/* state.c - statement routines for bcc */

/* Copyright (C) 1992 Bruce Evans */

#include "bcc.h"
#include "align.h"
#include "condcode.h"
#include "gencode.h"
#include "input.h"		/* just for ch and eof for label check */
#include "label.h"
#include "os.h"			/* just for EOL */
#include "parse.h"
#include "reg.h"
#include "scan.h"
#include "sizes.h"
#include "table.h"
#include "type.h"

#define COLONCHAR ':'		/* for label */
#define GROWCASES	64	/* extra cases for growth of switch struct */
#define INITIALCASES	16	/* initial cases in switch structure */

struct loopstruct
{
    label_no breaklab;		/* destination for break */
    label_no contlab;		/* destination for continue */
    struct nodestruct *etmark;	/* expression tree built during loop */
    struct symstruct *exprmark;	/* expression symbols built during loop */
    struct symstruct *locmark;	/* local variables built during loop */
    struct loopstruct *prevloop;   /* previous active for, switch or while */
    offset_T spmark;		/* stack value for continue and break */
};

struct switchstruct
{
    struct casestruct *caseptr;	/* current spot in caselist */
    struct casestruct *casetop;	/* last in caselist + 1 */
    bool_t charselector;	/* tells if case selector is char */
    label_no dfaultlab;		/* destination for default case (0 if none) */
    struct switchstruct *prevswitch;	/* previous active switch */
    struct casestruct
    {
	value_t casevalue;	/* value giving this case */
	label_no caselabel;	/* corresponding label */
    }
     caselist[INITIALCASES];	/* perhaps larger */
};

PRIVATE struct loopstruct *loopnow;	/* currently active for/switch/while */
					/* depends on NULL init */
PRIVATE bool_t returnflag;	/* set if last effective statement */
				/* was a return */
PRIVATE label_no swstacklab;	/* label giving stack for switch statement */

FORWARD void addloop P((struct loopstruct *newloop));
FORWARD void badloop P((void));
FORWARD void deleteloop P((void));
FORWARD void evalexpression P((struct nodestruct *exp));
FORWARD void exprstatement P((void));
FORWARD bool_pt isforever P((struct nodestruct *exp));
FORWARD void sort P((struct casestruct *caselist, int count));
FORWARD void dobreak P((void));
FORWARD void docase P((void));
FORWARD void docont P((void));
FORWARD void dodefault P((void));
FORWARD void dodowhile P((void));
FORWARD void dofor P((void));
FORWARD void dogoto P((void));
FORWARD void doif P((void));
FORWARD void doreturn P((void));
FORWARD void doswitch P((void));
FORWARD void dowhile P((void));
FORWARD void jumptocases P((void));
FORWARD void statement P((void));

/* --- utility routines --- */

PRIVATE void addloop(newloop)
struct loopstruct *newloop;
{
    newloop->breaklab = getlabel();
    newloop->contlab = getlabel();
    newloop->etmark = etptr;
    newloop->exprmark = exprptr;
    newloop->locmark = locptr;
    newloop->prevloop = loopnow;
    newloop->spmark = sp;
    loopnow = newloop;
}

PRIVATE void badloop()
{
    error(" no active fors, switches or whiles");
}

PRIVATE void deleteloop()
{
    etptr = loopnow->etmark;
    exprptr = loopnow->exprmark;
    locptr = loopnow->locmark;
    loopnow = loopnow->prevloop;
}

PRIVATE void evalexpression(exp)
struct nodestruct *exp;
{
    offset_T spmark;

    spmark = sp;
    makeleaf(exp);
    modstk(spmark);
}

PRIVATE void exprstatement()
{
    struct nodestruct *etmark;
    struct symstruct *exprmark;

    etmark = etptr;
    exprmark = exprptr;
    evalexpression(expression());
    etptr = etmark;
    exprptr = exprmark;
}

PRIVATE bool_pt isforever(exp)
register struct nodestruct *exp;
{
    return exp == NULL ||
	(exp->tag == LEAF && exp->left.symptr->storage == CONSTANT &&
	exp->left.symptr->offset.offv != 0);
}

