/*
 * Copyright (C) 1996-1997 Id Software, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.
 *
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

#include "quakedef.h"

typedef struct {
    int           s;
    dfunction_t  *f;
} prstack_t;

#define	MAX_STACK_DEPTH		32
prstack_t     pr_stack[MAX_STACK_DEPTH];
int           pr_depth;

#define	LOCALSTACK_SIZE		2048
int           localstack[LOCALSTACK_SIZE];
int           localstack_used;

qboolean      pr_trace;
dfunction_t  *pr_xfunction;
int           pr_xstatement;

int           pr_argc;

char         *pr_opnames[] = {
    "DONE",

    "MUL_F",
    "MUL_V",
    "MUL_FV",
    "MUL_VF",

    "DIV",

    "ADD_F",
    "ADD_V",

    "SUB_F",
    "SUB_V",

    "EQ_F",
    "EQ_V",
    "EQ_S",
    "EQ_E",
    "EQ_FNC",

    "NE_F",
    "NE_V",
    "NE_S",
    "NE_E",
    "NE_FNC",

    "LE",
    "GE",
    "LT",
    "GT",

    "INDIRECT",
    "INDIRECT",
    "INDIRECT",
    "INDIRECT",
    "INDIRECT",
    "INDIRECT",

    "ADDRESS",

    "STORE_F",
    "STORE_V",
    "STORE_S",
    "STORE_ENT",
    "STORE_FLD",
    "STORE_FNC",

    "STOREP_F",
    "STOREP_V",
    "STOREP_S",
    "STOREP_ENT",
    "STOREP_FLD",
    "STOREP_FNC",

    "RETURN",

    "NOT_F",
    "NOT_V",
    "NOT_S",
    "NOT_ENT",
    "NOT_FNC",

    "IF",
    "IFNOT",

    "CALL0",
    "CALL1",
    "CALL2",
    "CALL3",
    "CALL4",
    "CALL5",
    "CALL6",
    "CALL7",
    "CALL8",

    "STATE",

    "GOTO",

    "AND",
    "OR",

    "BITAND",
    "BITOR"
};

char         *PR_GlobalString (int ofs);
char         *PR_GlobalStringNoContents (int ofs);

// 

/*
 * PR_PrintStatement
 */
void PR_PrintStatement (dstatement_t * s) {
    int           i;

    if ((unsigned) s->op < sizeof (pr_opnames) / sizeof (pr_opnames[0])) {
        Con_Printf ("%s ", pr_opnames[s->op]);
        i = strlen (pr_opnames[s->op]);
        for (; i < 10; i++)
            Con_Printf (" ");
    }

    if (s->op == OP_IF || s->op == OP_IFNOT) {
        Con_Printf ("%sbranch %i", PR_GlobalString (s->a), s->b);
    } else if (s->op == OP_GOTO) {
        Con_Printf ("branch %i", s->a);
    } else if ((unsigned) (s->op - OP_STORE_F) < 6) {
        Con_Printf ("%s", PR_GlobalString (s->a));
        Con_Printf ("%s", PR_GlobalStringNoContents (s->b));
    } else {
        if (s->a)
            Con_Printf ("%s", PR_GlobalString (s->a));
        if (s->b)
            Con_Printf ("%s", PR_GlobalString (s->b));
        if (s->c)
            Con_Printf ("%s", PR_GlobalStringNoContents (s->c));
    }
    Con_Printf ("\n");
}

/*
 * PR_StackTrace
 */
void PR_StackTrace (void) {
    dfunction_t  *f;
    int           i;

    if (pr_depth == 0) {
        Con_Printf ("<NO STACK>\n");
        return;
    }

    pr_stack[pr_depth].f = pr_xfunction;
    for (i = pr_depth; i >= 0; i--) {
        f = pr_stack[i].f;

        if (!f)
            Con_Printf ("<NO FUNCTION>\n");
        else
            Con_Printf ("%12s : %s\n", pr_strings + f->s_file, pr_strings + f->s_name);
    }
}

