#ifndef UNDAR_VM_H
#define UNDAR_VM_H

#include "libc.h"

typedef enum {
  OP_NOOP,           /* noop              : no nothing for 1 cycle */
  OP_CALL,           /* call              : creates a new frame */  
  OP_RETURN,         /* return            : returns from a frame to the parent frame */
  OP_SYSCALL,        /* syscall           : syscall(u8 src1 count_args, u32 ptr_memory)  */
  OP_LOAD_IMM,       /* load_immediate    : locals[dest] = constant */
  OP_LOAD_IND_8,     /* load_indirect_8   : locals[dest] = memory[locals[src1]] as u8 */
  OP_LOAD_IND_16,    /* load_indirect_16  : locals[dest] = memory[locals[src1]] as u16 */
  OP_LOAD_IND_32,    /* load_indirect_32  : locals[dest] = memory[locals[src1]] as u32 */
  OP_LOAD_ABS_8,     /* load_absolute_8   : locals[dest] = memory[src1] as u8 */
  OP_LOAD_ABS_16,    /* load_absolute_16  : locals[dest] = memory[src1] as u16 */
  OP_LOAD_ABS_32,    /* load_absolute_32  : locals[dest] = memory[src1] as u32 */
  OP_LOAD_OFF_8,     /* load_offset_8     : locals[dest] = memory[locals[src1] + offset] as u8 */
  OP_LOAD_OFF_16,    /* load_offset_16    : locals[dest] = memory[locals[src1] + offset] as u16 */
  OP_LOAD_OFF_32,    /* load_offset_32    : locals[dest] = memory[locals[src1] + offset] as u32 */
  OP_STORE_ABS_8,    /* store_absolute_8  : memory[dest] = src1 && 0xFF */
  OP_STORE_ABS_16,   /* store_absolute_16 : memory[dest] = src1 && 0xFFFF */
  OP_STORE_ABS_32,   /* store_absolute_32 : memory[dest] = src1 */
  OP_STORE_IND_8,    /* store_indirect_8  : memory[dest] = locals[src1] && 0xFF */
  OP_STORE_IND_16,   /* store_indirect_16 : memory[dest] = locals[src1] && 0xFFFF*/
  OP_STORE_IND_32,   /* store_indirect_32 : memory[dest] = locals[src1] */
  OP_STORE_OFF_8,    /* store_offset_8    : memory[locals[dest] + offset] = locals[src1] && 0xFF */
  OP_STORE_OFF_16,   /* store_offset_16   : memory[locals[dest] + offset] = locals[src1] && 0xFFFF */
  OP_STORE_OFF_32,   /* store_offset_32   : memory[locals[dest] + offset] = locals[src1] */
  OP_MALLOC,         /* malloc            : dest = fat ptr to memory of ((src1 as size) + 4) */
  OP_MEMSET_8,       /* memset_8          : dest <-> dest+count = src1 as u8 */
  OP_MEMSET_16,      /* memset_16         : dest <-> dest+count = src1 as u16 */
  OP_MEMSET_32,      /* memset_32         : dest <-> dest+count = src1 as u32 */
  OP_REG_MOV,        /* register_move     : locals[dest] = locals[src1] */
  OP_ADD_INT,        /* add_int           : locals[dest] = locals[src1] + locals[src2]  */
  OP_SUB_INT,        /* sub_int           : locals[dest] = locals[src1] _ locals[src2]  */
  OP_MUL_INT,        /* mul_int           : locals[dest] = locals[src1] * locals[src2]  */
  OP_DIV_INT,        /* div_int           : locals[dest] = locals[src1] / locals[src2]  */
  OP_ABS_INT,        /* abs_int           : locals[dest] = | locals[src1] |  */
  OP_NEG_INT,        /* neg_int           : locals[dest] = -locals[src1] */  
  OP_ADD_NAT,        /* add_nat           : locals[dest] = locals[src1] + locals[src2]  */
  OP_SUB_NAT,        /* sub_nat           : locals[dest] = locals[src1] _ locals[src2]  */
  OP_MUL_NAT,        /* mul_nat           : locals[dest] = locals[src1] * locals[src2]  */
  OP_DIV_NAT,        /* div_nat           : locals[dest] = locals[src1] / locals[src2]  */
  OP_ABS_NAT,        /* abs_nat           : locals[dest] = | locals[src1] |  */
  OP_NEG_NAT,        /* neg_nat           : locals[dest] = -locals[src1] */
  OP_ADD_REAL,       /* add_real          : locals[dest] = locals[src1] + locals[src2]  */
  OP_SUB_REAL,       /* sub_real          : locals[dest] = locals[src1] _ locals[src2]  */