PRIVATE void sort(caselist, count)	/* shell sort */
struct casestruct *caselist;
int count;
{
    register int gap;
    register int i;
    int j;
    struct casestruct swaptemp;

    gap = 1;
    do
	gap = 3 * gap + 1;
    while (gap <= count);
    while (gap != 1)
    {
	gap /= 3;
	for (j = gap; j < count; ++j)
	    for (i = j - gap;
	      i >= 0 && caselist[i].casevalue > caselist[i + gap].casevalue;
		 i -= gap)
	    {
		swaptemp = caselist[i];
		caselist[i] = caselist[i + gap];
		caselist[i + gap] = swaptemp;
	    }
    }
}

/* --- syntax routines --- */

/* ----------------------------------------------------------------------------
	compound-statement:
		"{" <declaration-list> <statement-list> "}"
---------------------------------------------------------------------------- */

PUBLIC void compound()		/* have just seen "{" */
{
    struct symstruct *locmark;
    store_t regmark;
#ifdef FRAMEPOINTER
    offset_T framepmark;
    offset_T softspmark;
#else
    /* softsp == sp here unless level == ARGLEVEL so mark is unnec */
    /* this is also true if funcsaveregsize != 0 but the tests are too messy */
#endif
    offset_T spmark;

    locmark = locptr;
    regmark = reguse;
#ifdef FRAMEPOINTER
    softspmark = softsp;
    framepmark = framep;
#endif
    spmark = sp;
    newlevel();
    expect_statement++;
    decllist();
    softsp &= alignmask;
    if (sym != RBRACE)		/* no need for locals if empty compound */
	reslocals();
    returnflag = FALSE;
    while (sym != RBRACE && sym != EOFSYM)
	statement();
    expect_statement--;
    oldlevel();
    if (!returnflag)
    {
	if (level != ARGLEVEL)
	{
	    if (switchnow == NULL)
	    {
#ifdef FRAMEPOINTER
		if (framep != 0)
		{
		    /* some args or locals, maybe at lower levels */
		    modstk(softspmark);
		    if (framep != framepmark)
			/* frame was just set up */
			popframe();
		}
#else
		modstk(spmark);
#endif
	    }
	}
	else
	    ret();
    }
#ifdef FRAMEPOINTER
    framep = framepmark;
    sp = spmark;
    softsp = softspmark;
#else
    softsp = sp = spmark;
#endif
    reguse = regmark;
    locptr = locmark;
    rbrace();
}

PUBLIC void doasm()
{
    if (sym == LPAREN) nextsym();
    if (sym!=STRINGCONST)
    	error("string const expected");
    else {
	outnstr("!BCC_ASM");
	for(;;) 
	{
	    constant.value.s[charptr-constant.value.s]='\0';
	    outbyte('\t');
	    outnstr(constant.value.s);
	    /* XXX: Need to investigate: wasting memory?
	     *
	     * charptr = constant.value.s;
	     */

	    nextsym();
	    if (sym == COMMA) nextsym();
	    if (sym!=STRINGCONST) break;
	}
	outnstr("!BCC_ENDASM");
        if (sym == RPAREN) nextsym();
	semicolon();
    }
}

PRIVATE void dobreak()
{
    offset_T spmark;

    if (loopnow == NULL)
	badloop();
    else
    {
	if (switchnow == NULL)
	{
	    spmark = sp;
	    modstk(loopnow->spmark);
	    sp = spmark;
	}
	jump(loopnow->breaklab);
    }
}

PRIVATE void docase()
{
    value_t caseval;

    caseval = constexpression() & intmaskto;	/* FIXME: warn overflow */
    if (caseval > maxintto)
	caseval -= (maxuintto + 1);
    colon();
    if (switchnow == NULL)
	error("case not in switch");
    else
    {
	if (switchnow->charselector && (caseval < 0 || caseval > 255))
	    error("%wcase cannot be reached with char switch");
	else
	{
	    if (switchnow->caseptr >= switchnow->casetop)
	    {
		int ncases;

		ncases = (/* ptrdiff_t */ int)
			 (switchnow->caseptr - &switchnow->caselist[0]);
		switchnow = realloc(switchnow,
				    (/* size_t */ unsigned)
				    ((char *) switchnow->caseptr
				    - (char *) switchnow)
				    + GROWCASES * sizeof (struct casestruct));
#ifdef TS
++ts_n_case_realloc;
ts_s_case += GROWCASES * sizeof (struct casestruct);
ts_s_case_tot += GROWCASES * sizeof (struct casestruct);
#endif
		if (switchnow == NULL)
		    outofmemoryerror("");
		switchnow->caseptr = &switchnow->caselist[ncases];
		switchnow->casetop = switchnow->caseptr + GROWCASES;
	    }
	    switchnow->caseptr->casevalue = caseval;
	    deflabel(switchnow->caseptr->caselabel = getlabel());
	    ++switchnow->caseptr;
	}
    }
}