/*
 * PR_Profile_f
 *
 *
 */
void PR_Profile_f (void) {
    dfunction_t  *f, *best;
    int           i, max, num = 0;

    do {
        max = 0;
        best = NULL;
        for (i = 0; i < progs->numfunctions; i++) {
            f = &pr_functions[i];
            if (f->profile > max) {
                max = f->profile;
                best = f;
            }
        }
        if (best) {
            if (num < 10)
                Con_Printf ("%7i %s\n", best->profile, pr_strings + best->s_name);
            num++;
            best->profile = 0;
        }
    }
    while (best);
}

/*
 * PR_RunError
 *
 * Aborts the currently executing function
 */
void PR_RunError (char *error, ...) {
    va_list       argptr;
    char          string[1024];

    va_start (argptr, error);
    vsnprintf (string, sizeof (string), error, argptr);
    va_end (argptr);

    PR_PrintStatement (pr_statements + pr_xstatement);
    PR_StackTrace ();
    Con_Printf ("%s\n", string);

    pr_depth = 0;                      // dump the stack so host_error can
    // shutdown functions

    Host_Error ("Program error");
}

/*
 *
 * PR_ExecuteProgram
 *
 * The interpretation main loop
 *
 */

/*
 * PR_EnterFunction
 *
 * Returns the new program statement counter
 */
int PR_EnterFunction (dfunction_t * f) {
    int           i, j, c, o;

    pr_stack[pr_depth].s = pr_xstatement;
    pr_stack[pr_depth].f = pr_xfunction;
    pr_depth++;
    if (pr_depth >= MAX_STACK_DEPTH)
        PR_RunError ("stack overflow");

    // save off any locals that the new function steps on
    c = f->locals;
    if (localstack_used + c > LOCALSTACK_SIZE)
        PR_RunError ("PR_ExecuteProgram: locals stack overflow\n");

    for (i = 0; i < c; i++)
        localstack[localstack_used + i] = ((int *) pr_globals)[f->parm_start + i];
    localstack_used += c;

    // copy parameters
    o = f->parm_start;
    for (i = 0; i < f->numparms; i++) {
        for (j = 0; j < f->parm_size[i]; j++) {
            ((int *) pr_globals)[o] = ((int *) pr_globals)[OFS_PARM0 + i * 3 + j];
            o++;
        }
    }

    pr_xfunction = f;
    return f->first_statement - 1;     // offset the s++
}

/*
 * PR_LeaveFunction
 */
int PR_LeaveFunction (void) {
    int           i, c;

    if (pr_depth <= 0)
        Sys_Error ("prog stack underflow");

    // restore locals from the stack
    c = pr_xfunction->locals;
    localstack_used -= c;
    if (localstack_used < 0)
        PR_RunError ("PR_ExecuteProgram: locals stack underflow\n");

    for (i = 0; i < c; i++)
        ((int *) pr_globals)[pr_xfunction->parm_start + i] = localstack[localstack_used + i];

    // up stack
    pr_depth--;
    pr_xfunction = pr_stack[pr_depth].f;
    return pr_stack[pr_depth].s;
}

/*
 * PR_ExecuteProgram
 */
void PR_ExecuteProgram (func_t fnum) {
    eval_t       *a, *b, *c, *ptr;
    int           i, s, runaway, exitdepth;
    dstatement_t *st;
    dfunction_t  *f, *newf;
    edict_t      *ed;

    if (!fnum || fnum >= progs->numfunctions) {
        if (pr_global_struct->self)
            ED_Print (PROG_TO_EDICT (pr_global_struct->self));
        Host_Error ("PR_ExecuteProgram: NULL function");
    }

    f = &pr_functions[fnum];

    runaway = 100000;
    pr_trace = false;

