* Makefile.in: Add support for xstormy16.

	* configure.tgt: Ditto.
	* xstormy16-tdep.c: New file.
	* config/xstormy16/xstormy16.mt: New file.

1 files changed, 1133 insertions, 0 deletions

diff --git a/gdb/xstormy16-tdep.c b/gdb/xstormy16-tdep.c
new file mode 100644
index 0000000..bfadc7b
--- /dev/null
+++ b/gdb/xstormy16-tdep.c
@@ -0,0 +1,1133 @@
+/* Target-dependent code for the Sanyo Xstormy16a (LC590000) processor.
+   Copyright 2001, Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include "defs.h"
+#include "value.h"
+#include "inferior.h"
+#include "symfile.h"
+#include "arch-utils.h"
+#include "regcache.h"
+#include "gdbcore.h"
+#include "objfiles.h"
+
+struct gdbarch_tdep
+{
+  /* gdbarch target dependent data here. Currently unused for Xstormy16. */
+};
+
+/* Extra info which is saved in each frame_info. */
+struct frame_extra_info
+{
+  int framesize;
+  int frameless_p;
+};
+
+enum gdb_regnum
+{
+  /* Xstormy16 has 16 general purpose registers (R0-R15) plus PC.
+     Functions will return their values in register R2-R7 as they fit.
+     Otherwise a hidden pointer to an big enough area is given as argument
+     to the function in r2. Further arguments are beginning in r3 then.
+     R13 is used as frame pointer when GCC compiles w/o optimization
+     R14 is used as "PSW", displaying the CPU status.
+     R15 is used implicitely as stack pointer. */
+  E_R0_REGNUM,
+  E_R1_REGNUM,
+  E_R2_REGNUM, E_1ST_ARG_REGNUM = E_R2_REGNUM, E_PTR_RET_REGNUM = E_R2_REGNUM,
+  E_R3_REGNUM,
+  E_R4_REGNUM,
+  E_R5_REGNUM,
+  E_R6_REGNUM,
+  E_R7_REGNUM, E_LST_ARG_REGNUM = E_R7_REGNUM,
+  E_R8_REGNUM,
+  E_R9_REGNUM,
+  E_R10_REGNUM,
+  E_R11_REGNUM,
+  E_R12_REGNUM,
+  E_R13_REGNUM, E_FP_REGNUM = E_R13_REGNUM,
+  E_R14_REGNUM, E_PSW_REGNUM = E_R14_REGNUM,
+  E_R15_REGNUM, E_SP_REGNUM = E_R15_REGNUM,
+  E_PC_REGNUM,
+  E_NUM_REGS
+};
+
+/* Size of instructions, registers, etc. */
+enum
+{
+  xstormy16_inst_size = 2,
+  xstormy16_reg_size = 2,
+  xstormy16_pc_size = 4
+};
+
+/* Size of return datatype which fits into the remaining return registers. */
+#define E_MAX_RETTYPE_SIZE(regnum)	((E_LST_ARG_REGNUM - (regnum) + 1) \
+					* xstormy16_reg_size)
+
+/* Size of return datatype which fits into all return registers. */
+enum
+{
+  E_MAX_RETTYPE_SIZE_IN_REGS = E_MAX_RETTYPE_SIZE (E_R2_REGNUM)
+};
+
+
+/* Size of all registers as a whole. */
+enum
+{
+  E_ALL_REGS_SIZE = (E_NUM_REGS - 1) * xstormy16_reg_size + xstormy16_pc_size
+};
+
+/* Function: xstormy16_register_name
+   Returns the name of the standard Xstormy16 register N. */
+
+static char *
+xstormy16_register_name (int regnum)
+{
+  static char *register_names[] = {
+    "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
+    "r8", "r9", "r10", "r11", "r12", "r13",
+    "psw", "sp", "pc"
+  };
+
+  if (regnum < 0 ||
+      regnum >= sizeof (register_names) / sizeof (register_names[0]))
+    internal_error (__FILE__, __LINE__,
+		    "xstormy16_register_name: illegal register number %d",
+		    regnum);
+  else
+    return register_names[regnum];
+
+}
+
+/* Function: xstormy16_register_byte 
+   Returns the byte position in the register cache for register N. */
+
+static int
+xstormy16_register_byte (int regnum)
+{
+  if (regnum < 0 || regnum >= E_NUM_REGS)
+    internal_error (__FILE__, __LINE__,
+		    "xstormy16_register_byte: illegal register number %d",
+		    regnum);
+  else
+    /* All registers occupy 2 bytes in the regcache except for PC
+       which is the last one. Therefore the byte position is still
+       simply a multiple of 2. */
+    return regnum * xstormy16_reg_size;
+}
+
+/* Function: xstormy16_register_raw_size
+   Returns the number of bytes occupied by the register on the target. */
+
+static int
+xstormy16_register_raw_size (int regnum)
+{
+  if (regnum < 0 || regnum >= E_NUM_REGS)
+    internal_error (__FILE__, __LINE__,
+		    "xstormy16_register_raw_size: illegal register number %d",
+		    regnum);
+  /* Only the PC has 4 Byte, all other registers 2 Byte. */
+  else if (regnum == E_PC_REGNUM)
+    return xstormy16_pc_size;
+  else
+    return xstormy16_reg_size;
+}
+
+/* Function: xstormy16_register_virtual_size
+   Returns the number of bytes occupied by the register as represented
+   internally by gdb. */
+
+static int
+xstormy16_register_virtual_size (int regnum)
+{
+  return xstormy16_register_raw_size (regnum);
+}
+
+/* Function: xstormy16_reg_virtual_type 
+   Returns the default type for register N. */
+
+static struct type *
+xstormy16_reg_virtual_type (int regnum)
+{
+  if (regnum < 0 || regnum >= E_NUM_REGS)
+    internal_error (__FILE__, __LINE__,
+		    "xstormy16_register_virtual_type: illegal register number %d",
+		    regnum);
+  else if (regnum == E_PC_REGNUM)
+    return builtin_type_uint32;
+  else
+    return builtin_type_uint16;
+}
+
+/* Function: xstormy16_get_saved_register
+   Find a register's saved value on the call stack. */
+
+static void
+xstormy16_get_saved_register (char *raw_buffer,
+			      int *optimized,
+			      CORE_ADDR *addrp,
+			      struct frame_info *fi,
+			      int regnum, enum lval_type *lval)
+{
+  generic_get_saved_register (raw_buffer, optimized, addrp, fi, regnum, lval);
+}
+
+/* Function: xstormy16_type_is_scalar
+   Makes the decision if a given type is a scalar types.  Scalar
+   types are returned in the registers r2-r7 as they fit. */
+
+static int
+xstormy16_type_is_scalar (struct type *t)
+{
+  return (TYPE_CODE(t) != TYPE_CODE_STRUCT
+	  && TYPE_CODE(t) != TYPE_CODE_UNION
+	  && TYPE_CODE(t) != TYPE_CODE_ARRAY);
+}
+
+/* Function: xstormy16_extract_return_value
+   Copy the function's return value into VALBUF. 
