assembler.c

Ming is a library for generating Macromedia Flash files (.swf), written in C, and includes useful ut

/*
    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 "actiontypes.h"
#include "libming.h"


int len;
Buffer asmBuffer;
int nLabels;

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

struct label labels[256];


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

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

	return -1;
}


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

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


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

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

	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_JUMP ||
					 output[i] == SWFACTION_IF )
			{
				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:
 */