1 # write-stream: like write, but write streams rather than strings
  2 
  3 == code
  4 #   instruction                     effective address                                                   register    displacement    immediate
  5 # . op          subop               mod             rm32          base        index         scale       r32
  6 # . 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
  7 
  8 #? Entry:  # manual test
  9 #?     # write-stream(stdout, _test-stream2)
 10 #?     68/push  _test-stream2/imm32
 11 #?     68/push  1/imm32/stdout
 12 #?     e8/call write-stream/disp32
 13 #?     # syscall(exit, Num-test-failures)
 14 #?     8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           3/r32/ebx   Num-test-failures/disp32          # copy *Num-test-failures to ebx
 15 #?     e8/call  syscall_exit/disp32
 16 
 17 write-stream:  # f: fd or (addr stream byte), s: (addr stream byte)
 18     # . prologue
 19     55/push-ebp
 20     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
 21     # if (f < 0x08000000) _write-stream(f, s), return  # f can't be a user-mode address, so treat it as a kernel file descriptor
 22     81          7/subop/compare     1/mod/*+disp8   5/rm32/ebp    .           .             .           .           8/disp8         0x08000000/imm32  # compare *(ebp+8)
 23     73/jump-if-addr>=  $write-stream:fake/disp8
 24     # . . push args
 25     ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0xc/disp8       .                 # push *(ebp+12)
 26     ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           8/disp8         .                 # push *(ebp+8)
 27     # . . call
 28     e8/call  _write-stream/disp32
 29     # . . discard args
 30     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
 31     eb/jump  $write-stream:end/disp8
 32 $write-stream:fake:
 33     # otherwise, treat 'f' as a stream to append to
 34     # . save registers
 35     50/push-eax
 36     56/push-esi
 37     57/push-edi
 38     # edi = f
 39     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         7/r32/edi   8/disp8         .                 # copy *(ebp+8) to edi
 40     # esi = s
 41     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         6/r32/esi   0xc/disp8       .                 # copy *(ebp+12) to esi
 42     # eax = _append-4(&f->data[f->write], &f->data[f->size], &s->data[s->read], &s->data[s->write])
 43     # . . push &s->data[s->write]
 44     8b/copy                         0/mod/indirect  6/rm32/esi    .           .             .           0/r32/eax   .               .                 # copy *esi to eax
 45     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/esi  0/index/eax   .           0/r32/eax   0xc/disp8       .                 # copy esi+eax+12 to eax
 46     50/push-eax
 47     # . . push &s->data[s->read]
 48     8b/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           0/r32/eax   4/disp8         .                 # copy *(esi+4) to eax
 49     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/esi  0/index/eax   .           0/r32/eax   0xc/disp8       .                 # copy esi+eax+12 to eax
 50     50/push-eax
 51     # . . push &f->data[f->size]
 52     8b/copy                         1/mod/*+disp8   7/rm32/edi    .           .             .           0/r32/eax   8/disp8         .                 # copy *(edi+8) to eax
 53     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/edi  0/index/eax   .           0/r32/eax   0xc/disp8       .                 # copy edi+eax+12 to eax
 54     50/push-eax
 55     # . . push &f->data[f->write]
 56     8b/copy                         0/mod/indirect  7/rm32/edi    .           .             .           0/r32/eax   .               .                 # copy *edi to eax
 57     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/edi  0/index/eax   .           0/r32/eax   0xc/disp8       .                 # copy edi+eax+12 to eax
 58     50/push-eax
 59     # . . call
 60     e8/call  _append-4/disp32
 61     # . . discard args
 62     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0x10/imm32        # add to esp
 63     # f->write += eax
 64     01/add                          0/mod/indirect  7/rm32/edi    .           .             .           0/r32/eax   .               .                 # add eax to *edi
 65     # s->read += eax
 66     01/add                          1/mod/*+disp8   6/rm32/esi    .           .             .           0/r32/eax   4/disp8         .                 # add eax to *(esi+4)
 67     # . restore registers
 68     5f/pop-to-edi
 69     5e/pop-to-esi
 70     58/pop-to-eax
 71 $write-stream:end:
 72     # . epilogue
 73     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
 74     5d/pop-to-ebp
 75     c3/return
 76 
 77 _write-stream:  # fd: int, s: (addr stream byte)
 78     # . prologue
 79     55/push-ebp
 80     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
 81     # . save registers
 82     50/push-eax
 83     51/push-ecx
 84     52/push-edx
 85     53/push-ebx
 86     56/push-esi
 87     57/push-edi
 88     # esi = s
 89     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   0xc/disp8       .                 # copy *(ebp+12) to esi
 90     # edi = s->read
 91     8b/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           7/r32/edi   4/disp8         .                 # copy *(esi+4) to edi
 92     # edx = s->write
 93     8b/copy                         0/mod/indirect  6/rm32/esi    .           .             .           2/r32/edx   .               .                 # copy *esi to edx
