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.
244 lines
11 KiB
Plaintext
244 lines
11 KiB
Plaintext
# Helpers to compute widths of SubX arguments based on their metadata.
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# /imm8 => 1 byte,
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# /disp32 => 4 bytes,
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# and so on.
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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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compute-width: # word: (addr array byte) -> eax: 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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51/push-ecx
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# eax = word
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8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 8/disp8 . # copy *(ebp+8) to ecx
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# var ecx: (addr byte) = &word[word->size]
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8b/copy 0/mod/indirect 0/rm32/eax . . . 1/r32/ecx . . # copy *eax to ecx
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8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/eax 1/index/ecx . 1/r32/ecx 4/disp8 . # copy eax+ecx+4 to ecx
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# eax = word->data
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05/add-to-eax 4/imm32
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# var in/ecx: slice = {eax, ecx}
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51/push-ecx
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50/push-eax
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89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
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# return compute-width-of-slice(ecx)
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# . . push args
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51/push-ecx
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# . . call
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e8/call compute-width-of-slice/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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$compute-width:end:
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# . reclaim locals
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
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# . restore registers
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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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compute-width-of-slice: # s: (addr slice) -> eax: 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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51/push-ecx
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# ecx = s
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8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx
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# if (has-metadata?(word, "imm32")) return 4
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# . eax = has-metadata?(word, "imm32")
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# . . push args
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68/push "imm32"/imm32
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51/push-ecx
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# . . call
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e8/call has-metadata?/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 != false) return 4
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3d/compare-eax-and 0/imm32/false
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b8/copy-to-eax 4/imm32 # ZF is set, so we can overwrite eax now
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75/jump-if-!= $compute-width-of-slice:end/disp8
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# if (has-metadata?(word, "disp32")) return 4
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# . eax = has-metadata?(word, "disp32")
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# . . push args
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68/push "disp32"/imm32
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51/push-ecx
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# . . call
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e8/call has-metadata?/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 != false) return 4
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3d/compare-eax-and 0/imm32/false
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b8/copy-to-eax 4/imm32 # ZF is set, so we can overwrite eax now
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75/jump-if-!= $compute-width-of-slice:end/disp8
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# if (has-metadata?(word, "imm16")) return 2
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# . eax = has-metadata?(word, "imm16")
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# . . push args
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68/push "imm16"/imm32
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51/push-ecx
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# . . call
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e8/call has-metadata?/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 != false) return 2
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3d/compare-eax-and 0/imm32/false
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b8/copy-to-eax 2/imm32 # ZF is set, so we can overwrite eax now
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75/jump-if-!= $compute-width-of-slice:end/disp8
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# if (has-metadata?(word, "disp16")) return 2
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# . eax = has-metadata?(word, "disp16")
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# . . push args
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68/push "disp16"/imm32
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51/push-ecx
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# . . call
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e8/call has-metadata?/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 != false) return 2
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3d/compare-eax-and 0/imm32/false
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b8/copy-to-eax 2/imm32 # ZF is set, so we can overwrite eax now
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75/jump-if-!= $compute-width-of-slice:end/disp8
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# otherwise return 1
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b8/copy-to-eax 1/imm32
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$compute-width-of-slice:end:
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# . restore registers
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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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test-compute-width:
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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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$test-compute-width:imm8:
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# eax = compute-width("0x2/imm8")
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# . . push args
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68/push "0x2/imm8"/imm32
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# . . call
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e8/call compute-width/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# check-ints-equal(eax, 1, msg)
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# . . push args
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68/push "F - test-compute-width: 0x2/imm8"/imm32
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50/push-eax
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68/push 1/imm32
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
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$test-compute-width:imm16:
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# eax = compute-width("4/imm16")
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# . . push args
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68/push "4/imm16"/imm32
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# . . call
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e8/call compute-width/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, 2, msg)
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# . . push args
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68/push "F - test-compute-width: 4/imm16"/imm32
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50/push-eax
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68/push 2/imm32
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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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$test-compute-width:imm32:
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# eax = compute-width("4/imm32")
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# . . push args
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68/push "4/imm32"/imm32
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# . . call
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e8/call compute-width/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# check-ints-equal(eax, 4, msg)
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# . . push args
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68/push "F - test-compute-width: 4/imm32"/imm32
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50/push-eax
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68/push 4/imm32
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
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$test-compute-width:disp8:
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# eax = compute-width("foo/disp8")
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# . . push args
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68/push "foo/disp8"/imm32
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# . . call
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e8/call compute-width/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, 1, msg)
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# . . push args
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68/push "F - test-compute-width: foo/disp8"/imm32
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50/push-eax
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68/push 1/imm32
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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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$test-compute-width:disp16:
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# eax = compute-width("foo/disp16")
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# . . push args
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68/push "foo/disp16"/imm32
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# . . call
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e8/call compute-width/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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# check-ints-equal(eax, 2, msg)
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# . . push args
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68/push "F - test-compute-width: foo/disp16"/imm32
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50/push-eax
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68/push 2/imm32
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
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$test-compute-width:disp32:
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# eax = compute-width("foo/disp32")
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# . . push args
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68/push "foo/disp32"/imm32
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# . . call
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e8/call compute-width/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, 4, msg)
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# . . push args
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68/push "F - test-compute-width: foo/disp32"/imm32
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50/push-eax
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68/push 4/imm32
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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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$test-compute-width:no-metadata:
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# eax = compute-width("45")
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# . . push args
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68/push "45"/imm32
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# . . call
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e8/call compute-width/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, 1, msg)
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# . . push args
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68/push "F - test-compute-width: 45 (no metadata)"/imm32
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50/push-eax
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68/push 1/imm32
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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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# . 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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# . . vim:nowrap:textwidth=0
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