This vm has:
8 registers(int) and a stack of 255(int) (configurable from vm.h),
labels which have a colon (':') and any characters which are _not spaces_,
25 opcodes, which are:
//Arithmetics
ADD //adds two values from stack, pushes back result
SUB //same, substracting
MUL //same, multiplying
DIV //same, doing integer division
MOD //same, but pushes modulus operation
//Logical operators
CMP {EQ,LT,ST}//compares two values popped by EQual, LargerThan or SmallerThan
AND //pops two values from stack and pushes logical AND (&&)
OR // same, with logical OR (||)
NOT //pops one value and pushes logical not (!)
//Register arithmetics
INCR r // increments value of register r by 1
DECR r // decrements value of register r by 1
//Control flow
JUMP n // jumps to instruction n
JUMPF n // pops and if value is false(<=0) jumps to n
JUMPT n // pops and if value is true (>0) jumps to n
//Stack control
LOAD n // pushes n to stack
POP r //pops value from stack and stores in register r
PUSH r //pushes value from register r to stack
PEEK r //stores topmost value of stack in r but does not remove it
//Basic IO
PRINTI //pops and prints an integer
PRINTC // same, but prints as character (33 == '!'), etc
READI // reads and pushes a value
READC // same, but reading a single stroke
//Executing control
DUMP // dumps information about stack and registers
STOP //stops execution of program. Necesary at program's end
NOP //No OPeration, does nothing.
Warning, if you're gonna modify the MAXREG in vm.h, you'll have to modify void dump(BlackProgram *p); in vm.c!