PRIVATE void docont()
{
    struct loopstruct *contloop;
    offset_T spmark;
    struct switchstruct *switchthen;

    for (contloop = loopnow, switchthen = switchnow; ;
	 contloop = contloop->prevloop, switchthen = switchthen->prevswitch)
    {
	if (contloop == NULL)
	{
	    badloop();
	    return;
	}
	if (contloop->contlab != 0)
	    break;
    }
    if (switchnow == NULL)
    {
	spmark = sp;
	modstk(contloop->spmark);
	sp = spmark;
    }
    else if (switchthen == NULL)
    {
	outaddsp();
	outshex(contloop->spmark);
	outminus();
	outswstacklab();
#ifdef MC6809
	outcregname(LOCAL);
#endif
#ifdef I80386
	if (i386_32)
	    bumplc2();
#endif
	outnl();
    }
    jump(contloop->contlab);
}

PRIVATE void dodefault()
{
    colon();
    if (switchnow == NULL)
	error("default not in switch");
    else if (switchnow->dfaultlab != 0)
	error("multiple defaults");
    else
	deflabel(switchnow->dfaultlab = getlabel());
}

PRIVATE void dodowhile()
{
    struct loopstruct dwhileloop;
    label_no dolab;

    addloop(&dwhileloop);
    deflabel(dolab = getlabel());
    statement();
    if (sym == WHILESYM)
	nextsym();
    else
	error("missing while at end of do-while");
    deflabel(dwhileloop.contlab);
    lparen();
    jumptrue(expression(), dolab);
    rparen();
    semicolon();
    deflabel(dwhileloop.breaklab);
    deleteloop();
}

PRIVATE void dofor()
{
    struct loopstruct forloop;
    label_no forstatlab;
    label_no fortestlab = 0; /* for -Wall */
    struct nodestruct *testexp;
    struct nodestruct *loopexp;

    lparen();
    if (sym != SEMICOLON)
	exprstatement();
    semicolon();
    addloop(&forloop);
    if (sym == SEMICOLON)
	testexp = NULL;
    else
	testexp = expression();	/* remember test expression */
    semicolon();
    if (sym == RPAREN)
	loopexp = NULL;
    else
	loopexp = expression();	/* remember loop expression */
    rparen();
    if (!isforever(testexp))
	jump(fortestlab = getlabel());	/* test at bottom */
    deflabel(forstatlab = getlabel());	/* back here if test succeeds */
    statement();
    deflabel(forloop.contlab);
    if (loopexp != NULL)
	evalexpression(loopexp);
    if (isforever(testexp))
	jump(forstatlab);
    else
    {
	deflabel(fortestlab);	/* test label */
	jumptrue(testexp, forstatlab);
    }
    deflabel(forloop.breaklab);
    deleteloop();
}

PRIVATE void dogoto()
{
    struct symstruct *symptr;

    if (sym == IDENT || sym == TYPEDEFNAME)
    {
	symptr = namedlabel();
/*
	if (symptr->indcount == 4)
	    modstk(
	else
*/
	    adjsp(symptr->offset.offlabel);
	jump(symptr->offset.offlabel);
	nextsym();
    }
    else
	error("need identifier");
}

PRIVATE void doif()
{
    struct nodestruct *etmark;
    label_no elselab;
    label_no exitlab;
    struct symstruct *exprmark;

    lparen();
    etmark = etptr;
    exprmark = exprptr;
    jumpfalse(expression(), elselab = getlabel());
    etptr = etmark;
    exprptr = exprmark;
    rparen();
    statement();		/* true, do a statement */
    if (sym == ELSESYM)		/* "if .. else" statement */
    {
	nextsym();
	jump(exitlab = getlabel());	/* over "else" label and code */
	deflabel(elselab);
	statement();
	deflabel(exitlab);
    }
    else
	deflabel(elselab);
}

PRIVATE void doreturn()
{
    offset_T spmark;

    spmark = sp;
    if (sym != SEMICOLON)	/* returning expression */
	loadretexpression();
    ret();			/* clean up stack and return */
    sp = spmark;		/* restore stack for rest of function */
}

