about summary refs log tree commit diff stats
path: root/103glyph.subx
blob: 3fef28b456e01567fa33233c88bc34de456170b1 (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
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
# Use the built-in font to draw glyphs to screen.
#   https://en.wikipedia.org/wiki/Glyph#Typography
# Extremely hacky support for combining characters.
#   https://en.wikipedia.org/wiki/Code_point
#   https://en.wikipedia.org/wiki/Combining_character
# All we support is drawing combining characters atop the same screen cell as
# a single base code point. See the overlay? arguments below.
#
# We need to do this in machine code because Mu doesn't have global variables
# yet (for the start of the font).

== code

# The Mu computer's screen is 1024px wide and 768px tall.
# The Mu computer's font is 8px wide and 16px tall.
# Therefore 'x' here is in [0, 128), and 'y' is in [0, 48)
# Doesn't update the cursor; where the cursor should go after printing the
# current code-point is a higher-level concern.
draw-code-point-on-real-screen:  # c: code-point, x: int, y: int, color: int, background-color: int -> _/eax
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    #
    (draw-code-point-on-screen-buffer *Video-memory-addr *(ebp+8) *(ebp+0xc) *(ebp+0x10) *(ebp+0x14) *(ebp+0x18) 0 0x80 0x30)  # 0/no-overlay => eax
$draw-code-point-on-real-screen:end:
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

overlay-code-point-on-real-screen:  # c: code-point, x: int, y: int, color: int, background-color: int -> _/eax
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    #
    (draw-code-point-on-screen-buffer *Video-memory-addr *(ebp+8) *(ebp+0xc) *(ebp+0x10) *(ebp+0x14) *(ebp+0x18) 1 0x80 0x30)  # 1/overlay => eax
$overlay-code-point-on-real-screen:end:
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

draw-code-point-on-screen-array:  # screen-data: (addr array byte), c: code-point, x: int, y: int, color: int, background-color: int, screen-width: int, screen-height: int -> _/eax: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    51/push-ecx
    52/push-edx
    # if screen-width*screen-height > len(screen-data) abort
    {
      # ecx = len(screen-data)
      8b/-> *(ebp+8) 1/r32/ecx
      8b/-> *ecx 1/r32/ecx
      # eax = screen-width*screen-height
      ba/copy-to-edx 0/imm32
      8b/-> *(ebp+0x20) 0/r32/eax
      f7 4/subop/multiply-into-eax *(ebp+0x24)
      81 7/subop/compare %edx 0/imm32
      0f 85/jump-if-!= $draw-code-point-on-screen-array:overflow/disp32
      # if (eax > ecx) abort
      39/compare %eax 1/r32/ecx
      0f 8f/jump-if-> $draw-code-point-on-screen-array:abort/disp32
    }
    # eax = screen-data+4   (skip length)
    8b/-> *(ebp+8) 0/r32/eax
    05/add-to-eax 4/imm32
    #
    (draw-code-point-on-screen-buffer %eax *(ebp+0xc) *(ebp+0x10) *(ebp+0x14) *(ebp+0x18) *(ebp+0x1c) *(ebp+0x20) *(ebp+0x24))  # => eax
$draw-code-point-on-screen-array:end:
    # . restore registers
    5a/pop-to-edx
    59/pop-to-ecx
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

$draw-code-point-on-screen-array:overflow:
    (abort "draw-code-point-on-screen-array: screen dimensions too large")

$draw-code-point-on-screen-array:abort:
    (abort "draw-code-point-on-screen-array: coordinates are off the screen. Are the screen dimensions correct?")

