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 (from the subx/ directory):
  6 #   $ ./subx translate *.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 
 35 #?     # for debugging: run a single test; don't bother setting status code
 36 #?     e8/call test-get-num-reads-single-digit/disp32
 37 #?     eb/jump  $main:end/disp8
 38 
 39     # . prolog
 40     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
 41     # - if argc > 1 and argv[1] == "test", then return run_tests()
 42     # . argc > 1
 43     81          7/subop/compare     1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0/disp8         1/imm32           # compare *EBP
 44     7e/jump-if-lesser-or-equal  $run-main/disp8
 45     # . argv[1] == "test"
 46     # . . push args
 47     68/push  "test"/imm32
 48     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
 49     # . . call
 50     e8/call  kernel-string-equal?/disp32
 51     # . . discard args
 52     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
 53     # . check result
 54     3d/compare-EAX  1/imm32
 55     75/jump-if-not-equal  $run-main/disp8
 56     # . run-tests()
 57     e8/call  run-tests/disp32
 58     8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           3/r32/EBX   Num-test-failures/disp32          # copy *Num-test-failures to EBX
 59     eb/jump  $main:end/disp8
 60 $run-main:
 61     # - otherwise read a program from stdin and emit its translation to stdout
 62     # var ed/EAX : exit-descriptor
 63     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
 64     89/copy                         3/mod/direct    0/rm32/EAX    .           .             .           4/r32/ESP   .               .                 # copy ESP to EAX
 65     # configure ed to really exit()
 66     # . ed->target = 0
 67     c7          0/subop/copy        0/mod/direct    0/rm32/EAX    .           .             .           .           .               0/imm32           # copy to *EAX
 68     # return compile(Stdin, 1/stdout, 2/stderr, ed)
 69     # . . push args
 70     50/push-EAX/ed
 71     68/push  2/imm32/stderr
 72     68/push  1/imm32/stdout
 73     68/push  Stdin/imm32
 74     # . . call
 75     e8/call  compile/disp32
 76     # . . discard args
 77     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
 78     # . syscall(exit, 0)
 79     bb/copy-to-EBX  0/imm32
 80 $main:end:
 81     b8/copy-to-EAX  1/imm32/exit
 82     cd/syscall  0x80/imm8
 83 
 84 # the main entry point
 85 compile:  # in : (address buffered-file), out : fd or (address stream), err : fd or (address stream), ed : (address exit-descriptor) -> <void>
 86     # . prolog
 87     55/push-EBP
 88     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
 89     # . save registers
 90     50/push-EAX
 91     51/push-ECX
 92     # prime the pump
 93     # . Look = get-char(in)
 94     # . . push args
 95     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8      .                    # push *(EBP+8)
 96     # . . call
 97     e8/call  get-char/disp32
 98     # . . discard args
 99     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
100     # var num/ECX : (address stream) on the stack
101     # Numbers can be 32 bits or 8 hex bytes long. One of them will be in 'Look', so we need space for 7 bytes.
102     # Sizing the stream just right buys us overflow-handling for free inside 'get-num'.
103     # Add 12 bytes for 'read', 'write' and 'length' fields, for a total of 19 bytes, or 0x13 in hex.
104     # The stack pointer is no longer aligned, so dump_stack() can be misleading past this point.
