Mu - linux/116write-buffered.subx

From 3350c34a74844e21ea69077e01efff3bae64bdcd Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Tue, 23 Mar 2021 17:31:08 -0700 Subject: . --- html/linux/116write-buffered.subx.html | 291 +++++++++++++++++++++++++++++++++ 1 file changed, 291 insertions(+) create mode 100644 html/linux/116write-buffered.subx.html (limited to 'html/linux/116write-buffered.subx.html') diff --git a/html/linux/116write-buffered.subx.html b/html/linux/116write-buffered.subx.html new file mode 100644 index 00000000..94ca3278 --- /dev/null +++ b/html/linux/116write-buffered.subx.html @@ -0,0 +1,291 @@ + + + + +Mu - linux/116write-buffered.subx + + + + + + + + + + +https://github.com/akkartik/mu/blob/main/linux/116write-buffered.subx +
+  1 # write-buffered: like 'write', but for a buffered-file
+  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 write-buffered:  # f: (addr buffered-file), msg: (addr array byte)
+  9     # pseudocode:
+ 10     #   in = msg->data
+ 11     #   inend = &msg->data[msg->size]
+ 12     #   while (in < inend)
+ 13     #     if f->write >= f->size
+ 14     #       flush(f)
+ 15     #       clear-stream(f)
+ 16     #     c = *in
+ 17     #     f->data[f->write] = c
+ 18     #     ++f->write
+ 19     #     ++in
+ 20     #
+ 21     # registers:
+ 22     #   in: esi
+ 23     #   inend: ecx
+ 24     #   f: edi
+ 25     #   f->size: edx
+ 26     #   f->write: ebx (cached; need to keep in sync)
+ 27     #   c: eax
+ 28     #
+ 29     # . prologue
+ 30     55/push-ebp
+ 31     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+ 32     # . save registers
+ 33     50/push-eax
+ 34     51/push-ecx
+ 35     52/push-edx
+ 36     53/push-ebx
+ 37     56/push-esi
+ 38     57/push-edi
+ 39     # eax = msg
+ 40     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         0/r32/eax   0xc/disp8       .                 # copy *(ebp+12) to eax
+ 41     # var in/esi: (addr byte) = msg->data
+ 42     8d/copy-address                 1/mod/*+disp8   0/rm32/eax    .           .             .           6/r32/esi   4/disp8         .                 # copy eax+4 to esi
+ 43     # var inend/ecx: (addr byte) = &msg->data[msg->size]
+ 44     8b/copy                         0/mod/indirect  0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # copy *eax to ecx
+ 45     8d/copy-address                 0/mod/indirect  4/rm32/sib    6/base/esi  1/index/ecx   .           1/r32/ecx   .               .                 # copy esi+ecx to ecx
+ 46     # edi = f
+ 47     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         7/r32/edi   8/disp8         .                 # copy *(ebp+8) to edi
+ 48     # edx = f->size
+ 49     8b/copy                         1/mod/*+disp8   7/rm32/edi    .           .             .           2/r32/edx   0xc/disp8       .                 # copy *(edi+12) to edx
+ 50     # ebx = f->write
+ 51     8b/copy                         1/mod/*+disp8   7/rm32/edi    .           .             .           3/r32/ebx   4/disp8         .                 # copy *(edi+4) to ebx
+ 52 $write-buffered:loop:
+ 53     # if (in >= inend) break
+ 54     39/compare                      3/mod/direct    6/rm32/esi    .           .             .           1/r32/ecx   .               .                 # compare esi with ecx
+ 55     73/jump-if-addr>=  $write-buffered:loop-end/disp8
+ 56     # if (f->write >= f->size) flush and clear f's stream
+ 57     39/compare                      3/mod/direct    3/rm32/ebx    .           .             .           2/r32/edx   .               .                 # compare ebx with edx
+ 58     7c/jump-if-<  $write-buffered:to-stream/disp8
+ 59     # . persist f->write
+ 60     89/copy                         1/mod/*+disp8   7/rm32/edi    .           .             .           3/r32/ebx   4/disp8         .                 # copy ebx to *(edi+4)
+ 61     # . flush(f)
+ 62     # . . push args
+ 63     57/push-edi
+ 64     # . . call
+ 65     e8/call  flush/disp32
+ 66     # . . discard args
+ 67     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+ 68     # . clear-stream(stream = f+4)
+ 69     # . . push args
+ 70     8d/copy-address                 1/mod/*+disp8   7/rm32/edi    .           .             .           0/r32/eax   4/disp8         .                 # copy edi+4 to eax
+ 71     50/push-eax
+ 72     # . . call
+ 73     e8/call  clear-stream/disp32
+ 74     # . . discard args
+ 75     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+ 76     # . f->write must now be 0; update its cache at ebx
+ 77     31/xor                          3/mod/direct    3/rm32/ebx    .           .             .           3/r32/ebx   .               .                 # clear ebx
+ 78 $write-buffered:to-stream:
+ 79     # write to stream
+ 80     # f->data[f->write] = *in
+ 81     # . AL = *in
+ 82     31/xor                          3/mod/direct    0/rm32/eax    .           .             .           0/r32/eax   .               .                 # clear eax
+ 83     8a/copy-byte                    0/mod/indirect  6/rm32/esi    .           .             .           0/r32/AL    .               .                 # copy byte at *esi to AL
+ 84     # . f->data[f->write] = AL
+ 85     88/copy-byte                    1/mod/*+disp8   4/rm32/sib    7/base/edi  3/index/ebx   .           0/r32/AL    0x10/disp8      .                 # copy AL to *(edi+ebx+16)
+ 86     # ++f->write
+ 87     43/increment-ebx
