1 # Port of https://github.com/akkartik/crenshaw/blob/master/tutor2.1.pas
  2 # which corresponds to the section "single digits" in https://compilers.iecc.com/crenshaw/tutor2.txt
  3 # except that we support hex numbers of multiple digits.
  4 #
  5 # To run:
  6 #   $ ./subx translate 0*.subx apps/crenshaw2-1b.subx -o apps/crenshaw2-1b
  7 #   $ echo '1a'  |./subx run apps/crenshaw2-1b
  8 # Expected output:
  9 #   # syscall(exit, 1a)
 10 #   bb/copy-to-EBX  3/imm32
 11 #   b8/copy-to-EAX  1/imm32/exit
 12 #   cd/syscall  0x80/imm8
 13 #
 14 # To run the generated output:
 15 #   $ echo '1a'  |./subx run apps/crenshaw2-1b > z1.subx
 16 #   $ ./subx translate z1.subx -o z1
 17 #   $ ./subx run z1
 18 #   $ echo $?
 19 #   26  # 0x1a in decimal
 20 #
 21 # Stdin must contain just a single hex digit. Other input will print an error:
 22 #   $ echo 'xyz'  |./subx run apps/crenshaw2-1b
 23 #   Error: integer expected
 24 #
 25 # Names in this file sometimes follow Crenshaw's original rather than my usual
 26 # naming conventions.
 27 
 28 == code
 29 #   instruction                     effective address                                                   register    displacement    immediate
 30 # . op          subop               mod             rm32          base        index         scale       r32
 31 # . 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
 32 
 33 Entry:  # run tests if necessary, call 'compile' if not
 34     # initialize heap
 35     # . Heap = new-segment(64KB)
 36     # . . push args
 37     68/push  Heap/imm32
 38     68/push  0x10000/imm32/64KB
 39     # . . call
 40     e8/call  new-segment/disp32
 41     # . . discard args
 42     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
 43 
 44     # . prolog
 45     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
 46     # - if argc > 1 and argv[1] == "test", then return run_tests()
 47     # . argc > 1
 48     81          7/subop/compare     1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0/disp8         1/imm32           # compare *EBP
 49     7e/jump-if-lesser-or-equal  $run-main/disp8
 50     # . argv[1] == "test"
 51     # . . push args
 52     68/push  "test"/imm32
 53     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
 54     # . . call
 55     e8/call  kernel-string-equal?/disp32
 56     # . . discard args
 57     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
 58     # . check result
 59     3d/compare-EAX-and  1/imm32
 60     75/jump-if-not-equal  $run-main/disp8
 61     # . run-tests()
 62     e8/call  run-tests/disp32
 63     8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           3/r32/EBX   Num-test-failures/disp32          # copy *Num-test-failures to EBX
 64     eb/jump  $main:end/disp8
 65 $run-main:
 66     # - otherwise read a program from stdin and emit its translation to stdout
 67     # var ed/EAX : exit-descriptor
 68     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
 69     89/copy                         3/mod/direct    0/rm32/EAX    .           .             .           4/r32/ESP   .               .                 # copy ESP to EAX
 70     # configure ed to really exit()
 71     # . ed->target = 0
 72     c7          0/subop/copy        0/mod/direct    0/rm32/EAX    .           .             .           .           .               0/imm32           # copy to *EAX
 73     # return compile(Stdin, 1/stdout, 2/stderr, ed)
 74     # . . push args
 75     50/push-EAX/ed
 76     68/push  2/imm32/stderr
 77     68/push  1/imm32/stdout
 78     68/push  Stdin/imm32
 79     # . . call
 80     e8/call  compile/disp32
 81     # . . discard args
 82     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
 83     # . syscall(exit, 0)
 84     bb/copy-to-EBX  0/imm32
 85 $main:end:
 86     b8/copy-to-EAX  1/imm32/exit
 87     cd/syscall  0x80/imm8
 88 
 89 # the main entry point
 90 compile:  # in : (address buffered-file), out : fd or (address stream), err : fd or (address stream), ed : (address exit-descriptor) -> <void>
 91     # . prolog
 92     55/push-EBP
 93     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
 94     # . save registers
 95     50/push-EAX
 96     51/push-ECX
 97     # prime the pump
 98     # . Look = get-char(in)
 99     # . . push args
100     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8      .                    # push *(EBP+8)
101     # . . call
102     e8/call  get-char/disp32
103     # . . discard args
104     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
105     # var num/ECX : (address stream) on the stack
106     # Numbers can be 32 bits or 8 hex bytes long. One of them will be in 'Look', so we need space for 7 bytes.
