1 == code
  2 #   instruction                     effective address                                                   register    displacement    immediate
  3 # . op          subop               mod             rm32          base        index         scale       r32
  4 # . 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
  5 
  6 # read bytes from 'f' until (and including) a newline and store them into 's'
  7 # 's' fails to grow if and only if no data found
  8 # just abort if 's' is too small
  9 read-line-buffered:  # f: (addr buffered-file), s: (addr stream byte)
 10     # pseudocode:
 11     #   while true
 12     #     if (s->write >= s->size) abort
 13     #     if (f->read >= f->write) populate stream from file
 14     #     if (f->write == 0) break
 15     #     AL = f->data[f->read]
 16     #     s->data[s->write] = AL
 17     #     ++f->read
 18     #     ++s->write
 19     #     if (AL == '\n') break
 20     # . prologue
 21     55/push-ebp
 22     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
 23     # . save registers
 24     50/push-eax
 25     51/push-ecx
 26     52/push-edx
 27     56/push-esi
 28     57/push-edi
 29     # esi = f
 30     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
 31     # ecx = f->read
 32     8b/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           1/r32/ecx   8/disp8         .                 # copy *(esi+8) to ecx
 33     # edi = s
 34     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           7/r32/edi   0xc/disp8       .                 # copy *(ebp+12) to edi
 35     # edx = s->write
 36     8b/copy                         0/mod/indirect  7/rm32/edi    .           .             .           2/r32/edx   .               .                 # copy *edi to edx
 37 $read-line-buffered:loop:
 38     # if (s->write >= s->size) abort
 39     3b/compare                      1/mod/*+disp8   7/rm32/edi    .           .             .           2/r32/edx   8/disp8         .                 # compare edx with *(edi+8)
 40     7d/jump-if->=  $read-line-buffered:abort/disp8
 41     # if (f->read >= f->write) populate stream from file
 42     3b/compare                      1/mod/*+disp8   6/rm32/esi    .           .             .           1/r32/ecx   4/disp8         .                 # compare ecx with *(esi+4)
 43     7c/jump-if-<  $read-line-buffered:from-stream/disp8
 44     # . clear-stream(stream = f+4)
 45     # . . push args
 46     8d/copy-address                 1/mod/*+disp8   6/rm32/esi    .           .             .           0/r32/eax   4/disp8         .                 # copy esi+4 to eax
 47     50/push-eax
 48     # . . call
 49     e8/call  clear-stream/disp32
 50     # . . discard args
 51     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
 52     # . f->read must now be 0; update its cache at ecx
 53     31/xor                          3/mod/direct    1/rm32/ecx    .           .             .           1/r32/ecx   .               .                 # clear ecx
 54     # . eax = read(f->fd, stream = f+4)
 55     # . . push args
 56     50/push-eax
 57     ff          6/subop/push        0/mod/indirect  6/rm32/esi    .           .             .           .           .               .                 # push *esi
 58     # . . call
 59     e8/call  read/disp32
 60     # . . discard args
 61     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
 62     # if (f->write == 0) break
 63     # since f->read was initially 0, eax is the same as f->write
 64     # . if (eax == 0) return true
 65     3d/compare-eax-and  0/imm32
 66     74/jump-if-=  $read-line-buffered:end/disp8
 67 $read-line-buffered:from-stream:
 68     # AL = f->data[f->read]
 69     31/xor                          3/mod/direct    0/rm32/eax    .           .             .           0/r32/eax   .               .                 # clear eax
 70     8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/esi  1/index/ecx   .           0/r32/AL    0x10/disp8      .                 # copy byte at *(esi+ecx+16) to AL
 71     # s->data[s->write] = AL
 72     88/copy-byte                    1/mod/*+disp8   4/rm32/sib    7/base/edi  2/index/edx   .           0/r32/AL    0xc/disp8       .                 # copy AL to *(edi+edx+12)
 73     # ++f->read
 74     41/increment-ecx
 75     # ++s->write
 76     42/increment-edx
 77     # if (AL == '\n') return
 78     3d/compare-eax-and  0xa/imm32/newline
 79     75/jump-if-!=  $read-line-buffered:loop/disp8
 80 $read-line-buffered:end:
 81     # save f->read
 82     89/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           1/r32/ecx   8/disp8         .                 # copy ecx to *(esi+8)
 83     # save s->write
 84     89/copy                         0/mod/indirect  7/rm32/edi    .           .             .           2/r32/edx   .               .                 # copy edx to *edi
 85     # . restore registers
 86     5f/pop-to-edi
 87     5e/pop-to-esi
 88     5a/pop-to-edx
 89     59/pop-to-ecx
 90     58/pop-to-eax
 91     # . epilogue
 92     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
 93     5d/pop-to-ebp
 94     c3/return
 95 
 96 $read-line-buffered:abort:
 97     # . _write(2/stderr, error)
 98     # . . push args
 99     68/push  "read-line-buffered: line too long\n"/imm32
100     68/push  2/imm32/stderr
101     # . . call
102     e8/call  _write/disp32
103     # . . discard args
104     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
105     # . syscall(exit, 1)
106     bb/copy-to-ebx  1/imm32
