Instructions

LispKit Bytecode Instructions

Stack

Instruction	Explanation
pop	Drops the top element from stack.
dup	Duplicates the top element on the stack.
swap	Swaps the top two elements on the stack.
alloc n	Pushes n undefined values onto the stack.
reset o,n	Replaces n values on the stack with the undefined value starting from frame pointer offset o.

Constants

Instruction	Explanation
push_undef	Pushes the undefined value onto the stack.
push_void	Pushes the void value onto the stack.
push_eof	Pushes the EOF value onto the stack.
push_null	Pushes value null (empty list) onto the stack.
push_true	Pushes value #true onto the stack.
push_false	Pushes value #false onto the stack.
push_fixnum n	Pushes the fixnum n onto the stack.
push_bignum bn	Pushes the bignum bn onto the stack.
push_rat r	Pushes the rational number r onto the stack.
push_bigrat br	Pushes the given bigrat number br onto the stack.
push_flonum x	Pushes the flonum x onto the stack.
push_complex cx	Pushes the complex number cx onto the stack.
push_char ch	Pushes the character ch onto the stack.
push_constant c	Pushes the constant from the constant pool at index c onto the stack.

Functions

Instruction	Explanation
make_closure n,f	Creates a new closure from a capture list and a code fragment. The capture list is created from the top n elements on the stack. f is an index into the list of code fragments of the currently executed code.
make_frame	Pushes a new stack frame onto the stack.
call n	Calls a procedure with n arguments.
tail_call n	Calls a procedure with n arguments. This instruction is used for tail calls and does not require a new frame to be pushed.
apply n	This instruction expects on the stack a function, n - 1 individual arguments and an additional list of arguments. apply pushes the elements of the list onto the stack as well and then applies the function to all arguments on the stack. The instruction puts the result of the function application onto the stack.
return	Returns from the currently executed procedure.
assert_arg_count n	Checks that there are exactly n arguments on the stack.
assert_min_arg_count n	Checks that there are at least n arguments on the stack.
collect_rest n	Collects the arguments exceeding n into a list.
compile	Compiles the expression on top of the stack creating a thunk (a procedure without arguments) which is left on top of the stack.

Macros

Instruction	Explanation
make_syntax	Pops a syntax transformer function off the stack, creates a special form from it and pushes it onto the stack.

Promises

Instruction	Explanation
make_promise	Creates a new promise on the stack whose value will be computed by executing the closure on top of the stack.
force	Forces the value of the promise on top of the stack. If the promise has been evaluated already, push the value onto the stack and skip the next instruction (which is typically a store_in_promise instruction).
store_in_promise	Stores the value on top of the stack in the promise to which the second top-most entry on the stack The promise gets removed from the stack.

Variables

Instruction	Explanation
make_local_variable o	Creates a new variable, pops an expression from the stack and assignes the variable this expression as its initial value. The variable is then stored at the location specified by the frame pointer offset o.
make_variable_argument o	Creates a new variable and assignes the variable the expression at the location specified by the frame pointer offset o. The variable is then stored at the location specified by the frame pointer offset o, i.e. this instruction swaps a value on the stack with a variable with the same value.

Bindings

Instruction	Explanation
push_global c	c is an index into the constant pool referring to a symbol. push_global pushes the value to which this symbol is bound in the global environment onto the stack.
set_global c	c is an index into the constant pool referring to a symbol. set_global binds the symbol in the global environment to the value on top of the stack. set_global fails if the symbol has not previously been bound in the global environment.
define_global c	c is an index into the constant pool referring to a symbol. define_global binds the symbol in the global environment to the value on top of the stack. As opposed to set_global, the symbol does not have to be bound previously.
push_captured d	d is an index into the capture list. push_captured pushes the value d refers to onto the stack.
push_captured_value d	d is an index into the capture list referring to a variable. push_captured_value pushes the value of the variable to which d refers to onto the stack.
set_captured_value d	d is an index into the capture list referring to a variable. set_captured_value stores the value on top of the stack in the variable to which d refers to.
push_local o	o is an offset relative to the frame pointer. push_local pushes the value in this location onto the stack.
push_local_value o	o is an offset relative to the frame pointer referring to a variable. push_local_value pushes the value of this variable onto the stack.
set_local o	o is an offset relative to the frame pointer. set_local stores the value on top of the stack in this stack location overwriting the previous value.
set_local_value o	o is an offset relative to the frame pointer referring to a variable. set_local_value stores the value on top of the stack in this variable.

Control flow

Instruction	Explanation
branch i	i is an offset relative to the current instruction pointer. branch jumps to the instruction to which i refers to.
branch_if i	i is an offset relative to the current instruction pointer. branch_if jumps to the instruction to which i refers to if the value on the stack is not #false.
branch_if_not i	i is an offset relative to the current instruction pointer. branch_if jumps to the instruction to which i refers to if the value on the stack is #false.
or i	i is an offset relative to the current instruction pointer. or jumps to the instruction to which i refers to if the value on the stack is not #false. As opposed to branch_if, the value on top of the stack will remain there. Only if the value on top of the stack is #false, or will pop this value off the stack.
and i	i is an offset relative to the current instruction pointer. or jumps to the instruction to which i refers to if the value on the stack is #false. As opposed to branch_if_not, the value on top of the stack will remain there. Only if the value on top of the stack is not #false, and will pop this value off the stack.

Equivalences

Instruction	Explanation
eq	Compares the top two values on the stack via eq? and pushes the result onto the stack.
eqv	Compares the top two values on the stack via eqv? and pushes the result onto the stack.
equal	Compares the top two values on the stack via equal? and pushes the result onto the stack.

Containers

Instruction	Explanation
list n	Pops the top n values off the stack and constructs a list out of them on top of the stack.
cons	Pops the head and the tail of a new pair off the stack and pushes a new pair with this head and tail onto the stack.
car	Pops a pair off the stack and pushes its head onto the stack.
cdr	Pops a pair off the stack and pushes its tail onto the stack.
vector n	Pops the top n values off the stack and constructs a vector out of them on top of the stack.
list_to_vector	Converts a list to a vector.
vector_append n	Pops the top n vectors off the stack and constructs a new vector by concatenating the individual vectors.
is_vector	Pushes #false onto the stack if the current value on top of the stack is not a vector.

Math

Instruction	Explanation
fx_plus	Computes the sum of two fixnum values on the stack.
fx_minus	Computes the difference of two fixnum values on the stack.
fx_mult	Multiplies two fixnum values on the stack.
fx_div	Divides a fixnum value by another fixnum value on the stack.
fl_plus	Computes the sum of two flonum values on the stack.
fl_minus	Computes the difference of two flonum values on the stack.
fl_mult	Multiplies two flonum values on the stack.
fl_div	Divides a flonum value by another flonum value on the stack.

Miscellaneous

Instruction	Explanation
push_current_time	Pushes the current time as a flonum onto the stack. The time is expressed as seconds since January 1, 1970 at 00:00.
display	Displays the value on top of the stack on the console.
newline	Displays a newline character on the console.
noop	Empty instruction; proceeds to the next instruction.