# 'buffer' here is not a valid Mu type: a naked address without a length.
# returns number of 8x16 units printed to screen (1 or 2).
draw-code-point-on-screen-buffer:  # buffer: (addr byte), c: code-point, x: int, y: int, color: int, background-color: int, overlay?: boolean, screen-width: int, screen-height: int -> _/eax: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    56/push-esi
    # switch screen-width and screen-height from code-point to pixel units
    c1 4/subop/shift-left *(ebp+24) 3/imm8/log2-font-width
    c1 4/subop/shift-left *(ebp+28) 4/imm8/log2-font-height
    # esi = c
    8b/-> *(ebp+0xc) 6/r32/esi
    # if (c >= 4352) return  # unicode planes supported: latin, greek, cyrillic, armenian, hebrew, arabic, syriac, thaana, n'ko, indian (iscii), sinhala, thai, lao, tibetan, myanmar, georgian
                             # next few to support: CJK, ethiopic, cherokee, ...
    81 7/subop/compare %esi 0x1100/imm32/4352
    0f 8d/jump-if->= $draw-code-point-on-screen-buffer:end/disp32
    # var letter-bitmap/esi = font[c]
    69/multiply %esi 0x22/imm32/glyph-size 6/r32/esi
    81 0/subop/add %esi 0x0010000c/imm32/Font  # see boot.subx
    # dispatch based on letter-bitmap->size
    b8/copy-to-eax 0/imm32
    8a/byte-> *esi 0/r32/AL
    46/increment-esi  # skip size
    46/increment-esi  # skip size
    3d/compare-eax-and 8/imm32
    {
      75/jump-if-!= break/disp8
      (draw-narrow-code-point-on-screen-buffer *(ebp+8) %esi *(ebp+0x10) *(ebp+0x14) *(ebp+0x18) *(ebp+0x1c) *(ebp+0x20) *(ebp+0x24) *(ebp+0x28))
      b8/copy-to-eax 1/imm32
      eb/jump $draw-code-point-on-screen-buffer:end/disp8
    }
    (draw-wide-code-point-on-screen-buffer *(ebp+8) %esi *(ebp+0x10) *(ebp+0x14) *(ebp+0x18) *(ebp+0x1c) *(ebp+0x20) *(ebp+0x24) *(ebp+0x28))
    b8/copy-to-eax 2/imm32
$draw-code-point-on-screen-buffer:end:
    # . restore registers
    5e/pop-to-esi
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

wide-code-point?:  # c: code-point -> _/eax: boolean
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # eax = c
    8b/-> *(ebp+8) 0/r32/eax
    # if (c >= 4352) return false
    3d/compare-eax-and 0x1100/imm32
    0f 8d/jump-if->= $wide-code-point?:return-false/disp32
    # var letter-bitmap/eax = font[c]
    69/multiply %eax 0x22/imm32/glyph-size 0/r32/eax
    05/add-to-eax 0x0010000c/imm32/Font  # see boot.subx
    # dispatch based on letter-bitmap->size
    8a/byte-> *eax 0/r32/AL
    25/and-eax-with  0xff/imm32
    3d/compare-eax-and 8/imm32
    0f 95/set-if-!= %eax
$wide-code-point?:end:
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

$wide-code-point?:return-false:
    b8/copy-to-eax 0/imm32/false
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

combining-code-point?:  # c: code-point -> _/eax: boolean
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # eax = c
    8b/-> *(ebp+8) 0/r32/eax
    # if (c >= 4352) return false
    3d/compare-eax-and 0x1100/imm32
    0f 8d/jump-if->= $combining-code-point?:return-false/disp32
    # var letter-bitmap/eax = font[c]
    69/multiply %eax 0x22/imm32/glyph-size 0/r32/eax
    05/add-to-eax 0x0010000c/imm32/Font  # see boot.subx
    # dispatch based on letter-bitmap->is-combine?
    8a/byte-> *(eax+1) 0/r32/AL
    25/and-eax-with  0xff/imm32
$combining-code-point?:end:
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

$combining-code-point?:return-false:
    b8/copy-to-eax 0/imm32/false
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

