/*
  Copyright (C) 2010-2011  Charles Pence <charles@charlespence.net>
  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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "pch.h"
#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            max;
    int            num;
    int            i;

    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);
    vsprintf (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;
    int            s;
    dstatement_t    *st;
    dfunction_t    *f, *newf;
    int        runaway;
    int        i;
    edict_t    *ed;
    int        exitdepth;
    eval_t    *ptr;

    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);
        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);
        a = (eval_t *)((int *)&ed->v + b->_int);
        c->_int = a->_int;
        break;

    case OP_LOAD_V:
        ed = PROG_TO_EDICT(a->edict);
        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);
        ed->v.nextthink = pr_global_struct->time + 0.1;
        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);
    }
}

}