    // make a stack frame
    exitdepth = pr_depth;

    s = PR_EnterFunction (f);

    while (1) {
        s++;                           // next statement

        st = &pr_statements[s];
        a = (eval_t *) & pr_globals[st->a];
        b = (eval_t *) & pr_globals[st->b];
        c = (eval_t *) & pr_globals[st->c];

        if (!--runaway)
            PR_RunError ("runaway loop error");

        pr_xfunction->profile++;
        pr_xstatement = s;

        if (pr_trace)
            PR_PrintStatement (st);

        switch (st->op) {
            case OP_ADD_F:
                c->_float = a->_float + b->_float;
                break;
            case OP_ADD_V:
                c->vector[0] = a->vector[0] + b->vector[0];
                c->vector[1] = a->vector[1] + b->vector[1];
                c->vector[2] = a->vector[2] + b->vector[2];
                break;

            case OP_SUB_F:
                c->_float = a->_float - b->_float;
                break;
            case OP_SUB_V:
                c->vector[0] = a->vector[0] - b->vector[0];
                c->vector[1] = a->vector[1] - b->vector[1];
                c->vector[2] = a->vector[2] - b->vector[2];
                break;

            case OP_MUL_F:
                c->_float = a->_float * b->_float;
                break;
            case OP_MUL_V:
                c->_float = a->vector[0] * b->vector[0] + a->vector[1] * b->vector[1] + a->vector[2] * b->vector[2];
                break;
            case OP_MUL_FV:
                c->vector[0] = a->_float * b->vector[0];
                c->vector[1] = a->_float * b->vector[1];
                c->vector[2] = a->_float * b->vector[2];
                break;
            case OP_MUL_VF:
                c->vector[0] = b->_float * a->vector[0];
                c->vector[1] = b->_float * a->vector[1];
                c->vector[2] = b->_float * a->vector[2];
                break;

            case OP_DIV_F:
                c->_float = a->_float / b->_float;
                break;

            case OP_BITAND:
                c->_float = (int) a->_float & (int) b->_float;
                break;

            case OP_BITOR:
                c->_float = (int) a->_float | (int) b->_float;
                break;

            case OP_GE:
                c->_float = a->_float >= b->_float;
                break;
            case OP_LE:
                c->_float = a->_float <= b->_float;
                break;
            case OP_GT:
                c->_float = a->_float > b->_float;
                break;
            case OP_LT:
                c->_float = a->_float < b->_float;
                break;
            case OP_AND:
                c->_float = a->_float && b->_float;
                break;
            case OP_OR:
                c->_float = a->_float || b->_float;
                break;

            case OP_NOT_F:
                c->_float = !a->_float;
                break;
            case OP_NOT_V:
                c->_float = !a->vector[0] && !a->vector[1] && !a->vector[2];
                break;
            case OP_NOT_S:
                c->_float = !a->string || !pr_strings[a->string];
                break;
            case OP_NOT_FNC:
                c->_float = !a->function;
                break;
            case OP_NOT_ENT:
                c->_float = (PROG_TO_EDICT (a->edict) == sv.edicts);
                break;

            case OP_EQ_F:
                c->_float = a->_float == b->_float;
                break;
            case OP_EQ_V:
                c->_float = (a->vector[0] == b->vector[0]) && (a->vector[1] == b->vector[1])
                    && (a->vector[2] == b->vector[2]);
                break;
            case OP_EQ_S:
                c->_float = !strcmp (pr_strings + a->string, pr_strings + b->string);
                break;
            case OP_EQ_E:
                c->_float = a->_int == b->_int;
                break;
            case OP_EQ_FNC:
                c->_float = a->function == b->function;
                break;

            case OP_NE_F:
                c->_float = a->_float != b->_float;
                break;
            case OP_NE_V:
                c->_float = (a->vector[0] != b->vector[0]) || (a->vector[1] != b->vector[1])
                    || (a->vector[2] != b->vector[2]);
                break;
            case OP_NE_S:
                c->_float = strcmp (pr_strings + a->string, pr_strings + b->string);
                break;
            case OP_NE_E:
                c->_float = a->_int != b->_int;
                break;
            case OP_NE_FNC:
                c->_float = a->function != b->function;
                break;