107     # Sizing the stream just right buys us overflow-handling for free inside 'get-num'.
108     # Add 12 bytes for 'read', 'write' and 'length' fields, for a total of 19 bytes, or 0x13 in hex.
109     # The stack pointer is no longer aligned, so dump_stack() can be misleading past this point.
110     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x13/imm32        # subtract from ESP
111     89/copy                         3/mod/direct    1/rm32/ECX    .           .             .           4/r32/ESP   .               .                 # copy ESP to ECX
112     # initialize the stream
113     # . num->length = 7
114     c7          0/subop/copy        1/mod/*+disp8   1/rm32/ECX    .           .             .           .           8/disp8         7/imm32           # copy to *(ECX+8)
115     # . clear-stream(num)
116     # . . push args
117     51/push-ECX
118     # . . call
119     e8/call  clear-stream/disp32
120     # . . discard args
121     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
122     # read a digit from 'in' into 'num'
123     # . get-num(in, num, err, ed)
124     # . . push args
125     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x14/disp8      .                 # push *(EBP+20)
126     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x10/disp8      .                 # push *(EBP+16)
127     51/push-ECX/num
128     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8      .                    # push *(EBP+8)
129     # . . call
130     e8/call  get-num/disp32
131     # . . discard args
132     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
133     # render 'num' into the following template on 'out':
134     #   bb/copy-to-EBX  _num_
135     #   b8/copy-to-EAX  1/imm32/exit
136     #   cd/syscall  0x80/imm8
137     #
138     # . write(out, "bb/copy-to-EBX  ")
139     # . . push args
140     68/push  "bb/copy-to-EBX  "/imm32
141     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
142     # . . call
143     e8/call  write/disp32
144     # . . discard args
145     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
146     # . write-stream(out, num)
147     # . . push args
148     51/push-ECX/num
149     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
150     # . . call
151     e8/call  write-stream/disp32
152     # . . discard args
153     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
154     # . write(out, Newline)
155     # . . push args
156     68/push  Newline/imm32
157     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
158     # . . call
159     e8/call  write/disp32
160     # . . discard args
161     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
162     # . write(out, "b8/copy-to-EAX  1/imm32/exit\n")
163     # . . push args
164     68/push  "b8/copy-to-EAX  1/imm32/exit\n"/imm32
165     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
166     # . . call
167     e8/call  write/disp32
168     # . . discard args
169     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
170     # . write(out, "cd/syscall  0x80/imm8\n")
171     # . . push args
172     68/push  "cd/syscall  0x80/imm8\n"/imm32
173     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
174     # . . call
175     e8/call  write/disp32
176     # . . discard args
177     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
178 $compile:end:
179     # . restore registers
180     59/pop-to-ECX
181     58/pop-to-EAX
182     # . epilog
183     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
184     5d/pop-to-EBP
185     c3/return
186 
187 # Read a sequence of digits into 'out'. Abort if there are none, or if there is
188 # no space in 'out'.
189 # Input comes from the global variable 'Look' (first byte) and the argument
190 # 'in' (rest). We leave the next byte from 'in' into 'Look' on exit.
191 get-num:  # in : (address buffered-file), out : (address stream), err : fd or (address stream), ed : (address exit-descriptor) -> <void>
192     # pseudocode:
193     #   if (!is-digit?(Look)) expected(ed, err, "integer")
194     #   do
195     #     if out->write >= out->length
196     #       write(err, "Error: too many digits in number\n")
197     #       stop(ed, 1)
198     #     out->data[out->write] = LSB(Look)
199     #     ++out->write
200     #     Look = get-char(in)
201     #   while is-digit?(Look)
202     # This is complicated because I don't want to hard-code the error strategy in
203     # a general helper like write-byte-buffered. Maybe I should just create a
204     # local helper.
