   09/12/06  console commands
   (X) #1   09/12/06  quick find
   (X) #2   09/12/06  open with
   (X) #4   09/12/06  history for console
   (X) #13  09/12/27  display docstring of a command


General

   (X) #5   09/12/06  move code from fm into objects
   (X) #6   09/12/06  move main to __init__
   (X) #7   09/12/06  cooler titlebar
   (X) #8   09/12/17  Add operations to modify files/directories
   (X) #9   09/12/24  add a widget for managing running operations
   (X) #10  09/12/24  sorting
   (X) #11  09/12/27  filter
   (X) #12  09/12/27  jump through the list in a specific order
   (X) #14  09/12/29  make filelists inherit from pagers
   (X) #15  09/12/29  better way of running processes!!~
   (X) #16  10/01/01  list of bookmarks
   (X) #21  10/01/01  write help!
   (X) #22  10/01/03  add getopt options to change flags/mode
   (X) #29  10/01/06  add chmod command
   (X) #30  10/01/06  add a way to create symlinks
   (X) #32  10/01/08  place the (hidden) cursor to a meaningful position
   (X) #34  10/01/09  display free disk space
   (X) #35  10/01/09  display disk usage of files in current directory
   ( ) #36  10/01/11  help coloring is terribly inefficient
   ( ) #37  10/01/13  better tab completion for OpenConsole
   ( ) #38  10/01/16  searching in pager
   (X) #39  10/01/17  flushinput not always good
   (X) #42  10/01/17  memorize directory for `` when using :cd
   (X) #43  10/01/18  internally treat the bookmarks ` and ' the same
   ( ) #44  10/01/18  more error messages :P
   (X) #47  10/01/19  less restricive auto preview
   (X) #48  10/01/19  abbreviate commands with first unambiguous substring
   ( ) #50  10/01/19  add more unit tests


Bugs

   (X) #17  10/01/01  why do bookmarks disappear sometimes?
   (X) #18  10/01/01  fix notify widget (by adding a LogView?)
   (X) #19  10/01/01  resizing after pressing g
   (X) #23  10/01/04  stop dir loading with ^C -> wont load anymore
   (X) #25  10/01/06  directories sometimes dont reload correctly
   (X) #26  10/01/06  :delete on symlinks of directories fails
   (X) #31  10/01/06  ^C breaks cd-after-exit by stopping sourced shell script
   ( ) #40  10/01/17  freeze with unavailable sshfs
   (X) #41  10/01/17  capital file extensions are not recognized
   ( ) #46  10/01/19  old username displayed after using su
   (X) #49  10/01/19  fix unit tests :'(


Ideas

   ( ) #20  10/01/01  use inotify to monitor filesystem changes
   ( ) #24  10/01/06  progress bar
   (X) #27  10/01/06  hide bookmarks in list which contain hidden dir
   (X) #28  10/01/06  use regexp instead of string for searching
   ( ) #33  10/01/08  accelerate mousewheel speed
   ( ) #45  10/01/18  hooks for events like setting changes
title='Blame the previous revision' href='/akkartik/mu/blame/500fake-screen.mu?h=hlt&id=c22874a97f9e22f00b78b46b0647ea97325370f4'>^
6efc1ebe ^
34596b6e ^














