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//=============================================================================

//

//      openrisc_opcode.h

//

//  Define the instruction formats and opcode values for the OpenRISC

//  instruction set...or at least just enough of them to implement

//  single-stepping.

//

//=============================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

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//

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// or inline functions from this file, or you compile this file and link it

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//=============================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):   sfurman

// Contributors:

// Date:        2003-02-28

// Purpose:     Allow dissection of OpenRISC instructions

// Description: The types and macros defined here define the instruction

//              formats of the OpenRISC instruction set...or at least the

//              very limited subset necessary to allow single-stepping.

//              

//####DESCRIPTIONEND####

//

//=============================================================================

#ifndef _OPENRISC_OPCODE_H

#define _OPENRISC_OPCODE_H

// Define the instruction formats.

typedef union {

    unsigned word;

    // (Possibly conditional) relative jump w/ immediate displacement

    struct {

        unsigned op:      6;    // OP_J, OP_JAL, OP_BNF, or OP_BF

        signed   target: 26;

    } JType;

    // Absolute jump w/ register contents used as PC target address

    struct {

        unsigned op:      6;    // OP_JR or OP_JALR

        unsigned unused1:10;

        unsigned rB:      5;    // Register containing new PC

        unsigned unused2:11;

    } JRType;

} InstFmt;

/*

 * Values for the 'op' field.

 */

#define OP_J            0x00

#define OP_JAL          0x01

#define OP_BNF          0x03

#define OP_BF           0x04

#define OP_RFE          0x09

#define OP_JR           0x11

#define OP_JALR         0x12

#endif  /* _OPENRISC_OPCODE_H */