105     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x13/imm32        # subtract from ESP
106     89/copy                         3/mod/direct    1/rm32/ECX    .           .             .           4/r32/ESP   .               .                 # copy ESP to ECX
107     # initialize the stream
108     # . num->length = 7
109     c7          0/subop/copy        1/mod/*+disp8   1/rm32/ECX    .           .             .           .           8/disp8         7/imm32           # copy to *(ECX+8)
110     # . clear-stream(num)
111     # . . push args
112     51/push-ECX
113     # . . call
114     e8/call  clear-stream/disp32
115     # . . discard args
116     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
117     # read a digit from 'in' into 'num'
118     # . get-num(in, num, err, ed)
119     # . . push args
120     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x14/disp8      .                 # push *(EBP+20)
121     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x10/disp8      .                 # push *(EBP+16)
122     51/push-ECX/num
123     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8      .                    # push *(EBP+8)
124     # . . call
125     e8/call  get-num/disp32
126     # . . discard args
127     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
128     # render 'num' into the following template on 'out':
129     #   bb/copy-to-EBX  _num_
130     #   b8/copy-to-EAX  1/imm32/exit
131     #   cd/syscall  0x80/imm8
132     #
133     # . write(out, "bb/copy-to-EBX  ")
134     # . . push args
135     68/push  "bb/copy-to-EBX  "/imm32
136     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
137     # . . call
138     e8/call  write/disp32
139     # . . discard args
140     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
141     # . write-stream(out, num)
142     # . . push args
143     51/push-ECX/num
144     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
145     # . . call
146     e8/call  write-stream/disp32
147     # . . discard args
148     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
149     # . write(out, Newline)
150     # . . push args
151     68/push  Newline/imm32
152     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
153     # . . call
154     e8/call  write/disp32
155     # . . discard args
156     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
157     # . write(out, "b8/copy-to-EAX  1/imm32/exit")
158     # . . push args
159     68/push  "b8/copy-to-EAX  1/imm32/exit"/imm32
160     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
161     # . . call
162     e8/call  write/disp32
163     # . . discard args
164     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
165     # . write(out, Newline)
166     # . . push args
167     68/push  Newline/imm32
168     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
169     # . . call
170     e8/call  write/disp32
171     # . . discard args
172     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
173     # . write(out, "cd/syscall  0x80/imm8")
174     # . . push args
175     68/push  "cd/syscall  0x80/imm8"/imm32
176     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
177     # . . call
178     e8/call  write/disp32
179     # . . discard args
180     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
181     # . write(out, Newline)
182     # . . push args
183     68/push  Newline/imm32
184     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
185     # . . call
186     e8/call  write/disp32
187     # . . discard args
188     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
189 $compile:end:
190     # . restore registers
191     59/pop-to-ECX
192     58/pop-to-EAX
193     # . epilog
194     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
195     5d/pop-to-EBP
196     c3/return
197 
198 # Read a sequence of digits into 'out'. Abort if there are none, or if there is
199 # no space in 'out'.
200 # Input comes from the global variable 'Look' (first byte) and the argument
201 # 'in' (rest). We leave the next byte from 'in' into 'Look' on exit.
202 get-num:  # in : (address buffered-file), out : (address stream), err : fd or (address stream), ed : (address exit-descriptor) -> <void>
203     # pseudocode:
204     #   if (!is-digit?(Look)) expected(ed, err, "integer")
205     #   do
206     #     if (out->write >= out->length)
207     #       write(err, "Error: too many digits in number\n")
208     #       stop(ed, 1)
209     #     out->data[out->write] = LSB(Look)
210     #     ++out->write
211     #     Look = get-char(in)
212     #   while (is-digit?(Look))
213     # This is complicated because I don't want to hard-code the error strategy in
214     # a general helper like write-byte. Maybe I should just create a local helper.
215     #
216     # within the loop we'll try to keep things in registers:
217     #   in: ESI
218     #   out: EDI
219     #   out->write: ECX (cached copy; need to keep in sync)
220     #   out->length: EDX
221     #   temporaries: EAX, EBX
222     # We can't allocate Look to a register because it gets written implicitly in
223     # get-char in each iteration of the loop. (Thereby demonstrating that it's
224     # not the right interface for us. But we'll keep it just to follow Crenshaw.)