107     e8/call  syscall_exit/disp32
108     # never gets here
109 
110 test-read-line-buffered:
111     # - check that read-line-buffered stops at a newline
112     # setup
113     # . clear-stream(_test-stream)
114     # . . push args
115     68/push  _test-stream/imm32
116     # . . call
117     e8/call  clear-stream/disp32
118     # . . discard args
119     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
120     # . clear-stream($_test-buffered-file->buffer)
121     # . . push args
122     68/push  $_test-buffered-file->buffer/imm32
123     # . . call
124     e8/call  clear-stream/disp32
125     # . . discard args
126     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
127     # . clear-stream(_test-tmp-stream)
128     # . . push args
129     68/push  _test-tmp-stream/imm32
130     # . . call
131     e8/call  clear-stream/disp32
132     # . . discard args
133     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
134     # write(_test-stream, "ab\ncd")
135     # . . push args
136     68/push  "ab\ncd"/imm32
137     68/push  _test-stream/imm32
138     # . . call
139     e8/call  write/disp32
140     # . . discard args
141     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
142     # read a line from _test-stream (buffered by _test-buffered-file) into _test-tmp-stream
143     # . eax = read-line-buffered(_test-buffered-file, _test-tmp-stream)
144     # . . push args
145     68/push  _test-tmp-stream/imm32
146     68/push  _test-buffered-file/imm32
147     # . . call
148     e8/call  read-line-buffered/disp32
149     # . . discard args
150     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
151     # check-next-stream-line-equal(_test-tmp-stream, "ab", msg)
152     # . . push args
153     68/push  "F - test-read-line-buffered"/imm32
154     68/push  "ab"/imm32
155     68/push  _test-tmp-stream/imm32
156     # . . call
157     e8/call  check-next-stream-line-equal/disp32
158     # . . discard args
159     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
160     # end
161     c3/return
162 
163 test-read-line-buffered-reads-final-line-until-Eof:
164     # setup
165     # . clear-stream(_test-stream)
166     # . . push args
167     68/push  _test-stream/imm32
168     # . . call
169     e8/call  clear-stream/disp32
170     # . . discard args
171     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
172     # . clear-stream($_test-buffered-file->buffer)
173     # . . push args
174     68/push  $_test-buffered-file->buffer/imm32
175     # . . call
176     e8/call  clear-stream/disp32
177     # . . discard args
178     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
179     # . clear-stream(_test-tmp-stream)
180     # . . push args
181     68/push  _test-tmp-stream/imm32
182     # . . call
183     e8/call  clear-stream/disp32
184     # . . discard args
185     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
186     # write(_test-stream, "cd")
187     # . . push args
188     68/push  "cd"/imm32
189     68/push  _test-stream/imm32
190     # . . call
191     e8/call  write/disp32
192     # . . discard args
193     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
194     # read a line from _test-stream (buffered by _test-buffered-file) into _test-tmp-stream
195     # . eax = read-line-buffered(_test-buffered-file, _test-tmp-stream)
196     # . . push args
197     68/push  _test-tmp-stream/imm32
198     68/push  _test-buffered-file/imm32
199     # . . call
200     e8/call  read-line-buffered/disp32
201     # . . discard args
202     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
203     # check-stream-equal(_test-tmp-stream, "cd", msg)
204     # . . push args
205     68/push  "F - test-read-line-buffered-reads-final-line-until-Eof"/imm32
206     68/push  "cd"/imm32
207     68/push  _test-tmp-stream/imm32
208     # . . call
209     e8/call  check-stream-equal/disp32
210     # . . discard args
211     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
212     # end
213     c3/return
214 
215 # read bytes from 'f' until (and including) a newline and store them into 's'
216 # 's' fails to grow if and only if no data found
217 # just abort if 's' is too small
218 read-line:  # f: (addr stream byte), s: (addr stream byte)
219     # pseudocode:
220     #   while true
221     #     if (s->write >= s->size) abort
222     #     if (f->read >= f->write) break
223     #     AL = f->data[f->read]
224     #     s->data[s->write] = AL
225     #     ++f->read
226     #     ++s->write
227     #     if (AL == '\n') break
228     # . prologue
229     55/push-ebp
230     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
231     # . save registers
232     50/push-eax
233     51/push-ecx
234     52/push-edx
235     56/push-esi
236     57/push-edi
237     # esi = f
238     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
239     # ecx = f->read
240     8b/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           1/r32/ecx   4/disp8         .                 # copy *(esi+4) to ecx
241     # edi = s
242     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           7/r32/edi   0xc/disp8       .                 # copy *(ebp+12) to edi
243     # edx = s->write
244     8b/copy                         0/mod/indirect  7/rm32/edi    .           .             .           2/r32/edx   .               .                 # copy *edi to edx
245 $read-line:loop:
246     # if (s->write >= s->size) abort
247     3b/compare                      1/mod/*+disp8   7/rm32/edi    .           .             .           2/r32/edx   8/disp8         .                 # compare edx with *(edi+8)