PRIVATE void doswitch()
{
    struct switchstruct *sw;
    struct loopstruct switchloop;
    offset_T spmark = 0; /* for -Wall */
    label_no sdecidelab;

    sw = (struct switchstruct *) ourmalloc(sizeof *sw);
#ifdef TS
++ts_n_case;
ts_s_case += sizeof *sw;
ts_s_case_tot += sizeof *sw;
#endif
    lparen();
    sw->charselector = loadexpression(DREG, NULLTYPE)->scalar & CHAR;
    rparen();
    if (switchnow == NULL)
	spmark = lowsp = sp;
    addloop(&switchloop);
    sw->dfaultlab = switchloop.contlab = 0; /* kill to show this is a switch */
    sw->casetop = (sw->caseptr = sw->caselist) + INITIALCASES;
    sw->prevswitch = switchnow;
    jump(sdecidelab = getlabel());	/* to case decision label */
    if (switchnow == NULL)
	swstacklab = gethighlabel();
    switchnow = sw;
    statement();		/* cases */
    sw = switchnow;
    jump(switchloop.breaklab);	/* over case decision to break label */
    deflabel(sdecidelab);
    if (sw->prevswitch == NULL)
	modstk(lowsp);
    jumptocases();
    deflabel(switchloop.breaklab);
    if ((switchnow = sw->prevswitch) == NULL)
    {
	equlab(swstacklab, lowsp);
	clearswitchlabels();
	modstk(spmark);
    }
    deleteloop();
#ifdef TS
ts_s_case_tot -= (char *) sw->casetop - (char *) sw;
#endif
    ourfree(sw);
}

PRIVATE void dowhile()
{
    struct loopstruct whileloop;
    struct nodestruct *testexp;
    label_no wstatlab;

    lparen();
    addloop(&whileloop);
    testexp = expression();
    rparen();
    if (!isforever(testexp))
	jump(whileloop.contlab);	/* test at bottom */
    deflabel(wstatlab = getlabel());	/* back here if test succeeds */
    statement();
    deflabel(whileloop.contlab);
    jumptrue(testexp, wstatlab);
    deflabel(whileloop.breaklab);
    deleteloop();
}

PRIVATE void jumptocases()
{
    value_t basevalue;
    struct casestruct *case1ptr;
    struct casestruct *caseptr;
    struct casestruct *casetop;
    value_t caseval;
    bool_t charselector;
    bool_t dfaultflag;
    label_no dfaultlab;
    label_no jtablelab;
    ccode_t lowcondition;
    store_pt targreg;
    label_no zjtablelab;

    caseptr = switchnow->caselist;
    casetop = switchnow->caseptr;
    sort(caseptr, (/* ptrdiff_t */ int) (casetop - caseptr));
    basevalue = 0;
    if ((charselector = switchnow->charselector) != 0)
    {
	targreg = BREG;
	lowcondition = LO;
    }
    else
    {
	targreg = DREG;
	lowcondition = LT;
    }
    dfaultflag = TRUE;
    if ((dfaultlab = switchnow->dfaultlab) == 0)
    {
	dfaultflag = FALSE;
	dfaultlab = loopnow->breaklab;
    }
    --casetop;
    for (case1ptr = caseptr; case1ptr < casetop; ++case1ptr)
	if (case1ptr->casevalue == (case1ptr + 1)->casevalue)
	    error("duplicate case in switch");
    while (caseptr <= casetop)
    {
	outsub();
	outimadj((offset_T) (caseptr->casevalue - basevalue), targreg);
	basevalue = caseptr->casevalue;
	for (case1ptr = caseptr; case1ptr < casetop; ++case1ptr)
	    if (case1ptr->casevalue < (case1ptr + 1)->casevalue - 10)
		break;
	if (case1ptr < caseptr + 5)
	{
	    lbranch(EQ, caseptr->caselabel);
	    ++caseptr;
	}
	else
	{
	    lbranch(lowcondition, dfaultlab);
	    outcmp();
	    outimadj((offset_T) (case1ptr->casevalue - basevalue), targreg);
	    lbranch(HI, zjtablelab = getlabel());
	    if (charselector)
		ctoi();
#ifdef MC6809
	    else
		bumplc();	/* extra for CMPD */
#endif
	    slconst((value_t) (ptypesize / 2), DREG);
					/* really log ptypesize */
	    deflabel(jtablelab = casejump());
#ifdef I8088
	    jtablelab = jtablelab; 	/* not used, allocated for regress */
#endif
	    for (caseval = caseptr->casevalue; caseval <= case1ptr->casevalue;
		 ++caseval)
	    {
#ifdef I8088
		if (ptypesize > 2)
		    defdword();
		else
#endif
		    defword();
		if (caseval != caseptr->casevalue)
		    outlabel(dfaultlab);
		else
		{
		    outlabel(caseptr->caselabel);
		    ++caseptr;
		}
#ifdef MC6809
		if (posindependent)
		{
		    outminus();
		    outlabel(jtablelab);
		}
#endif
		bumplc2();
#ifdef I8088
		if (ptypesize > 2)
		    bumplc2();
#endif
		outnl();
	    }
	    deflabel(zjtablelab);
	}
	lowcondition = LO;	/* 1st subtraction makes rest unsigned */
    }
    if (dfaultflag)
	jump(dfaultlab);
}

