#ifndef DCPU16_H_3XXIQQG2
#define DCPU16_H_3XXIQQG2

#include <stdlib.h>

/* the target system's concept of a word */
typedef unsigned short DCPU16_WORD;

/* how much ram the system has */
#define DCPU16_RAM 0x10000
#define DCPU16_INTERRUPT_QUEUE_SIZE 256

/* a self-contained dcpu16 core */
struct dcpu16 {
    struct dcpu16_acct_cb *cb_table_;   /* list of callbacks to invoke for certain events */
    size_t cb_table_entries_;           /* callback list maintenance */
    size_t cb_table_allocated_;         /* callback list maintenance */

    struct dcpu16_hw *hw_table_;        /* list of hardware attached to system */
    size_t hw_table_entries_;           /* hardware list maintenance */
    size_t hw_table_allocated_;         /* hardware list maintenance */

    unsigned int skip_ : 1;             /* skip execution of next instruction */
    unsigned int interrupts_deferred_ : 1; /* queue software interrupts */
    unsigned int on_fire_ : 1;          /* cpu is on fire */
    DCPU16_WORD reg_work_[2];           /* work registers for holding literal values while decoding instructions */
    DCPU16_WORD interrupts_[DCPU16_INTERRUPT_QUEUE_SIZE];    /* fifo of pending interrupts */
    size_t interrupts_head_;            /* interrupt queue maintenance */
    size_t interrupts_tail_;            /* interrupt queue maintenance */

    unsigned long long cycle;           /* number of cycles this core has executed */
    DCPU16_WORD reg[8];                 /* system registers, a b c x y z i j */
    DCPU16_WORD pc;                     /* program counter */
    DCPU16_WORD sp;                     /* stack pointer */
    DCPU16_WORD ex;                     /* overflow */
    DCPU16_WORD ia;                     /* interrupt address */
    DCPU16_WORD ram[DCPU16_RAM];        /* memory */
};

/* these are used for accounting/watchpointing/modules/&c */
typedef unsigned int dcpu16_acct_event;
typedef void (dcpu16_ev_cb_t)(struct dcpu16 *, dcpu16_acct_event, DCPU16_WORD, void *);
#define DCPU16_ACCT_EV_CYCLE    (1<<1)
#define DCPU16_ACCT_EV_READ     (1<<2)
#define DCPU16_ACCT_EV_WRITE    (1<<3)
#define DCPU16_ACCT_EV_NOP      (1<<4)
#define DCPU16_ACCT_EV_RESET    (1<<5)
struct dcpu16_acct_cb {
    dcpu16_ev_cb_t *fn;
    void *data;
    dcpu16_acct_event mask;
};

/* these are used to define hardware attached to the system */
struct dcpu16_hw {
    char *name_;
    DCPU16_WORD id_l;
    DCPU16_WORD id_h;
    DCPU16_WORD ver;
    DCPU16_WORD mfg_l;
    DCPU16_WORD mfg_h;
    void (*int_fn)(struct dcpu16 *, void *);
    void *data;
};

/* instantiate a new core */
struct dcpu16 *dcpu16_new(void);

/* reset a core to initial state */
void dcpu16_reset(struct dcpu16 *);

/* print the current state of a core */
void dcpu16_state_print(struct dcpu16 *);

/* print the contents of ram from second to third argument */
void dcpu16_dump_ram(struct dcpu16 *, DCPU16_WORD, DCPU16_WORD);

/* print words in buf as asm */
DCPU16_WORD dcpu16_mnemonify_buf(DCPU16_WORD *);

/* print the instruction at the specified address, returns number of words consumed in decoding */
DCPU16_WORD dcpu16_disassemble_print(struct dcpu16 *, DCPU16_WORD);

/* register new 'hardware' device with system */
int dcpu16_hw_add(struct dcpu16 *, struct dcpu16_hw *);

/* register a callback for an accounting event */
int dcpu16_acct_add(struct dcpu16 *, dcpu16_acct_event, dcpu16_ev_cb_t *, void *);

/* execute the next instruction */
void dcpu16_step(struct dcpu16 *);

/* release a core */
void dcpu16_delete(struct dcpu16 **);

/* register callbacks to handle warning and debug messages, default is writing to stderr, may be set to null */
void dcpu16_warn_cb_set(void (*)(char *, ...));
void dcpu16_trace_cb_set(void (*)(char *, ...));

#endif /* DCPU16_H_3XXIQQG2 */