205     #
206     # within the loop we'll try to keep things in registers:
207     #   in: ESI
208     #   out: EDI
209     #   out->write: ECX (cached copy; need to keep in sync)
210     #   out->length: EDX
211     #   temporaries: EAX, EBX
212     # We can't allocate Look to a register because it gets written implicitly in
213     # get-char in each iteration of the loop. (Thereby demonstrating that it's
214     # not the right interface for us. But we'll keep it just to follow Crenshaw.)
215     #
216     # . prolog
217     55/push-EBP
218     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
219     # - if (is-digit?(Look)) expected(ed, err, "integer")
220     # . EAX = is-digit?(Look)
221     # . . push args
222     ff          6/subop/push        0/mod/indirect  5/rm32/.disp32            .             .           .           Look/disp32     .                 # push *Look
223     # . . call
224     e8/call  is-digit?/disp32
225     # . . discard args
226     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
227     # . if (EAX == 0)
228     3d/compare-EAX-and  0/imm32
229     75/jump-if-not-equal  $get-num:main/disp8
230     # . expected(ed, err, "integer")
231     # . . push args
232     68/push  "integer"/imm32
233     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x10/disp8      .                 # push *(EBP+16)
234     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x14/disp8      .                 # push *(EBP+20)
235     # . . call
236     e8/call  expected/disp32  # never returns
237     # . . discard args
238     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
239 $get-num:main:
240     # - otherwise read a digit
241     # . save registers
242     50/push-EAX
243     51/push-ECX
244     52/push-EDX
245     53/push-EBX
246     56/push-ESI
247     57/push-EDI
248     # read necessary variables to registers
249     # ESI = in
250     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           6/r32/ESI   8/disp8         .                 # copy *(EBP+8) to ESI
251     # EDI = out
252     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           7/r32/EDI   0xc/disp8       .                 # copy *(EBP+12) to EDI
253     # ECX = out->write
254     8b/copy                         0/mod/indirect  7/rm32/EDI    .           .             .           1/r32/ECX   .               .                 # copy *EDI to ECX
255     # EDX = out->length
256     8b/copy                         1/mod/*+disp8   7/rm32/EDI    .           .             .           2/r32/EDX   8/disp8         .                 # copy *(EDI+8) to EDX
257 $get-num:loop:
258     # if (out->write >= out->length) error
259     39/compare                      3/mod/direct    2/rm32/EDX    .           .             .           1/r32/ECX   .               .                 # compare EDX with ECX
260     7d/jump-if-lesser  $get-num:loop-stage2/disp8
261     # . error(ed, err, msg)  # TODO: show full number
262     # . . push args
263     68/push  "get-num: too many digits in number"/imm32
264     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x10/disp8      .                 # push *(EBP+16)
265     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x14/disp8      .                 # push *(EBP+20)
266     # . . call
267     e8/call  error/disp32  # never returns
268     # . . discard args
269     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
270 $get-num:loop-stage2:
271     # out->data[out->write] = LSB(Look)
272     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/EDI  1/index/ECX   .           3/r32/EBX   0xc/disp8       .                 # copy EDI+ECX+12 to EBX
273     8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           0/r32/EAX   Look/disp32     .                 # copy *Look to EAX
274     88/copy-byte                    0/mod/indirect  3/rm32/EBX    .           .             .           0/r32/AL    .               .                 # copy byte at AL to *EBX
275     # ++out->write
276     41/increment-ECX
277     # Look = get-char(in)
278     # . . push args
279     56/push-ESI
280     # . . call
281     e8/call  get-char/disp32
282     # . . discard args
283     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
284     # if (is-digit?(Look)) loop
285     # . EAX = is-digit?(Look)
286     # . . push args
287     ff          6/subop/push        0/mod/indirect  5/rm32/.disp32            .             .           .           Look/disp32     .                 # push *Look
288     # . . call
289     e8/call  is-digit?/disp32
290     # . . discard args
291     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
292     # . if (EAX != 0) loop
293     3d/compare-EAX-and  0/imm32
294     0f 85/jump-if-not-equal  $get-num:loop/disp32
295 $get-num:loop-end:
296     # persist necessary variables from registers
297     89/copy                         0/mod/indirect  7/rm32/EDI    .           .             .           1/r32/ECX   .               .                 # copy ECX to *EDI
298 $get-num:end:
299     # . restore registers
300     5f/pop-to-EDI
301     5e/pop-to-ESI
302     5b/pop-to-EBX
303     5a/pop-to-EDX
304     59/pop-to-ECX
305     58/pop-to-EAX
306     # . epilog
307     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
308     5d/pop-to-EBP
309     c3/return
310 
311 test-get-num-reads-single-digit:
312     # - check that get-num returns first character if it's a digit
313     # This test uses exit-descriptors. Use EBP for setting up local variables.