+ 88     # ++in
+ 89     46/increment-esi
+ 90     eb/jump  $write-buffered:loop/disp8
+ 91 $write-buffered:loop-end:
+ 92     # persist necessary variables from registers
+ 93     89/copy                         1/mod/*+disp8   7/rm32/edi    .           .             .           3/r32/ebx   4/disp8         .                 # copy ebx to *(edi+4)
+ 94 $write-buffered:end:
+ 95     # . restore registers
+ 96     5f/pop-to-edi
+ 97     5e/pop-to-esi
+ 98     5b/pop-to-ebx
+ 99     5a/pop-to-edx
+100     59/pop-to-ecx
+101     58/pop-to-eax
+102     # . epilogue
+103     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+104     5d/pop-to-ebp
+105     c3/return
+106 
+107 test-write-buffered:
+108     # - check that write-buffered writes to the file
+109     # setup
+110     # . clear-stream(_test-stream)
+111     # . . push args
+112     68/push  _test-stream/imm32
+113     # . . call
+114     e8/call  clear-stream/disp32
+115     # . . discard args
+116     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+117     # . clear-stream($_test-buffered-file->buffer)
+118     # . . push args
+119     68/push  $_test-buffered-file->buffer/imm32
+120     # . . call
+121     e8/call  clear-stream/disp32
+122     # . . discard args
+123     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+124     # write-buffered(_test-buffered-file, "Abc")
+125     # . . push args
+126     68/push  "Abc"/imm32
+127     68/push  _test-buffered-file/imm32
+128     # . . call
+129     e8/call  write-buffered/disp32
+130     # . . discard args
+131     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+132     # flush(_test-buffered-file)
+133     # . . push args
+134     68/push  _test-buffered-file/imm32
+135     # . . call
+136     e8/call  flush/disp32
+137     # . . discard args
+138     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+139     # check-stream-equal(_test-stream, "Abc", msg)
+140     # . . push args
+141     68/push  "F - test-write-buffered-single"/imm32
+142     68/push  "Abc"/imm32
+143     68/push  _test-stream/imm32
+144     # . . call
+145     e8/call  check-stream-equal/disp32
+146     # . . discard args
+147     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+148     # . end
+149     c3/return
+150 
+151 test-write-buffered-with-intermediate-flush:
+152     # - check that write-buffered flushes in the middle if its buffer fills up
+153     # setup
+154     # . clear-stream(_test-stream)
+155     # . . push args
+156     68/push  _test-stream/imm32
+157     # . . call
+158     e8/call  clear-stream/disp32
+159     # . . discard args
+160     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+161     # . clear-stream($_test-buffered-file->buffer)
+162     # . . push args
+163     68/push  $_test-buffered-file->buffer/imm32
+164     # . . call
+165     e8/call  clear-stream/disp32
+166     # . . discard args
+167     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+168     # _test-stream can hold 8 bytes, but _test-buffered-file can hold only 6.
+169     # Try to write 7 bytes.
+170     # . write-buffered(_test-buffered-file, "Abcdefg")
+171     # . . push args
+172     68/push  "Abcdefg"/imm32
+173     68/push  _test-buffered-file/imm32
+174     # . . call
+175     e8/call  write-buffered/disp32
+176     # . . discard args
+177     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+178     # don't flush
+179     # 6 bytes should still have gotten to _test-stream
+180     # . check-ints-equal(*_test-stream->write, 6, msg)
+181     # . . push args
+182     68/push  "F - test-write-buffered-with-intermediate-flush: flushed data"/imm32
+183     68/push  6/imm32
+184     # . . push *_test-stream->write
+185     b8/copy-to-eax  _test-stream/imm32
+186     ff          6/subop/push        0/mod/indirect  0/rm32/eax    .           .             .           .           .               .                 # push *eax
+187     # . . call
+188     e8/call  check-ints-equal/disp32
+189     # . . discard args
+190     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+191     # and 1 byte should still be in _test-buffered-file
+192     # . check-ints-equal(*_test-buffered-file->write, 1, msg)
+193     # . . push args
+194     68/push  "F - test-write-buffered-with-intermediate-flush: unflushed bytes"/imm32
+195     68/push  1/imm32
+196     # . . push *_test-buffered-file->write
+197     b8/copy-to-eax  _test-buffered-file/imm32
+198     ff          6/subop/push        1/mod/*+disp8   0/rm32/eax    .           .             .           .           4/disp8         .                 # push *(eax+4)
+199     # . . call
+200     e8/call  check-ints-equal/disp32
+201     # . . discard args
+202     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+203     # . end
+204     c3/return
+205 
+206 == data
+207 
+208 # The buffered file for standard error.
+209 Stderr:  # buffered-file
+210     # file descriptor or (addr stream byte)
+211     2/imm32  # standard error
+212 $Stderr->buffer:
+213     # inlined fields for a stream
+214     #   current write index
+215     0/imm32
+216     #   current read index
+217     0/imm32
+218     #   size
+219     8/imm32
+220     #   data
+221     00 00 00 00 00 00 00 00  # 8 bytes
+222 
+223 # TODO: 8 bytes is too small. We'll need to grow the buffer for efficiency. But
+224 # I don't want to type in 1024 bytes here.
+225 
+226 # . . vim:nowrap:textwidth=0
+
+ + + -- cgit 1.4.1-2-gfad0