Ein Brainfuck Interpreter/Compiler in x86 Assembly, zwar nicht von mir, aber egal.
Code: 
;; bf.asm: Copyright (C) 1999-2001 by Brian Raiter, under the GNU
;; General Public License (version 2 or later). No warranty.
;;
;; To build:
;;nasm -f bin -o bf bf.asm && chmod +x bf
;; To use:
;;bf < foo.b > foo && chmod +x foo

BITS 32

;; This is the size of the data area supplied to compiled programs.

%define arraysize30000

;; For the compiler, the text segment is also the data segment. The
;; memory image of the compiler is inside the code buffer, and is
;; modified in place to become the memory image of the compiled
;; program. The area of memory that is the data segment for compiled
;; programs is not used by the compiler. The text and data segments of
;; compiled programs are really only different areas in a single
;; segment, from the system's point of view. Both the compiler and
;; compiled programs load the entire file contents into a single
;; memory segment which is both writable and executable.

%defineTEXTORG0x45E9B000
%defineDATAOFFSET0x2000
%defineDATAORG(TEXTORG + DATAOFFSET)

;; Here begins the file image.

orgTEXTORG

;; At the beginning of the text segment is the ELF header and the
;; program header table, the latter consisting of a single entry. The
;; two structures overlap for a space of eight bytes. Nearly all
;; unused fields in the structures are used to hold bits of code.

;; The beginning of the ELF header.

db0x7F, "ELF"; ehdr.e_ident

;; The top(s) of the main compiling loop. The loop jumps back to
;; different positions, depending on how many bytes to copy into the
;; code buffer. After doing that, esi is initialized to point to the
;; epilog code chunk, a copy of edi (the pointer to the end of the
;; code buffer) is saved in ebp, the high bytes of eax are reset to
;; zero (via the exchange with ebx), and then the next character of
;; input is retrieved.

emitputchar:addesi, byte (putchar - decchar) - 4
emitgetchar:lodsd
emit6bytes:movsd
emit2bytes:movsb
emit1byte:movsb
compile:leaesi, [byte ecx + epilog - filesize]
xchgeax, ebx
cmpeax, 0x00030002; ehdr.e_type    (0x0002)
; ehdr.e_machine (0x0003)
movebp, edi; ehdr.e_version
jmpshort getchar

;; The entry point for the compiler (and compiled programs), and the
;; location of the program header table.

dd_start; ehdr.e_entry
ddproghdr - $$; ehdr.e_phoff

;; The last routine of the compiler, called when there is no more
;; input. The epilog code chunk is copied into the code buffer. The
;; text origin is popped off the stack into ecx, and subtracted from
;; edi to determine the size of the compiled program. This value is
;; stored in the program header table, and then is moved into edx.
;; The program then jumps to the putchar routine, which sends the
;; compiled program to stdout before falling through to the epilog
;; routine and exiting.

eof:movsd; ehdr.e_shoff
xchgeax, ecx
popecx
subedi, ecx; ehdr.e_flags
xchgeax, edi
stosd
xchgeax, edx
jmpshort putchar; ehdr.e_ehsize

;; 0x20 == the size of one program header table entry.

dw0x20; ehdr.e_phentsize

;; The beginning of the program header table. 1 == PT_LOAD, indicating
;; that the segment is to be loaded into memory.

proghdr:dd1; ehdr.e_phnum & phdr.p_type
; ehdr.e_shentsize
dd0; ehdr.e_shnum & phdr.p_offset
; ehdr.e_shstrndx

;; (Note that the next four bytes, in addition to containing the first
;; two instructions of the bracket routine, also comprise the memory
;; address of the text origin.)

db0; phdr.p_vaddr

;; The bracket routine emits code for the "[" instruction. This
;; instruction translates to a simple "jmp near", but the target of
;; the jump will not be known until the matching "]" is seen. The
;; routine thus outputs a random target, and pushes the location of
;; the target in the code buffer onto the stack.

bracket:moval, 0xE9
incebp
pushebp; phdr.p_paddr
stosd
jmpshort emit1byte

;; This is where the size of the executable file is stored in the
;; program header table. The compiler updates this value just before
;; it outputs the compiled program. This is the only field in the two
;; headers that differs between the compiler and its compiled
;; programs. (While the compiler is reading input, the first byte of
;; this field is also used as an input buffer.)

filesize:ddcompilersize; phdr.p_filesz

;; The size of the program in memory. This entry creates an area of
;; bytes, arraysize in size, all initialized to zero, starting at
;; DATAORG.