314     55/push-EBP
315     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
316     # clear all streams
317     # . clear-stream(_test-stream)
318     # . . push args
319     68/push  _test-stream/imm32
320     # . . call
321     e8/call  clear-stream/disp32
322     # . . discard args
323     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
324     # . clear-stream(_test-buffered-file+4)
325     # . . push args
326     b8/copy-to-EAX  _test-buffered-file/imm32
327     05/add-to-EAX  4/imm32
328     50/push-EAX
329     # . . call
330     e8/call  clear-stream/disp32
331     # . . discard args
332     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
333     # . clear-stream(_test-output-stream)
334     # . . push args
335     68/push  _test-output-stream/imm32
336     # . . call
337     e8/call  clear-stream/disp32
338     # . . discard args
339     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
340     # . clear-stream(_test-error-stream)
341     # . . push args
342     68/push  _test-error-stream/imm32
343     # . . call
344     e8/call  clear-stream/disp32
345     # . . discard args
346     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
347     # initialize 'in'
348     # . write(_test-stream, "3")
349     # . . push args
350     68/push  "3"/imm32
351     68/push  _test-stream/imm32
352     # . . call
353     e8/call  write/disp32
354     # . . discard args
355     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
356     # initialize exit-descriptor 'ed' for the call to 'get-num' below
357     # . var ed/EAX : exit-descriptor
358     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
359     89/copy                         3/mod/direct    0/rm32/EAX    .           .             .           4/r32/ESP   .               .                 # copy ESP to EAX
360     # . tailor-exit-descriptor(ed, 16)
361     # . . push args
362     68/push  0x10/imm32/nbytes-of-args-for-get-num
363     50/push-EAX/ed
364     # . . call
365     e8/call  tailor-exit-descriptor/disp32
366     # . . discard args
367     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
368     # prime the pump
369     # . get-char(_test-buffered-file)
370     # . . push args
371     68/push  _test-buffered-file/imm32
372     # . . call
373     e8/call  get-char/disp32
374     # . . discard args
375     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
376     # get-num(in, out, err, ed)
377     # . . push args
378     50/push-EAX/ed
379     68/push  _test-error-stream/imm32
380     68/push  _test-output-stream/imm32
381     68/push  _test-buffered-file/imm32
382     # . . call
383     e8/call  get-num/disp32
384     # registers except ESP may be clobbered at this point
385     # . . discard args
386     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
387     # check-ints-equal(*_test-output-stream->data, '3', msg)
388     # . . push args
389     68/push  "F - test-get-num-reads-single-digit"/imm32
390     68/push  0x33/imm32
391     b8/copy-to-EAX  _test-output-stream/imm32
392     ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX    .           .             .           .           0xc/disp8       .                 # push *(EAX+12)
393     # . . call
394     e8/call  check-ints-equal/disp32
395     # . . discard args
396     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
397     # . reclaim locals
398     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
399     5d/pop-to-EBP
400     c3/return
401 
402 test-get-num-aborts-on-non-digit-in-Look:
403     # - check that get-num returns first character if it's a digit
404     # This test uses exit-descriptors. Use EBP for setting up local variables.