6efc1ebe ^

30018fd6 ^
6efc1ebe ^

30018fd6 ^
6efc1ebe ^


dbf434f0 ^
30018fd6 ^

6efc1ebe ^




74f1512f ^
6efc1ebe ^

30018fd6 ^
6efc1ebe ^
30018fd6 ^
6efc1ebe ^



7363c6df ^
30018fd6 ^

6e36ce06 ^


8f34dfd1 ^
6e36ce06 ^

6efc1ebe ^
30018fd6 ^

6efc1ebe ^






1d7aae96 ^




6efc1ebe ^

08c55cb2 ^





bfcf5c72 ^
30018fd6 ^

8e38b86a ^




bfcf5c72 ^




8e38b86a ^







34596b6e ^
8e38b86a ^



bfcf5c72 ^
72f9fdbd ^
6efc1ebe ^
72f9fdbd ^
6efc1ebe ^

6e36ce06 ^

30018fd6 ^

6e36ce06 ^







6efc1ebe ^
30018fd6 ^

6efc1ebe ^
6e36ce06 ^

30018fd6 ^

6e36ce06 ^


63be7b7d ^
6e36ce06 ^

6efc1ebe ^
6efc1ebe ^







30018fd6 ^
6efc1ebe ^












30018fd6 ^
6efc1ebe ^





30018fd6 ^
6efc1ebe ^


30018fd6 ^
6efc1ebe ^

63be7b7d ^

cec5ef31 ^
63be7b7d ^


cec5ef31 ^
63be7b7d ^


1b09418c ^

63be7b7d ^
8f34dfd1 ^
6e36ce06 ^

30018fd6 ^

6e36ce06 ^





6efc1ebe ^
63be7b7d ^
79e6d41b ^
30018fd6 ^
6efc1ebe ^

79e6d41b ^

30018fd6 ^
6efc1ebe ^

79e6d41b ^
08c55cb2 ^
6efc1ebe ^





63be7b7d ^
34596b6e ^

d604e68c ^










6e36ce06 ^

90748fa4 ^

























34596b6e ^






























90748fa4 ^

30018fd6 ^

d6d28b8c ^







d6d28b8c ^



















6efc1ebe ^

6e36ce06 ^


74f1512f ^
6e36ce06 ^


74f1512f ^
6e36ce06 ^
74f1512f ^
6e36ce06 ^






6efc1ebe ^
d6d28b8c ^

34596b6e ^
d6d28b8c ^
34596b6e ^
d6d28b8c ^



34596b6e ^
d6d28b8c ^
34596b6e ^
d6d28b8c ^











30018fd6 ^



6efc1ebe ^


30018fd6 ^


6efc1ebe ^







30018fd6 ^



6efc1ebe ^


30018fd6 ^


6efc1ebe ^







8f34dfd1 ^
30018fd6 ^



8f34dfd1 ^


30018fd6 ^


8f34dfd1 ^







c22874a9 ^








34596b6e ^


c22874a9 ^
34596b6e ^


c22874a9 ^
34596b6e ^







































c22874a9 ^
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
                                            
 









                                                                              
 
             
             


                                  


                              
                             




                  
                       

 
                                                                                                
                                               


                                    
                           


                           
                            

                    
                         
   














                                                                        

                        
                              

                        
                              


                  
              

                                                                 




                               
                            

               
                                              
                    
                           



                      
                           

                                                                                                         


                     
                                                                 

          
               

                                                                      






                                                                  




                                               

 





                                                                                                            
                                                                      

                                                                           




                                         




                                                 







                                         
                                                  



                                         
   
                                                     
                               
                                

                 

 

                                                                     







                                          
               

                                                           
                                       

 

                                                               


                     
                                           

          
               







                     
                                                       












                                          
                                                         





                                            
                                                  


                            
                              

                    

 
                                                   


                     
                                


               

                                 
                                              
                                                         

 

                                               





                     
               
                                  
                          
                                                  

                      

                            
                                                  

                       
                 
                                                                      





                    
                                  

                                                                   










                                                

 

























                                                                






























                                                                   

 

                                                                                                         







                                                                      



















                                                                      

                                                                              


                          
                                      


                            
                                        
                 
                                              






                    
 

                                                                                                
                                    
                                
                                       



                               
                                     
                                  
                                        











                                                 



                                                                                 


               


                                                                                        







                                                                  



                                                                         


               


                                                                                







                                                                  
 



                                                                                    


               


                                                                                           







                                                                  








                                                            


                                                                   
   


                                                      
   







































                                                                     
 
# Testable primitives for writing to screen.
#
# Mu mostly uses the screen for text, but it builds it out of pixel graphics
# and a bitmap font. There is no support for a blinking cursor, scrolling and
# so on.
#
# Fake screens are primarily for testing text-mode prints. However, they do
# support some rudimentary pixel operations as well. Caveats:
#
# - Drawing pixels atop text or vice versa is not supported. Results in a fake
#   screen will not mimic real screens in these situations.
# - Fake screens currently also assume a fixed-width 8x16 font.