225     #
226     # . prolog
227     55/push-EBP
228     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
229     # - if (is-digit?(Look)) expected(ed, err, "integer")
230     # . EAX = is-digit?(Look)
231     # . . push args
232     ff          6/subop/push        0/mod/indirect  5/rm32/.disp32            .             .           .           Look/disp32     .                 # push *Look
233     # . . call
234     e8/call  is-digit?/disp32
235     # . . discard args
236     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
237     # . if (EAX == 0)
238     3d/compare-EAX  0/imm32
239     75/jump-if-not-equal  $get-num:main/disp8
240     # . expected(ed, err, "integer")
241     # . . push args
242     68/push  "integer"/imm32
243     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x10/disp8      .                 # push *(EBP+16)
244     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x14/disp8      .                 # push *(EBP+20)
245     # . . call
246     e8/call  expected/disp32  # never returns
247     # . . discard args
248     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
249 $get-num:main:
250     # - otherwise read a digit
251     # . save registers
252     50/push-EAX
253     51/push-ECX
254     52/push-EDX
255     53/push-EBX
256     56/push-ESI
257     57/push-EDI
258     # read necessary variables to registers
259     # ESI = in
260     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           6/r32/ESI   8/disp8         .                 # copy *(EBP+8) to ESI
261     # EDI = out
262     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           7/r32/EDI   0xc/disp8       .                 # copy *(EBP+12) to EDI
263     # ECX = out->write
264     8b/copy                         0/mod/indirect  7/rm32/EDI    .           .             .           1/r32/ECX   .               .                 # copy *EDI to ECX
265     # EDX = out->length
266     8b/copy                         1/mod/*+disp8   7/rm32/EDI    .           .             .           2/r32/EDX   8/disp8         .                 # copy *(EDI+8) to EDX
267 $get-num:loop:
268     # if (out->write >= out->length) error
269     39/compare                      3/mod/direct    2/rm32/EDX    .           .             .           1/r32/ECX   .               .                 # compare EDX with ECX
270     7d/jump-if-lesser  $get-num:loop-stage2/disp8
271     # . error(ed, err, msg)  # TODO: show full number
272     # . . push args
273     68/push  "get-num: too many digits in number"/imm32
274     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x10/disp8      .                 # push *(EBP+16)
275     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x14/disp8      .                 # push *(EBP+20)
276     # . . call
277     e8/call  error/disp32  # never returns
278     # . . discard args
279     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
280 $get-num:loop-stage2:
281     # out->data[out->write] = LSB(Look)
282     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
283     8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           0/r32/EAX   Look/disp32     .                 # copy *Look to EAX
284     88/copy-byte                    0/mod/indirect  3/rm32/EBX    .           .             .           0/r32/AL    .               .                 # copy byte at AL to *EBX
285     # ++out->write
286     41/increment-ECX
287     # Look = get-char(in)
288     # . . push args
289     56/push-ESI
290     # . . call
291     e8/call  get-char/disp32
292     # . . discard args
293     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
294     # if (is-digit?(Look)) loop
295     # . EAX = is-digit?(Look)
296     # . . push args
297     ff          6/subop/push        0/mod/indirect  5/rm32/.disp32            .             .           .           Look/disp32     .                 # push *Look
298     # . . call
299     e8/call  is-digit?/disp32
300     # . . discard args
301     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
302     # . if (EAX != 0) loop
303     3d/compare-EAX  0/imm32
304     0f 85/jump-if-not-equal  $get-num:loop/disp32
305 $get-num:loop-end:
306     # persist necessary variables from registers
307     89/copy                         0/mod/indirect  7/rm32/EDI    .           .             .           1/r32/ECX   .               .                 # copy ECX to *EDI
308 $get-num:end:
309     # . restore registers
310     5f/pop-to-EDI
311     5e/pop-to-ESI
312     5b/pop-to-EBX
313     5a/pop-to-EDX
314     59/pop-to-ECX
315     58/pop-to-EAX
316     # . epilog
317     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
318     5d/pop-to-EBP
319     c3/return
320 
321 test-get-num-reads-single-digit:
322     # - check that get-num returns first character if it's a digit
323     # This test uses exit-descriptors. Use EBP for setting up local variables.
