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November 24, 2013 23:33
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| # | |
| # CRAP2a for Darwin-i386-MachO | |
| # Copyright (C) 2013, Dan Glastonbury <dan.glastonbury@gmail.com> | |
| # | |
| # Uses BSS section for data storage. | |
| # | |
| # Based on: | |
| # HEX2a for Linux-i386-ELF | |
| # Copyright (C) 2001, Edmund GRIMLEY EVANS <edmundo@rano.org> | |
| # | |
| # _mach_header: # struct mach_header | |
| ce fa ed fe # magic | |
| 07 00 00 00 # cputype (CPU_TYPE_X86_TYPE_X86) | |
| 03 00 00 00 # cpusubtype (CPU_SUBTYPE_I386_ALL) | |
| 02 00 00 00 # filetype (MH_EXECUTE) | |
| 03 00 00 00 # ncmds | |
| 48 01 00 00 # sizeofcmds = 328 | |
| 00 00 00 00 # flags | |
| # +28 | |
| # Text Segment # struct segment_command | |
| 01 00 00 00 # cmd (LC_SEGMENT) | |
| 7c 00 00 00 # cmdsize = 124 | |
| 5f 5f 54 45 58 54 00 00 00 00 00 00 00 00 00 00 # segname[16] = '__TEXT' | |
| 00 10 00 00 # vmaddr = 0x1000 | |
| 00 10 00 00 # vmsize = 0x1000 | |
| 00 00 00 00 # fileoff | |
| 5e 02 00 00 # filesize = 605 | |
| 07 00 00 00 # maxprot | |
| 05 00 00 00 # initprot | |
| 01 00 00 00 # nsects | |
| 00 00 00 00 # flags | |
| # +56 | |
| # Text section # struct section | |
| 5f 5f 74 65 78 74 00 00 00 00 00 00 00 00 00 00 # sectname[16] = '__text' | |
| 5f 5f 54 45 58 54 00 00 00 00 00 00 00 00 00 00 # segname[16] = '__TEXT' | |
| 64 11 00 00 # addr = 0x10E8 | |
| fa 00 00 00 # size = 0xF9 (249) | |
| 64 01 00 00 # offset = 0x164 (356) | |
| 02 00 00 00 # align | |
| 00 00 00 00 # reloff | |
| 00 00 00 00 # nreloc | |
| 00 00 00 00 # flags | |
| 00 00 00 00 # reserved1 | |
| 00 00 00 00 # reserved2 | |
| # +68 | |
| # Data Segment # struct segment_command | |
| 01 00 00 00 # cmd (LC_SEGMENT) | |
| 7c 00 00 00 # cmdsize = 124 | |
| 5f 5f 44 41 54 41 00 00 00 00 00 00 00 00 00 00 # segname[16] = '__DATA' | |
| 00 20 00 00 # vmaddr = 0x1000 | |
| 00 10 00 00 # vmsize = 0x1000 | |
| 00 00 00 00 # fileoff | |
| 00 00 00 00 # filesize = 484 | |
| 07 00 00 00 # maxprot | |
| 03 00 00 00 # initprot | |
| 01 00 00 00 # nsects | |
| 00 00 00 00 # flags | |
| # +56 | |
| # BSS section # struct section | |
| 5f 5f 62 73 73 00 00 00 00 00 00 00 00 00 00 00 # sectname[16] = '__text' | |
| 5f 5f 44 41 54 41 00 00 00 00 00 00 00 00 00 00 # segname[16] = '__DATA' | |
| 00 20 00 00 # addr = 0x2000 | |
| 04 04 00 00 # size = 0x0404 (1028) | |
| 00 00 00 00 # offset | |
| 02 00 00 00 # align | |
| 00 00 00 00 # reloff | |
| 00 00 00 00 # nreloc | |
| 01 00 00 00 # flags | |
| 00 00 00 00 # reserved1 | |
| 00 00 00 00 # reserved2 | |
| # +68 | |
| # Unix Thread # struct thread_command | |
| 05 00 00 00 # cmd (LC_UNIXTHREAD) | |
| 50 00 00 00 # cmdsize = 80 | |
| 01 00 00 00 # flavor = i386_THREAD_STATE | |
| 10 00 00 00 # count | |
| # state: dd 0, 0, 0, 0, 0, 0, 0, 0 | |
| # dd 0, 0, _start, 0, 0, 0, 0, 0 | |
| 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | |
| 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | |
| 00 00 00 00 00 00 00 00 3f 12 00 00 00 00 00 00 | |
| 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | |
| # +80 | |
| # Enter here: = 0x164 | |
| # _syscall: | |
| cd 80 # int 80h | |
| c3 # ret | |
| # _exit: | |
| 31 c0 # xor eax, eax | |
| 50 # push eax ; return 0 | |
| b0 01 # mov al, sys_exit | |
| e8 f3 ff ff ff # call _syscall | |
| # _getchar: ; read a byte from stdin | |
| 31 c0 # xor eax, eax | |
| 50 # push eax ; storage for ch | |
| 89 e1 # mov ecx, esp ; &ch | |
| 6a 01 # push 1 ; read 1 byte | |
| 51 # push ecx ; into [ecx] | |
| 6a 00 # push stdin_fileno ; from standard input | |
| b0 03 # mov al, sys_read | |
| e8 e2 ff ff ff # call _syscall | |
| 85 c0 # test eax, eax | |
| 74 e1 # je _exit | |
| 83 c4 0c # add esp, 12 | |
| 58 # pop eax ; result in eax | |
| c3 # ret | |
| # _putchar: | |
| 8d 4c 24 04 # lea ecx, [esp+4] | |
| 31 c0 # xor eax, eax | |
| 6a 01 # push 1 ; write 1 byte | |
| 51 # push ecx ; from [ecx] | |
| 6a 01 # push stdout_fileno ; into standard output | |
| b0 04 # mov al, sys_write | |
| e8 c7 ff ff ff # call _syscall | |
| 83 c4 0c # add esp, 12 | |
| c3 # ret | |
| # _gethex: | |
| e8 cb ff ff ff # call _getchar | |
| 83 f8 20 # cmp eax, ' ' | |
| 7e f6 # jle _gethex | |
| 83 f8 23 # cmp eax, '#' | |
| 75 0c # jne .l1 | |
| # .loop: ; comment | |
| e8 bc ff ff ff # call _getchar | |
| 83 f8 0a # cmp eax, lf | |
| 75 f6 # jne .loop | |
| eb e5 # jmp _gethex | |
| # .l1: ; if .x, store position into label[x] | |
| 83 f8 2e # cmp eax, '.' | |
| 75 1b # jne .l2 | |
| e8 ab ff ff ff # call _getchar | |
| 25 ff 00 00 00 # and eax, 0xff | |
| 8d 3c 85 00 20 00 00 # lea edi, [labels+4*eax] | |
| 8b 15 00 24 00 00 # mov edx, [pos] | |
| 89 17 # mov [edi], edx | |
| eb c5 # jmp _gethex | |
| # .l2: ; check for 0-9 | |
| 83 f8 30 # cmp eax, '0' | |
| 7c 09 # jl .l3 | |
| 83 f8 3a # cmp eax, ':' | |
| 7d 04 # jge .l3 | |
| 83 e8 30 # sub eax, '0' | |
| c3 # ret | |
| # .l3: ; check for a-f | |
| 83 f8 61 # cmp eax, 'a' | |
| 7c 09 # jl .l4 | |
| 83 f8 67 # cmp eax, 'g' | |
| 7d 04 # jge .l4 | |
| 83 e8 57 # sub eax, 0x57 | |
| c3 # ret | |
| # .l4: ; handle single char label | |
| 25 ff 00 00 00 # and eax, 0xff | |
| 8d 34 85 00 20 00 00 # lea esi, [labels+4*eax] | |
| 8b 16 # mov edx, [esi] ; .x position | |
| a1 00 24 00 00 # mov eax, [pos] ; current position | |
| 83 c0 04 # add eax, 4 | |
| a3 00 24 00 00 # mov [pos], eax ; update position | |
| 29 c2 # sub edx, eax | |
| 52 # push edx | |
| e8 70 ff ff ff # call _putchar | |
| 5a # pop edx | |
| c1 fa 08 # sar edx, 8 | |
| 52 # push edx | |
| e8 66 ff ff ff # call _putchar | |
| 5a # pop edx | |
| c1 fa 08 # sar edx, 8 | |
| 52 # push edx | |
| e8 5c ff ff ff # call _putchar | |
| 5a # pop edx | |
| c1 fa 08 # sar edx, 8 | |
| 52 # push edx | |
| e8 52 ff ff ff # call _putchar | |
| 5a # pop edx | |
| e9 62 ff ff ff # jmp _gethex | |
| # _start: | |
| e8 5d ff ff ff # call _gethex | |
| c1 e0 04 # sal eax, 4 | |
| 50 # push eax | |
| e8 54 ff ff ff # call _gethex | |
| 01 04 24 # add [esp], eax | |
| e8 36 ff ff ff # call _putchar | |
| 58 # pop eax | |
| ff 05 00 24 00 00 # inc dword [pos] | |
| eb e1 # jmp _start | |
| # _end: |
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