type screen {
  # text mode
  width: int
  height: int
  data: (handle array screen-cell)
  cursor-x: int  # [0..width)
  cursor-y: int  # [0..height)
  # pixel graphics
  pixels: (handle array byte)
}

type screen-cell {
  data: grapheme
  color: int
  background-color: int
}

fn initialize-screen _screen: (addr screen), width: int, height: int, pixel-graphics?: boolean {
  var screen/esi: (addr screen) <- copy _screen
  var tmp/eax: int <- copy 0
  var dest/edi: (addr int) <- copy 0
  # screen->width = width
  dest <- get screen, width
  tmp <- copy width
  copy-to *dest, tmp
  # screen->height = height
  dest <- get screen, height
  tmp <- copy height
  copy-to *dest, tmp
  # populate screen->data
  {
    var data-ah/edi: (addr handle array screen-cell) <- get screen, data
    var capacity/eax: int <- copy width
    capacity <- multiply height
    populate data-ah, capacity
  }
  # if necessary, populate screen->pixels
  {
    compare pixel-graphics?, 0/false
    break-if-=
    var pixels-ah/edi: (addr handle array byte) <- get screen, pixels
    var capacity/eax: int <- copy width
    capacity <- shift-left 3/log2-font-width
    capacity <- multiply height
    capacity <- shift-left 4/log2-font-height
    populate pixels-ah, capacity
  }
  # screen->cursor-x = 0
  dest <- get screen, cursor-x
  copy-to *dest, 0
  # screen->cursor-y = 0
  dest <- get screen, cursor-y
  copy-to *dest, 0
}

# in graphemes
fn screen-size _screen: (addr screen) -> _/eax: int, _/ecx: int {
  var screen/esi: (addr screen) <- copy _screen
  var width/eax: int <- copy 0
  var height/ecx: int <- copy 0
  compare screen, 0
  {
    break-if-!=
    return 0x80/128, 0x30/48
  }
  # fake screen
  var tmp/edx: (addr int) <- get screen, width
  width <- copy *tmp
  tmp <- get screen, height
  height <- copy *tmp
  return width, height
}

# testable screen primitive
fn draw-grapheme _screen: (addr screen), g: grapheme, x: int, y: int, color: int, background-color: int {
  var screen/esi: (addr screen) <- copy _screen
  {
    compare screen, 0
    break-if-!=
    draw-grapheme-on-real-screen g, x, y, color, background-color
    return
  }
  # fake screen
  var idx/ecx: int <- screen-cell-index screen, x, y
  var data-ah/eax: (addr handle array screen-cell) <- get screen, data
  var data/eax: (addr array screen-cell) <- lookup *data-ah
  var offset/ecx: (offset screen-cell) <- compute-offset data, idx
  var dest-cell/ecx: (addr screen-cell) <- index data, offset
  var dest-grapheme/eax: (addr grapheme) <- get dest-cell, data
  var g2/edx: grapheme <- copy g
  copy-to *dest-grapheme, g2
  var dest-color/eax: (addr int) <- get dest-cell, color
  var src-color/edx: int <- copy color
  copy-to *dest-color, src-color
  dest-color <- get dest-cell, background-color
  src-color <- copy background-color
  copy-to *dest-color, src-color
}

# we can't really render non-ASCII yet, but when we do we'll be ready
fn draw-code-point screen: (addr screen), c: code-point, x: int, y: int, color: int, background-color: int {
  var g/eax: grapheme <- copy c
  draw-grapheme screen, g, x, y, color, background-color
}

