about summary refs log tree commit diff stats
path: root/linux/203stack.subx
blob: 965f7301ba5b4f764f6218468c1f4b974bc41d03 (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
# A stack looks like this:
#   top: int
#   data: (array byte)  # prefixed by size as usual
#
# TODO: is it confusing that the push opcodes grow memory downward, but the
# push function grows stacks upward?

== code
#   instruction                     effective address                                                   register    displacement    immediate
# . op          subop               mod             rm32          base        index         scale       r32
# . 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes

clear-stack:  # s: (addr stack)
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    50/push-eax
    51/push-ecx
    # eax = s
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           0/r32/eax   8/disp8         .                 # copy *(ebp+8) to eax
    # var max/ecx: (addr byte) = &s->data[s->size]
    8b/copy                         1/mod/*+disp8   0/rm32/eax    .           .             .           1/r32/ecx   4/disp8         .                 # copy *(eax+4) to eax
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/eax  1/index/ecx   .           1/r32/ecx   8/disp8         .                 # copy eax+ecx+8 to ecx
    # s->top = 0
    c7          0/subop/copy        0/mod/direct    0/rm32/eax    .           .             .           .           .               0/imm32           # copy to *eax
    # var curr/eax: (addr byte) = s->data
    81          0/subop/add         3/mod/direct    0/rm32/eax    .           .             .           .           .               8/imm32           # add to eax
$clear-stack:loop:
    # if (curr >= max) break
    39/compare                      3/mod/direct    0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # compare eax with ecx
    73/jump-if-addr>=  $clear-stack:end/disp8
    # *curr = 0
    c6          0/subop/copy-byte   0/mod/direct    0/rm32/eax    .           .             .           .           .               0/imm8            # copy byte to *eax
    # ++curr
    40/increment-eax
    eb/jump $clear-stack:loop/disp8
$clear-stack:end:
    # . restore registers
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-clear-stack:
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # var stack/ecx = stack of size 8 with random data in it
    68/push 34/imm32
    68/push 35/imm32
    68/push 8/imm32/size
    68/push 14/imm32/top
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # clear(stack)
    # . . push args
    51/push-ecx
    # . . call
    e8/call  clear-stack/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
    # top should be 0
    58/pop-to-eax
    # . check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-clear-stack: top"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # size should remain 8
    58/pop-to-eax
    # . check-ints-equal(eax, 8, msg)
    # . . push args
    68/push  "F - test-clear-stack: size"/imm32
    68/push  8/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # first word is 0
    58/pop-to-eax
    # . check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-clear-stack: data[0..3]"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # second word is 0
    58/pop-to-eax
    # . check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-clear-stack: data[4..7]"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

# TODO: make this generic
push:  # s: (addr stack), n: int
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    50/push-eax
    51/push-ecx
    56/push-esi
    # esi = s
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
    # ecx = s->top
    8b/copy                         0/mod/indirect  6/rm32/esi    .           .             .           1/r32/ecx   .               .                 # copy *esi to ecx
    # if (s->top >= s->size) abort
    39/compare                      1/mod/*+disp8   6/rm32/esi    .           .             .           1/r32/ecx   4/disp8         .                 # compare *(esi+4) and ecx
    7e/jump-if-<=  $push:abort/disp8
    # s->data[s->top] = n
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           0/r32/eax   0xc/disp8       .                 # copy *(ebp+12) to eax
    89/copy                         1/mod/*+disp8   4/rm32/sib    6/base/esi  1/index/ecx   .           0/r32/eax   8/disp8         .                 # copy eax to *(esi+ecx+8)
    # s->top += 4
    81          0/subop/add         0/mod/direct    6/rm32/esi    .           .             .           .           .               4/imm32           # subtract from *esi
$push:end:
    # . restore registers
    5e/pop-to-esi
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

$push:abort:
    # print(stderr, "error: push: no space left")
    # . write-buffered(Stderr, "error: push: no space left")
    # . . push args
    68/push  "error: push: no space left"/imm32
    68/push  Stderr/imm32
    # . . call
    e8/call  write-buffered/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # . flush(Stderr)
    # . . push args
    68/push  Stderr/imm32
    # . . call
    e8/call  flush/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
    # . syscall(exit, 1)
    bb/copy-to-ebx  1/imm32
    e8/call  syscall_exit/disp32
    # never gets here

test-push:
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # var stack/ecx = empty stack of size 8
    68/push 0/imm32
    68/push 0/imm32
    68/push 8/imm32/size
    68/push 0/imm32/top
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # push(stack, 0x42)
    # . . push args
    68/push  0x42/imm32
    51/push-ecx
    # . . call
    e8/call  push/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # check top
    58/pop-to-eax
    # . check-ints-equal(eax, 4, msg)
    # . . push args
    68/push  "F - test-push: top"/imm32
    68/push  4/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # check size
    58/pop-to-eax
    # . check-ints-equal(eax, 8, msg)
    # . . push args
    68/push  "F - test-push: size"/imm32
    68/push  8/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # first word is 0x42
    58/pop-to-eax
    # . check-ints-equal(eax, 0x42, msg)
    # . . push args
    68/push  "F - test-push: data[0..3]"/imm32
    68/push  0x42/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # second word is 0
    58/pop-to-eax
    # . check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-push: data[4..7]"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

