/*
 * Copyright (c) 1988,1991 by Sozobon, Limited.  Author: Joseph M Treat
 *
 * Permission is granted to anyone to use this software for any purpose
 * on any computer system, and to redistribute it freely, with the
 * following restrictions:
 * 1) No charge may be made other than reasonable charges for reproduction.
 * 2) Modified versions must be clearly marked as such.
 * 3) The authors are not responsible for any harmful consequences
 *    of using this software, even if they result from defects in it.
 *
 *  AMENDMENT HISTORY
 *  ~~~~~~~~~~~~~~~~~
 *  October 94        - Modified by Thorsten Roskowetz
 *                      Fixes problem with branches greater than 32K
 *
 *  11 Dec 94   DJW   - Fixes merged with QDOS version
 */

#include "jas.h"
#include "proto.h"

BRANCH *brlist = (BRANCH *) NULL;

#ifndef GENERIC
static void moveup  (BRANCH *, int);
#endif

VOID add_brnch( cptr, where )
        CBUF *cptr;
        long where;
{
        register BRANCH *bp;

        bp = ALLO(BRANCH);

        bp->where = where;
#ifndef GENERIC
        /*
         *  This is a check against the fact that one of the exit paths
         *  from generate() can return NULL, and possibly end up here.
         *  It is not clear without exhaustive logic flow analysis
         */
        if (cptr == NULL) {
            fprintf (stderr, "AS68: OPT/add_brnch:  cptr == NULL\n");
        }
#endif
        bp->cptr = cptr;
        bp->link = brlist;
        brlist = bp;
}

#ifndef GENERIC
static void moveup( bp, cnt )
        register BRANCH *bp;
        register int cnt;
{       register BRANCH *xbp;

        dottxt += cnt;
        /*
         * move all text symbols after this point up 'cnt' bytes
         */
        fixsymval( bp->where, (long)cnt, TXT );
        /*
         * move the location of all branches after this point up
         */
        for ( xbp = brlist; xbp != bp; xbp = xbp->link )
                xbp->where += cnt;
}
#endif

void do_opt()
{
#ifdef GENERIC
        BRANCH *bp, **lbp;
#else
        BRANCH *bq, **lbp;
        register BRANCH *bp;
        int     changed = 0;
        long    val;
#endif
        register CBUF *cp;
        SYM *sp;
#if defined (QDOS) || defined (XTC68)
        extern int Optimize;
#ifdef QDOS
        BRANCH *fbp=0;
#endif
#endif
        /*
         * first take care of jsr's to external routines
         */
        lbp = &brlist;
#if defined (QDOS) || defined (XTC68)
        if( Optimize ) {
#endif
        for ( bp = brlist; bp != (BRANCH *) NULL; bp = bp->link ) {
#ifdef QDOS
                if( fbp ) {
                        free( fbp );
                        fbp=0;
                }
#endif
                bq = bp->link;
                cp = bp->cptr;
                if ( cp->value.value != 0x61 /* BSR */ ) {
                        lbp = &bp->link;
                        continue;
                }
                sp = cp[1].value.psym;
                if ( sp->flags & SEGMT ) {
                        lbp = &bp->link;
                        continue;
                }
                /*
                 * change it to a jsr
                 */
                cp[0].nbits = 16;
                cp[0].value.value = 0x4eb9;     /* jsr abs.l */
                cp[1].nbits = 32;
                cp[1].action = GENRELOC;
#ifdef GENERIC
                dottxt += 4;
                /*
                 * move all text symbols after this point up four bytes
                 */
                fixsymval( bp->where, 4L, TXT );
                /*
                 * move the location of all branches after this point up
                 */
                {
                        register BRANCH *xbp;

                        for ( xbp = brlist; xbp != bp; xbp = xbp->link )
                                xbp->where += 4;
                }
#else
                moveup (bp, 4);
#endif /* GENERIC */
                /*
                 * remove this entry from the branch list
                 */
                *lbp = bp->link;
#ifndef QDOS
                /*
                 * don't bother to free it, it will just make later ALLO's
                 * slower
                 */
#else
                /*
                 * do bother. maybe this will make jas/as68 less memory-hungry
                 * Erling Jacobsen, 27 Jun '92
                 */
                fbp=bp; /* cannot free just now, as referenced in for(;;) */
                        /* see above (and below) */
#endif
        }
#ifdef QDOS
        if( fbp ) {
                free( fbp );
                fbp=0;
        }
#endif
        }

        /*
         * now do normal branches and remaining bsr's
         */
        do {
                changed = 0;
                lbp = &brlist;
#ifdef GENERIC
                for ( bp = brlist; bp != (BRANCH *) NULL; bp = bp->link ) {
                        register long val;
#else
                for ( bp = brlist; bp != (BRANCH *) NULL; bp = bq ) {
                        bq = bp->link;
#endif
                        cp = bp->cptr;
                        sp = cp[1].value.psym;

                        val = cp[1].value.value + sp->value - bp->where;
#ifdef GENERIC
                        if ( val >= -128 && val <= 127 && val != 0 ) {
#else
                        if ( val >= -128 && val < 128 && val != 0 ) {
#endif
                                lbp = &bp->link;
                                continue;
                        }
#ifdef GENERIC
                        /*
                         * change it to a 16-bit displacement
                         */
                        cp[0].nbits = 16;
                        cp[0].value.value <<= 8;
                        cp[1].nbits = 16;
                        cp[1].action = GENPCREL;
                        dottxt += 2;
                        /*
                         * move all text symbols after this point up two bytes
                         */
                        fixsymval( bp->where, 2L, TXT );
                        /*
                         * move the location of all branches after this point up
                         */
                        {
                                register BRANCH *xbp;

                                for ( xbp = brlist; xbp != bp; xbp = xbp->link )
                                        xbp->where += 2;
                        }
                        /*
                         * remove this entry from the branch list
                         */
                        *lbp = bp->link;
#else
                        /* 
                         * change it to a 16-bit displacement if possible
                         */
                        if ( val >= -32768 && val < 32768 ) {
                                if ( cp[1].nbits != 16 )
                                {       cp[0].nbits = 16;
                                        cp[0].value.value <<= 8;
                                        cp[1].nbits = 16;
                                        cp[1].action = GENPCREL;
                                        moveup( bp, 2 );
                                        changed = 1;
                                }
                                lbp = &bp->link;
                                continue;
                        }
                        /*
                         * change it to jsr or jmp
                         */
                        cp[0].nbits = 16;
                        switch ( (int)cp[0].value.value ) {
                        case 0x61:
                        case 0x6100:    /* bsr */
                                cp[0].value.value = 0x4eb9; /* jsr */
                                break;
                        case 0x60:
                        case 0x6000:    /* bra */
                                cp[0].value.value = 0x4ef9; /* jmp */
                                break;
                        default:
                                error( 0, "conditional branch out of range" );
                        }
                        moveup( bp, cp[1].nbits == 16 ? 2 : 4 );
                        cp[1].nbits = 32;
                        cp[1].action = GENRELOC;
                        /*
                         * remove this entry from the branch list
                         */
                        *lbp = bq;
                        free( bp );
                        bp = 0;
#endif /* ! GENERIC */
                        changed = 1;
                }

        } while ( changed );
}