interp.c

这个是LINUX下的GDB调度工具的源码

    }

  if (cpu->register_widths[rn] == 32)
    {
      if (length == 8)
	{
	  *(unsigned64*)memory =
	    H2T_8 ((unsigned32) (cpu->registers[rn]));
	  return 8;
	}
      else
	{
	  *(unsigned32*)memory = H2T_4 ((unsigned32)(cpu->registers[rn]));
	  return 4;
	}
    }
  else
    {
      *(unsigned64*)memory = H2T_8 ((unsigned64)(cpu->registers[rn]));
      return 8;
    }

  return 0;
}


SIM_RC
sim_create_inferior (sd, abfd, argv,env)
     SIM_DESC sd;
     struct bfd *abfd;
     char **argv;
     char **env;
{

#ifdef DEBUG
#if 0 /* FIXME: doesn't compile */
  printf("DBG: sim_create_inferior entered: start_address = 0x%s\n",
	 pr_addr(PC));
#endif
#endif /* DEBUG */

  ColdReset(sd);

  if (abfd != NULL)
    {
      /* override PC value set by ColdReset () */
      int cpu_nr;
      for (cpu_nr = 0; cpu_nr < sim_engine_nr_cpus (sd); cpu_nr++)
	{
	  sim_cpu *cpu = STATE_CPU (sd, cpu_nr);
	  CIA_SET (cpu, (unsigned64) bfd_get_start_address (abfd));
	}
    }

#if 0 /* def DEBUG */
  if (argv || env)
    {
      /* We should really place the argv slot values into the argument
	 registers, and onto the stack as required. However, this
	 assumes that we have a stack defined, which is not
	 necessarily true at the moment. */
      char **cptr;
      sim_io_printf(sd,"sim_create_inferior() : passed arguments ignored\n");
      for (cptr = argv; (cptr && *cptr); cptr++)
	printf("DBG: arg \"%s\"\n",*cptr);
    }
#endif /* DEBUG */

  return SIM_RC_OK;
}

void
sim_do_command (sd,cmd)
     SIM_DESC sd;
     char *cmd;
{
  if (sim_args_command (sd, cmd) != SIM_RC_OK)
    sim_io_printf (sd, "Error: \"%s\" is not a valid MIPS simulator command.\n",
		   cmd);
}

/*---------------------------------------------------------------------------*/
/*-- Private simulator support interface ------------------------------------*/
/*---------------------------------------------------------------------------*/

/* Read a null terminated string from memory, return in a buffer */
static char *
fetch_str (SIM_DESC sd,
	   address_word addr)
{
  char *buf;
  int nr = 0;
  char null;
  while (sim_read (sd, addr + nr, &null, 1) == 1 && null != 0)
    nr++;
  buf = NZALLOC (char, nr + 1);
  sim_read (sd, addr, buf, nr);
  return buf;
}


/* Implements the "sim firmware" command:
	sim firmware NAME[@ADDRESS] --- emulate ROM monitor named NAME.
		NAME can be idt, pmon, or lsipmon.  If omitted, ADDRESS
		defaults to the normal address for that monitor.
	sim firmware none --- don't emulate any ROM monitor.  Useful
		if you need a clean address space.  */
static SIM_RC
sim_firmware_command (SIM_DESC sd, char *arg)
{
  int address_present = 0;
  SIM_ADDR address;

  /* Signal occurrence of this option. */
  firmware_option_p = 1;

  /* Parse out the address, if present.  */
  {
    char *p = strchr (arg, '@');
    if (p)
      {
	char *q;
	address_present = 1;
	p ++; /* skip over @ */

	address = strtoul (p, &q, 0);
	if (*q != '\0') 
	  {
	    sim_io_printf (sd, "Invalid address given to the"
			   "`sim firmware NAME@ADDRESS' command: %s\n",
			   p);
	    return SIM_RC_FAIL;
	  }
      }
    else
      {
	address_present = 0;
	address = -1; /* Dummy value.  */
      }
  }

  if (! strncmp (arg, "idt", 3))
    {
      idt_monitor_base = address_present ? address : 0xBFC00000;
      pmon_monitor_base = 0;
      lsipmon_monitor_base = 0;
    }
  else if (! strncmp (arg, "pmon", 4))
    {
      /* pmon uses indirect calls.  Hook into implied idt. */
      pmon_monitor_base = address_present ? address : 0xBFC00500;
      idt_monitor_base = pmon_monitor_base - 0x500;
      lsipmon_monitor_base = 0;
    }
  else if (! strncmp (arg, "lsipmon", 7))
    {
      /* lsipmon uses indirect calls.  Hook into implied idt. */
      pmon_monitor_base = 0;
      lsipmon_monitor_base = address_present ? address : 0xBFC00200;
      idt_monitor_base = lsipmon_monitor_base - 0x200;
    }
  else if (! strncmp (arg, "none", 4))
    {
      if (address_present)
	{
	  sim_io_printf (sd,
			 "The `sim firmware none' command does "
			 "not take an `ADDRESS' argument.\n");
	  return SIM_RC_FAIL;
	}
      idt_monitor_base = 0;
      pmon_monitor_base = 0;
      lsipmon_monitor_base = 0;
    }
  else
    {
      sim_io_printf (sd, "\
Unrecognized name given to the `sim firmware NAME' command: %s\n\
Recognized firmware names are: `idt', `pmon', `lsipmon', and `none'.\n",
		     arg);
      return SIM_RC_FAIL;
    }
  