# not really needed for a real screen, though it shouldn't do any harm
fn screen-cell-index _screen: (addr screen), x: int, y: int -> _/ecx: int {
  var screen/esi: (addr screen) <- copy _screen
  {
    compare x, 0
    break-if->=
    abort "screen-cell-index: negative x"
  }
  {
    var xmax/eax: (addr int) <- get screen, width
    var xcurr/ecx: int <- copy x
    compare xcurr, *xmax
    break-if-<
    abort "screen-cell-index: x too high"
  }
  {
    compare y, 0
    break-if->=
    abort "screen-cell-index: negative y"
  }
  {
    var ymax/eax: (addr int) <- get screen, height
    var ycurr/ecx: int <- copy y
    compare ycurr, *ymax
    break-if-<
    abort "screen-cell-index: y too high"
  }
  var width-addr/eax: (addr int) <- get screen, width
  var result/ecx: int <- copy y
  result <- multiply *width-addr
  result <- add x
  return result
}

fn cursor-position _screen: (addr screen) -> _/eax: int, _/ecx: int {
  var screen/esi: (addr screen) <- copy _screen
  {
    compare screen, 0
    break-if-!=
    var x/eax: int <- copy 0
    var y/ecx: int <- copy 0
    x, y <- cursor-position-on-real-screen
    return x, y
  }
  # fake screen
  var cursor-x-addr/eax: (addr int) <- get screen, cursor-x
  var cursor-y-addr/ecx: (addr int) <- get screen, cursor-y
  return *cursor-x-addr, *cursor-y-addr
}

fn set-cursor-position _screen: (addr screen), x: int, y: int {
  var screen/esi: (addr screen) <- copy _screen
  {
    compare screen, 0
    break-if-!=
    set-cursor-position-on-real-screen x, y
    return
  }
  # fake screen
  # ignore x < 0
  {
    compare x, 0
    break-if->=
    return
  }
  # ignore x >= width
  {
    var width-addr/eax: (addr int) <- get screen, width
    var width/eax: int <- copy *width-addr
    compare x, width
    break-if-<=
    return
  }
  # ignore y < 0
  {
    compare y, 0
    break-if->=
    return
  }
  # ignore y >= height
  {
    var height-addr/eax: (addr int) <- get screen, height
    var height/eax: int <- copy *height-addr
    compare y, height
    break-if-<
    return
  }
  # screen->cursor-x = x
  var dest/edi: (addr int) <- get screen, cursor-x
  var src/eax: int <- copy x
  copy-to *dest, src
  # screen->cursor-y = y
  dest <- get screen, cursor-y
  src <- copy y
  copy-to *dest, src
}

fn draw-cursor screen: (addr screen), g: grapheme {
  {
    compare screen, 0
    break-if-!=
    draw-cursor-on-real-screen g
    return
  }
  # fake screen
  var cursor-x/eax: int <- copy 0
  var cursor-y/ecx: int <- copy 0
  cursor-x, cursor-y <- cursor-position screen
  draw-grapheme screen, g, cursor-x, cursor-y, 0/fg, 7/bg
}

fn clear-screen _screen: (addr screen) {
  var screen/esi: (addr screen) <- copy _screen
  {
    compare screen, 0
    break-if-!=
    clear-real-screen
    return
  }
  # fake screen
  set-cursor-position screen, 0, 0
  var y/eax: int <- copy 0
  var height/ecx: (addr int) <- get screen, height
  {
    compare y, *height
    break-if->=
    var x/edx: int <- copy 0
    var width/ebx: (addr int) <- get screen, width
    {
      compare x, *width
      break-if->=
      draw-code-point screen, 0x20/space, x, y, 0/fg=black, 0/bg=black
      x <- increment
      loop
    }
    y <- increment
    loop
  }
  set-cursor-position screen, 0, 0
  var pixels-ah/eax: (addr handle array byte) <- get screen, pixels
  var pixels/eax: (addr array byte) <- lookup *pixels-ah
  var i/ecx: int <- copy 0
  var max/edx: int <- length pixels
  {
    compare i, max
    break-if->=
    var curr/eax: (addr byte) <- index pixels, i
    var zero/ebx: byte <- copy 0
    copy-byte-to *curr, zero
    i <- increment
    loop
  }
}