324     55/push-EBP
325     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
326     # clear all streams
327     # . clear-stream(_test-stream)
328     # . . push args
329     68/push  _test-stream/imm32
330     # . . call
331     e8/call  clear-stream/disp32
332     # . . discard args
333     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
334     # . clear-stream(_test-buffered-file+4)
335     # . . push args
336     b8/copy-to-EAX  _test-buffered-file/imm32
337     05/add-to-EAX  4/imm32
338     50/push-EAX
339     # . . call
340     e8/call  clear-stream/disp32
341     # . . discard args
342     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
343     # . clear-stream(_test-output-stream)
344     # . . push args
345     68/push  _test-output-stream/imm32
346     # . . call
347     e8/call  clear-stream/disp32
348     # . . discard args
349     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
350     # . clear-stream(_test-error-stream)
351     # . . push args
352     68/push  _test-error-stream/imm32
353     # . . call
354     e8/call  clear-stream/disp32
355     # . . discard args
356     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
357     # initialize 'in'
358     # . write(_test-stream, "3")
359     # . . push args
360     68/push  "3"/imm32
361     68/push  _test-stream/imm32
362     # . . call
363     e8/call  write/disp32
364     # . . discard args
365     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
366     # initialize exit-descriptor 'ed' for the call to 'get-num' below
367     # . var ed/EAX : exit-descriptor
368     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
369     89/copy                         3/mod/direct    0/rm32/EAX    .           .             .           4/r32/ESP   .               .                 # copy ESP to EAX
370     # . tailor-exit-descriptor(ed, 16)
371     # . . push args
372     68/push  0x10/imm32/nbytes-of-args-for-get-num
373     50/push-EAX/ed
374     # . . call
375     e8/call  tailor-exit-descriptor/disp32
376     # . . discard args
377     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
378     # prime the pump
379     # . get-char(_test-buffered-file)
380     # . . push args
381     68/push  _test-buffered-file/imm32
382     # . . call
383     e8/call  get-char/disp32
384     # . . discard args
385     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
386     # get-num(in, out, err, ed)
387     # . . push args
388     50/push-EAX/ed
389     68/push  _test-error-stream/imm32
390     68/push  _test-output-stream/imm32
391     68/push  _test-buffered-file/imm32
392     # . . call
393     e8/call  get-num/disp32
394     # registers except ESP may be clobbered at this point
395     # . . discard args
396     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
397     # check-ints-equal(*_test-output-stream->data, '3', msg)
398     # . . push args
399     68/push  "F - test-get-num-reads-single-digit"/imm32
400     68/push  0x33/imm32
401     b8/copy-to-EAX  _test-output-stream/imm32
402     ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX    .           .             .           .           0xc/disp8       .                 # push *(EAX+12)
403     # . . call
404     e8/call  check-ints-equal/disp32
405     # . . discard args
406     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
407     # . reclaim locals
408     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
409     5d/pop-to-EBP
410     c3/return
411 
412 test-get-num-aborts-on-non-digit-in-Look:
413     # - check that get-num returns first character if it's a digit
414     # This test uses exit-descriptors. Use EBP for setting up local variables.
