/*
Copyright (C) 1996-2001 Id Software, Inc.
Copyright (C) 2010-2014 QuakeSpasm developers

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
{
	int32_t         s;
	dfunction_t     *f;
} prstack_t;

#define MAX_STACK_DEPTH         64      /* was 32 */
static prstack_t        pr_stack[MAX_STACK_DEPTH];
static int32_t          pr_depth;

#define LOCALSTACK_SIZE         2048
static int32_t          localstack[LOCALSTACK_SIZE];
static int32_t          localstack_used;

bool    pr_trace;
dfunction_t     *pr_xfunction;
int32_t         pr_xstatement;
int32_t         pr_argc;

static const 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"
};

const char *PR_GlobalString(int32_t ofs);
const char *PR_GlobalStringNoContents(int32_t ofs);


//=============================================================================

/*
=================
PR_PrintStatement
=================
*/
static void PR_PrintStatement(dstatement_t *s)
{
	int32_t i;

	if((uint32_t)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 %" PRIi32 "", PR_GlobalString(s->a), s->b);
	else if(s->op == OP_GOTO)
	{
		Con_Printf("branch %" PRIi32 "", s->a);
	}
	else if((uint32_t)(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
============
*/
static void PR_StackTrace(void)
{
	int32_t         i;
	dfunction_t     *f;

	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_GetString(f->s_file), PR_GetString(f->s_name));
		}
	}
}


/*
============
PR_Profile_f

============
*/
void PR_Profile_f(void)
{
	int32_t         i, num;
	int32_t         pmax;
	dfunction_t     *f, *best;

	if(!sv.active)
		return;

	num = 0;
	do
	{
		pmax = 0;
		best = NULL;
		for(i = 0; i < progs->numfunctions; i++)
		{
			f = &pr_functions[i];
			if(f->profile > pmax)
			{
				pmax = f->profile;
				best = f;
			}
		}
		if(best)
		{
			if(num < 10)
				Con_Printf("%7" PRIi32 " %s\n", best->profile, PR_GetString(best->s_name));
			num++;
			best->profile = 0;
		}
	}
	while(best);
}


/*
============
PR_RunError

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

	va_start(argptr, error);
	q_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_EnterFunction

Returns the new program statement counter
====================
*/
static int32_t PR_EnterFunction(dfunction_t *f)
{
	int32_t 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] = ((int32_t *)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++)
		{
			((int32_t *)pr_globals)[o] = ((int32_t *)pr_globals)[OFS_PARM0 + i * 3 + j];
			o++;
		}
	}

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

/*
====================
PR_LeaveFunction
====================
*/
static int32_t PR_LeaveFunction(void)
{
	int32_t i, c;

	if(pr_depth <= 0)
		Host_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");

	for(i = 0; i < c; i++)
		((int32_t *)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

The interpretation main loop
====================
*/
#define OPA ((eval_t *)&pr_globals[(uint16_t)st->a])
#define OPB ((eval_t *)&pr_globals[(uint16_t)st->b])
#define OPC ((eval_t *)&pr_globals[(uint16_t)st->c])

void PR_ExecuteProgram(func_t fnum)
{
	eval_t          *ptr;
	dstatement_t    *st;
	dfunction_t     *f, *newf;
	int32_t profile, startprofile;
	edict_t         *ed;
	int32_t         exitdepth;

	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];

	pr_trace = false;

// make a stack frame
	exitdepth = pr_depth;

	st = &pr_statements[PR_EnterFunction(f)];
	startprofile = profile = 0;

	while(1)
	{
		st++;   /* next statement */

		if(++profile > 100000)
		{
			pr_xstatement = st - pr_statements;
			PR_RunError("runaway loop error");
		}

		if(pr_trace)
			PR_PrintStatement(st);

		switch(st->op)
		{
		case OP_ADD_F:
			OPC->_float = OPA->_float + OPB->_float;
			break;
		case OP_ADD_V:
			OPC->vector[0] = OPA->vector[0] + OPB->vector[0];
			OPC->vector[1] = OPA->vector[1] + OPB->vector[1];
			OPC->vector[2] = OPA->vector[2] + OPB->vector[2];
			break;

		case OP_SUB_F:
			OPC->_float = OPA->_float - OPB->_float;
			break;
		case OP_SUB_V:
			OPC->vector[0] = OPA->vector[0] - OPB->vector[0];
			OPC->vector[1] = OPA->vector[1] - OPB->vector[1];
			OPC->vector[2] = OPA->vector[2] - OPB->vector[2];
			break;

		case OP_MUL_F:
			OPC->_float = OPA->_float * OPB->_float;
			break;
		case OP_MUL_V:
			OPC->_float = OPA->vector[0] * OPB->vector[0] +
			              OPA->vector[1] * OPB->vector[1] +
			              OPA->vector[2] * OPB->vector[2];
			break;
		case OP_MUL_FV:
			OPC->vector[0] = OPA->_float * OPB->vector[0];
			OPC->vector[1] = OPA->_float * OPB->vector[1];
			OPC->vector[2] = OPA->_float * OPB->vector[2];
			break;
		case OP_MUL_VF:
			OPC->vector[0] = OPB->_float * OPA->vector[0];
			OPC->vector[1] = OPB->_float * OPA->vector[1];
			OPC->vector[2] = OPB->_float * OPA->vector[2];
			break;

		case OP_DIV_F:
			OPC->_float = OPA->_float / OPB->_float;
			break;

		case OP_BITAND:
			OPC->_float = (int32_t)OPA->_float & (int32_t)OPB->_float;
			break;

		case OP_BITOR:
			OPC->_float = (int32_t)OPA->_float | (int32_t)OPB->_float;
			break;

		case OP_GE:
			OPC->_float = OPA->_float >= OPB->_float;
			break;
		case OP_LE:
			OPC->_float = OPA->_float <= OPB->_float;
			break;
		case OP_GT:
			OPC->_float = OPA->_float > OPB->_float;
			break;
		case OP_LT:
			OPC->_float = OPA->_float < OPB->_float;
			break;
		case OP_AND:
			OPC->_float = OPA->_float && OPB->_float;
			break;
		case OP_OR:
			OPC->_float = OPA->_float || OPB->_float;
			break;