+   This function is called only in the context of "target function calls",
+   ie. when the debugger forces a function to be called in the child, and
+   when the debugger forces a function to return prematurely via the
+   "return" command. */
+
+static void
+xstormy16_extract_return_value (struct type *type, char *regbuf, char *valbuf)
+{
+  CORE_ADDR return_buffer;
+  int offset = 0;
+
+  if (xstormy16_type_is_scalar (type)
+      && TYPE_LENGTH (type) <= E_MAX_RETTYPE_SIZE_IN_REGS)
+    {
+      /* Scalar return values of <= 12 bytes are returned in 
+         E_1ST_ARG_REGNUM to E_LST_ARG_REGNUM. */
+      memcpy (valbuf,
+	      &regbuf[REGISTER_BYTE (E_1ST_ARG_REGNUM)] + offset,
+	      TYPE_LENGTH (type));
+    }
+  else
+    {
+      /* Aggregates and return values > 12 bytes are returned in memory,
+         pointed to by R2. */
+      return_buffer =
+	extract_address (regbuf + REGISTER_BYTE (E_PTR_RET_REGNUM),
+			 REGISTER_RAW_SIZE (E_PTR_RET_REGNUM));
+
+      read_memory (return_buffer, valbuf, TYPE_LENGTH (type));
+    }
+}
+
+/* Function: xstormy16_push_arguments
+   Setup the function arguments for GDB to call a function in the inferior.
+   Called only in the context of a target function call from the debugger.
+   Returns the value of the SP register after the args are pushed.
+*/
+
+static CORE_ADDR
+xstormy16_push_arguments (int nargs, struct value **args, CORE_ADDR sp,
+			  int struct_return, CORE_ADDR struct_addr)
+{
+  CORE_ADDR stack_dest = sp;
+  int argreg = E_1ST_ARG_REGNUM;
+  int i, j;
+  int typelen, slacklen;
+  char *val;
+
+  /* If struct_return is true, then the struct return address will
+     consume one argument-passing register.  */
+  if (struct_return)
+    argreg++;
+
+  /* Arguments are passed in R2-R7 as they fit. If an argument doesn't
+     fit in the remaining registers we're switching over to the stack.
+     No argument is put on stack partially and as soon as we switched
+     over to stack no further argument is put in a register even if it
+     would fit in the remaining unused registers. */
+  for (i = 0; i < nargs && argreg <= E_LST_ARG_REGNUM; i++)
+    {
+      typelen = TYPE_LENGTH (VALUE_ENCLOSING_TYPE (args[i]));
+      if (typelen > E_MAX_RETTYPE_SIZE (argreg))
+	break;
+
+      /* Put argument into registers wordwise. */
+      val = VALUE_CONTENTS (args[i]);
+      for (j = 0; j < typelen; j += xstormy16_reg_size)
+	write_register (argreg++,
+			extract_unsigned_integer (val + j,
+						  typelen - j ==
+						  1 ? 1 :
+						  xstormy16_reg_size));
+    }
+
+  /* Align SP */
+  if (stack_dest & 1)
+    ++stack_dest;
+
+  /* Loop backwards through remaining arguments and push them on the stack,
+     wordaligned. */
+  for (j = nargs - 1; j >= i; j--)
+    {
+      typelen = TYPE_LENGTH (VALUE_ENCLOSING_TYPE (args[j]));
+      slacklen = typelen & 1;
+      val = alloca (typelen + slacklen);
+      memcpy (val, VALUE_CONTENTS (args[j]), typelen);
+      memset (val + typelen, 0, slacklen);
+
+      /* Now write this data to the stack. The stack grows upwards. */
+      write_memory (stack_dest, val, typelen + slacklen);
+      stack_dest += typelen + slacklen;
+    }
+
+  /* And that should do it.  Return the new stack pointer. */
+  return stack_dest;
+}
+
+/* Function: xstormy16_push_return_address (pc)
+   Setup the return address for GDB to call a function in the inferior.
+   Called only in the context of a target function call from the debugger.