  return SIM_RC_OK;
}



/* Simple monitor interface (currently setup for the IDT and PMON monitors) */
int
sim_monitor (SIM_DESC sd,
	     sim_cpu *cpu,
	     address_word cia,
	     unsigned int reason)
{
#ifdef DEBUG
  printf("DBG: sim_monitor: entered (reason = %d)\n",reason);
#endif /* DEBUG */

  /* The IDT monitor actually allows two instructions per vector
     slot. However, the simulator currently causes a trap on each
     individual instruction. We cheat, and lose the bottom bit. */
  reason >>= 1;

  /* The following callback functions are available, however the
     monitor we are simulating does not make use of them: get_errno,
     isatty, lseek, rename, system, time and unlink */
  switch (reason)
    {

    case 6: /* int open(char *path,int flags) */
      {
	char *path = fetch_str (sd, A0);
	V0 = sim_io_open (sd, path, (int)A1);
	zfree (path);
	break;
      }

    case 7: /* int read(int file,char *ptr,int len) */
      {
	int fd = A0;
	int nr = A2;
	char *buf = zalloc (nr);
	V0 = sim_io_read (sd, fd, buf, nr);
	sim_write (sd, A1, buf, nr);
	zfree (buf);
      }
      break;

    case 8: /* int write(int file,char *ptr,int len) */
      {
	int fd = A0;
	int nr = A2;
	char *buf = zalloc (nr);
	sim_read (sd, A1, buf, nr);
	V0 = sim_io_write (sd, fd, buf, nr);
	zfree (buf);
	break;
      }

    case 10: /* int close(int file) */
      {
	V0 = sim_io_close (sd, (int)A0);
	break;
      }

    case 2:  /* Densan monitor: char inbyte(int waitflag) */
      {
	if (A0 == 0)	/* waitflag == NOWAIT */
	  V0 = (unsigned_word)-1;
      }
     /* Drop through to case 11 */

    case 11: /* char inbyte(void) */
      {
        char tmp;
	/* ensure that all output has gone... */
	sim_io_flush_stdout (sd);
        if (sim_io_read_stdin (sd, &tmp, sizeof(char)) != sizeof(char))
	  {
	    sim_io_error(sd,"Invalid return from character read");
	    V0 = (unsigned_word)-1;
	  }
        else
	  V0 = (unsigned_word)tmp;
	break;
      }

    case 3:  /* Densan monitor: void co(char chr) */
    case 12: /* void outbyte(char chr) : write a byte to "stdout" */
      {
        char tmp = (char)(A0 & 0xFF);
        sim_io_write_stdout (sd, &tmp, sizeof(char));
	break;
      }

    case 17: /* void _exit() */
      {
	sim_io_eprintf (sd, "sim_monitor(17): _exit(int reason) to be coded\n");
	sim_engine_halt (SD, CPU, NULL, NULL_CIA, sim_exited,
			 (unsigned int)(A0 & 0xFFFFFFFF));
	break;
      }

    case 28: /* PMON flush_cache */
      break;

    case 55: /* void get_mem_info(unsigned int *ptr) */
      /* in:  A0 = pointer to three word memory location */
      /* out: [A0 + 0] = size */
      /*      [A0 + 4] = instruction cache size */
      /*      [A0 + 8] = data cache size */
      {
	unsigned_4 value = MEM_SIZE /* FIXME STATE_MEM_SIZE (sd) */;
	unsigned_4 zero = 0;
	H2T (value);
	sim_write (sd, A0 + 0, (char *)&value, 4);
	sim_write (sd, A0 + 4, (char *)&zero, 4);
	sim_write (sd, A0 + 8, (char *)&zero, 4);
	/* sim_io_eprintf (sd, "sim: get_mem_info() deprecated\n"); */
	break;
      }
    