                // 
            case OP_STORE_F:
            case OP_STORE_ENT:
            case OP_STORE_FLD:        // integers
            case OP_STORE_S:
            case OP_STORE_FNC:        // pointers
                b->_int = a->_int;
                break;
            case OP_STORE_V:
                b->vector[0] = a->vector[0];
                b->vector[1] = a->vector[1];
                b->vector[2] = a->vector[2];
                break;

            case OP_STOREP_F:
            case OP_STOREP_ENT:
            case OP_STOREP_FLD:       // integers
            case OP_STOREP_S:
            case OP_STOREP_FNC:       // pointers
                ptr = (eval_t *) ((byte *) sv.edicts + b->_int);
                ptr->_int = a->_int;
                break;
            case OP_STOREP_V:
                ptr = (eval_t *) ((byte *) sv.edicts + b->_int);
                ptr->vector[0] = a->vector[0];
                ptr->vector[1] = a->vector[1];
                ptr->vector[2] = a->vector[2];
                break;

            case OP_ADDRESS:
                ed = PROG_TO_EDICT (a->edict);
#ifdef __PARANOID__
                NUM_FOR_EDICT (ed);    // make sure it's in range
#endif
                if (ed == (edict_t *) sv.edicts && sv.state == ss_active)
                    PR_RunError ("assignment to world entity");
                c->_int = (byte *) ((int *) &ed->v + b->_int) - (byte *) sv.edicts;
                break;

            case OP_LOAD_F:
            case OP_LOAD_FLD:
            case OP_LOAD_ENT:
            case OP_LOAD_S:
            case OP_LOAD_FNC:
                ed = PROG_TO_EDICT (a->edict);
#ifdef __PARANOID__
                NUM_FOR_EDICT (ed);    // make sure it's in range
#endif
                a = (eval_t *) ((int *) &ed->v + b->_int);
                c->_int = a->_int;
                break;

            case OP_LOAD_V:
                ed = PROG_TO_EDICT (a->edict);
#ifdef __PARANOID__
                NUM_FOR_EDICT (ed);    // make sure it's in range
#endif
                a = (eval_t *) ((int *) &ed->v + b->_int);
                c->vector[0] = a->vector[0];
                c->vector[1] = a->vector[1];
                c->vector[2] = a->vector[2];
                break;

                // 

            case OP_IFNOT:
                if (!a->_int)
                    s += st->b - 1;    // offset the s++
                break;

            case OP_IF:
                if (a->_int)
                    s += st->b - 1;    // offset the s++
                break;

            case OP_GOTO:
                s += st->a - 1;        // offset the s++
                break;

            case OP_CALL0:
            case OP_CALL1:
            case OP_CALL2:
            case OP_CALL3:
            case OP_CALL4:
            case OP_CALL5:
            case OP_CALL6:
            case OP_CALL7:
            case OP_CALL8:
                pr_argc = st->op - OP_CALL0;
                if (!a->function)
                    PR_RunError ("NULL function");

                newf = &pr_functions[a->function];

                if (newf->first_statement < 0) {        // negative statements
                    // are built in
                    // functions
                    i = -newf->first_statement;
                    if (i >= pr_numbuiltins)
                        PR_RunError ("Bad builtin call number");
                    pr_builtins[i] ();
                    break;
                }

                s = PR_EnterFunction (newf);
                break;

            case OP_DONE:
            case OP_RETURN:
                pr_globals[OFS_RETURN] = pr_globals[st->a];
                pr_globals[OFS_RETURN + 1] = pr_globals[st->a + 1];
                pr_globals[OFS_RETURN + 2] = pr_globals[st->a + 2];

                s = PR_LeaveFunction ();
                if (pr_depth == exitdepth)
                    return;            // all done
                break;

            case OP_STATE:
                ed = PROG_TO_EDICT (pr_global_struct->self);
#ifdef FPS_20
                ed->v.nextthink = pr_global_struct->time + 0.05;
#else
                ed->v.nextthink = pr_global_struct->time + 0.1;
#endif
                if (a->_float != ed->v.frame) {
                    ed->v.frame = a->_float;
                }
                ed->v.think = b->function;
                break;

            default:
                PR_RunError ("Bad opcode %i", st->op);
        }
    }

}