+   Returns the value of the SP register when the operation is finished
+   (which may or may not be the same as before).
+*/
+
+CORE_ADDR
+xstormy16_push_return_address (CORE_ADDR pc, CORE_ADDR sp)
+{
+  unsigned char buf[xstormy16_pc_size];
+
+  store_unsigned_integer (buf, xstormy16_pc_size, CALL_DUMMY_ADDRESS ());
+  write_memory (sp, buf, xstormy16_pc_size);
+  return sp + xstormy16_pc_size;
+}
+
+/* Function: xstormy16_pop_frame
+   Destroy the innermost (Top-Of-Stack) stack frame, restoring the 
+   machine state that was in effect before the frame was created. 
+   Used in the contexts of the "return" command, and of 
+   target function calls from the debugger.
+*/
+
+static void
+xstormy16_pop_frame (void)
+{
+  struct frame_info *fi = get_current_frame ();
+  int i;
+
+  if (fi == NULL)
+    return;			/* paranoia */
+
+  if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
+    {
+      generic_pop_dummy_frame ();
+    }
+  else
+    {
+      /* Restore the saved regs. */
+      for (i = 0; i < NUM_REGS; i++)
+	if (fi->saved_regs[i])
+	  {
+	    if (i == SP_REGNUM)
+	      write_register (i, fi->saved_regs[i]);
+	    else if (i == E_PC_REGNUM)
+	      write_register (i, read_memory_integer (fi->saved_regs[i],
+						      xstormy16_pc_size));
+	    else
+	      write_register (i, read_memory_integer (fi->saved_regs[i],
+						      xstormy16_reg_size));
+	  }
+      /* Restore the PC */
+      write_register (PC_REGNUM, FRAME_SAVED_PC (fi));
+      flush_cached_frames ();
+    }
+  return;
+}
+
+/* Function: xstormy16_store_struct_return
+   Copy the (struct) function return value to its destined location. 
+   Called only in the context of a target function call from the debugger.
+*/
+
+static void
+xstormy16_store_struct_return (CORE_ADDR addr, CORE_ADDR sp)
+{
+  write_register (E_PTR_RET_REGNUM, addr);
+}
+
+/* Function: xstormy16_store_return_value
+   Copy the function return value from VALBUF into the 
+   proper location for a function return. 
+   Called only in the context of the "return" command.
+*/
+
+static void
+xstormy16_store_return_value (struct type *type, char *valbuf)
+{
+  CORE_ADDR return_buffer;
+  char buf[xstormy16_reg_size];
+
+  if (xstormy16_type_is_scalar (type) && TYPE_LENGTH (type) == 1)
+    {
+      /* Add leading zeros to the value. */
+      memset (buf, 0, xstormy16_reg_size);
+      memcpy (buf, valbuf, 1);
+      write_register_gen (E_1ST_ARG_REGNUM, buf);
+    }
+  else if (xstormy16_type_is_scalar (type) &&
+	   TYPE_LENGTH (type) <= E_MAX_RETTYPE_SIZE_IN_REGS)
+    write_register_bytes (REGISTER_BYTE (E_1ST_ARG_REGNUM),
+			  valbuf, TYPE_LENGTH (type));
+  else
+    {
+      return_buffer = read_register (E_PTR_RET_REGNUM);
+      write_memory (return_buffer, valbuf, TYPE_LENGTH (type));
+    }
+}
+
+/* Function: xstormy16_extract_struct_value_address
+   Returns the address in which a function should return a struct value. 
+   Used in the contexts of the "return" command, and of 
+   target function calls from the debugger.
+*/
+
+static CORE_ADDR
+xstormy16_extract_struct_value_address (char *regbuf)
+{
+  return extract_address (regbuf +
+			  xstormy16_register_byte (E_PTR_RET_REGNUM),
+			  xstormy16_reg_size);
+}
+
+/* Function: xstormy16_use_struct_convention 
+   Returns non-zero if the given struct type will be returned using
+   a special convention, rather than the normal function return method. 
+   7sed in the contexts of the "return" command, and of 
+   target function calls from the debugger.
+*/
+
+static int
+xstormy16_use_struct_convention (int gcc_p, struct type *type)
+{
+  return !xstormy16_type_is_scalar (type)
+    || TYPE_LENGTH (type) > E_MAX_RETTYPE_SIZE_IN_REGS;
+}
+
+/* Function: frame_saved_register
+   Returns the value that regnum had in frame fi
+   (saved in fi or in one of its children).  
+*/
+
+static CORE_ADDR
+xstormy16_frame_saved_register (struct frame_info *fi, int regnum)
+{
+  int size = xstormy16_register_raw_size (regnum);
+  char *buf = (char *) alloca (size);
+
+  generic_get_saved_register (buf, NULL, NULL, fi, regnum, NULL);
+  return (CORE_ADDR) extract_unsigned_integer (buf, size);
+}
+
+/* Function: xstormy16_scan_prologue
+   Decode the instructions within the given address range.
+   Decide when we must have reached the end of the function prologue.
+   If a frame_info pointer is provided, fill in its saved_regs etc.
+
+   Returns the address of the first instruction after the prologue. 
+*/
+
+static CORE_ADDR
+xstormy16_scan_prologue (CORE_ADDR start_addr,
+			 CORE_ADDR end_addr, struct frame_info *fi)
+{
+  CORE_ADDR sp = 0, fp = 0;
+  CORE_ADDR next_addr;
+  ULONGEST inst, inst2;
+  LONGEST offset;
+  int regnum;
+
+  if (fi)
+    {
+      /* In a call dummy, don't touch the frame. */
+      if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
+	return start_addr;
+
+      /* Grab the frame-relative values of SP and FP, needed below. 