fn fake-screen-empty? _screen: (addr screen) -> _/eax: boolean {
  var screen/esi: (addr screen) <- copy _screen
  var y/eax: int <- copy 0
  var height/ecx: (addr int) <- get screen, height
  {
    compare y, *height
    break-if->=
    var x/edx: int <- copy 0
    var width/ebx: (addr int) <- get screen, width
    {
      compare x, *width
      break-if->=
      var g/eax: grapheme <- screen-grapheme-at screen, x, y
      {
        compare g, 0
        break-if-=
        compare g, 0x20/space
        break-if-=
        return 0/false
      }
      x <- increment
      loop
    }
    y <- increment
    loop
  }
  var pixels-ah/eax: (addr handle array byte) <- get screen, pixels
  var pixels/eax: (addr array byte) <- lookup *pixels-ah
  var y/ebx: int <- copy 0
  var height-addr/edx: (addr int) <- get screen, height
  var height/edx: int <- copy *height-addr
  height <- shift-left 4/log2-font-height
  {
    compare y, height
    break-if->=
    var width-addr/edx: (addr int) <- get screen, width
    var width/edx: int <- copy *width-addr
    width <- shift-left 3/log2-font-width
    var x/edi: int <- copy 0
    {
      compare x, width
      break-if->=
      var idx/ecx: int <- pixel-index screen, x, y
      var color-addr/ecx: (addr byte) <- index pixels, idx
      var color/ecx: byte <- copy-byte *color-addr
      compare color, 0
      {
        break-if-=
        return 0/false
      }
      x <- increment
      loop
    }
    y <- increment
    loop
  }
  return 1/true
}

fn clear-rect _screen: (addr screen), xmin: int, ymin: int, xmax: int, ymax: int, background-color: int {
  var screen/esi: (addr screen) <- copy _screen
  {
    compare screen, 0
    break-if-!=
    clear-rect-on-real-screen xmin, ymin, xmax, ymax, background-color
    return
  }
  # fake screen
  set-cursor-position screen, 0, 0
  var y/eax: int <- copy ymin
  var ymax/ecx: int <- copy ymax
  {
    compare y, ymax
    break-if->=
    var x/edx: int <- copy xmin
    var xmax/ebx: int <- copy xmax
    {
      compare x, xmax
      break-if->=
      draw-code-point screen, 0x20/space, x, y, 0/fg, background-color
      x <- increment
      loop
    }
    y <- increment
    loop
  }
  set-cursor-position screen, 0, 0
}

# there's no grapheme that guarantees to cover every pixel, so we'll bump down
# to pixels for a real screen
fn clear-real-screen {
  var y/eax: int <- copy 0
  {
    compare y, 0x300/screen-height=768
    break-if->=
    var x/edx: int <- copy 0
    {
      compare x, 0x400/screen-width=1024
      break-if->=
      pixel-on-real-screen x, y, 0/color=black
      x <- increment
      loop
    }
    y <- increment
    loop
  }
}

fn clear-rect-on-real-screen xmin: int, ymin: int, xmax: int, ymax: int, background-color: int {
  var y/eax: int <- copy ymin
  y <- shift-left 4/log2-font-height
  var ymax/ecx: int <- copy ymax
  ymax <- shift-left 4/log2-font-height
  {
    compare y, ymax
    break-if->=
    var x/edx: int <- copy xmin
    x <- shift-left 3/log2-font-width
    var xmax/ebx: int <- copy xmax
    xmax <- shift-left 3/log2-font-width
    {
      compare x, xmax
      break-if->=
      pixel-on-real-screen x, y, background-color
      x <- increment
      loop
    }
    y <- increment
    loop
  }
}

fn screen-grapheme-at _screen: (addr screen), x: int, y: int -> _/eax: grapheme {
  var screen/esi: (addr screen) <- copy _screen
  var idx/ecx: int <- screen-cell-index screen, x, y
  var result/eax: grapheme <- screen-grapheme-at-idx screen, idx
  return result
}