    case 158: /* PMON printf */
      /* in:  A0 = pointer to format string */
      /*      A1 = optional argument 1 */
      /*      A2 = optional argument 2 */
      /*      A3 = optional argument 3 */
      /* out: void */
      /* The following is based on the PMON printf source */
      {
	address_word s = A0;
	char c;
	signed_word *ap = &A1; /* 1st argument */
        /* This isn't the quickest way, since we call the host print
           routine for every character almost. But it does avoid
           having to allocate and manage a temporary string buffer. */
	/* TODO: Include check that we only use three arguments (A1,
           A2 and A3) */
	while (sim_read (sd, s++, &c, 1) && c != '\0')
	  {
            if (c == '%')
	      {
		char tmp[40];
		enum {FMT_RJUST, FMT_LJUST, FMT_RJUST0, FMT_CENTER} fmt = FMT_RJUST;
		int width = 0, trunc = 0, haddot = 0, longlong = 0;
		while (sim_read (sd, s++, &c, 1) && c != '\0')
		  {
		    if (strchr ("dobxXulscefg%", c))
		      break;
		    else if (c == '-')
		      fmt = FMT_LJUST;
		    else if (c == '0')
		      fmt = FMT_RJUST0;
		    else if (c == '~')
		      fmt = FMT_CENTER;
		    else if (c == '*')
		      {
			if (haddot)
			  trunc = (int)*ap++;
			else
			  width = (int)*ap++;
		      }
		    else if (c >= '1' && c <= '9')
		      {
			address_word t = s;
			unsigned int n;
			while (sim_read (sd, s++, &c, 1) == 1 && isdigit (c))
			  tmp[s - t] = c;
			tmp[s - t] = '\0';
			n = (unsigned int)strtol(tmp,NULL,10);
			if (haddot)
			  trunc = n;
			else
			  width = n;
			s--;
		      }
		    else if (c == '.')
		      haddot = 1;
		  }
		switch (c)
		  {
		  case '%':
		    sim_io_printf (sd, "%%");
		    break;
		  case 's':
		    if ((int)*ap != 0)
		      {
			address_word p = *ap++;
			char ch;
			while (sim_read (sd, p++, &ch, 1) == 1 && ch != '\0')
			  sim_io_printf(sd, "%c", ch);
		      }
		    else
		      sim_io_printf(sd,"(null)");
		    break;
		  case 'c':
		    sim_io_printf (sd, "%c", (int)*ap++);
		    break;
		  default:
		    if (c == 'l')
		      {
			sim_read (sd, s++, &c, 1);
			if (c == 'l')
			  {
			    longlong = 1;
			    sim_read (sd, s++, &c, 1);
			  }
		      }
		    if (strchr ("dobxXu", c))
		      {
			word64 lv = (word64) *ap++;
			if (c == 'b')
			  sim_io_printf(sd,"<binary not supported>");
			else
			  {
			    sprintf (tmp, "%%%s%c", longlong ? "ll" : "", c);
			    if (longlong)
			      sim_io_printf(sd, tmp, lv);
			    else
			      sim_io_printf(sd, tmp, (int)lv);
			  }
		      }
		    else if (strchr ("eEfgG", c))
		      {
			double dbl = *(double*)(ap++);
			sprintf (tmp, "%%%d.%d%c", width, trunc, c);
			sim_io_printf (sd, tmp, dbl);
			trunc = 0;
		      }
		  }
	      }
	    else
	      sim_io_printf(sd, "%c", c);
	  }
	break;
      }

    default:
      /* Unknown reason.  */
      return 0;
  }
  return 1;
}

/* Store a word into memory.  */

static void
store_word (SIM_DESC sd,
	    sim_cpu *cpu,
	    address_word cia,
	    uword64 vaddr,
	    signed_word val)
{
  address_word paddr;
  int uncached;

  if ((vaddr & 3) != 0)
    SignalExceptionAddressStore ();
  else
    {
      if (AddressTranslation (vaddr, isDATA, isSTORE, &paddr, &uncached,
			      isTARGET, isREAL))
	{
	  const uword64 mask = 7;
	  uword64 memval;
	  unsigned int byte;

	  paddr = (paddr & ~mask) | ((paddr & mask) ^ (ReverseEndian << 2));
	  byte = (vaddr & mask) ^ (BigEndianCPU << 2);
	  memval = ((uword64) val) << (8 * byte);
	  StoreMemory (uncached, AccessLength_WORD, memval, 0, paddr, vaddr,
		       isREAL);
	}
    }
}

/* Load a word from memory.  */

static signed_word
load_word (SIM_DESC sd,
	   sim_cpu *cpu,
	   address_word cia,
	   uword64 vaddr)
{
  if ((vaddr & 3) != 0)
    {
      SIM_CORE_SIGNAL (SD, cpu, cia, read_map, AccessLength_WORD+1, vaddr, read_transfer, sim_core_unaligned_signal);
    }
  else
    {
      address_word paddr;