+         The frame_saved_register function will find them on the
+         stack or in the registers as appropriate. */
+      sp = xstormy16_frame_saved_register (fi, E_SP_REGNUM);
+      fp = xstormy16_frame_saved_register (fi, E_FP_REGNUM);
+
+      /* Initialize framesize with size of PC put on stack by CALLF inst. */
+      fi->extra_info->framesize = xstormy16_pc_size;
+    }
+  for (next_addr = start_addr;
+       next_addr < end_addr; next_addr += xstormy16_inst_size)
+    {
+      inst = read_memory_unsigned_integer (next_addr, xstormy16_inst_size);
+      inst2 = read_memory_unsigned_integer (next_addr + xstormy16_inst_size,
+					    xstormy16_inst_size);
+
+      if (inst >= 0x0082 && inst <= 0x008d)	/* push r2 .. push r13 */
+	{
+	  if (fi)
+	    {
+	      regnum = inst & 0x000f;
+	      fi->saved_regs[regnum] = fi->extra_info->framesize;
+	      fi->extra_info->framesize += xstormy16_reg_size;
+	    }
+	}
+
+      /* optional stack allocation for args and local vars <= 4 byte */
+      else if (inst == 0x301f || inst == 0x303f)	/* inc r15, #0x1/#0x3 */
+	{
+	  if (fi)		/* Record the frame size. */
+	    fi->extra_info->framesize += ((inst & 0x0030) >> 4) + 1;
+	}
+
+      /* optional stack allocation for args and local vars > 4 && < 16 byte */
+      else if ((inst & 0xff0f) == 0x510f)	/* 51Hf   add r15, #0xH */
+	{
+	  if (fi)		/* Record the frame size. */
+	    fi->extra_info->framesize += (inst & 0x00f0) >> 4;
+	}
+
+      /* optional stack allocation for args and local vars >= 16 byte */
+      else if (inst == 0x314f && inst2 >= 0x0010)	/* 314f HHHH  add r15, #0xH */
+	{
+	  if (fi)		/* Record the frame size. */
+	    fi->extra_info->framesize += inst2;
+	  next_addr += xstormy16_inst_size;
+	}
+
+      else if (inst == 0x46fd)	/* mov r13, r15 */
+	{
+	  if (fi)		/* Record that the frame pointer is in use. */
+	    fi->extra_info->frameless_p = 0;
+	}
+
+      /* optional copying of args in r2-r7 to r10-r13 */
+      /* Probably only in optimized case but legal action for prologue */
+      else if ((inst & 0xff00) == 0x4600	/* 46SD   mov rD, rS */
+	       && (inst & 0x00f0) >= 0x0020 && (inst & 0x00f0) <= 0x0070
+	       && (inst & 0x000f) >= 0x00a0 && (inst & 0x000f) <= 0x000d)
+	;
+
+      /* optional copying of args in r2-r7 to stack */
+      /* 72DS HHHH   mov.b (rD, 0xHHHH), r(S-8) (bit3 always 1, bit2-0 = reg) */
+      /* 73DS HHHH   mov.w (rD, 0xHHHH), r(S-8) */
+      else if ((inst & 0xfed8) == 0x72d8 && (inst & 0x0007) >= 2)
+	{
+	  if (fi)
+	    {
+	      regnum = inst & 0x0007;
+	      /* Only 12 of 16 bits of the argument are used for the
+	         signed offset. */
+	      offset = (LONGEST) (inst2 & 0x0fff);
+	      if (offset & 0x0800)
+		offset -= 0x1000;
+
+	      fi->saved_regs[regnum] = fi->extra_info->framesize + offset;
+	    }
+	  next_addr += xstormy16_inst_size;
+	}
+
+#if 0
+      /* 2001-08-10: Not part of the prologue anymore due to change in
+         ABI. r8 and r9 are not used for argument passing anymore. */
+
+      /* optional copying of r8, r9 to stack */
+      /* 46S7; 73Df HHHH   mov.w r7,rS; mov.w (rD, 0xHHHH), r7 D=8,9; S=13,15 */
+      /* 46S7; 72df HHHH   mov.w r7,rS; mov.b (rD, 0xHHHH), r7 D=8,9; S=13,15 */
+      else if ((inst & 0xffef) == 0x4687 && (inst2 & 0xfedf) == 0x72df)
+	{
+	  next_addr += xstormy16_inst_size;
+	  if (fi)
+	    {
+	      regnum = (inst & 0x00f0) >> 4;
+	      inst = inst2;
+	      inst2 = read_memory_unsigned_integer (next_addr
+						    + xstormy16_inst_size,
+						    xstormy16_inst_size);
+	      /* Only 12 of 16 bits of the argument are used for the
+	         signed offset. */
+	      offset = (LONGEST) (inst2 & 0x0fff);
+	      if (offset & 0x0800)
+		offset -= 0x1000;
+
+	      fi->saved_regs[regnum] = fi->extra_info->framesize + offset;
+	    }
+	  next_addr += xstormy16_inst_size;
+	}
+#endif
+
+      else			/* Not a prologue instruction. */
+	break;
+    }
+
+  if (fi)
+    {
+      /* Special handling for the "saved" address of the SP:
+         The SP is of course never saved on the stack at all, so
+         by convention what we put here is simply the previous 
+         _value_ of the SP (as opposed to an address where the
+         previous value would have been pushed).  */
+      if (fi->extra_info->frameless_p)
+	{
+	  fi->saved_regs[E_SP_REGNUM] = sp - fi->extra_info->framesize;
+	  fi->frame = sp;
+	}
+      else
+	{
+	  fi->saved_regs[E_SP_REGNUM] = fp - fi->extra_info->framesize;
+	  fi->frame = fp;
+	}
+
+      /* So far only offsets to the beginning of the frame are
+         saved in the saved_regs. Now we now the relation between
+         sp, fp and framesize. We know the beginning of the frame
+         so we can translate the register offsets to real addresses. */
+      for (regnum = 0; regnum < E_SP_REGNUM; ++regnum)
+	if (fi->saved_regs[regnum])
+	  fi->saved_regs[regnum] += fi->saved_regs[E_SP_REGNUM];
+
+      /* Save address of PC on stack. */
+      fi->saved_regs[E_PC_REGNUM] = fi->saved_regs[E_SP_REGNUM];
+    }
+
+  return next_addr;
+}
+
+/* Function: xstormy16_skip_prologue
+   If the input address is in a function prologue, 
+   returns the address of the end of the prologue;
+   else returns the input address.