PUBLIC void outswoffset (offset)
offset_T offset;
{
#ifdef FRAMEPOINTER
    outoffset(offset - softsp - framep);
#else
    outoffset(offset - softsp - sp);
#endif
    outplus();
    outswstacklab();
#ifdef I8088
    bumplc();
#ifdef I80386
    if (i386_32)
	bumplc2();
#endif
#endif
}

PUBLIC void outswstacklab()
{
    outbyte(LOCALSTARTCHAR);
    outlabel(swstacklab);
}

/* ----------------------------------------------------------------------------
	statement:
		<compound-statement>
		<if-statement>
		<while-statement>
		<do-statement>
		<for-statement>
		<switch-statement>
		<case-statement>
		<default-statement>
		<break-statement>
		<continue-statement>
		<return-statement>
		<goto-statement>
		<labelled-statement>
		<null-statement>
		<expression> ;
---------------------------------------------------------------------------- */

PRIVATE void statement()
{
#if 1
    struct symstruct *symptr;
#endif

more:
    switch (sym)
    {
    case LBRACE:
	nextsym();
	compound();
	return;
    case IFSYM:
	nextsym();
	doif();
	break;
    case ELSESYM:
	error("unexpected else");
	nextsym();
	break;
    case WHILESYM:
	nextsym();
	dowhile();
	break;
    case FORSYM:
	nextsym();
	dofor();
	break;
    case RETURNSYM:
	nextsym();
	doreturn();
	semicolon();
	returnflag = TRUE;
	return;
    case SWITCHSYM:
	nextsym();
	doswitch();
	break;
    case BREAKSYM:
	nextsym();
	dobreak();
	semicolon();
	break;
    case CASESYM:
	nextsym();
	docase();
	goto more;
    case DEFAULTSYM:
	nextsym();
	dodefault();
	goto more;
    case DOSYM:
	nextsym();
	dodowhile();
	break;
    case CONTSYM:
	nextsym();
	docont();
	semicolon();
	break;
    case GOTOSYM:
	nextsym();
	dogoto();
	semicolon();
	break;
    case SEMICOLON:
	nextsym();
	return;
    case ASMSYM:
	nextsym();
	doasm();
	break;
    case IDENT:
    case TYPEDEFNAME:
	blanks();		/* cannot afford nextsym() */
	while (ch == EOL && !eofile)
	{
	    /* this now fails only on #controls and macros giving ':' */
	    skipeol();
	    blanks();
	}
	if (ch == COLONCHAR)
	{
#if 0
	    struct symstruct *symptr;
#endif
	    symptr = namedlabel();
	    if (symptr->indcount != 2)
		error("redefined label");
	    else
	    {
		deflabel(symptr->offset.offlabel);
		if (switchnow != NULL)
		    symptr->indcount = 3;
		else
		{
		    symptr->indcount = 4;
		    outbyte(LOCALSTARTCHAR);
		    outlabel(symptr->offset.offlabel);
		    outop0str("\t=\t");
		    outshex(sp);
		    outnl();
		}
	    }
	    nextsym();
	    nextsym();
	    goto more;
	}
	/* else fall into default */
    default:
	exprstatement();
	semicolon();
	break;
    }
    returnflag = FALSE;
}