72c42f90cf
We don't yet support emulating these instructions in `bootstrap`. But generated binaries containing them run natively just fine.
419 lines
19 KiB
Plaintext
419 lines
19 KiB
Plaintext
# read-byte-buffered: one higher-level abstraction atop 'read'.
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#
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# There are many situations where 'read' is a lot to manage, and we need
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# to abstract some details away. One of them is when we want to read a file
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# character by character. In this situation we follow C's FILE data structure,
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# which manages the underlying file descriptor together with the buffer it
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# reads into. We call our version 'buffered-file'. Should be useful with other
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# primitives as well, in later layers.
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== data
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# The buffered file for standard input. Also illustrates the layout for
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# buffered-file: a pointer to the backing store, followed by a 'buffer' stream
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Stdin: # buffered-file
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# file descriptor or (addr stream byte)
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0/imm32 # standard input
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$Stdin->buffer:
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# inlined fields for a stream
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# current write index
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0/imm32
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# current read index
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0/imm32
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# size
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8/imm32
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# data
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00 00 00 00 00 00 00 00 # 8 bytes
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# TODO: 8 bytes is too small. We'll need to grow the buffer for efficiency. But
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# I don't want to type in 1024 bytes here.
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== code
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# instruction effective address register displacement immediate
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# . op subop mod rm32 base index scale r32
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# . 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
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# Return next byte value in eax, with top 3 bytes cleared.
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# On reaching end of file, return 0xffffffff (Eof).
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read-byte-buffered: # f: (addr buffered-file) -> byte-or-Eof/eax: byte
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# . prologue
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55/push-ebp
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89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
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# . save registers
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51/push-ecx
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56/push-esi
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# esi = f
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8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 8/disp8 . # copy *(ebp+8) to esi
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# ecx = f->read
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8b/copy 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 8/disp8 . # copy *(esi+8) to ecx
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# if (f->read >= f->write) populate stream from file
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3b/compare 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 4/disp8 . # compare ecx with *(esi+4)
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7c/jump-if-< $read-byte-buffered:from-stream/disp8
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# . clear-stream(stream = f+4)
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# . . push args
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8d/copy-address 1/mod/*+disp8 6/rm32/esi . . . 0/r32/eax 4/disp8 . # copy esi+4 to eax
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50/push-eax
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# . f->read must now be 0; update its cache at ecx
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31/xor 3/mod/direct 1/rm32/ecx . . . 1/r32/ecx . . # clear ecx
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# . eax = read(f->fd, stream = f+4)
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# . . push args
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50/push-eax
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ff 6/subop/push 0/mod/indirect 6/rm32/esi . . . . . . # push *esi
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# . . call
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e8/call read/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
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# if (eax == 0) return 0xffffffff
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3d/compare-eax-and 0/imm32
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75/jump-if-!= $read-byte-buffered:from-stream/disp8
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b8/copy-to-eax 0xffffffff/imm32/Eof
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eb/jump $read-byte-buffered:end/disp8
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$read-byte-buffered:from-stream:
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# byte-or-Eof = f->data[f->read]
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31/xor 3/mod/direct 0/rm32/eax . . . 0/r32/eax . . # clear eax
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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
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# ++f->read
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ff 0/subop/increment 1/mod/*+disp8 6/rm32/esi . . . . 8/disp8 . # increment *(esi+8)
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$read-byte-buffered:end:
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# . restore registers
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5e/pop-to-esi
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59/pop-to-ecx
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# . epilogue
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89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
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5d/pop-to-ebp
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c3/return
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# - tests
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test-read-byte-buffered-single:
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# - check that read-byte-buffered returns first byte of 'file'
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# setup
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# . clear-stream(_test-stream)
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# . . push args
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68/push _test-stream/imm32
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# . clear-stream(_test-buffered-file->buffer)
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# . . push args
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68/push $_test-buffered-file->buffer/imm32
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# . write(_test-stream, "Ab")
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# . . push args
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68/push "Ab"/imm32
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68/push _test-stream/imm32
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# . . call
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e8/call write/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
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# read-byte-buffered(_test-buffered-file)
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# . . push args
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68/push _test-buffered-file/imm32
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# . . call
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e8/call read-byte-buffered/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# check-ints-equal(eax, 'A', msg)
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# . . push args
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68/push "F - test-read-byte-buffered-single"/imm32
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68/push 0x41/imm32
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50/push-eax
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
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# . end
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c3/return
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test-read-byte-buffered-multiple:
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# - call read-byte-buffered twice, check that second call returns second byte
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# setup
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# . clear-stream(_test-stream)
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# . . push args
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68/push _test-stream/imm32
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# . clear-stream($_test-buffered-file->buffer)
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# . . push args
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68/push $_test-buffered-file->buffer/imm32
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# . write(_test-stream, "Ab")
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# . . push args
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68/push "Ab"/imm32
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68/push _test-stream/imm32
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# . . call
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e8/call write/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
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# read-byte-buffered(_test-buffered-file)
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# . . push args
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68/push _test-buffered-file/imm32
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# . . call
