/**
 *  payloads/stack.h
 *
 *  a Lisp stack frame.
 *
 *  Sits in a pso4.
 *
 *  (c) 2026 Simon Brooke <simon@journeyman.cc>
 *  Licensed under GPL version 2.0, or, at your option, any later version.
 */

#ifndef __psse_payloads_stack_h
#define __psse_payloads_stack_h

#include "memory/pointer.h"

/*
 * number of arguments stored in a stack frame
 */
#define args_in_frame 8

/**
 * A stack frame. 
 */
struct stack_frame_payload {
    /** the previous frame. */
    struct pso_pointer previous;
    /** first 8 arument bindings. */
    struct pso_pointer arg[args_in_frame];
    /** list of any further argument bindings. */
    struct pso_pointer more;
    /** the function to be called. */
    struct pso_pointer function;
  /** the execute-time environment */
    struct pso_pointer env;
  /** a list of objects created in the context of this frame */
    struct pso_pointer locals;
    /** the number of arguments provided. */
    uint32_t args;
    /** the depth of the stack below this frame */
    uint32_t depth;
};

struct pso_pointer make_frame( int arg_count, struct pso_pointer previous,
                               ... );

struct pso_pointer make_frame_with_env( int arg_count,
                                        struct pso_pointer previous,
                                        struct pso_pointer env, ... );

struct pso_pointer make_frame_with_arglist_and_env( struct pso_pointer
                                                    previous,
                                                    struct pso_pointer
                                                    argvalues,
                                                    struct pso_pointer env );

struct pso_pointer make_frame_with_arglist( struct pso_pointer previous,
                                            struct pso_pointer argvalues );

struct pso_pointer destroy_stack_frame( struct pso_pointer fp,
                                        struct pso_pointer env );

#endif