+
+   Note: the input address is likely to be the function start, 
+   since this function is mainly used for advancing a breakpoint
+   to the first line, or stepping to the first line when we have
+   stepped into a function call.  */
+
+static CORE_ADDR
+xstormy16_skip_prologue (CORE_ADDR pc)
+{
+  CORE_ADDR func_addr = 0, func_end = 0;
+  char *func_name;
+
+  if (find_pc_partial_function (pc, &func_name, &func_addr, &func_end))
+    {
+      struct symtab_and_line sal;
+      struct symbol *sym;
+
+      /* Found a function.  */
+      sym = lookup_symbol (func_name, NULL, VAR_NAMESPACE, NULL, NULL);
+      if (sym && SYMBOL_LANGUAGE (sym) != language_asm)
+	{
+	  /* Don't use this trick for assembly source files. */
+	  sal = find_pc_line (func_addr, 0);
+	  if (sal.end && sal.end < func_end)
+	    {
+	      /* Found a line number, use it as end of prologue.  */
+	      return sal.end;
+	    }
+	}
+      /* No useable line symbol.  Use prologue parsing method. */
+      return xstormy16_scan_prologue (func_addr, func_end, NULL);
+    }
+
+  /* No function symbol -- just return the PC. */
+
+  return (CORE_ADDR) pc;
+}
+
+/* The epilogue is defined here as the area at the end of a function,
+   either on the `ret' instruction itself or after an instruction which
+   destroys the function's stack frame. */
+static int
+xstormy16_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  CORE_ADDR addr, func_addr = 0, func_end = 0;
+
+  if (find_pc_partial_function (pc, NULL, &func_addr, &func_end))
+    {
+      ULONGEST inst, inst2;
+      CORE_ADDR addr = func_end - xstormy16_inst_size;
+
+      /* The Xstormy16 epilogue is max. 14 bytes long. */
+      if (pc < func_end - 7 * xstormy16_inst_size)
+	return 0;
+
+      /* Check if we're on a `ret' instruction.  Otherwise it's
+         too dangerous to proceed. */
+      inst = read_memory_unsigned_integer (addr, xstormy16_inst_size);
+      if (inst != 0x0003)
+	return 0;
+
+      while ((addr -= xstormy16_inst_size) >= func_addr)
+	{
+	  inst = read_memory_unsigned_integer (addr, xstormy16_inst_size);
+	  if (inst >= 0x009a && inst <= 0x009d)	/* pop r10...r13 */
+	    continue;
+	  if (inst == 0x305f || inst == 0x307f)	/* dec r15, #0x1/#0x3 */
+	    break;
+	  inst2 = read_memory_unsigned_integer (addr - xstormy16_inst_size,
+						xstormy16_inst_size);
+	  if (inst2 == 0x314f && inst >= 0x8000)	/* add r15, neg. value */
+	    {
+	      addr -= xstormy16_inst_size;
+	      break;
+	    }
+	  return 0;
+	}
+      if (pc > addr)
+	return 1;
+    }
+  return 0;
+}
+
+/* Function: xstormy16_frame_init_saved_regs
+   Set up the 'saved_regs' array.
+   This is a data structure containing the addresses on the stack 
+   where each register has been saved, for each stack frame.  
+   Registers that have not been saved will have zero here.
+   The stack register is special: rather than the address where the 
+   stack register has been saved, saved_regs[SP_REGNUM] will have the
+   actual value of the previous frame's stack register. 
+
+   This function may be called in any context where the saved register
+   values may be needed (backtrace, frame_info, get_saved_register).
+   On many targets, it is called directly by init_extra_frame_info, 
+   in part because the information may be needed immediately by 
+   frame_chain.
+*/
+
+static void
+xstormy16_frame_init_saved_regs (struct frame_info *fi)
+{
+  CORE_ADDR func_addr, func_end;
+
+  if (!fi->saved_regs)
+    {
+      frame_saved_regs_zalloc (fi);
+
+      /* Find the beginning of this function, so we can analyze its
+         prologue. */
+      if (find_pc_partial_function (fi->pc, NULL, &func_addr, &func_end))
+	xstormy16_scan_prologue (func_addr, fi->pc, fi);
+      /* Else we're out of luck (can't debug completely stripped code). 
+         FIXME. */
+    }
+}
+
+/* Function: xstormy16_frame_saved_pc
+   Returns the return address for the selected frame. 
+   Called by frame_info, frame_chain_valid, and sometimes by
+   get_prev_frame.