405     55/push-EBP
406     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
407     # clear all streams
408     # . clear-stream(_test-stream)
409     # . . push args
410     68/push  _test-stream/imm32
411     # . . call
412     e8/call  clear-stream/disp32
413     # . . discard args
414     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
415     # . clear-stream(_test-buffered-file+4)
416     # . . push args
417     b8/copy-to-EAX  _test-buffered-file/imm32
418     05/add-to-EAX  4/imm32
419     50/push-EAX
420     # . . call
421     e8/call  clear-stream/disp32
422     # . . discard args
423     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
424     # . clear-stream(_test-output-stream)
425     # . . push args
426     68/push  _test-output-stream/imm32
427     # . . call
428     e8/call  clear-stream/disp32
429     # . . discard args
430     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
431     # . clear-stream(_test-error-stream)
432     # . . push args
433     68/push  _test-error-stream/imm32
434     # . . call
435     e8/call  clear-stream/disp32
436     # . . discard args
437     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
438     # initialize 'in'
439     # . write(_test-stream, "3")
440     # . . push args
441     68/push  "3"/imm32
442     68/push  _test-stream/imm32
443     # . . call
444     e8/call  write/disp32
445     # . . discard args
446     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
447     # initialize exit-descriptor 'ed' for the call to 'get-num' below
448     # . var ed/EAX : (address exit-descriptor)
449     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
450     89/copy                         3/mod/direct    0/rm32/EAX    .           .             .           4/r32/ESP   .               .                 # copy ESP to EAX
451     # . tailor-exit-descriptor(ed, 16)
452     # . . push args
453     68/push  0x10/imm32/nbytes-of-args-for-get-num
454     50/push-EAX/ed
455     # . . call
456     e8/call  tailor-exit-descriptor/disp32
457     # . . discard args
458     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
459     # *don't* prime the pump
460     # get-num(in, out, err, ed)
461     # . . push args
462     50/push-EAX/ed
463     68/push  _test-error-stream/imm32
464     68/push  _test-output-stream/imm32
465     68/push  _test-buffered-file/imm32
466     # . . call
467     e8/call  get-num/disp32
468     # registers except ESP may be clobbered at this point
469     # . . discard args
470     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
471     # check that get-num tried to call exit(1)
472     # . check-ints-equal(ed->value, 2, msg)  # i.e. stop was called with value 1
473     # . . push args
474     68/push  "F - test-get-num-aborts-on-non-digit-in-Look"/imm32
475     68/push  2/imm32
476     # . . push ed->value
477     ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX    .           .             .           .           4/disp8         .                 # push *(EAX+4)
478     # . . call
479     e8/call  check-ints-equal/disp32
480     # . . discard args
481     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
482     # . reclaim locals
483     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
484     5d/pop-to-EBP
485     c3/return
486 
487 test-get-num-reads-multiple-digits:
488     # - check that get-num returns all initial digits until it encounters a non-digit
489     # This test uses exit-descriptors. Use EBP for setting up local variables.
