package cpu_pkg;

typedef enum logic [2:0] {
  REG8_B   = 3'h00,
  REG8_C   = 3'h01,
  REG8_D   = 3'h02,
  REG8_E   = 3'h03,
  REG8_H   = 3'h04,
  REG8_L   = 3'h05,
  REG8_PHL = 3'h06,
  REG8_A   = 3'h07
} reg8_t;

typedef enum logic [1:0] {
  REG16_BC    = 2'h00,
  REG16_DE    = 2'h01,
  REG16_HL    = 2'h02,
  REG16_SP_AF = 2'h03
} reg16_t;

typedef enum logic [1:0] {
  CC_NZ = 2'h00,
  CC_Z  = 2'h01,
  CC_NC = 2'h02,
  CC_C  = 2'h03
} cc_t;

typedef enum logic [2:0] {
  ALU_OP_ADD  = 3'h00,
  ALU_OP_ADC  = 3'h01,
  ALU_OP_SUB  = 3'h02,
  ALU_OP_SBC  = 3'h03,
  ALU_OP_AND  = 3'h04,
  ALU_OP_XOR  = 3'h05,
  ALU_OP_OR   = 3'h06,
  ALU_OP_CP   = 3'h07
} alu_op_t;

typedef enum logic [2:0] {
  SHIFT_OP_RLC = 3'h00,
  SHIFT_OP_RRC = 3'h01,
  SHIFT_OP_RL  = 3'h02,
  SHIFT_OP_RR  = 3'h03,
  SHIFT_OP_SLA = 3'h04,
  SHIFT_OP_SRA = 3'h05,
  SHIFT_OP_SLL = 3'h06,
  SHIFT_OP_SRL = 3'h07
} shift_op_t;

typedef struct packed {
  logic       b;
  logic       s;
  logic       r;
  logic [2:0] operand;
} bsr_op_t;

typedef struct packed {
  logic inc;
  logic dec;
  logic dst_a;
} incdec_op_t;

typedef struct packed {
  logic       update_a;
  logic       update_f;
  logic       alu_op_valid;
  alu_op_t    alu_op;
  logic       shift_op_valid;
  shift_op_t  shift_op;
  logic       bsr_op_valid;
  bsr_op_t    bsr_op;
  logic       incdec_op_valid;
  incdec_op_t incdec_op;
} alu_ctrl_t;

typedef enum {
  ADDR_SRC_PC,
  ADDR_SRC_SP,
  ADDR_SRC_REG16, // TODO reuse BUS_Q
  ADDR_SRC_REG8,  // TODO reuse BUS_Q
  ADDR_SRC_OPERAND8,
  ADDR_SRC_OPERAND16,
  ADDR_SRC_BUS_P,
  ADDR_SRC_BUS_Q
} addr_src_t;

typedef enum {
  BUS_SRC_A,
  BUS_SRC_F,
  BUS_SRC_REG8,
  BUS_SRC_OPERAND8_H,
  BUS_SRC_OPERAND8_L,
  BUS_SRC_ALU,
  BUS_SRC_MEM,
  BUS_SRC_PC_H,
  BUS_SRC_PC_L,
  BUS_SRC_REG16_H,
  BUS_SRC_REG16_L
} bus_src_t;

typedef enum {
  BUS_DST_SP_H,
  BUS_DST_SP_L,
  BUS_DST_ALU,
  BUS_DST_REG8,
  BUS_DST_REG16_H,
  BUS_DST_REG16_L,
  BUS_DST_PC_H,
  BUS_DST_PC_L,
  BUS_DST_MEM
} bus_dst_t;

typedef struct packed {
  bus_src_t   src;
  bus_dst_t   dst;
  logic       wen;
} bus_ctrl_t;

typedef enum {
  BUS16_SRC_REG16,
  BUS16_SRC_ALU16,
  BUS16_SRC_SP
} bus16_src_t;

typedef enum {
  BUS16_DST_REG16,
  BUS16_DST_ALU16,
  BUS16_DST_SP
} bus16_dst_t;

typedef struct packed {
  bus16_src_t src;
  bus16_dst_t dst;
  logic       wen;
} bus16_ctrl_t;

typedef enum {
  PC_SRC_INC,
  PC_SRC_OPERAND8,
  PC_SRC_OPERAND16,
  PC_SRC_BUS
} pc_src_t;

endpackage : cpu_pkg