4906 - helper to allocate streams on the heap
This commit is contained in:
Kartik Agaram
parent
7b548ff5c5
commit
bc20cc3d45
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@ -149,4 +149,53 @@ test-allocate-failure:
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5d/pop-to-EBP
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c3/return
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# helper: create a nested allocation descriptor (useful for tests)
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allocate-region: # ad : (address allocation-descriptor), n : int -> new-ad : (address allocation-descriptor)
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# . prolog
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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 = allocate(ad, n)
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# . . push args
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ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 . # push *(EBP+12)
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ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8)
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# . . call
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e8/call allocate/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 abort
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81 7/subop/compare 3/mod/direct 0/rm32/EAX . . . . . 0/imm32 # compare EAX
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74/jump-if-equal $allocate-region:abort/disp8
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# earmark 8 bytes at the start for a new allocation descriptor
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# . *EAX = EAX + 8
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89/copy 3/mod/direct 1/rm32/ECX . . . 0/r32/EAX . . # copy EAX to ECX
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81 0/subop/add 3/mod/direct 1/rm32/ECX . . . . . 8/imm32 # add to ECX
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89/copy 0/mod/indirect 0/rm32/EAX . . . 1/r32/ECX . . # copy ECX to *EAX
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# . *(EAX+4) = EAX + n
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89/copy 3/mod/direct 1/rm32/ECX . . . 0/r32/EAX . . # copy EAX to ECX
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03/add 1/mod/*+disp8 5/rm32/EBP . . . 1/r32/ECX 0xc/disp8 . # add *(EBP+12) to ECX
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89/copy 1/mod/*+disp8 0/rm32/EAX . . . 1/r32/ECX 4/disp8 . # copy ECX to *(EAX+4)
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# . restore registers
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59/pop-to-ECX
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# . epilog
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89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
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5d/pop-to-EBP
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c3/return
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$allocate-region:abort:
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# . _write(2/stderr, error)
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# . . push args
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68/push "allocate-region: failed to allocate"/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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# . . vim:nowrap:textwidth=0
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@ -0,0 +1,126 @@
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# Helper to allocate a stream on the heap.
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#
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# We'll now start gingerly supporting streams containing arbitrary types.
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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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# main:
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e8/call run-tests/disp32 # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'.
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# syscall(exit, Num-test-failures)
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8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX
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b8/copy-to-EAX 1/imm32/exit
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cd/syscall 0x80/imm8
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new-stream: # ad : (address allocation-descriptor), length : int, elemsize : int -> address/EAX
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# . prolog
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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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52/push-EDX
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# n = elemsize * length + 12 (for read, write and length)
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# . EAX = elemsize
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8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 0/r32/EAX 0x10/disp8 . # copy *(EBP+16) to EAX
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# . EAX *= length
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31/xor 3/mod/direct 2/rm32/EDX . . . 2/r32/EDX . . # clear EDX
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f7 4/subop/multiply 1/mod/*+disp8 5/rm32/EBP . . 0xc/disp8 . # multiply *(EBP+12) into EAX
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# . if overflow abort
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81 7/subop/compare 3/mod/direct 2/rm32/EDX . . . . . 0/imm32 # compare EDX
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75/jump-if-not-equal $new-stream:abort/disp8
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# . EDX = elemsize*length
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89/copy 3/mod/direct 2/rm32/EDX . . . 0/r32/EAX . . # copy EAX to EDX
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# . EAX += 12
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05/add-to-EAX 0xc/imm32
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# allocate(ad, n)
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# . . push args
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50/push-EAX
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ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8)
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# . . call
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e8/call allocate/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
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# EAX->length = elemsize*length
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89/copy 1/mod/*+disp8 0/rm32/EAX . . . 2/r32/EDX 8/disp8 . # copy EDX to *(EAX+8)
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# clear-stream(EAX)
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# . . push args
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50/push-EAX
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
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$new-stream:end:
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# . restore registers
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5a/pop-to-EDX
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# . epilog
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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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$new-stream:abort:
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# . _write(2/stderr, error)
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# . . push args
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68/push "new-stream: size too large"/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-new-stream:
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# . prolog
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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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# var ad/ECX : (address allocation-descriptor) = allocate-region(512)
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# . EAX = allocate-region(512)
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# . . push args
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68/push 0x200/imm32
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68/push Heap/imm32
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# . . call
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e8/call allocate-region/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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# . ECX = EAX
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89/copy 3/mod/direct 1/rm32/ECX . . . 0/r32/EAX . . # copy EAX to ECX
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# var start/EDX = ad->curr
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8b/copy 0/mod/indirect 1/rm32/ECX . . . 2/r32/EDX . . # copy *ECX to EDX
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# EAX = new-stream(ad, 3, 2)
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# . . push args
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68/push 2/imm32
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68/push 3/imm32
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51/push-ECX
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# . . call
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e8/call new-stream/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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# check-ints-equal(EAX, EDX, msg)
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# . . push args
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68/push "F - test-new-stream: returns current pointer of allocation descriptor"/imm32
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52/push-EDX
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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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# check-ints-equal(EAX->length, 6, msg)
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# . . push args
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68/push "F - test-new-stream: sets length correctly"/imm32
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68/push 6/imm32
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ff 6/subop/push 1/mod/*+disp8 0/rm32/EAX . . . . . 8/disp8 # push *(EAX+8)
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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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# the rest is delegated to clear-stream() so we won't bother checking it
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# . epilog
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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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