490     55/push-EBP
491     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
492     # clear all streams
493     # . clear-stream(_test-stream)
494     # . . push args
495     68/push  _test-stream/imm32
496     # . . call
497     e8/call  clear-stream/disp32
498     # . . discard args
499     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
500     # . clear-stream(_test-buffered-file+4)
501     # . . push args
502     b8/copy-to-EAX  _test-buffered-file/imm32
503     05/add-to-EAX  4/imm32
504     50/push-EAX
505     # . . call
506     e8/call  clear-stream/disp32
507     # . . discard args
508     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
509     # . clear-stream(_test-output-stream)
510     # . . push args
511     68/push  _test-output-stream/imm32
512     # . . call
513     e8/call  clear-stream/disp32
514     # . . discard args
515     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
516     # . clear-stream(_test-error-stream)
517     # . . push args
518     68/push  _test-error-stream/imm32
519     # . . call
520     e8/call  clear-stream/disp32
521     # . . discard args
522     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
523     # initialize 'in'
524     # . write(_test-stream, "3456 x")
525     # . . push args
526     68/push  "3456"/imm32
527     68/push  _test-stream/imm32
528     # . . call
529     e8/call  write/disp32
530     # . . discard args
531     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
532     # initialize exit-descriptor 'ed' for the call to 'get-num' below
533     # . var ed/EAX : (address exit-descriptor)
534     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
535     89/copy                         3/mod/direct    0/rm32/EAX    .           .             .           4/r32/ESP   .               .                 # copy ESP to EAX
536     # . tailor-exit-descriptor(ed, 16)
537     # . . push args
538     68/push  0x10/imm32/nbytes-of-args-for-get-num
539     50/push-EAX/ed
540     # . . call
541     e8/call  tailor-exit-descriptor/disp32
542     # . . discard args
543     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
544     # prime the pump
545     # . get-char(_test-buffered-file)
546     # . . push args
547     68/push  _test-buffered-file/imm32
548     # . . call
549     e8/call  get-char/disp32
550     # . . discard args
551     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
552     # get-num(in, out, err, ed)
553     # . . push args
554     50/push-EAX/ed
555     68/push  _test-error-stream/imm32
556     68/push  _test-output-stream/imm32
557     68/push  _test-buffered-file/imm32
558     # . . call
559     e8/call  get-num/disp32
560     # registers except ESP may be clobbered at this point
561     # . . discard args
562     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
563     # check-ints-equal(*_test-output-stream->data, '3456', msg)
564     # . . push args
565     68/push  "F - test-get-num-reads-multiple-digits"/imm32
566     68/push  0x36353433/imm32
567     b8/copy-to-EAX  _test-output-stream/imm32
568     ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX    .           .             .           .           0xc/disp8       .                 # push *(EAX+12)
569     # . . call
570     e8/call  check-ints-equal/disp32
571     # . . discard args
572     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
573     # . reclaim locals
574     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
575     5d/pop-to-EBP
576     c3/return
577 
578 test-get-num-reads-multiple-digits-followed-by-nondigit:
579     # - check that get-num returns all initial digits until it encounters a non-digit
580     # This test uses exit-descriptors. Use EBP for setting up local variables.
581     55/push-EBP
582     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
583     # clear all streams
584     # . clear-stream(_test-stream)
585     # . . push args
586     68/push  _test-stream/imm32
587     # . . call
588     e8/call  clear-stream/disp32
589     # . . discard args
590     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
591     # . clear-stream(_test-buffered-file+4)
592     # . . push args
593     b8/copy-to-EAX  _test-buffered-file/imm32
594     05/add-to-EAX  4/imm32
595     50/push-EAX
596     # . . call
597     e8/call  clear-stream/disp32
598     # . . discard args
599     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
600     # . clear-stream(_test-output-stream)
601     # . . push args
602     68/push  _test-output-stream/imm32
603     # . . call
604     e8/call  clear-stream/disp32
605     # . . discard args
606     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
607     # . clear-stream(_test-error-stream)
608     # . . push args
609     68/push  _test-error-stream/imm32
610     # . . call
611     e8/call  clear-stream/disp32
612     # . . discard args
613     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
614     # initialize 'in'
615     # . write(_test-stream, "3456 x")
616     # . . push args
617     68/push  "3456 x"/imm32
618     68/push  _test-stream/imm32
619     # . . call
620     e8/call  write/disp32
621     # . . discard args
622     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
623     # initialize exit-descriptor 'ed' for the call to 'get-num' below
624     # . var ed/EAX : (address exit-descriptor)
625     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