# buffer: naked address to raw screen RAM without a length
# letter-bitmap: naked address to 8-pixel wide font glyph
draw-narrow-code-point-on-screen-buffer:  # buffer: (addr byte), letter-bitmap: (addr byte), x: int, y: int, color: int, background-color: int, overlay?: boolean, screen-width: int, screen-height: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    52/push-edx
    53/push-ebx
    56/push-esi
    57/push-edi
    # esi = letter-bitmap
    8b/-> *(ebp+0xc) 6/r32/esi
    # var ycurr/edx: int = y*16
    8b/-> *(ebp+0x14) 2/r32/edx
    c1 4/subop/shift-left %edx 4/imm8
    # var ymax/edi: int = ycurr + 16
    8b/-> *(ebp+0x14) 7/r32/edi
    c1 4/subop/shift-left %edi 4/imm8
    81 0/subop/add %edi 0x10/imm32
    {
      # if (ycurr >= ymax) break
      39/compare %edx 7/r32/edi
      0f 8d/jump-if->= break/disp32
      # var row-bitmap/ebx: byte = *letter-bitmap
      bb/copy-to-ebx 0/imm32
      8a/byte-> *esi 3/r32/BL
      (draw-run-of-pixels-from-glyph *(ebp+8) %ebx *(ebp+0x10) %edx *(ebp+0x18) *(ebp+0x1c) *(ebp+0x20) *(ebp+0x24) *(ebp+0x28))
      # ++y
      42/increment-edx
      # next bitmap row
      46/increment-esi
      #
      e9/jump loop/disp32
    }
$draw-narrow-code-point-on-screen-buffer:end:
    # . restore registers
    5f/pop-to-edi
    5e/pop-to-esi
    5b/pop-to-ebx
    5a/pop-to-edx
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

# buffer: naked address to raw screen RAM without a length
# letter-bitmap: naked address to 16-pixel wide font glyph
draw-wide-code-point-on-screen-buffer:  # buffer: (addr byte), letter-bitmap: (addr byte), x: int, y: int, color: int, background-color: int, overlay?: boolean, screen-width: int, screen-height: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    51/push-ecx
    52/push-edx
    53/push-ebx
    56/push-esi
    57/push-edi
    # esi = letter-bitmap
    8b/-> *(ebp+0xc) 6/r32/esi
    #
    bb/copy-to-ebx 0/imm32
    # var ycurr/edx: int = y*16
    8b/-> *(ebp+0x14) 2/r32/edx
    c1 4/subop/shift-left %edx 4/imm8
    # var ymax/edi: int = ycurr + 16
    8b/-> *(ebp+0x14) 7/r32/edi
    c1 4/subop/shift-left %edi 4/imm8
    81 0/subop/add %edi 0x10/imm32
    {
      # if (ycurr >= ymax) break
      39/compare %edx 7/r32/edi
      0f 8d/jump-if->= break/disp32
      # var row-bitmap/ebx: byte = *letter-bitmap
      8a/byte-> *esi 3/r32/BL
      # ecx = x
      8b/-> *(ebp+0x10) 1/r32/ecx
      # first half-row
      (draw-run-of-pixels-from-glyph *(ebp+8) %ebx %ecx %edx *(ebp+0x18) *(ebp+0x1c) *(ebp+0x20) *(ebp+0x24) *(ebp+0x28))
      # second half-row
      8a/byte-> *(esi+1) 3/r32/BL
      41/increment-ecx
      (draw-run-of-pixels-from-glyph *(ebp+8) %ebx %ecx %edx *(ebp+0x18) *(ebp+0x1c) *(ebp+0x20) *(ebp+0x24) *(ebp+0x28))
      # ++y
      42/increment-edx
      # next bitmap row
      81 0/subop/add %esi 2/imm32
      #
      e9/jump loop/disp32
    }
$draw-wide-code-point-on-screen-buffer:end:
    # . restore registers
    5f/pop-to-edi
    5e/pop-to-esi
    5b/pop-to-ebx
    5a/pop-to-edx
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

