pet-projects/DLW-1e/das/opcode.h

   1 #ifndef _DAS_OPCODE_H
   2 #define _DAS_OPCODE_H
   3
   4 #include <stdint.h>
   5
   6 /* type definitions*/
   7
   8 typedef uint16_t inst_t;  // instruction
   9 typedef uint8_t  oper_t;   // operand
  10
  11 /* operand struct */
  12 struct operand {
  13         int type;
  14         oper_t value;
  15 };
  16
  17 /* operand definitions */
  18
  19 #define OP_INV 0x0  /* invalid or not used */
  20 #define OP_REG 0x1  /* register */
  21 #define OP_IMM 0x2  /* immediate */
  22
  23 /* just for your convenience */
  24 #define OP_RI (OP_REG | OP_IMM)
  25
  26 /* maximum number of operands */
  27 #define OP_MAX 3
  28
  29 /* opcode table */
  30 struct opcode {
  31         const char *mnemonic;
  32         int opcode;
  33         int type;
  34         int nr_operands;
  35         struct operand operands[OP_MAX];
  36 };
  37
  38 /* instruction types */
  39 #define INST_ARIT 0
  40 #define INST_BRAN 1
  41 #define INST_MEM  2
  42 #define INST_COMP 3
  43 #define INST_NARG 4
  44
  45 /* instruction offsets */
  46 #define OFF_INST 12
  47 #define OFF_SRC1 10
  48 #define OFF_SRC2  8
  49 #define OFF_IMM_DEST OFF_SRC2
  50 #define OFF_DEST  6
  51
  52 #define OFF_MEM_REG_SRC1 10
  53 #define OFF_MEM_REG_DEST  6
  54 #define OFF_MEM_IMM_DEST  8
  55
  56 /* masks */
  57 #define MASK_IMM 0xFF
  58
  59 /* special bits */
  60 #define BIT_IMM 0x8000
  61
  62 /* helper macros */
  63
  64 /* set_reg(): set register 'reg' at offset 'off' in 'instruction' */
  65 static inline void set_reg(inst_t *instruction, oper_t reg, int off)
  66 {
  67         *instruction |= ((inst_t) (reg << off));
  68 }
  69
  70 /* set_imm(): set immediate 'imm' in 'instruction' */
  71 static inline void set_imm(inst_t *instruction, oper_t imm)
  72 {
  73         *instruction |= BIT_IMM;
  74         *instruction |= ((inst_t) (MASK_IMM & imm));
  75 }
  76
  77 /* exported functions */
  78 struct opcode *opcode_lookup(const char *mnemonic);
  79
  80 #endif /* _DAS_OPCODE_H */