+*/
+
+static CORE_ADDR
+xstormy16_frame_saved_pc (struct frame_info *fi)
+{
+  CORE_ADDR saved_pc;
+
+  if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
+    {
+      saved_pc = generic_read_register_dummy (fi->pc, fi->frame, E_PC_REGNUM);
+    }
+  else
+    {
+      saved_pc = read_memory_unsigned_integer (fi->saved_regs[E_PC_REGNUM],
+					       xstormy16_pc_size);
+    }
+
+  return saved_pc;
+}
+
+/* Function: xstormy16_init_extra_frame_info
+   This is the constructor function for the frame_info struct, 
+   called whenever a new frame_info is created (from create_new_frame,
+   and from get_prev_frame).
+*/
+
+static void
+xstormy16_init_extra_frame_info (int fromleaf, struct frame_info *fi)
+{
+  if (!fi->extra_info)
+    {
+      fi->extra_info = (struct frame_extra_info *)
+	frame_obstack_alloc (sizeof (struct frame_extra_info));
+      fi->extra_info->framesize = 0;
+      fi->extra_info->frameless_p = 1;	/* Default frameless, detect framed */
+
+      /* By default, the fi->frame is set to the value of the FP reg by gdb.
+         This may not always be right; we may be in a frameless function,
+         or we may be in the prologue, before the FP has been set up.
+         Unfortunately, we can't make this determination without first
+         calling scan_prologue, and we can't do that unles we know the
+         fi->pc.  */
+
+      if (!fi->pc)
+	{
+	  /* Sometimes we are called from get_prev_frame without
+	     the PC being set up first.  Long history, don't ask.
+	     Fortunately this will never happen from the outermost
+	     frame, so we should be able to get the saved pc from
+	     the next frame. */
+	  if (fi->next)
+	    fi->pc = xstormy16_frame_saved_pc (fi->next);
+	}
+
+      /* Take care of the saved_regs right here (non-lazy). */
+      xstormy16_frame_init_saved_regs (fi);
+    }
+}
+
+/* Function: xstormy16_frame_chain
+   Returns a pointer to the stack frame of the calling function.
+   Called only from get_prev_frame.  Needed for backtrace, "up", etc.
+*/
+
+static CORE_ADDR
+xstormy16_frame_chain (struct frame_info *fi)
+{
+  if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame))
+    {
+      /* Call dummy's frame is the same as caller's.  */
+      return fi->frame;
+    }
+  else
+    {
+      /* Return computed offset from this frame's fp. */
+      return fi->frame - fi->extra_info->framesize;
+    }
+}
+
+static int
+xstormy16_frame_chain_valid (CORE_ADDR chain, struct frame_info *thisframe)
+{
+  return chain < 0x8000 && FRAME_SAVED_PC (thisframe) >= 0x8000 &&
+    (thisframe->extra_info->frameless_p ||
+     thisframe->frame - thisframe->extra_info->framesize == chain);
+}
+
+/* Function: xstormy16_saved_pc_after_call
+   Returns the previous PC immediately after a function call.
+   This function is meant to bypass the regular get_saved_register
+   mechanism, ie. it is meant to work even if the frame isn't complete. 
+   Called by step_over_function, and sometimes by get_prev_frame.
+*/
+
+static CORE_ADDR
+xstormy16_saved_pc_after_call (struct frame_info *ignore)
+{
+  CORE_ADDR sp, pc, tmp;
+
+  sp = read_register (E_SP_REGNUM) - xstormy16_pc_size;
+  pc = read_memory_integer (sp, xstormy16_pc_size);
+
+  /* Skip over jump table entry if necessary.  */
+  if ((tmp = SKIP_TRAMPOLINE_CODE (pc)))
+    pc = tmp;
+
+  return pc;
+}
+
+static unsigned char *
+xstormy16_breakpoint_from_pc (CORE_ADDR *pcptr, int *lenptr)
+{
+  static unsigned char breakpoint[] = { 0x06, 0x0 };
+  *lenptr = sizeof (breakpoint);
+  return breakpoint;
+}
+
+/* Given a pointer to a jump table entry, return the address
+   of the function it jumps to.  Return 0 if not found. */
+static CORE_ADDR
+xstormy16_resolve_jmp_table_entry (CORE_ADDR faddr)
+{
+  struct obj_section *faddr_sect = find_pc_section (faddr);
+
+  if (faddr_sect)
+    {
+      LONGEST inst, inst2, addr;
