the BFVM interprets BFB, a Brainfuck-based binary format.
conceptually, there are two tapes of memory, and six "free" registers.
<> move left and right on the current tape.
+- increment and decrement the current tape.
[] do a loop-like thing, the same as Brainfuck.
,. read input and write output, again see Brainfuck.
$ jumps between tapes.
# moves to tape 0.
& writes the tape index to the r register.
^ reads tape index from r, and jumps to it.
&^ and && are equivalent to &.
r* and R* read from, and write to, a register *. The other operand is always the tape.
there are three "special" registers, and thirteen "regular" ones.
regular: abcdeABCDErxy
i increments on every instruction processed. ri at the start of execution reads 0, as does Riri.
m increments on every > and decrements on every <.
t increments on every $ and is zeroed on every #.
~ flips all bits of the current tape cell.
| is binary OR. one operand (and the return value) is always the current position on the tape.
0 writes 0.
) is right-shift, ( is left-shift.
ALL ARITHMETIC OPERATIONS WRITE THEIR RESULTS TO THE r REGISTER.
also, most (except %) have an alternate floating-point version by prefixing '.
all binary ones operate on x and y registers.
!+ is addition, !- is subtraction.
* is multiplication, / is division
% is modulus, = is greater-or-equal
abs is absolute value, sgn is signum.
with ', the following unary functions (operating on x) are available:
sin, cos, tan, asin, acos, atan
sinh, cosh, tanh, asinh, acosh, atan
exp, ln
the ; character signifies a one-line comment