415     55/push-EBP
416     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
417     # clear all streams
418     # . clear-stream(_test-stream)
419     # . . push args
420     68/push  _test-stream/imm32
421     # . . call
422     e8/call  clear-stream/disp32
423     # . . discard args
424     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
425     # . clear-stream(_test-buffered-file+4)
426     # . . push args
427     b8/copy-to-EAX  _test-buffered-file/imm32
428     05/add-to-EAX  4/imm32
429     50/push-EAX
430     # . . call
431     e8/call  clear-stream/disp32
432     # . . discard args
433     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
434     # . clear-stream(_test-output-stream)
435     # . . push args
436     68/push  _test-output-stream/imm32
437     # . . call
438     e8/call  clear-stream/disp32
439     # . . discard args
440     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
441     # . clear-stream(_test-error-stream)
442     # . . push args
443     68/push  _test-error-stream/imm32
444     # . . call
445     e8/call  clear-stream/disp32
446     # . . discard args
447     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
448     # initialize 'in'
449     # . write(_test-stream, "3")
450     # . . push args
451     68/push  "3"/imm32
452     68/push  _test-stream/imm32
453     # . . call
454     e8/call  write/disp32
455     # . . discard args
456     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
457     # initialize exit-descriptor 'ed' for the call to 'get-num' below
458     # . var ed/EAX : (address exit-descriptor)
459     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
460     89/copy                         3/mod/direct    0/rm32/EAX    .           .             .           4/r32/ESP   .               .                 # copy ESP to EAX
461     # . tailor-exit-descriptor(ed, 16)
462     # . . push args
463     68/push  0x10/imm32/nbytes-of-args-for-get-num
464     50/push-EAX/ed
465     # . . call
466     e8/call  tailor-exit-descriptor/disp32
467     # . . discard args
468     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
469     # *don't* prime the pump
470     # get-num(in, out, err, ed)
471     # . . push args
472     50/push-EAX/ed
473     68/push  _test-error-stream/imm32
474     68/push  _test-output-stream/imm32
475     68/push  _test-buffered-file/imm32
476     # . . call
477     e8/call  get-num/disp32
478     # registers except ESP may be clobbered at this point
479     # . . discard args
480     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
481     # check that get-num tried to call exit(1)
482     # . check-ints-equal(ed->value, 2, msg)  # i.e. stop was called with value 1
483     # . . push args
484     68/push  "F - test-get-num-aborts-on-non-digit-in-Look"/imm32
485     68/push  2/imm32
486     # . . push ed->value
487     ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX    .           .             .           .           4/disp8         .                 # push *(EAX+4)
488     # . . call
489     e8/call  check-ints-equal/disp32
490     # . . discard args
491     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
492     # . reclaim locals
493     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
494     5d/pop-to-EBP
495     c3/return
496 
497 test-get-num-reads-multiple-digits:
498     # - check that get-num returns all initial digits until it encounters a non-digit
499     # This test uses exit-descriptors. Use EBP for setting up local variables.
500     55/push-EBP
501     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
502     # clear all streams
503     # . clear-stream(_test-stream)
504     # . . push args
505     68/push  _test-stream/imm32
506     # . . call
507     e8/call  clear-stream/disp32
508     # . . discard args
509     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
510     # . clear-stream(_test-buffered-file+4)
511     # . . push args
512     b8/copy-to-EAX  _test-buffered-file/imm32
513     05/add-to-EAX  4/imm32
514     50/push-EAX
515     # . . call
516     e8/call  clear-stream/disp32
517     # . . discard args
518     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
519     # . clear-stream(_test-output-stream)
520     # . . push args
521     68/push  _test-output-stream/imm32
522     # . . call
523     e8/call  clear-stream/disp32
524     # . . discard args
525     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
526     # . clear-stream(_test-error-stream)
527     # . . push args
528     68/push  _test-error-stream/imm32
529     # . . call
530     e8/call  clear-stream/disp32
531     # . . discard args
532     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
533     # initialize 'in'
534     # . write(_test-stream, "3456 x")
535     # . . push args
536     68/push  "3456"/imm32
537     68/push  _test-stream/imm32
538     # . . call
539     e8/call  write/disp32
540     # . . discard args
541     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
