bfcc0f858a
So far it's unclear how to do this in a series of small commits. Still nibbling around the edges. In this commit we standardize some terminology: The length of an array or stream is denominated in the high-level elements. The _size_ is denominated in bytes. The thing we encode into the type is always the size, not the length. There's still an open question of what to do about the Mu `length` operator. I'd like to modify it to provide the length. Currently it provides the size. If I can't fix that I'll rename it.
123 lines
5.5 KiB
Plaintext
123 lines
5.5 KiB
Plaintext
# write-int: add a single int to a stream
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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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write-int: # out: (addr stream byte), n: int
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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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50/push-eax
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51/push-ecx
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57/push-edi
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# edi = out
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8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 7/r32/edi 8/disp8 . # copy *(ebp+8) to edi
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# ecx = out->write
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8b/copy 0/mod/indirect 7/rm32/edi . . . 1/r32/ecx . . # copy *edi to ecx
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# if (out->write >= out->size) abort
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3b/compare 1/mod/*+disp8 7/rm32/edi . . . 1/r32/ecx 8/disp8 . # compare ecx with *(edi+8)
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7d/jump-if->= $write-int:abort/disp8
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$write-int:to-stream:
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# out->data[out->write] = n
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8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0xc/disp8 . # copy *(ebp+12) to eax
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89/copy 1/mod/*+disp8 4/rm32/sib 7/base/edi 1/index/ecx . 0/r32/eax 0xc/disp8 . # copy eax to *(edi+ecx+12)
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# out->write += 4
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81 0/subop/add 0/mod/indirect 7/rm32/edi . . . . . 4/imm32 # add to *edi
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$write-int:end:
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# . restore registers
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5f/pop-to-edi
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59/pop-to-ecx
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58/pop-to-eax
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# . epilogue
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89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
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5d/pop-to-ebp
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c3/return
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$write-int:abort:
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# . _write(2/stderr, error)
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# . . push args
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68/push "write-int: out of space\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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b8/copy-to-eax 1/imm32/exit
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cd/syscall 0x80/imm8
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# never gets here
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test-write-int-single:
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# - check that write-int writes to first int of 'stream'
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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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# write-int(_test-stream, "abcd")
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# . . push args
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68/push 0x64636261/imm32
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68/push _test-stream/imm32
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# . . call
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e8/call write-int/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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# check-stream-equal(_test-stream, "abcd", msg)
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# . . push args
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68/push "F - test-write-int-single"/imm32
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68/push "abcd"/imm32
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68/push _test-stream/imm32
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# . . call
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e8/call check-stream-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-write-byte-buffered-multiple:
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# - check that write-int correctly appends multiple writes
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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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# write-int(_test-stream, "abcd")
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# . . push args
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68/push 0x64636261/imm32
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68/push _test-stream/imm32
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# . . call
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e8/call write-int/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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# write-int(_test-stream, "efgh")
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# . . push args
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68/push 0x68676665/imm32
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68/push _test-stream/imm32
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# . . call
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e8/call write-int/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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# check-stream-equal(_test-stream, "abcdefgh", msg)
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# . . push args
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68/push "F - test-write-byte-buffered-multiple"/imm32
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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 check-stream-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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# . . vim:nowrap:textwidth=0
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