mu/linux/125write-stream-data.subx

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== code
# instruction effective address register displacement immediate
# . op subop mod rm32 base index scale r32
# . 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
# write an entire stream's contents to a buffered-file
# ways to do this:
# - construct a 'maximal slice' and pass it to write-slice-buffered
# - flush the buffered-file and pass the stream directly to its fd (disabling buffering)
# we'll go with the first way for now
write-stream-data: # f: (addr buffered-file), s: (addr stream byte)
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
51/push-ecx
56/push-esi
# esi = s
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 0xc/disp8 . # copy *(ebp+12) to esi
# var slice/ecx: slice = {s->data, &s->data[s->write]}
# . push &s->data[s->write]
8b/copy 0/mod/indirect 6/rm32/esi . . . 0/r32/eax . . # copy *esi to eax
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/push-eax
# . push s->data
8d/copy-address 1/mod/*+disp8 6/rm32/esi . . . 0/r32/eax 0xc/disp8 . # copy esi+12 to eax
50/push-eax
# . ecx = esp
89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
# write-slice-buffered(f, slice)
# . . push args
51/push-ecx
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8)
# . . call
e8/call write-slice-buffered/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
$write-stream-data:end:
# . restore locals
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# . restore registers
5e/pop-to-esi
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
test-write-stream-data:
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# setup
# . clear-stream(_test-output-stream)
# . . push args
68/push _test-output-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . clear-stream($_test-output-buffered-file->buffer)
# . . push args
68/push $_test-output-buffered-file->buffer/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . clear-stream(_test-input-stream)
# . . push args
68/push _test-input-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# initialize input
# . write(_test-input-stream, "abcd")
# . . push args
68/push "abcd"/imm32
68/push _test-input-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# write-stream-data(_test-output-buffered-file, _test-input-stream)
# . . push args
68/push _test-input-stream/imm32
68/push _test-output-buffered-file/imm32
# . . call
e8/call write-stream-data/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# check that the write happened as expected
# . flush(_test-output-buffered-file)
# . . push args
68/push _test-output-buffered-file/imm32
# . . call
e8/call flush/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . check-stream-equal(_test-output-stream, "abcd", msg)
# . . push args
68/push "F - test-write-stream-data"/imm32
68/push "abcd"/imm32
68/push _test-output-stream/imm32
# . . call
e8/call check-stream-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return