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

		case OP_EQ_F:
			OPC->_float = OPA->_float == OPB->_float;
			break;
		case OP_EQ_V:
			OPC->_float = (OPA->vector[0] == OPB->vector[0]) &&
			              (OPA->vector[1] == OPB->vector[1]) &&
			              (OPA->vector[2] == OPB->vector[2]);
			break;
		case OP_EQ_S:
			OPC->_float = !strcmp(PR_GetString(OPA->string), PR_GetString(OPB->string));
			break;
		case OP_EQ_E:
			OPC->_float = OPA->_int == OPB->_int;
			break;
		case OP_EQ_FNC:
			OPC->_float = OPA->function == OPB->function;
			break;

		case OP_NE_F:
			OPC->_float = OPA->_float != OPB->_float;
			break;
		case OP_NE_V:
			OPC->_float = (OPA->vector[0] != OPB->vector[0]) ||
			              (OPA->vector[1] != OPB->vector[1]) ||
			              (OPA->vector[2] != OPB->vector[2]);
			break;
		case OP_NE_S:
			OPC->_float = strcmp(PR_GetString(OPA->string), PR_GetString(OPB->string));
			break;
		case OP_NE_E:
			OPC->_float = OPA->_int != OPB->_int;
			break;
		case OP_NE_FNC:
			OPC->_float = OPA->function != OPB->function;
			break;

		case OP_STORE_F:
		case OP_STORE_ENT:
		case OP_STORE_FLD:      // integers
		case OP_STORE_S:
		case OP_STORE_FNC:      // pointers
			OPB->_int = OPA->_int;
			break;
		case OP_STORE_V:
			OPB->vector[0] = OPA->vector[0];
			OPB->vector[1] = OPA->vector[1];
			OPB->vector[2] = OPA->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 + OPB->_int);
			ptr->_int = OPA->_int;
			break;
		case OP_STOREP_V:
			ptr = (eval_t *)((byte *)sv.edicts + OPB->_int);
			ptr->vector[0] = OPA->vector[0];
			ptr->vector[1] = OPA->vector[1];
			ptr->vector[2] = OPA->vector[2];
			break;

		case OP_ADDRESS:
			ed = PROG_TO_EDICT(OPA->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_xstatement = st - pr_statements;
				PR_RunError("assignment to world entity");
			}
			OPC->_int = (byte *)((int32_t *)&ed->v + OPB->_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(OPA->edict);
#ifdef PARANOID
			NUM_FOR_EDICT(ed);      // Make sure it's in range
#endif
			OPC->_int = ((eval_t *)((int32_t *)&ed->v + OPB->_int))->_int;
			break;

		case OP_LOAD_V:
			ed = PROG_TO_EDICT(OPA->edict);
#ifdef PARANOID
			NUM_FOR_EDICT(ed);      // Make sure it's in range
#endif
			ptr = (eval_t *)((int32_t *)&ed->v + OPB->_int);
			OPC->vector[0] = ptr->vector[0];
			OPC->vector[1] = ptr->vector[1];
			OPC->vector[2] = ptr->vector[2];
			break;

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

		case OP_IF:
			if(OPA->_int)
				st += st->b - 1;        /* -1 to offset the st++ */
			break;

		case OP_GOTO:
			st += st->a - 1;                /* -1 to offset the st++ */
			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_xfunction->profile += profile - startprofile;
			startprofile = profile;
			pr_xstatement = st - pr_statements;
			pr_argc = st->op - OP_CALL0;
			if(!OPA->function)
				PR_RunError("NULL function");
			newf = &pr_functions[OPA->function];
			if(newf->first_statement < 0)
			{
				// Built-in function
				int32_t i = -newf->first_statement;
				if(i >= pr_numbuiltins)
					PR_RunError("Bad builtin call number %" PRIi32 "", i);
				pr_builtins[i]();
				break;
			}
			// Normal function
			st = &pr_statements[PR_EnterFunction(newf)];
			break;

		case OP_DONE:
		case OP_RETURN:
			pr_xfunction->profile += profile - startprofile;
			startprofile = profile;
			pr_xstatement = st - pr_statements;
			pr_globals[OFS_RETURN] = pr_globals[(uint16_t)st->a];
			pr_globals[OFS_RETURN + 1] = pr_globals[(uint16_t)st->a + 1];
			pr_globals[OFS_RETURN + 2] = pr_globals[(uint16_t)st->a + 2];
			st = &pr_statements[PR_LeaveFunction()];
			if(pr_depth == exitdepth)
			{
				// Done
				return;
			}
			break;

		case OP_STATE:
			ed = PROG_TO_EDICT(pr_global_struct->self);
			ed->v.nextthink = pr_global_struct->time + 0.1;
			ed->v.frame = OPA->_float;
			ed->v.think = OPB->function;
			break;

		default:
			pr_xstatement = st - pr_statements;
			PR_RunError("Bad opcode %" PRIi32 "", st->op);
		}
	}   /* end of while(1) loop */
}
#undef OPA
#undef OPB
#undef OPC