Crypt can be used for (de-)crypting code or data with some simple
algorithm. Single byte, word or dword of code or data is crypted at a time
(press F2 to change crypt width). Crypt routine must end with "LOOP lineNumber"
operator.

Available commands:

Reg mode : neg,mul,div
Reg-Reg mode: mov,xor,add,sub,rol,ror,xchg,and,or
Reg-Imm mode: mov,xor,add,sub,rol,ror,and,or
Imm mode : loop

All 8/16/32 bit registers are available, except for AL/AX/EAX that is
used for (de-)crypted byte/word/dword input and output.

Differences from usual assembler:
* there are no jumps;
* 'loop' means jump or stop
* 'rol/ror' operands must have the same width, i.e. ROL AX,CL is not
allowed.
* 32-bit registers cannot be used as 'div' and 'mul' operands

Example:
a. XOR byte with 0AAh:
1. XOR al,0aah
2. LOOP 1

b. XOR word with mask increment
1. MOV dx,0
2. XOR ax,dx
3. ADD dx,1
4. LOOP 2