ddDATAOFFSET + arraysize; phdr.p_memsz

;; The code chunk for the "." instruction. eax is set to 4 to invoke
;; the write system call. ebx, the file handle to write to, is set to
;; 1 for stdout. ecx points to the buffer containing the bytes to
;; output, and edx equals the number of bytes to output. (Note that
;; the first byte of the first instruction, which is also the least
;; significant byte of the p_flags field, encodes to 0xB3. Having the
;; 2-bit set marks the memory containing the compiler, and its
;; compiled programs, as writeable.)

putchar:movbl, 1; phdr.p_flags
moval, 4
int0x80; phdr.p_align

;; The epilog code chunk. After restoring the initialized registers,
;; eax and ebx are both zero. eax is incremented to 1, so as to invoke
;; the exit system call. ebx specifies the process's return value.

epilog:popa
inceax
int0x80

;; The code chunks for the ">", "<", "+", and "-" instructions.

incptr:incecx
decptr:dececx
incchar:incbyte [ecx]
decchar:decbyte [ecx]

;; The main loop of the compiler continues here, by obtaining the next
;; character of input. This is also the code chunk for the ","
;; instruction. eax is set to 3 to invoke the read system call. ebx,
;; the file handle to read from, is set to 0 for stdin. ecx points to
;; a buffer to receive the bytes that are read, and edx equals the
;; number of bytes to read.

getchar:moval, 3
xorebx, ebx
int0x80

;; If eax is zero or negative, then there is no more input, and the
;; compiler proceeds to the eof routine.

oreax, eax
jleeof

;; Otherwise, esi is advanced four bytes (from the epilog code chunk
;; to the incptr code chunk), and the character read from the input is
;; stored in al, with the high bytes of eax reset to zero.

lodsd
moveax, [ecx]

;; The compiler compares the input character with ">" and "<". esi is
;; advanced to the next code chunk with each failed test.

cmpal, '>'
jzemit1byte
incesi
cmpal, '<'
jzemit1byte
incesi

;; The next four tests check for the characters "+", ",", "-", and
;; ".", respectively. These four characters are contiguous in ASCII,
;; and so are tested for by doing successive decrements of eax.

subal, '+'
jzemit2bytes
deceax
jzemitgetchar
incesi
incesi
deceax
jzemit2bytes
deceax
jzemitputchar

;; The remaining instructions, "[" and "]", have special routines for
;; emitting the proper code. (Note that the jump back to the main loop
;; is at the edge of the short-jump range. Routines below here
;; therefore use this jump as a relay to return to the main loop;
;; however, in order to use it correctly, the routines must be sure
;; that the zero flag is cleared at the time.)

cmpal, '[' - '.'
jzbracket
cmpal, ']' - '.'
relay:jnzcompile

;; The endbracket routine emits code for the "]" instruction, as well
;; as completing the code for the matching "[". The compiler first
;; emits "cmp dh, [ecx]" and the first two bytes of a "jnz near". The
;; location of the missing target in the code for the "[" instruction
;; is then retrieved from the stack, the correct target value is
;; computed and stored, and then the current instruction's jmp target
;; is computed and emitted.

endbracket:moveax, 0x850F313A
stosd
leaesi, [byte edi - 8]
popeax
subesi, eax
mov[eax], esi
subeax, edi
stosd
jmpshort relay

;; This is the entry point, for both the compiler and its compiled
;; programs. The shared initialization code sets eax and ebx to zero,
;; ecx to the beginning of the array that is the compiled programs's
;; data area, and edx to one. (This also clears the zero flag for the
;; relay jump below.) The registers are then saved on the stack, to be
;; restored at the very end.

_start:
xoreax, eax
xorebx, ebx
movecx, DATAORG
cdq
incedx
pusha

;; At this point, the compiler and its compiled programs diverge.
;; Although every compiled program includes all the code in this file
;; above this point, only the eleven bytes directly above are actually
;; used by both. This point is where the compiler begins storing the
;; generated code, so only the compiler sees the instructions below.
;; This routine first modifies ecx to contain TEXTORG, which is stored
;; on the stack, and then offsets it to point to filesize. edi is set
;; equal to codebuf, and then the compiler enters the main loop.

codebuf:
movch, (TEXTORG >> 8) & 0xFF
pushecx
movcl, filesize - $$
leaedi, [byte ecx + codebuf - filesize]
jmpshort relay


;; Here ends the file image.

compilersizeequ$ - $$
(Hab ich bisher nur unter OpenBSD, Gentoo und Debian getestet.)