 94     # syscall(write, fd, &s->data[s->read], s->write - s->read)
 95     # . . fd: ebx
 96     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           3/r32/ebx   8/disp8         .                 # copy *(ebp+8) to ebx
 97     # . . data: ecx = &s->data[s->read]
 98     8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/esi  7/index/edi   .           1/r32/ecx   0xc/disp8       .                 # copy esi+edi+12 to ecx
 99     # . . size: edx = s->write - s->read
100     29/subtract                     3/mod/direct    2/rm32/edx    .           .             .           7/r32/edi   .               .                 # subtract edi from edx
101     # . . syscall
102     e8/call  syscall_write/disp32
103     # if (eax < 0) abort
104     3d/compare-eax-with  0/imm32
105     0f 8c/jump-if-<  $_write-stream:abort/disp32
106     # s->read += eax
107     01/add                          1/mod/*+disp8   6/rm32/esi    .           .             .           0/r32/eax   4/disp8         .                 # add eax to *(esi+4)
108     # . restore registers
109     5f/pop-to-edi
110     5e/pop-to-esi
111     5b/pop-to-ebx
112     5a/pop-to-edx
113     59/pop-to-ecx
114     58/pop-to-eax
115     # . epilogue
116     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
117     5d/pop-to-ebp
118     c3/return
119 
120 $_write-stream:abort:
121     # . _write(2/stderr, error)
122     # . . push args
123     68/push  "_write-stream: failed to write to file\n"/imm32
124     68/push  2/imm32/stderr
125     # . . call
126     e8/call  _write/disp32
127     # . . discard args
128     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
129     # . syscall(exit, 1)
130     bb/copy-to-ebx  1/imm32
131     e8/call  syscall_exit/disp32
132     # never gets here
133 
134 test-write-stream-single:
135     # setup
136     # . clear-stream(_test-stream)
137     # . . push args
138     68/push  _test-stream/imm32
139     # . . call
140     e8/call  clear-stream/disp32
141     # . . discard args
142     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
143     # . clear-stream(_test-stream2)
144     # . . push args
145     68/push  _test-stream2/imm32
146     # . . call
147     e8/call  clear-stream/disp32
148     # . . discard args
149     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
150     # . write(_test-stream2, "Ab")
151     # . . push args
152     68/push  "Ab"/imm32
153     68/push  _test-stream2/imm32
154     # . . call
155     e8/call  write/disp32
156     # . . discard args
157     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
158     # write-stream(_test-stream, _test-stream2)
159     # . . push args
160     68/push  _test-stream2/imm32
161     68/push  _test-stream/imm32
162     # . . call
163     e8/call  write-stream/disp32
164     # . . discard args
165     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
166     # check-stream-equal(_test-stream, "Ab", msg)
167     # . . push args
168     68/push  "F - test-write-stream-single"/imm32
169     68/push  "Ab"/imm32
170     68/push  _test-stream/imm32
171     # . . call
172     e8/call  check-stream-equal/disp32
173     # . . discard args
174     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
175     # . end
176     c3/return
177 
178 test-write-stream-appends:
179     # setup
180     # . clear-stream(_test-stream)
181     # . . push args
182     68/push  _test-stream/imm32
183     # . . call
184     e8/call  clear-stream/disp32
185     # . . discard args
186     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
187     # . clear-stream(_test-stream2)
188     # . . push args
189     68/push  _test-stream2/imm32
190     # . . call
191     e8/call  clear-stream/disp32
192     # . . discard args
193     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
194     # . write(_test-stream2, "C")
195     # . . push args
196     68/push  "C"/imm32
197     68/push  _test-stream2/imm32
198     # . . call
199     e8/call  write/disp32
200     # . . discard args
201     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
202     # first write
203     # . write-stream(_test-stream, _test-stream2)
204     # . . push args
205     68/push  _test-stream2/imm32
206     68/push  _test-stream/imm32
207     # . . call
208     e8/call  write-stream/disp32
209     # . . discard args
210     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
211     # second write
212     # . write(_test-stream2, "D")
213     # . . push args
214     68/push  "D"/imm32
215     68/push  _test-stream2/imm32
216     # . . call
217     e8/call  write/disp32
218     # . . discard args
219     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
220     # . write-stream(_test-stream, _test-stream2)
221     # . . push args
222     68/push  _test-stream2/imm32
223     68/push  _test-stream/imm32
224     # . . call
225     e8/call  write-stream/disp32
226     # . . discard args
227     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
228     # check-stream-equal(_test-stream, "CD", msg)
229     # . . push args
230     68/push  "F - test-write-stream-appends"/imm32
231     68/push  "CD"/imm32
232     68/push  _test-stream/imm32
233     # . . call
234     e8/call  check-stream-equal/disp32
235     # . . discard args
236     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
237     # . end
238     c3/return
239 
240 == data
241 
242 _test-stream2:  # (stream byte)
243     # current write index
244     4/imm32
245     # current read index
246     1/imm32
247     # size
248     8/imm32
249     # data
250     41/A 42/B 43/C 44/D 00 00 00 00  # 8 bytes
251 
252 # . . vim:nowrap:textwidth=0