542     # initialize exit-descriptor 'ed' for the call to 'get-num' below
543     # . var ed/EAX : (address exit-descriptor)
544     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
545     89/copy                         3/mod/direct    0/rm32/EAX    .           .             .           4/r32/ESP   .               .                 # copy ESP to EAX
546     # . tailor-exit-descriptor(ed, 16)
547     # . . push args
548     68/push  0x10/imm32/nbytes-of-args-for-get-num
549     50/push-EAX/ed
550     # . . call
551     e8/call  tailor-exit-descriptor/disp32
552     # . . discard args
553     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
554     # prime the pump
555     # . get-char(_test-buffered-file)
556     # . . push args
557     68/push  _test-buffered-file/imm32
558     # . . call
559     e8/call  get-char/disp32
560     # . . discard args
561     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
562     # get-num(in, out, err, ed)
563     # . . push args
564     50/push-EAX/ed
565     68/push  _test-error-stream/imm32
566     68/push  _test-output-stream/imm32
567     68/push  _test-buffered-file/imm32
568     # . . call
569     e8/call  get-num/disp32
570     # registers except ESP may be clobbered at this point
571     # . . discard args
572     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
573     # check-ints-equal(*_test-output-stream->data, '3456', msg)
574     # . . push args
575     68/push  "F - test-get-num-reads-multiple-digits"/imm32
576     68/push  0x36353433/imm32
577     b8/copy-to-EAX  _test-output-stream/imm32
578     ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX    .           .             .           .           0xc/disp8       .                 # push *(EAX+12)
579     # . . call
580     e8/call  check-ints-equal/disp32
581     # . . discard args
582     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
583     # . reclaim locals
584     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
585     5d/pop-to-EBP
586     c3/return
587 
588 test-get-num-reads-multiple-digits-followed-by-nondigit:
589     # - check that get-num returns all initial digits until it encounters a non-digit
590     # This test uses exit-descriptors. Use EBP for setting up local variables.
591     55/push-EBP
592     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
593     # clear all streams
594     # . clear-stream(_test-stream)
595     # . . push args
596     68/push  _test-stream/imm32
597     # . . call
598     e8/call  clear-stream/disp32
599     # . . discard args
600     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
601     # . clear-stream(_test-buffered-file+4)
602     # . . push args
603     b8/copy-to-EAX  _test-buffered-file/imm32
604     05/add-to-EAX  4/imm32
605     50/push-EAX
606     # . . call
607     e8/call  clear-stream/disp32
608     # . . discard args
609     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
610     # . clear-stream(_test-output-stream)
611     # . . push args
612     68/push  _test-output-stream/imm32
613     # . . call
614     e8/call  clear-stream/disp32
615     # . . discard args
616     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
617     # . clear-stream(_test-error-stream)
618     # . . push args
619     68/push  _test-error-stream/imm32
620     # . . call
621     e8/call  clear-stream/disp32
622     # . . discard args
623     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
624     # initialize 'in'
625     # . write(_test-stream, "3456 x")
626     # . . push args
627     68/push  "3456 x"/imm32
628     68/push  _test-stream/imm32
629     # . . call
630     e8/call  write/disp32
631     # . . discard args
632     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
633     # initialize exit-descriptor 'ed' for the call to 'get-num' below
634     # . var ed/EAX : (address exit-descriptor)
635     81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
636     89/copy                         3/mod/direct    0/rm32/EAX    .           .             .           4/r32/ESP   .               .                 # copy ESP to EAX
637     # . tailor-exit-descriptor(ed, 16)
638     # . . push args
639     68/push  0x10/imm32/nbytes-of-args-for-get-num
640     50/push-EAX/ed
641     # . . call
642     e8/call  tailor-exit-descriptor/disp32
643     # . . discard args
644     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
645     # prime the pump
646     # . get-char(_test-buffered-file)
647     # . . push args
648     68/push  _test-buffered-file/imm32
649     # . . call
650     e8/call  get-char/disp32
651     # . . discard args
652     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
653     # get-num(in, out, err, ed)
654     # . . push args
655     50/push-EAX/ed
656     68/push  _test-error-stream/imm32
657     68/push  _test-output-stream/imm32
658     68/push  _test-buffered-file/imm32
659     # . . call
660     e8/call  get-num/disp32
661     # registers except ESP may be clobbered at this point
