avm/lib/inst.h

/* Copyright (C) 2023 Aryadev Chavali

 * You may distribute and modify this code under the terms of the
 * GPLv2 license.  You should have received a copy of the GPLv2
 * license with this file.  If not, please write to:
 * aryadev@aryadevchavali.com.

 * Created: 2023-10-15
 * Author: Aryadev Chavali
 * Description: Instructions and opcodes
 */

#ifndef INST_H
#define INST_H

#include <lib/base.h>
#include <stdio.h>
#include <stdlib.h>

#define UNSIGNED_OPCODE_IS_TYPE(OPCODE, OP_TYPE) \
  (((OPCODE) >= OP_TYPE##_BYTE) && ((OPCODE) <= OP_TYPE##_WORD))

#define SIGNED_OPCODE_IS_TYPE(OPCODE, OP_TYPE) \
  (((OPCODE) >= OP_TYPE##_BYTE) && ((OPCODE) <= OP_TYPE##_LONG))

#define OPCODE_DATA_TYPE(OPCODE, OP_TYPE) (OPCODE - OP_TYPE##_BYTE)

typedef enum
{
  OP_NOOP = 0,

  // Dealing with data and registers
  OP_PUSH_BYTE,
  OP_PUSH_HWORD,
  OP_PUSH_WORD,

  OP_POP_BYTE,
  OP_POP_HWORD,
  OP_POP_WORD,

  OP_PUSH_REGISTER_BYTE,
  OP_PUSH_REGISTER_HWORD,
  OP_PUSH_REGISTER_WORD,

  OP_MOV_BYTE,
  OP_MOV_HWORD,
  OP_MOV_WORD,

  OP_DUP_BYTE,
  OP_DUP_HWORD,
  OP_DUP_WORD,

  // Dealing with the heap
  OP_MALLOC_BYTE,
  OP_MALLOC_HWORD,
  OP_MALLOC_WORD,

  OP_MALLOC_STACK_BYTE,
  OP_MALLOC_STACK_HWORD,
  OP_MALLOC_STACK_WORD,

  OP_MSET_BYTE,
  OP_MSET_HWORD,
  OP_MSET_WORD,

  OP_MSET_STACK_BYTE,
  OP_MSET_STACK_HWORD,
  OP_MSET_STACK_WORD,

  OP_MGET_BYTE,
  OP_MGET_HWORD,
  OP_MGET_WORD,

  OP_MGET_STACK_BYTE,
  OP_MGET_STACK_HWORD,
  OP_MGET_STACK_WORD,

  OP_MDELETE,
  OP_MSIZE,

  // Boolean operations
  OP_NOT_BYTE,
  OP_NOT_HWORD,
  OP_NOT_WORD,

  OP_OR_BYTE,
  OP_OR_HWORD,
  OP_OR_WORD,

  OP_AND_BYTE,
  OP_AND_HWORD,
  OP_AND_WORD,

  OP_XOR_BYTE,
  OP_XOR_HWORD,
  OP_XOR_WORD,

  OP_EQ_BYTE,
  OP_EQ_HWORD,
  OP_EQ_WORD,

  // Mathematical operations
  OP_PLUS_BYTE,
  OP_PLUS_HWORD,
  OP_PLUS_WORD,

  OP_SUB_BYTE,
  OP_SUB_HWORD,
  OP_SUB_WORD,

  OP_MULT_BYTE,
  OP_MULT_HWORD,
  OP_MULT_WORD,

  // Comparison operations
  OP_LT_BYTE,
  OP_LT_CHAR,
  OP_LT_HWORD,
  OP_LT_INT,
  OP_LT_WORD,
  OP_LT_LONG,

  OP_LTE_BYTE,
  OP_LTE_CHAR,
  OP_LTE_HWORD,
  OP_LTE_INT,
  OP_LTE_WORD,
  OP_LTE_LONG,

  OP_GT_BYTE,
  OP_GT_CHAR,
  OP_GT_HWORD,
  OP_GT_INT,
  OP_GT_WORD,
  OP_GT_LONG,

  OP_GTE_BYTE,
  OP_GTE_CHAR,
  OP_GTE_HWORD,
  OP_GTE_INT,
  OP_GTE_WORD,
  OP_GTE_LONG,

  // Simple I/O
  OP_PRINT_BYTE,
  OP_PRINT_CHAR,
  OP_PRINT_HWORD,
  OP_PRINT_INT,
  OP_PRINT_WORD,
  OP_PRINT_LONG,

  // Program control flow
  OP_JUMP_ABS,
  OP_JUMP_STACK,
  OP_JUMP_IF_BYTE,
  OP_JUMP_IF_HWORD,
  OP_JUMP_IF_WORD,

  // Subroutines
  OP_CALL,
  OP_CALL_STACK,
  OP_RET,

  // Should not be an opcode
  NUMBER_OF_OPCODES,
  OP_HALT = 0b11111111, // top of the byte is a HALT
} opcode_t;

size_t opcode_bytecode_size(opcode_t);
const char *opcode_as_cstr(opcode_t);

typedef struct
{
  opcode_t opcode;
  data_t operand;
} inst_t;

/**
   @brief Serialise an instruction into a byte buffer

   @details Given an instruction and a suitably sized byte buffer,
   write the bytecode for the instruction into the buffer.  NOTE: This
   function does NOT check the bounds of `bytes` i.e. we assume the
   caller has created a suitably sized buffer.

   @param[inst] Instruction to serialise
   @param[bytes] Buffer to write on

   @return[size_t] Number of bytes written to `bytes`.
 */
size_t inst_write_bytecode(inst_t inst, byte_t *bytes);

typedef enum
{
  READ_ERR_INVALID_OPCODE = -1,
  READ_ERR_OPERAND_NO_FIT = -2,
  READ_ERR_EXPECTED_MORE  = -3,
  READ_ERR_END            = -4
} read_err_t;

/**
   @brief Deserialise an instruction from a bytecode buffer

   @details Given a buffer of bytes, deserialise an instruction,
   storing the result in the pointer given.  The number of bytes read
   in the buffer is returned, which should be opcode_bytecode_size().
   NOTE: If bytes is not suitably sized for the instruction expected
   or it is not well formed i.e. not the right schema then a negative
   number is returned.

   @param[inst] Pointer to instruction which will store result
   @param[bytes] Bytecode buffer to deserialise
   @param[size_bytes] Number of bytes in buffer

   @return[int] Number of bytes read.  If negative then an error
   occurred in deserialisation (either buffer was not suitably sized
   or instruction was not well formed) so any result must be
   considered invalid.
 */
int inst_read_bytecode(inst_t *inst, byte_t *bytes, size_t size_bytes);

void inst_print(inst_t, FILE *);

typedef struct
{
  word_t start_address;
  word_t count;
  inst_t *instructions;
} prog_t;

#define PROG_HEADER_SIZE (WORD_SIZE * 2)

size_t prog_bytecode_size(prog_t);

size_t prog_write_bytecode(prog_t program, byte_t *bytes, size_t size_bytes);

size_t prog_read_header(prog_t *program, byte_t *bytes, size_t size_bytes);

typedef struct
{
  read_err_t type;
  size_t index;
} read_err_prog_t;

read_err_prog_t prog_read_instructions(prog_t *program, size_t *size_bytes_read,
                                       byte_t *bytes, size_t size_bytes);

#endif