+      char buf[2 * xstormy16_inst_size];
+
+      /* Return faddr if it's not pointing into the jump table. */
+      if (strcmp (faddr_sect->the_bfd_section->name, ".plt"))
+	return faddr;
+
+      if (!target_read_memory (faddr, buf, sizeof buf))
+	{
+	  inst = extract_unsigned_integer (buf, xstormy16_inst_size);
+	  inst2 = extract_unsigned_integer (buf + xstormy16_inst_size,
+					    xstormy16_inst_size);
+	  addr = inst2 << 8 | (inst & 0xff);
+	  return addr;
+	}
+    }
+  return 0;
+}
+
+/* Given a function's address, attempt to find (and return) the
+   address of the corresponding jump table entry.  Return 0 if
+   not found. */
+static CORE_ADDR
+xstormy16_find_jmp_table_entry (CORE_ADDR faddr)
+{
+  struct obj_section *faddr_sect = find_pc_section (faddr);
+
+  if (faddr_sect)
+    {
+      struct obj_section *osect;
+
+      /* Return faddr if it's already a pointer to a jump table entry. */
+      if (!strcmp (faddr_sect->the_bfd_section->name, ".plt"))
+	return faddr;
+
+      ALL_OBJFILE_OSECTIONS (faddr_sect->objfile, osect)
+      {
+	if (!strcmp (osect->the_bfd_section->name, ".plt"))
+	  break;
+      }
+
+      if (osect < faddr_sect->objfile->sections_end)
+	{
+	  CORE_ADDR addr;
+	  for (addr = osect->addr;
+	       addr < osect->endaddr; addr += 2 * xstormy16_inst_size)
+	    {
+	      int status;
+	      LONGEST inst, inst2, faddr2;
+	      char buf[2 * xstormy16_inst_size];
+
+	      if (target_read_memory (addr, buf, sizeof buf))
+		return 0;
+	      inst = extract_unsigned_integer (buf, xstormy16_inst_size);
+	      inst2 = extract_unsigned_integer (buf + xstormy16_inst_size,
+						xstormy16_inst_size);
+	      faddr2 = inst2 << 8 | (inst & 0xff);
+	      if (faddr == faddr2)
+		return addr;
+	    }
+	}
+    }
+  return 0;
+}
+
+static CORE_ADDR
+xstormy16_skip_trampoline_code (CORE_ADDR pc)
+{
+  int tmp = xstormy16_resolve_jmp_table_entry (pc);
+
+  if (tmp && tmp != pc)
+    return tmp;
+  return 0;
+}
+
+static int
+xstormy16_in_solib_call_trampoline (CORE_ADDR pc, char *name)
+{
+  return xstormy16_skip_trampoline_code (pc) != 0;
+}
+
+static CORE_ADDR
+xstormy16_pointer_to_address (struct type *type, void *buf)
+{
+  enum type_code target = TYPE_CODE (TYPE_TARGET_TYPE (type));
+  CORE_ADDR addr = extract_address (buf, TYPE_LENGTH (type));
+
+  if (target == TYPE_CODE_FUNC || target == TYPE_CODE_METHOD)
+    {
+      CORE_ADDR addr2 = xstormy16_resolve_jmp_table_entry (addr);
+      if (addr2)
+	addr = addr2;
+    }
+
+  return addr;
+}
+
+static void
+xstormy16_address_to_pointer (struct type *type, void *buf, CORE_ADDR addr)
+{
+  enum type_code target = TYPE_CODE (TYPE_TARGET_TYPE (type));
+
+  if (target == TYPE_CODE_FUNC || target == TYPE_CODE_METHOD)
+    {
+      CORE_ADDR addr2 = xstormy16_find_jmp_table_entry (addr);
+      if (addr2)
+	addr = addr2;
+    }
+  store_address (buf, TYPE_LENGTH (type), addr);
+}
+
+static CORE_ADDR
+xstormy16_stack_align (CORE_ADDR addr)
+{
+  if (addr & 1)
+    ++addr;
+  return addr;
+}
+
+void
+xstormy16_save_dummy_frame_tos (CORE_ADDR sp)
+{
+  generic_save_dummy_frame_tos (sp - xstormy16_pc_size);
+}
+
+/* Function: xstormy16_gdbarch_init
+   Initializer function for the xstormy16 gdbarch vector.
+   Called by gdbarch.  Sets up the gdbarch vector(s) for this target. */
+
+static struct gdbarch *
+xstormy16_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
+{
+  static LONGEST call_dummy_words[1] = { 0 };
+  struct gdbarch_tdep *tdep = NULL;
+  struct gdbarch *gdbarch;
+
+  /* find a candidate among the list of pre-declared architectures. */
+  arches = gdbarch_list_lookup_by_info (arches, &info);
+  if (arches != NULL)
+    return (arches->gdbarch);
+
+#if 0
+  tdep = (struct gdbarch_tdep *) xmalloc (sizeof (struct gdbarch_tdep));
+#endif
+
+  gdbarch = gdbarch_alloc (&info, 0);
+
+  /*
+   * Basic register fields and methods.