# TODO: make this generic
pop:  # s: (addr stack) -> n/eax: int
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    51/push-ecx
    56/push-esi
    # esi = s
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
    # if (s->top <= 0) abort
    81          7/subop/compare     0/mod/indirect  6/rm32/esi    .           .             .           .           .               0/imm32           # compare *esi
    7e/jump-if-<=  $pop:abort/disp8
    # s->top -= 4
    81          5/subop/subtract    0/mod/direct    6/rm32/esi    .           .             .           .           .               4/imm32           # subtract from *esi
    # eax = s->data[s->top]
    8b/copy                         0/mod/indirect  6/rm32/esi    .           .             .           1/r32/ecx   .               .                 # copy *esi to ecx
    8b/copy                         1/mod/*+disp8   4/rm32/sib    6/base/esi  1/index/ecx   .           0/r32/eax   8/disp8         .                 # copy *(esi+ecx+8) to eax
    # s->data[s->top] = 0
    c7          0/subop/copy        1/mod/*+disp8   4/rm32/sib    6/base/esi  1/index/ecx   .           0/r32/eax   8/disp8         0/imm32           # copy to *(esi+ecx+8)
$pop:end:
    # . restore registers
    5e/pop-to-esi
    59/pop-to-ecx
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

$pop:abort:
    # print(stderr, "error: pop: nothing left in stack")
    # . write-buffered(Stderr, "error: pop: nothing left in stack")
    # . . push args
    68/push  "error: pop: nothing left in stack"/imm32
    68/push  Stderr/imm32
    # . . call
    e8/call  write-buffered/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # . flush(Stderr)
    # . . push args
    68/push  Stderr/imm32
    # . . call
    e8/call  flush/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
    # . syscall(exit, 1)
    bb/copy-to-ebx  1/imm32
    e8/call  syscall_exit/disp32
    # never gets here

test-pop:
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # var stack/ecx = stack of size 8 containing just 0x42
    68/push 0/imm32
    68/push 0x42/imm32
    68/push 8/imm32/size
    68/push 4/imm32/top
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # eax = pop(stack)
    # . . push args
    51/push-ecx
    # . . call
    e8/call  pop/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
    # check-ints-equal(eax, 0x42, msg)
    # . . push args
    68/push  "F - test-pop: result"/imm32
    68/push  0x42/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # check top
    58/pop-to-eax
    # . check-ints-equal(eax, 0, msg)
    # . . push args
    68/push  "F - test-pop: top"/imm32
    68/push  0/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # check size
    58/pop-to-eax
    # . check-ints-equal(eax, 8, msg)
    # . . push args
    68/push  "F - test-pop: size"/imm32
    68/push  8/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

# TODO: make this generic
top:  # s: (addr stack) -> n/eax: int
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    51/push-ecx
    56/push-esi
    # esi = s
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
    # if (s->top <= 0) abort
    81          7/subop/compare     0/mod/indirect  6/rm32/esi    .           .             .           .           .               0/imm32           # compare *esi
    7e/jump-if-<=  $top:abort/disp8
    # n = s->data[s->top - 4]
    8b/copy                         0/mod/indirect  6/rm32/esi    .           .             .           1/r32/ecx   .               .                 # copy *esi to ecx
    81          5/subop/subtract    3/mod/direct    1/rm32/ecx    .           .             .           .           .               4/imm32           # subtract from ecx
    8b/copy                         1/mod/*+disp8   4/rm32/sib    6/base/esi  1/index/ecx   .           0/r32/eax   8/disp8         .                 # copy *(esi+ecx+8) to eax
$top:end:
    # . restore registers
    5e/pop-to-esi
    59/pop-to-ecx
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

$top:abort:
    # print(stderr, "error: top: nothing left in stack")
    # . write-buffered(Stderr, "error: top: nothing left in stack")
    # . . push args
    68/push  "error: top: nothing left in stack"/imm32
    68/push  Stderr/imm32
    # . . call
    e8/call  write-buffered/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    # . flush(Stderr)
    # . . push args
    68/push  Stderr/imm32
    # . . call
    e8/call  flush/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
    # . syscall(exit, 1)
    bb/copy-to-ebx  1/imm32
    e8/call  syscall_exit/disp32
    # never gets here

test-top:
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # var stack/ecx = stack of size 8 containing just 0x42
    68/push  0/imm32
    68/push  0x42/imm32
    68/push  8/imm32/size
    68/push  4/imm32/top
    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
    # eax = top(stack)
    # . . push args
    51/push-ecx
    # . . call
    e8/call  top/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
    # check-ints-equal(eax, 42, msg")
    # . . push args
    68/push  "F - test-top: result"/imm32
    68/push  0x42/imm32
    50/push-eax
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

# . . vim:nowrap:textwidth=0