/**

  * $Id: xlat.h 931 2008-10-31 02:57:59Z nkeynes $

  * 

  * Internal translation data structures and functions.

  *

  * Copyright (c) 2009 Nathan Keynes.

  *

  * 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.

  */

 #ifndef lxdream_xlat_H

 #define lxdream_xlat_H 1

 #include "xlat/xiropt.h"

 #include "xlat/xltcache.h"

 typedef struct target_data *target_data_t;

 /**

  * Source machine description. This should be immutable once constructed.

  **/

 struct xlat_source_machine {

     const char *name;

     void *state_data;   /* Pointer to source machine state structure */

     const char **reg_names; /* Register names, indexed by offset/4 */

     uint32_t pc_offset; /* Offset of source PC, relative to state_data */

     uint32_t delayed_pc_offset; /* Offset of source delayed PC offset, relative to state_data */

     uint32_t t_offset; /* Offset of source T reg, relative to state_data */

     uint32_t m_offset;

     uint32_t q_offset;

     uint32_t s_offset;

     /**

      * Decode a basic block of instructions from start, stopping after a

      * control transfer or before the given end instruction.

      * @param sd source data. This method should set the address_space field.

      * @return the pc value after the last decoded instruction.

      */ 

     uint32_t (*decode_basic_block)(xir_basic_block_t xbb);

 };

 /* Target machine description (no these are not meant to be symmetrical) */

 struct xlat_target_machine {

     const char *name;

     /* Register information */

     const char **reg_names;

     /* Required functions */

     /**

      * Test if the given operands are legal for the opcode. Note that it is assumed that

      * target register operands are always legal. This is used by the register allocator

      * to determine when it can fuse load/stores with another operation.

      */

     gboolean (*is_legal)( xir_opcode_t op, xir_operand_type_t arg0, xir_operand_type_t arg1 );

     /**

      * Lower IR closer to the machine, handling machine-specific issues that can't

      * wait until final code-gen. Can add additional instructions where required.

      */

     void (*lower)( xir_basic_block_t xbb, xir_op_t begin, xir_op_t end );

     /**

      * Determine the memory required to emit code for the specified block excluding

      * exceptions. This can be an overestimate,

      * as long as it is at least large enough for the final code.

      * @param begin start of code block

      * @param end end of code block

      * @return estimated size of emitted code.

      */

     uint32_t (*get_code_size)( xir_op_t begin, xir_op_t end );

     /**

      * Final target code generation.

      * @param td target_data information.

      * @param begin start of code block

      * @param end end of code block

      * @param exception_table Table of pointers to exception code 

      * @return number of bytes actually emitted.

      */

     uint32_t (*codegen)( target_data_t td, xir_op_t begin, xir_op_t end ); 

 };

 /**

  * Fixup records generated while assembling the code. Records are one of the

  * following types:

  *    Constant (32 or 64-bit)

  *    Exception (from a memory call or RAISEME instruction)

  *    

  * Relocations may be 32/64 bit absolute or 32-bit PC-relative. The value in the

  * relocation cell is taken as the addend if nonzero. For relative relocations, 

  * the relative displacement is calculated from the end of the fixup value - 

  * that is, for a REL32, the result will be

  *   *fixup_loc += &target - (fixup_loc+4)

  *  

  * In principle we could use a global constant table, but that adds complexity

  * at this stage. 

  */

 #define TARGET_FIXUP_CONST32  0x00  

 #define TARGET_FIXUP_CONST64  0x01

 #define TARGET_FIXUP_RAISE    0x02

 #define TARGET_FIXUP_RAISEEXT 0x03 /* An exception that can be raised from outside the generated code */

 #define TARGET_FIXUP_OFFSET   0x04 /* Offset within the code block */

 #define TARGET_FIXUP_POINTER  0x05 /* Absolute pointer */

 #define TARGET_FIXUP_ABS32    0x00

 #define TARGET_FIXUP_ABS64    0x10

 #define TARGET_FIXUP_REL32    0x20

 #define TARGET_FIXUP_REL64    0x30

 #define TARGET_FIXUP_TARGET(x) ((x)&0x0F)

 #define TARGET_FIXUP_MODE(x)   ((x)&0xF0)

 typedef struct target_fixup_struct {

     int fixup_type; /* Combination of TARGET_FIXUP flags above */

     uint32_t fixup_offset; /* Location of fixup (to be modified) relative to start of block */

     uint32_t target_offset;

     union {

         uint32_t i;

         uint64_t q;

         float f;

         double d;

         void *p;

         xir_op_t *exc;

     } value;

 } *target_fixup_t;

 /**

  * Temporary data maintained during code generation

  */

 struct target_data {

     struct xlat_target_machine *mach;

     struct xlat_source_macine *src;

     xlat_cache_block_t block;

     uint8_t *xlat_output;

     target_fixup_t fixup_table;

     int fixup_table_posn;

     int fixup_table_size;

 };

 /** Add fixup to a 32-bit constant memory value, adding the value to the constant table */

 void target_add_const32_fixup( target_data_t td, int mode, void *location, uint32_t i );

 /** Add fixup to a 64-bit constant memory value, adding the value to the constant table */

 void target_add_const64_fixup( target_data_t td, int mode, void *location, uint64_t i );

 /** Add fixup to an internal exception handler block */

 void target_add_raise_fixup( target_data_t td, int type, void *location, xir_op_t *exc );

 /** Add fixup to an externally accessible exception handle block */

 void target_add_raiseext_fixup( target_data_t td, int type, void *location, xir_op_t *exc );

 /** Add fixup to an arbitrary offset within the code block */

 void target_add_offset_fixup( target_data_t td, int type, void *location, uint32_t off );

 /** Add fixup to an arbitrary pointer */

 void target_add_pointer_fixup( target_data_t td, int type, void *location, void *p );

 /**

  * Generate final code for the block.

  * @return entry point of the code block.

  */ 

 void *target_codegen( xlat_target_machine_t target, xir_basic_block_t xbb );   

 #endif /* lxdream_xlat_H */