+   */
+
+  set_gdbarch_num_regs (gdbarch, E_NUM_REGS);
+  set_gdbarch_num_pseudo_regs (gdbarch, 0);
+  set_gdbarch_sp_regnum (gdbarch, E_SP_REGNUM);
+  set_gdbarch_fp_regnum (gdbarch, E_FP_REGNUM);
+  set_gdbarch_pc_regnum (gdbarch, E_PC_REGNUM);
+  set_gdbarch_register_name (gdbarch, xstormy16_register_name);
+  set_gdbarch_register_size (gdbarch, xstormy16_reg_size);
+  set_gdbarch_register_bytes (gdbarch, E_ALL_REGS_SIZE);
+  set_gdbarch_register_byte (gdbarch, xstormy16_register_byte);
+  set_gdbarch_register_raw_size (gdbarch, xstormy16_register_raw_size);
+  set_gdbarch_max_register_raw_size (gdbarch, xstormy16_pc_size);
+  set_gdbarch_register_virtual_size (gdbarch, xstormy16_register_raw_size);
+  set_gdbarch_max_register_virtual_size (gdbarch, 4);
+  set_gdbarch_register_virtual_type (gdbarch, xstormy16_reg_virtual_type);
+
+  /*
+   * Frame Info
+   */
+  set_gdbarch_init_extra_frame_info (gdbarch,
+				     xstormy16_init_extra_frame_info);
+  set_gdbarch_frame_init_saved_regs (gdbarch,
+				     xstormy16_frame_init_saved_regs);
+  set_gdbarch_frame_chain (gdbarch, xstormy16_frame_chain);
+  set_gdbarch_get_saved_register (gdbarch, xstormy16_get_saved_register);
+  set_gdbarch_saved_pc_after_call (gdbarch, xstormy16_saved_pc_after_call);
+  set_gdbarch_frame_saved_pc (gdbarch, xstormy16_frame_saved_pc);
+  set_gdbarch_skip_prologue (gdbarch, xstormy16_skip_prologue);
+  set_gdbarch_frame_chain_valid (gdbarch, xstormy16_frame_chain_valid);
+  set_gdbarch_frame_args_address (gdbarch, default_frame_address);
+  set_gdbarch_frame_locals_address (gdbarch, default_frame_address);
+
+  set_gdbarch_in_function_epilogue_p (gdbarch,
+				      xstormy16_in_function_epilogue_p);
+
+  /* 
+   * Miscelany
+   */
+  /* Stack grows up. */
+  set_gdbarch_inner_than (gdbarch, core_addr_greaterthan);
+  /* PC stops zero byte after a trap instruction
+     (which means: exactly on trap instruction). */
+  set_gdbarch_decr_pc_after_break (gdbarch, 0);
+  /* This value is almost never non-zero... */
+  set_gdbarch_function_start_offset (gdbarch, 0);
+  /* This value is almost never non-zero... */
+  set_gdbarch_frame_args_skip (gdbarch, 0);
+  /* OK to default this value to 'unknown'. */
+  set_gdbarch_frame_num_args (gdbarch, frame_num_args_unknown);
+
+  /* W/o prototype, coerce float args to double. */
+  set_gdbarch_coerce_float_to_double (gdbarch,
+				      standard_coerce_float_to_double);
+
+  /*
+   * Call Dummies
+   * 
+   * These values and methods are used when gdb calls a target function.  */
+  set_gdbarch_use_generic_dummy_frames (gdbarch, 1);
+  set_gdbarch_push_dummy_frame (gdbarch, generic_push_dummy_frame);
+  set_gdbarch_push_return_address (gdbarch, xstormy16_push_return_address);
+  set_gdbarch_extract_return_value (gdbarch, xstormy16_extract_return_value);
+  set_gdbarch_push_arguments (gdbarch, xstormy16_push_arguments);
+  set_gdbarch_pop_frame (gdbarch, xstormy16_pop_frame);
+  set_gdbarch_store_struct_return (gdbarch, xstormy16_store_struct_return);
+  set_gdbarch_store_return_value (gdbarch, xstormy16_store_return_value);
+  set_gdbarch_extract_struct_value_address (gdbarch,
+					    xstormy16_extract_struct_value_address);
+  set_gdbarch_use_struct_convention (gdbarch,
+				     xstormy16_use_struct_convention);
+  set_gdbarch_call_dummy_location (gdbarch, AT_ENTRY_POINT);
+  set_gdbarch_call_dummy_address (gdbarch, entry_point_address);
+  set_gdbarch_call_dummy_start_offset (gdbarch, 0);
+  set_gdbarch_call_dummy_breakpoint_offset (gdbarch, 0);
+  set_gdbarch_call_dummy_breakpoint_offset_p (gdbarch, 1);
+  set_gdbarch_call_dummy_length (gdbarch, 0);
+  set_gdbarch_pc_in_call_dummy (gdbarch, generic_pc_in_call_dummy);
+  set_gdbarch_call_dummy_p (gdbarch, 1);
+  set_gdbarch_call_dummy_words (gdbarch, call_dummy_words);
+  set_gdbarch_sizeof_call_dummy_words (gdbarch, 0);
+  set_gdbarch_call_dummy_stack_adjust_p (gdbarch, 0);
+  /* set_gdbarch_call_dummy_stack_adjust */
+  set_gdbarch_fix_call_dummy (gdbarch, generic_fix_call_dummy);
+  set_gdbarch_breakpoint_from_pc (gdbarch, xstormy16_breakpoint_from_pc);
+
+  set_gdbarch_int_bit (gdbarch, 2 * TARGET_CHAR_BIT);
+  set_gdbarch_ptr_bit (gdbarch, 2 * TARGET_CHAR_BIT);
+  set_gdbarch_addr_bit (gdbarch, 4 * TARGET_CHAR_BIT);
+  set_gdbarch_long_double_bit (gdbarch, 8 * TARGET_CHAR_BIT);
+
+  set_gdbarch_address_to_pointer (gdbarch, xstormy16_address_to_pointer);
+  set_gdbarch_pointer_to_address (gdbarch, xstormy16_pointer_to_address);
+
+  set_gdbarch_stack_align (gdbarch, xstormy16_stack_align);
+  set_gdbarch_extra_stack_alignment_needed (gdbarch, 0);
+
+  set_gdbarch_save_dummy_frame_tos (gdbarch, xstormy16_save_dummy_frame_tos);
+
+  set_gdbarch_skip_trampoline_code (gdbarch, xstormy16_skip_trampoline_code);
+
+  set_gdbarch_in_solib_call_trampoline (gdbarch,
+					xstormy16_in_solib_call_trampoline);
+
+  return gdbarch;
+}
+
+/* Function: _initialize_xstormy16_tdep
+   Initializer function for the Sanyo Xstormy16a module.
+   Called by gdb at start-up. */
+
+void
+_initialize_xstormy16_tdep (void)
+{
+  extern int print_insn_xstormy16 ();
+
+  register_gdbarch_init (bfd_arch_xstormy16, xstormy16_gdbarch_init);
+  tm_print_insn = print_insn_xstormy16;
+}