248     0f 8d/jump-if->=  $read-line:abort/disp32
249     # if (f->read >= f->write) break
250     3b/compare                      0/mod/indirect  6/rm32/esi    .           .             .           1/r32/ecx   .               .                 # compare ecx with *esi
251     7d/jump-if->=  $read-line:end/disp8
252     # AL = f->data[f->read]
253     31/xor                          3/mod/direct    0/rm32/eax    .           .             .           0/r32/eax   .               .                 # clear eax
254     8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/esi  1/index/ecx   .           0/r32/AL    0xc/disp8       .                 # copy byte at *(esi+ecx+12) to AL
255     # s->data[s->write] = AL
256     88/copy-byte                    1/mod/*+disp8   4/rm32/sib    7/base/edi  2/index/edx   .           0/r32/AL    0xc/disp8       .                 # copy AL to *(edi+edx+12)
257     # ++f->read
258     41/increment-ecx
259     # ++s->write
260     42/increment-edx
261     # if (AL == '\n') return
262     3d/compare-eax-and  0xa/imm32/newline
263     0f 85/jump-if-!=  $read-line:loop/disp32
264 $read-line:end:
265     # save f->read
266     89/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           1/r32/ecx   4/disp8         .                 # copy ecx to *(esi+4)
267     # save s->write
268     89/copy                         0/mod/indirect  7/rm32/edi    .           .             .           2/r32/edx   .               .                 # copy edx to *edi
269     # . restore registers
270     5f/pop-to-edi
271     5e/pop-to-esi
272     5a/pop-to-edx
273     59/pop-to-ecx
274     58/pop-to-eax
275     # . epilogue
276     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
277     5d/pop-to-ebp
278     c3/return
279 
280 $read-line:abort:
281     # . _write(2/stderr, error)
282     # . . push args
283     68/push  "read-line: line too long\n"/imm32
284     68/push  2/imm32/stderr
285     # . . call
286     e8/call  _write/disp32
287     # . . discard args
288     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
289     # . syscall(exit, 1)
290     bb/copy-to-ebx  1/imm32
291     e8/call  syscall_exit/disp32
292     # never gets here
293 
294 test-read-line:
295     # - check that read-line stops at a newline
296     # setup
297     # . clear-stream(_test-stream)
298     # . . push args
299     68/push  _test-stream/imm32
300     # . . call
301     e8/call  clear-stream/disp32
302     # . . discard args
303     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
304     # . clear-stream(_test-tmp-stream)
305     # . . push args
306     68/push  _test-tmp-stream/imm32
307     # . . call
308     e8/call  clear-stream/disp32
309     # . . discard args
310     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
311     # write(_test-stream, "ab\ncd")
312     # . . push args
313     68/push  "ab\ncd"/imm32
314     68/push  _test-stream/imm32
315     # . . call
316     e8/call  write/disp32
317     # . . discard args
318     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
319     # read a line from _test-stream into _test-tmp-stream
320     # . eax = read-line(_test-stream, _test-tmp-stream)
321     # . . push args
322     68/push  _test-tmp-stream/imm32
323     68/push  _test-stream/imm32
324     # . . call
325     e8/call  read-line/disp32
326     # . . discard args
327     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
328     # check-next-stream-line-equal(_test-tmp-stream, "ab", msg)
329     # . . push args
330     68/push  "F - test-read-line"/imm32
331     68/push  "ab"/imm32
332     68/push  _test-tmp-stream/imm32
333     # . . call
334     e8/call  check-next-stream-line-equal/disp32
335     # . . discard args
336     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
337     # end
338     c3/return
339 
340 test-read-line-reads-final-line-until-Eof:
341     # setup
342     # . clear-stream(_test-stream)
343     # . . push args
344     68/push  _test-stream/imm32
345     # . . call
346     e8/call  clear-stream/disp32
347     # . . discard args
348     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
349     # . clear-stream(_test-tmp-stream)
350     # . . push args
351     68/push  _test-tmp-stream/imm32
352     # . . call
353     e8/call  clear-stream/disp32
354     # . . discard args
355     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
356     # write(_test-stream, "cd")
357     # . . push args
358     68/push  "cd"/imm32
359     68/push  _test-stream/imm32
360     # . . call
361     e8/call  write/disp32
362     # . . discard args
363     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
364     # read a line from _test-stream into _test-tmp-stream
365     # . eax = read-line(_test-stream, _test-tmp-stream)
366     # . . push args
367     68/push  _test-tmp-stream/imm32
368     68/push  _test-stream/imm32
369     # . . call
370     e8/call  read-line/disp32
371     # . . discard args
372     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
373     # check-stream-equal(_test-tmp-stream, "cd", msg)
374     # . . push args
375     68/push  "F - test-read-line-reads-final-line-until-Eof"/imm32
376     68/push  "cd"/imm32
377     68/push  _test-tmp-stream/imm32
378     # . . call
379     e8/call  check-stream-equal/disp32
380     # . . discard args
381     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
382     # end
383     c3/return
384 
385 # . . vim:nowrap:textwidth=0