/* Lama SM Bytecode interpreter */

#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include "../runtime/runtime.h"

void *__start_custom_data;
void *__stop_custom_data;

/* The unpacked representation of bytecode file */
typedef struct
{
  char *string_ptr;          /* A pointer to the beginning of the string table */
  int *public_ptr;           /* A pointer to the beginning of publics table    */
  char *code_ptr;            /* A pointer to the bytecode itself               */
  int *global_ptr;           /* A pointer to the global area                   */
  int stringtab_size;        /* The size (in bytes) of the string table        */
  int global_area_size;      /* The size (in words) of global area             */
  int public_symbols_number; /* The number of public symbols                   */
  char buffer[0];
} bytefile;

/* Gets a string from a string table by an index */
char *get_string(bytefile *f, int pos)
{
  return &f->string_ptr[pos];
}

/* Gets a name for a public symbol */
char *get_public_name(bytefile *f, int i)
{
  return get_string(f, f->public_ptr[i * 2]);
}

/* Gets an offset for a publie symbol */
int get_public_offset(bytefile *f, int i)
{
  return f->public_ptr[i * 2 + 1];
}

/* Reads a binary bytecode file by name and unpacks it */
bytefile *read_file(char *fname)
{
  FILE *f = fopen(fname, "rb");
  long size;
  bytefile *file;

  if (f == 0)
  {
    failure("%s\n", strerror(errno));
  }

  if (fseek(f, 0, SEEK_END) == -1)
  {
    failure("%s\n", strerror(errno));
  }

  file = (bytefile *)malloc(sizeof(int) * 4 + (size = ftell(f)));

  if (file == 0)
  {
    failure("*** FAILURE: unable to allocate memory.\n");
  }

  rewind(f);

  if (size != fread(&file->stringtab_size, 1, size, f))
  {
    failure("%s\n", strerror(errno));
  }

  fclose(f);

  file->string_ptr = &file->buffer[file->public_symbols_number * 2 * sizeof(int)];
  file->public_ptr = (int *)file->buffer;
  file->code_ptr = &file->string_ptr[file->stringtab_size];
  file->global_ptr = (int *)malloc(file->global_area_size * sizeof(int));

  return file;
}

/* Disassembles the bytecode pool */
void disassemble(FILE *f, bytefile *bf)
{

#define INT (ip += sizeof(int), *(int *)(ip - sizeof(int)))
#define BYTE *ip++
#define STRING get_string(bf, INT)
#define FAIL failure("ERROR: invalid opcode %d-%d\n", h, l)

  char *ip = bf->code_ptr;
  char *ops[] = {"+", "-", "*", "/", "%", "<", "<=", ">", ">=", "==", "!=", "&&", "!!"};
  char *pats[] = {"=str", "#string", "#array", "#sexp", "#ref", "#val", "#fun"};
  char *lds[] = {"LD", "LDA", "ST"};
  do
  {
    char x = BYTE,
         h = (x & 0xF0) >> 4,
         l = x & 0x0F;

    fprintf(f, "0x%.8x:\t", ip - bf->code_ptr - 1);

    switch (h)
    {
    case 15:
      goto stop;

    /* BINOP */
    case 0:
      fprintf(f, "BINOP\t%s", ops[l - 1]);
      break;

    case 1:
      switch (l)
      {
      case 0:
        fprintf(f, "CONST\t%d", INT);
        break;

      case 1:
        fprintf(f, "STRING\t%s", STRING);
        break;

      case 2:
        fprintf(f, "SEXP\t%s ", STRING);
        fprintf(f, "%d", INT);
        break;

      case 3:
        fprintf(f, "STI");
        break;

      case 4:
        fprintf(f, "STA");
        break;

      case 5:
        fprintf(f, "JMP\t0x%.8x", INT);
        break;

      case 6:
        fprintf(f, "END");
        break;

      case 7:
        fprintf(f, "RET");
        break;