# draw 8 pixels from a single glyph byte in a font bitmap
draw-run-of-pixels-from-glyph:  # buffer: (addr byte), glyph-byte: byte, x: int, y: int, color: int, background-color: int, overlay?: boolean, screen-width: int, screen-height: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    51/push-ecx
    56/push-esi
    # esi = glyph-byte
    8b/-> *(ebp+0xc) 6/r32/esi
    # var xcurr/eax: int = x*8 + 7
    8b/-> *(ebp+0x10) 0/r32/eax
    c1 4/subop/shift-left %eax 3/imm8
    05/add-to-eax 7/imm32
    # var xmin/ecx: int = x*8
    8b/-> *(ebp+0x10) 1/r32/ecx
    c1 4/subop/shift-left %ecx 3/imm8
    {
      # if (xcurr < xmin) break
      39/compare %eax 1/r32/ecx
      7c/jump-if-< break/disp8
      # shift LSB from row-bitmap into carry flag (CF)
      c1 5/subop/shift-right-logical %esi 1/imm8
      # if LSB, draw a pixel in the given color
      {
        73/jump-if-not-CF break/disp8
        (pixel-on-screen-buffer *(ebp+8) %eax *(ebp+0x14) *(ebp+0x18) *(ebp+0x24) *(ebp+0x28))
        eb/jump $draw-code-point-on-screen-buffer:continue/disp8
      }
      # otherwise use the background color (except when overlay?)
      {
        81 7/subop/compare *(ebp+0x20) 0/imm32/false
        75/jump-if-!= break/disp8
        (pixel-on-screen-buffer *(ebp+8) %eax *(ebp+0x14) *(ebp+0x1c) *(ebp+0x24) *(ebp+0x28))
      }
$draw-code-point-on-screen-buffer:continue:
      # --x
      48/decrement-eax
      #
      eb/jump loop/disp8
    }
$draw-run-of-pixels-from-glyph:end:
    # . restore registers
    5e/pop-to-esi
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

cursor-position-on-real-screen:  # -> _/eax: int, _/ecx: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # TODO: support fake screen; we currently assume 'screen' is always 0 (real)
    8b/-> *Real-screen-cursor-x 0/r32/eax
    8b/-> *Real-screen-cursor-y 1/r32/ecx
$cursor-position-on-real-screen:end:
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

set-cursor-position-on-real-screen:  # x: int, y: int
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    #
    8b/-> *(ebp+8) 0/r32/eax
    89/<- *Real-screen-cursor-x 0/r32/eax
    8b/-> *(ebp+0xc) 0/r32/eax
    89/<- *Real-screen-cursor-y 0/r32/eax
$set-cursor-position-on-real-screen:end:
    # . restore registers
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

# Not a real `show-cursor` primitive:
#   - does not clear previous location cursor was shown at.
#   - does not preserve what was at the cursor. Caller is responsible for
#     tracking what was on the screen at this position before and passing it
#     in again.
#   - does not stop showing the cursor at this location when the cursor moves
draw-cursor-on-real-screen:  # c: code-point
    # . prologue
    55/push-ebp
    89/<- %ebp 4/r32/esp
    # . save registers
    50/push-eax
    51/push-ecx
    #
    (cursor-position-on-real-screen)  # => eax, ecx
    (draw-code-point-on-real-screen *(ebp+8) %eax %ecx 0 7)  # => eax
$draw-cursor-on-real-screen:end:
    # . restore registers
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/<- %esp 5/r32/ebp
    5d/pop-to-ebp
    c3/return

== data

# The cursor is where certain Mu functions (usually of the form
# 'draw*cursor*') print to by default.
#
# We don't bother displaying the cursor when drawing. It only becomes visible
# on draw-cursor, which is quite rickety (see above)
#
# It's up to applications to manage cursor display:
#   - clean up where it used to be
#   - display the cursor before waiting for a key
#   - ensure its location appropriately suggests the effect keystrokes will have
#   - ensure its contents (and colors) appropriately reflect the state of the
#     screen
#
# There's no blinking, etc. We aren't using any hardware-supported text mode
# here.
Real-screen-cursor-x:
  0/imm32
Real-screen-cursor-y:
  0/imm32