  OP_MUL_REAL,       /* mul_real          : locals[dest] = locals[src1] * locals[src2]  */
  OP_DIV_REAL,       /* div_real          : locals[dest] = locals[src1] / locals[src2]  */
  OP_ABS_REAL,       /* abs_real          : locals[dest] = | locals[src1] |  */
  OP_NEG_REAL,       /* neg_real          : locals[dest] = _locals[src1] */
  OP_INT_TO_REAL,    /* int_to_real       : locals[dest] = locals[src1] as real */
  OP_INT_TO_NAT,     /* int_to_nat        : locals[dest] = locals[src1] as nat */
  OP_NAT_TO_REAL,    /* nat_to_real       : locals[dest] = locals[src1] as real */
  OP_NAT_TO_INT,     /* nat_to_int        : locals[dest] = locals[src1] as int */
  OP_REAL_TO_INT,    /* real_to_int       : locals[dest] = locals[src1] as int  */
  OP_REAL_TO_NAT,    /* real_to_nat       : locals[dest] = locals[src1] as nat */
  OP_BIT_SHIFT_LEFT, /* bit_shift_left    : locals[dest] = locals[src1] << locals[src2] */
  OP_BIT_SHIFT_RIGHT,/* bit_shift_right   : locals[dest] = locals[src1] >> locals[src2] */
  OP_BIT_SHIFT_R_EXT,/* bit_shift_r_ext   : locals[dest] as i32 = locals[src1] >> locals[src2] */
  OP_BAND,           /* bit_and           : locals[dest] = locals[src1] & locals[src2] */
  OP_BOR,            /* bit_or            : locals[dest] = locals[src1] | locals[src2] */
  OP_BXOR,           /* bit_xor           : locals[dest] = locals[src1] ^ locals[src2] */
  OP_JMP,            /* jump              : jump to &dest unconditionally */
  OP_JMPF,           /* jump_if_flag      : jump to &dest if flag != 0 */  
  OP_JEQ_INT,        /* jump_eq_int       : jump to &dest if locals[src1] as int == locals[src2] as int */
  OP_JNEQ_INT,       /* jump_neq_int      : jump to &dest if locals[src1] as int != locals[src2] as int */
  OP_JGT_INT,        /* jump_gt_int       : jump to &dest if locals[src1] as int >  locals[src2] as int */
  OP_JLT_INT,        /* jump_lt_int       : jump to &dest if locals[src1] as int <  locals[src2] as int */
  OP_JLE_INT,        /* jump_le_int       : jump to &dest if locals[src1] as int <= locals[src2] as int */
  OP_JGE_INT,        /* jump_ge_int       : jump to &dest if locals[src1] as int >= locals[src2] as int */
  OP_JEQ_NAT,        /* jump_eq_nat       : jump to &dest if locals[src1] as nat == locals[src2] as nat */
  OP_JNEQ_NAT,       /* jump_neq_nat      : jump to &dest if locals[src1] as nat != locals[src2] as nat */
  OP_JGT_NAT,        /* jump_gt_nat       : jump to &dest if locals[src1] as nat >  locals[src2] as nat */
  OP_JLT_NAT,        /* jump_lt_nat       : jump to &dest if locals[src1] as nat <  locals[src2] as nat */
  OP_JLE_NAT,        /* jump_le_nat       : jump to &dest if locals[src1] as nat <= locals[src2] as nat */
  OP_JGE_NAT,        /* jump_ge_nat       : jump to &dest if locals[src1] as nat >= locals[src2] as nat */
  OP_JEQ_REAL,       /* jump_eq_real      : jump to &dest if locals[src1] as real == locals[src2] as real */
  OP_JNEQ_REAL,      /* jump_neq_real     : jump to &dest if locals[src1] as real != locals[src2] as real */
  OP_JGE_REAL,       /* jump_ge_real      : jump to &dest if locals[src1] as real >= locals[src2] as real */
  OP_JGT_REAL,       /* jump_gt_real      : jump to &dest if locals[src1] as real >  locals[src2] as real */
  OP_JLT_REAL,       /* jump_lt_real      : jump to &dest if locals[src1] as real <  locals[src2] as real */
  OP_JLE_REAL,       /* jump_le_real      : jump to &dest if locals[src1] as real <= locals[src2] as real */
  OP_MAX_OPCODE  /* not really an opcode but used to check max length of ops */
} Opcode;

typedef struct vm_s VM;

#define MEM_SIZE 65536

struct vm_s {
  u32 pc;
  u8 mem[MEM_SIZE];
};

extern bool init_vm(VM *vm);
bool step_vm(VM *vm);

#endif