      case 8:
        fprintf(f, "DROP");
        break;

      case 9:
        fprintf(f, "DUP");
        break;

      case 10:
        fprintf(f, "SWAP");
        break;

      case 11:
        fprintf(f, "ELEM");
        break;

      default:
        FAIL;
      }
      break;

    case 2:
    case 3:
    case 4:
      fprintf(f, "%s\t", lds[h - 2]);
      switch (l)
      {
      case 0:
        fprintf(f, "G(%d)", INT);
        break;
      case 1:
        fprintf(f, "L(%d)", INT);
        break;
      case 2:
        fprintf(f, "A(%d)", INT);
        break;
      case 3:
        fprintf(f, "C(%d)", INT);
        break;
      default:
        FAIL;
      }
      break;

    case 5:
      switch (l)
      {
      case 0:
        fprintf(f, "CJMPz\t0x%.8x", INT);
        break;

      case 1:
        fprintf(f, "CJMPnz\t0x%.8x", INT);
        break;

      case 2:
        fprintf(f, "BEGIN\t%d ", INT);
        fprintf(f, "%d", INT);
        break;

      case 3:
        fprintf(f, "CBEGIN\t%d ", INT);
        fprintf(f, "%d", INT);
        break;

      case 4:
        fprintf(f, "CLOSURE\t0x%.8x", INT);
        {
          int n = INT;
          for (int i = 0; i < n; i++)
          {
            switch (BYTE)
            {
            case 0:
              fprintf(f, "G(%d)", INT);
              break;
            case 1:
              fprintf(f, "L(%d)", INT);
              break;
            case 2:
              fprintf(f, "A(%d)", INT);
              break;
            case 3:
              fprintf(f, "C(%d)", INT);
              break;
            default:
              FAIL;
            }
          }
        };
        break;

      case 5:
        fprintf(f, "CALLC\t%d", INT);
        break;

      case 6:
        fprintf(f, "CALL\t0x%.8x ", INT);
        fprintf(f, "%d", INT);
        break;

      case 7:
        fprintf(f, "TAG\t%s ", STRING);
        fprintf(f, "%d", INT);
        break;

      case 8:
        fprintf(f, "ARRAY\t%d", INT);
        break;

      case 9:
        fprintf(f, "FAIL\t%d", INT);
        fprintf(f, "%d", INT);
        break;

      case 10:
        fprintf(f, "LINE\t%d", INT);
        break;

      default:
        FAIL;
      }
      break;

    case 6:
      fprintf(f, "PATT\t%s", pats[l]);
      break;

    case 7:
    {
      switch (l)
      {
      case 0:
        fprintf(f, "CALL\tLread");
        break;

      case 1:
        fprintf(f, "CALL\tLwrite");
        break;

      case 2:
        fprintf(f, "CALL\tLlength");
        break;

      case 3:
        fprintf(f, "CALL\tLstring");
        break;

      case 4:
        fprintf(f, "CALL\tBarray\t%d", INT);
        break;

      default:
        FAIL;
      }
    }
    break;

    default:
      FAIL;
    }

    fprintf(f, "\n");
  } while (1);
stop:
  fprintf(f, "<end>\n");
}

/* Dumps the contents of the file */
void dump_file(FILE *f, bytefile *bf)
{
  int i;

  fprintf(f, "String table size       : %d\n", bf->stringtab_size);
  fprintf(f, "Global area size        : %d\n", bf->global_area_size);
  fprintf(f, "Number of public symbols: %d\n", bf->public_symbols_number);
  fprintf(f, "Public symbols          :\n");

  for (i = 0; i < bf->public_symbols_number; i++)
    fprintf(f, "   0x%.8x: %s\n", get_public_offset(bf, i), get_public_name(bf, i));

  fprintf(f, "Code:\n");
  disassemble(f, bf);
}

int main(int argc, char *argv[])
{
  bytefile *f = read_file(argv[1]);
  dump_file(stdout, f);
  return 0;
}