662     # . . discard args
663     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
664     # check-ints-equal(*_test-output-stream->data, '3456', msg)
665     # . . push args
666     68/push  "F - test-get-num-reads-multiple-digits-followed-by-nondigit"/imm32
667     68/push  0x36353433/imm32
668     b8/copy-to-EAX  _test-output-stream/imm32
669     ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX    .           .             .           .           0xc/disp8       .                 # push *(EAX+12)
670     # . . call
671     e8/call  check-ints-equal/disp32
672     # . . discard args
673     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
674     # . reclaim locals
675     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
676     5d/pop-to-EBP
677     c3/return
678 
679 ## helpers
680 
681 # write(f, "Error: "+s+" expected\n") then stop(ed, 1)
682 expected:  # ed : (address exit-descriptor), f : fd or (address stream), s : (address array byte) -> <void>
683     # . prolog
684     55/push-EBP
685     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
686     # write(f, "Error: ")
687     # . . push args
688     68/push  "Error: "/imm32
689     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
690     # . . call
691     e8/call  write/disp32
692     # . . discard args
693     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
694     # write(f, s)
695     # . . push args
696     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0x10/disp8      .                 # push *(EBP+16)
697     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
698     # . . call
699     e8/call  write/disp32
700     # . . discard args
701     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
702     # write(f, " expected")
703     # . . push args
704     68/push  " expected"/imm32
705     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
706     # . . call
707     e8/call  write/disp32
708     # . . discard args
709     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
710     # write(f, Newline)
711     # . . push args
712     68/push  Newline/imm32
713     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           0xc/disp8       .                 # push *(EBP+12)
714     # . . call
715     e8/call  write/disp32
716     # . . discard args
717     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
718     # stop(ed, 1)
719     # . . push args
720     68/push  1/imm32
721     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
722     # . . call
723     e8/call  stop/disp32
724     # should never get past this point
725     # . epilog
726     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
727     5d/pop-to-EBP
728     c3/return
729 
730 # read a byte from 'f', and save it in 'Look'
731 get-char:  # f : (address buffered-file) -> <void>
732     # . prolog
733     55/push-EBP
734     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
735     # . save registers
736     50/push-EAX
737     # read-byte(f)
738     # . . push args
739     ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
740     # . . call
741     e8/call  read-byte/disp32
742     # . . discard args
743     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
744     # save EAX to Look
745     89/copy                         0/mod/indirect  5/rm32/.disp32            .             .           0/r32/EAX   Look/disp32     .                 # copy EAX to *Look
746     # . restore registers
747     58/pop-to-EAX
748     # . epilog
749     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
750     5d/pop-to-EBP
751     c3/return
752 
753 is-digit?:  # c : int -> EAX : boolean
754     # . prolog
755     55/push-EBP
756     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
757     # EAX = false
758     b8/copy-to-EAX  0/imm32
759     # if (c < '0') return false
760     81          7/subop/compare     1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         0x30/imm32        # compare *(EBP+8)
761     7c/jump-if-lesser  $is-digit?:end/disp8
762     # if (c > '9') return false
763     81          7/subop/compare     1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         0x39/imm32        # compare *(EBP+8)
764     7f/jump-if-greater  $is-digit?:end/disp8
765     # otherwise return true
766     b8/copy-to-EAX  1/imm32
767 $is-digit?:end:
768     # . epilog
769     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
770     5d/pop-to-EBP
771     c3/return
772 
773 == data
774 
775 Look:  # (char with some extra padding)
776     0/imm32
777 
778 _test-output-stream:
779     # current write index
780     0/imm32
781     # current read index
782     0/imm32
783     # length
784     8/imm32
785     # data
786     00 00 00 00 00 00 00 00  # 8 bytes
787 
788 _test-error-stream:
789     # current write index
790     0/imm32
791     # current read index
792     0/imm32
793     # length
794     8/imm32
795     # data
796     00 00 00 00 00 00 00 00  # 8 bytes
797 
798 # . . vim:nowrap:textwidth=0