Program Listing for File dds_opcodes.h

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/*
 * Copyright(c) 2021 ADLINK Technology Limited and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
 * v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

#ifndef DDS_OPCODES_H
#define DDS_OPCODES_H

#if defined (__cplusplus)
extern "C" {
#endif

/* Topic encoding instruction types */

enum dds_stream_opcode {
  /* return from subroutine, exits top-level
     [RTS,   0,   0, 0] */
  DDS_OP_RTS = 0x00 << 24,
  /* data field
     [ADR, nBY,   0, k] [offset]
     [ADR, STR,   0, k] [offset]
     [ADR, BST,   0, k] [offset] [bound]
     [ADR, SEQ, nBY, 0] [offset]
     [ADR, SEQ, STR, 0] [offset]
     [ADR, SEQ, BST, 0] [offset] [bound]
     [ADR, SEQ,   s, 0] [offset] [elem-size] [next-insn, elem-insn]
       where s = {SEQ,ARR,UNI,STU}
     [ADR, ARR, nBY, k] [offset] [alen]
     [ADR, ARR, STR, 0] [offset] [alen]
     [ADR, ARR, BST, 0] [offset] [alen] [0] [bound]
     [ADR, ARR,   s, 0] [offset] [alen] [next-insn, elem-insn] [elem-size]
         where s = {SEQ,ARR,UNI,STU}
     [ADR, UNI,   d, z] [offset] [alen] [next-insn, cases]
       where
         d = discriminant type of {1BY,2BY,4BY}
         z = default present/not present (DDS_OP_FLAG_DEF)
         offset = discriminant offset
       followed by alen case labels: in JEQ format
     note: [ADR, STU, ...] is illegal
   where
     s            = subtype
     k            = key/not key (DDS_OP_FLAG_KEY)
     [offset]     = field offset from start of element in memory
     [elem-size]  = element size in memory
     [bound]      = string bound + 1
     [alen]       = array length, number of cases
     [next-insn]  = (unsigned 16 bits) offset to instruction for next field, from start of insn
     [elem-insn]  = (unsigned 16 bits) offset to first instruction for element, from start of insn
     [cases]      = (unsigned 16 bits) offset to first case label, from start of insn
   */
  DDS_OP_ADR = 0x01 << 24,
  /* jump-to-subroutine (apparently not used at the moment)
     [JSR,   0, e]
       where
         e = (signed 16 bits) offset to first instruction in subroutine, from start of insn
             instruction sequence must end in RTS, execution resumes at instruction
             following JSR */
  DDS_OP_JSR = 0x02 << 24,
  /* union case
     [JEQ, nBY, 0] [disc] [offset]
     [JEQ, STR, 0] [disc] [offset]
     [JEQ,   s, e] [disc] [offset]
       where
         s  = subtype other than {nBY,STR}
         e  = (unsigned 16 bits) offset to first instruction for case, from start of insn
              instruction sequence must end in RTS, at which point executes continues
              at the next field's instruction as specified by the union */
  DDS_OP_JEQ = 0x03 << 24
};

enum dds_stream_typecode {
  DDS_OP_VAL_1BY = 0x01, /* one byte simple type (char, octet, boolean) */
  DDS_OP_VAL_2BY = 0x02, /* two byte simple type ((unsigned) short) */
  DDS_OP_VAL_4BY = 0x03, /* four byte simple type ((unsigned) long, enums, float) */
  DDS_OP_VAL_8BY = 0x04, /* eight byte simple type ((unsigned) long long, double) */
  DDS_OP_VAL_STR = 0x05, /* string */
  DDS_OP_VAL_BST = 0x06, /* bounded string */
  DDS_OP_VAL_SEQ = 0x07, /* sequence */
  DDS_OP_VAL_ARR = 0x08, /* array */
  DDS_OP_VAL_UNI = 0x09, /* union */
  DDS_OP_VAL_STU = 0x0a  /* struct */
};

/* primary type code for DDS_OP_ADR, DDS_OP_JEQ */
enum dds_stream_typecode_primary {
  DDS_OP_TYPE_1BY = DDS_OP_VAL_1BY << 16,
  DDS_OP_TYPE_2BY = DDS_OP_VAL_2BY << 16,
  DDS_OP_TYPE_4BY = DDS_OP_VAL_4BY << 16,
  DDS_OP_TYPE_8BY = DDS_OP_VAL_8BY << 16,
  DDS_OP_TYPE_STR = DDS_OP_VAL_STR << 16,
  DDS_OP_TYPE_BST = DDS_OP_VAL_BST << 16,
  DDS_OP_TYPE_SEQ = DDS_OP_VAL_SEQ << 16,
  DDS_OP_TYPE_ARR = DDS_OP_VAL_ARR << 16,
  DDS_OP_TYPE_UNI = DDS_OP_VAL_UNI << 16,
  DDS_OP_TYPE_STU = DDS_OP_VAL_STU << 16
};
#define DDS_OP_TYPE_BOO DDS_OP_TYPE_1BY

/* sub-type code:
   - encodes element type for DDS_OP_TYPE_{SEQ,ARR},
   - discriminant type for DDS_OP_TYPE_UNI */
enum dds_stream_typecode_subtype {
  DDS_OP_SUBTYPE_1BY = DDS_OP_VAL_1BY << 8,
  DDS_OP_SUBTYPE_2BY = DDS_OP_VAL_2BY << 8,
  DDS_OP_SUBTYPE_4BY = DDS_OP_VAL_4BY << 8,
  DDS_OP_SUBTYPE_8BY = DDS_OP_VAL_8BY << 8,
  DDS_OP_SUBTYPE_STR = DDS_OP_VAL_STR << 8,
  DDS_OP_SUBTYPE_BST = DDS_OP_VAL_BST << 8,
  DDS_OP_SUBTYPE_SEQ = DDS_OP_VAL_SEQ << 8,
  DDS_OP_SUBTYPE_ARR = DDS_OP_VAL_ARR << 8,
  DDS_OP_SUBTYPE_UNI = DDS_OP_VAL_UNI << 8,
  DDS_OP_SUBTYPE_STU = DDS_OP_VAL_STU << 8
};
#define DDS_OP_SUBTYPE_BOO DDS_OP_SUBTYPE_1BY

#define DDS_OP_FLAG_KEY 0x01 /* key field: applicable to {1,2,4,8}BY, STR, BST, ARR-of-{1,2,4,8}BY */
#define DDS_OP_FLAG_DEF 0x02 /* union has a default case (for DDS_OP_ADR | DDS_OP_TYPE_UNI) */

/* For a union: (1) the discriminator may be a key field; (2) there may be a default value;
   and (3) the discriminator can be an integral type (or enumerated - here treated as equivalent).
   What it can't be is a floating-point type. So DEF and FP need never be set at the same time.
   There are only a few flag bits, so saving one is not such a bad idea. */
#define DDS_OP_FLAG_FP  0x02 /* floating-point: applicable to {4,8}BY and arrays, sequences of them */
#define DDS_OP_FLAG_SGN 0x04 /* signed: applicable to {1,2,4,8}BY and arrays, sequences of them */

/* Topic descriptor flag values */

#define DDS_TOPIC_NO_OPTIMIZE 0x0001
#define DDS_TOPIC_FIXED_KEY 0x0002
#define DDS_TOPIC_CONTAINS_UNION 0x0004
#define DDS_TOPIC_DISABLE_TYPECHECK 0x0008
#define DDS_TOPIC_FIXED_SIZE 0x0010

#if defined(__cplusplus)
}
#endif

#endif /* DDS_OPCODES_H */