root/lib/action/assembler.c

DEFINITIONS

1. findLabel
2. addLabel
3. bufferBranchTarget
4. bufferPatchTargets

/*
    Ming, an SWF output library
    Copyright (C) 2002  Opaque Industries - http://www.opaque.net/

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "assembler.h"
#include "compile.h"
#include "action.h"


int len;
Buffer asmBuffer;
int nLabels;

struct label
{
        char *name;
        int offset;
};

struct label labels[256];


static int
findLabel(char *label)
{
        int i;

        for ( i=0; i<nLabels; ++i )
        {
                if ( strcmp(label, labels[i].name) == 0 )
                        return i;
        }

        return -1;
}


static void
addLabel(char *label)
{
        int i = findLabel(label);

        if ( i == -1 )
        {
                labels[nLabels].name = strdup(label);
                labels[nLabels].offset = len;
                ++nLabels;
        }
        else
                labels[i].offset = len;
}


int
bufferBranchTarget(Buffer output, char *label)
{
        int i = findLabel(label);

        if ( i == -1 )
        {
                i = nLabels;
                addLabel(label);
        }

        return bufferWriteS16(output, i);
}


void
bufferPatchTargets(Buffer buffer)
{
        int l, i = 0;
        unsigned char *output = buffer->buffer;

        while ( i < len )
        {
                if ( output[i] & 0x80 ) /* then it's a multibyte instruction */
                {
                        if ( output[i] == SWFACTION_BRANCHALWAYS ||
                                         output[i] == SWFACTION_BRANCHIFTRUE )
                        {
                                int target, offset;

                                i += 3; /* plus instruction plus two-byte length */

                                target = output[i];
                                offset = labels[target].offset - (i+2);
                                output[i] = offset & 0xff;
                                output[++i] = (offset>>8) & 0xff;
                                ++i;
                        }
                        else
                        {
                                ++i;
                                l = output[i];
                                ++i;
                                l += output[i]<<8;

                                i += l+1;
                        }
                }
                else
                        ++i;
        }
}


/*
 * Local variables:
 * tab-width: 2
 * c-basic-offset: 2
 * End:
 */