626     89/copy                         3/mod/direct    0/rm32/EAX    .           .             .           4/r32/ESP   .               .                 # copy ESP to EAX
627     # . tailor-exit-descriptor(ed, 16)
628     # . . push args
629     68/push  0x10/imm32/nbytes-of-args-for-get-num
630     50/push-EAX/ed
631     # . . call
632     e8/call  tailor-exit-descriptor/disp32
633     # . . discard args
634     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
635     # prime the pump
636     # . get-char(_test-buffered-file)
637     # . . push args
638     68/push  _test-buffered-file/imm32
639     # . . call
640     e8/call  get-char/disp32
641     # . . discard args
642     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
643     # get-num(in, out, err, ed)
644     # . . push args
645     50/push-EAX/ed
646     68/push  _test-error-stream/imm32
647     68/push  _test-output-stream/imm32
648     68/push  _test-buffered-file/imm32
649     # . . call
650     e8/call  get-num/disp32
651     # registers except ESP may be clobbered at this point
652     # . . discard args
653     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
654     # check-ints-equal(*_test-output-stream->data, '3456', msg)
655     # . . push args
656     68/push  "F - test-get-num-reads-multiple-digits-followed-by-nondigit"/imm32
657     68/push  0x36353433/imm32
658     b8/copy-to-EAX  _test-output-stream/imm32
659     ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX    .           .             .           .           0xc/disp8       .                 # push *(EAX+12)
660     # . . call
661     e8/call  check-ints-equal/disp32
662     # . . discard args
663     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
664     # . reclaim locals
665     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
666     5d/pop-to-EBP
667     c3/return
668 
669 ## helpers
670 
671 # write(f, "Error: "+s+" expected\n") then stop(ed, 1)
672 expected:  # ed : (address exit-descriptor), f : fd or (address stream), s : (address array byte) -> <void>
673     # . prolog
674     55/push-EBP
675     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
676     # write(f, "Error: ")
677     # . . push args
678     68/push  "Error: "/imm32
679     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
680     # . . call
681     e8/call  write/disp32
682     # . . discard args
683     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
684     # write(f, s)
685     # . . push args
686     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x10/disp8      .                 # push *(EBP+16)
687     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
688     # . . call
689     e8/call  write/disp32
690     # . . discard args
691     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
692     # write(f, " expected\n")
693     # . . push args
694     68/push  " expected\n"/imm32
695     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
696     # . . call
697     e8/call  write/disp32
698     # . . discard args
699     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
700     # stop(ed, 1)
701     # . . push args
702     68/push  1/imm32
703     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
704     # . . call
705     e8/call  stop/disp32
706     # should never get past this point
707 $expected:dead-end:
708     # . epilog
709     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
710     5d/pop-to-EBP
711     c3/return
712 
713 # read a byte from 'f', and save it in 'Look'
714 get-char:  # f : (address buffered-file) -> <void>
715     # . prolog
716     55/push-EBP
717     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
718     # . save registers
719     50/push-EAX
720     # EAX = read-byte-buffered(f)
721     # . . push args
722     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
723     # . . call
724     e8/call  read-byte-buffered/disp32
725     # . . discard args
726     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
727     # save EAX to Look
728     89/copy                         0/mod/indirect  5/rm32/.disp32            .             .           0/r32/EAX   Look/disp32     .                 # copy EAX to *Look
729 $get-char:end:
730     # . restore registers
731     58/pop-to-EAX
732     # . epilog
733     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
734     5d/pop-to-EBP
735     c3/return
736 
737 is-digit?:  # c : int -> EAX : boolean
738     # . prolog
739     55/push-EBP
740     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
741     # EAX = false
742     b8/copy-to-EAX  0/imm32
743     # if (c < '0') return false
744     81          7/subop/compare     1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         0x30/imm32        # compare *(EBP+8)
745     7c/jump-if-lesser  $is-digit?:end/disp8
746     # if (c > '9') return false
747     81          7/subop/compare     1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         0x39/imm32        # compare *(EBP+8)
748     7f/jump-if-greater  $is-digit?:end/disp8
749     # otherwise return true
750     b8/copy-to-EAX  1/imm32
751 $is-digit?:end:
752     # . epilog
753     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
754     5d/pop-to-EBP
755     c3/return
756 
757 == data
758 
759 Look:  # (char with some extra padding)
760     0/imm32
761 
762 # . . vim:nowrap:textwidth=0