assembler.cpp

flash文件的解码程序

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "compile.h"
#include "assembler.h"

extern FILE *yyin;

int yyparse();

int len;
Buffer asmBuffer;
int nLabels;

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

struct label labels[256];

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

  return -1;
}

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 = (unsigned char *)buffer->buffer;

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

	i += 3; /* plus instruction plus two-sbyte 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;
  }
}