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e8/call read-byte-buffered/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# read-byte-buffered(_test-buffered-file)
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# . . push args
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68/push _test-buffered-file/imm32
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# . . call
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e8/call read-byte-buffered/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# check-ints-equal(eax, 'b', msg)
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# . . push args
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68/push "F - test-read-byte-buffered-multiple"/imm32
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68/push 0x62/imm32
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50/push-eax
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
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# . end
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c3/return
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test-read-byte-buffered-end-of-file:
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# - call read-byte-buffered on an empty 'file', check that it returns Eof
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# setup
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# . clear-stream(_test-stream)
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# . . push args
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68/push _test-stream/imm32
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# . clear-stream($_test-buffered-file->buffer)
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# . . push args
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68/push $_test-buffered-file->buffer/imm32
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# read-byte-buffered(_test-buffered-file)
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# . . push args
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68/push _test-buffered-file/imm32
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# . . call
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e8/call read-byte-buffered/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# check-ints-equal(eax, 0xffffffff, msg)
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# . . push args
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68/push "F - test-read-byte-buffered-end-of-file"/imm32
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68/push 0xffffffff/imm32/Eof
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50/push-eax
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
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# . end
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c3/return
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test-read-byte-buffered-refills-buffer:
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# - consume buffered-file's buffer, check that next read-byte-buffered still works
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# setup
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# . clear-stream(_test-stream)
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# . . push args
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68/push _test-stream/imm32
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# . clear-stream($_test-buffered-file->buffer)
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# . . push args
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68/push $_test-buffered-file->buffer/imm32
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# . write(_test-stream, "Abcdefgh")
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# . . push args
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68/push "Abcdefgh"/imm32
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68/push _test-stream/imm32
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# . . call
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e8/call write/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
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# pretend buffer is full
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# . _test-buffered-file->read = 6 # >= _test-buffered-file->size
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b8/copy-to-eax _test-buffered-file/imm32
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c7 0/subop/copy 1/mod/*+disp8 0/rm32/eax . . . . 8/disp8 6/imm32 # copy to *(eax+8)
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# read-byte-buffered(_test-buffered-file)
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# . . push args
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68/push _test-buffered-file/imm32
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# . . call
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e8/call read-byte-buffered/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# check-ints-equal(eax, 'A', msg)
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# . . push args
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68/push "F - test-read-byte-buffered-refills-buffer"/imm32
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68/push 0x41/imm32
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50/push-eax
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
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# . end
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c3/return
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# Return next byte value in eax, with top 3 bytes cleared.
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# Abort on reaching end of stream.
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read-byte: # s: (addr stream byte) -> result/eax: byte
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# . prologue
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55/push-ebp
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89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
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# . save registers
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51/push-ecx
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56/push-esi
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# esi = s
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8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 8/disp8 . # copy *(ebp+8) to esi
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# ecx = s->read
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8b/copy 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 4/disp8 . # copy *(esi+4) to ecx
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# if (f->read >= f->write) abort
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3b/compare 0/mod/indirect 6/rm32/esi . . . 1/r32/ecx . . # compare ecx with *esi
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0f 8d/jump-if->= $read-byte:abort/disp32
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# result = f->data[f->read]
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31/xor 3/mod/direct 0/rm32/eax . . . 0/r32/eax . . # clear eax
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8a/copy-byte 1/mod/*+disp8 4/rm32/sib 6/base/esi 1/index/ecx . 0/r32/AL 0xc/disp8 . # copy byte at *(esi+ecx+12) to AL
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# ++f->read
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ff 0/subop/increment 1/mod/*+disp8 6/rm32/esi . . . . 4/disp8 . # increment *(esi+4)
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$read-byte:end:
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# . restore registers
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5e/pop-to-esi
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59/pop-to-ecx
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# . epilogue
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89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
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5d/pop-to-ebp
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c3/return
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$read-byte:abort:
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# . _write(2/stderr, error)
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# . . push args
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68/push "read-byte: empty stream\n"/imm32
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68/push 2/imm32/stderr
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# . . call
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e8/call _write/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
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# . syscall(exit, 1)
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bb/copy-to-ebx 1/imm32
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e8/call syscall_exit/disp32
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# never gets here
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== data
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# a test buffered file for _test-stream
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_test-buffered-file: # buffered-file
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# file descriptor or (addr stream byte)
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_test-stream/imm32
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$_test-buffered-file->buffer:
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# current write index
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0/imm32
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# current read index
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0/imm32
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# size
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6/imm32
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# data
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00 00 00 00 00 00 # 6 bytes
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_test-input-stream: # (stream byte)
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# current write index
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0/imm32
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# current read index
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0/imm32
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# size
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0x400/imm32 # 1024 bytes
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# data (64 lines x 16 bytes/line)
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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# a test buffered file for _test-input-stream
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_test-input-buffered-file: # buffered-file
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# file descriptor or (addr stream byte)
|
|
_test-input-stream/imm32
|
|
$_test-input-buffered-file->buffer:
|
|
# current write index
|
|
0/imm32
|
|
# current read index
|
|
0/imm32
|
|
# size
|
|
6/imm32
|
|
# data
|
|
00 00 00 00 00 00 # 6 bytes
|
|
|
|
# . . vim:nowrap:textwidth=0
|