fn screen-grapheme-at-idx _screen: (addr screen), idx-on-stack: int -> _/eax: grapheme {
  var screen/esi: (addr screen) <- copy _screen
  var data-ah/eax: (addr handle array screen-cell) <- get screen, data
  var data/eax: (addr array screen-cell) <- lookup *data-ah
  var idx/ecx: int <- copy idx-on-stack
  var offset/ecx: (offset screen-cell) <- compute-offset data, idx
  var cell/eax: (addr screen-cell) <- index data, offset
  var src/eax: (addr grapheme) <- get cell, data
  return *src
}

fn screen-color-at _screen: (addr screen), x: int, y: int -> _/eax: int {
  var screen/esi: (addr screen) <- copy _screen
  var idx/ecx: int <- screen-cell-index screen, x, y
  var result/eax: int <- screen-color-at-idx screen, idx
  return result
}

fn screen-color-at-idx _screen: (addr screen), idx-on-stack: int -> _/eax: int {
  var screen/esi: (addr screen) <- copy _screen
  var data-ah/eax: (addr handle array screen-cell) <- get screen, data
  var data/eax: (addr array screen-cell) <- lookup *data-ah
  var idx/ecx: int <- copy idx-on-stack
  var offset/ecx: (offset screen-cell) <- compute-offset data, idx
  var cell/eax: (addr screen-cell) <- index data, offset
  var src/eax: (addr int) <- get cell, color
  var result/eax: int <- copy *src
  return result
}

fn screen-background-color-at _screen: (addr screen), x: int, y: int -> _/eax: int {
  var screen/esi: (addr screen) <- copy _screen
  var idx/ecx: int <- screen-cell-index screen, x, y
  var result/eax: int <- screen-background-color-at-idx screen, idx
  return result
}

fn screen-background-color-at-idx _screen: (addr screen), idx-on-stack: int -> _/eax: int {
  var screen/esi: (addr screen) <- copy _screen
  var data-ah/eax: (addr handle array screen-cell) <- get screen, data
  var data/eax: (addr array screen-cell) <- lookup *data-ah
  var idx/ecx: int <- copy idx-on-stack
  var offset/ecx: (offset screen-cell) <- compute-offset data, idx
  var cell/eax: (addr screen-cell) <- index data, offset
  var src/eax: (addr int) <- get cell, background-color
  var result/eax: int <- copy *src
  return result
}

fn pixel screen: (addr screen), x: int, y: int, color: int {
  {
    compare screen, 0
    break-if-!=
    pixel-on-real-screen x, y, color
    return
  }
  # fake screen
  var screen/esi: (addr screen) <- copy screen
  var pixels-ah/eax: (addr handle array byte) <- get screen, pixels
  var pixels/eax: (addr array byte) <- lookup *pixels-ah
  {
    compare pixels, 0
    break-if-!=
    abort "pixel graphics not enabled for this screen"
  }
  var idx/ecx: int <- pixel-index screen, x, y
  var dest/ecx: (addr byte) <- index pixels, idx
  var src/eax: byte <- copy-byte color
  copy-byte-to *dest, src
}

fn pixel-index _screen: (addr screen), x: int, y: int -> _/ecx: int {
  var screen/esi: (addr screen) <- copy _screen
  {
    compare x, 0
    break-if->=
    abort "screen-cell-index: negative x"
  }
  {
    var xmax-a/eax: (addr int) <- get screen, width
    var xmax/eax: int <- copy *xmax-a
    xmax <- shift-left 3/log2-font-width
    compare x, xmax
    break-if-<
    abort "screen-cell-index: x too high"
  }
  {
    compare y, 0
    break-if->=
    abort "screen-cell-index: negative y"
  }
  {
    var ymax-a/eax: (addr int) <- get screen, height
    var ymax/eax: int <- copy *ymax-a
    ymax <- shift-left 4/log2-font-height
    compare y, ymax
    break-if-<
    abort "screen-cell-index: y too high"
  }
  var width-addr/eax: (addr int) <- get screen, width
  var result/ecx: int <- copy y
  result <- multiply *width-addr
  result <- shift-left 3/log2-font-width
  result <- add x
  return result
}