Branflake is a compiler for the Brainf--- language. Its target platform is 16-bit DOS. I made it using the techniques in NC State University's CSC 236 class.
Most people don't have 16-bit DOS lying around on an actual machine, so the best approach (and the one that I used when developing it) is to install DOSBox.
Branflake, and the assembler it generates, is written for the Microsoft Macro
Assembler (MASM), since that is what CSC 236 uses. I plan to support
JWASM as well since it is free, open-source, and MASM-compatible,
and if compatibility with other assemblers can be provided without adding
complexity to bftrans, that's great. Pull requests are welcome.
Branflake, as a dialect of Brainf---, is an esoteric and rather difficult language to write in. However, it's very easy to compile, and Branflake even performs some optimizations on the generated assembly.
A Branflake program has access to the entire 64K data segment, which it can access one byte at a time, like the mathematical ideal of a Turing machine. It has one register (the "data pointer"), which indicates the byte in memory it is currently manipulating (the "current byte").
There are eight instructions in Branflake (names given only to explain the source code):
>(next) increments the data pointer by one.<(prev) decrements the data pointer by one.+(inc) increments the current byte by one.-(dec) decrements the current byte by one.[(skip) skips the bracketed section if the current byte is zero.](loop) repeats the bracketed section if the current byte is nonzero..(write) writes the current byte to standard output.,(read) reads a byte from standard input and stores it in the current byte.
All other characters are comments. The only syntax errors are mismatched
brackets -- either having a ] when all previous [ have been closed, or
having a [ that is not closed by a ]. These are reported by dropping a
.ERR directive in the generated source so that assembly fails.
Each instruction is executed sequentially (taking the effects of [ and ]
into account), until the last instruction completes, at which point the
program will exit.
Branflake offers no mechanisms for handling overflows, underflows, or other mathematical imprecisions. As a consequence, the data pointer will "wrap around" if increased above 65535 or decreased below 0, and individual bytes in memory will wrap around if increased above 255 or decreased below 0.
The core of Branflake is bftrans.asm, which is a very simple translator.
It accepts Branflake instructions on standard input, and writes assembler
code on standard output. You can assemble and link bftrans using MASM
by running the included make.bat file.
bftrans is supported by bfio.asm, which contains some I/O abstraction
subroutines (which are prototyped in bfio.inc). These provide character
and line counting, and some functions for formatting output.
Once bftrans has been linked, you can invoke it directly, or use bfml.bat
to translate, assemble, and link your Branflake source in a single step.
Its usage is:
bfml hello
Which will assemble a file named hello.bf into hello.exe, generating
hello.asm and hello.obj along the way.
In the generated assembly, the data pointer is represented by bx, and the
current byte by [bx]. The ax and dx registers are used temporarily
for I/O purposes, but in general, all operations are done in memory.
- Currently, there are no optimizations.
- All assembler files must be terminated by a DOS EOF character (1Ah).
- Most Brainf--- code on the Internet isn't used to having to check for a DOS EOF to end input.