TPM B3D Map Decompression

b3d_decompress.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

typedef struct file_struct
{
    FILE* real_fhand;
    int is_compressed;
    int seek_pos_maybe;
    int tmpbuf1_pos;
    int tmpbuf2_pos;
    int tmpbuf2_left;
    int tmpbuf1_left;
    int field_18;
    int field_14;
    int field_20;
    uint8_t reading_bitmask;
    uint8_t last_read_tmpbuf2;
    uint8_t tmpbuf_1[0x1000];
    uint8_t tmpbuf_2[0x1000];
} file_struct;

int decompress_helper_1(file_struct *fhand, char a2)
{
  int v3; // [esp+0h] [ebp-8h]
  unsigned int v4; // [esp+4h] [ebp-4h]

  v4 = 1 << (a2 - 1);
  v3 = 0;
  while ( v4 )
  {
    if ( fhand->reading_bitmask == 0x80 )
    {
      if ( fhand->tmpbuf2_pos >= fhand->tmpbuf2_left )
        return 0;
      fhand->last_read_tmpbuf2 = (uint8_t)fhand->tmpbuf_2[fhand->tmpbuf2_pos++];
    }
    if ( (fhand->reading_bitmask & fhand->last_read_tmpbuf2) != 0 )
      v3 |= v4;
    v4 >>= 1;
    fhand->reading_bitmask >>= 1;
    if ( !fhand->reading_bitmask )
      fhand->reading_bitmask = 0x80;
  }
  return v3;
}

int file_decompressy_idk(file_struct *fhand)
{
  int result; // eax
  int bit_masked; // [esp+8h] [ebp-24h]
  int to_read_tmpbuf2; // [esp+Ch] [ebp-20h]
  int i; // [esp+10h] [ebp-1Ch]
  int v5; // [esp+14h] [ebp-18h]
  size_t v6; // [esp+18h] [ebp-14h]
  char v7; // [esp+1Ch] [ebp-10h]
  char v8; // [esp+1Ch] [ebp-10h]
  int v9; // [esp+24h] [ebp-8h]
  int16_t v10; // [esp+28h] [ebp-4h]

  v5 = fhand->tmpbuf2_left - 0x80;
  fhand->seek_pos_maybe = 0;
  result = (int)fhand;
  fhand->tmpbuf1_pos = 0;
  if ( !fhand->field_18 )
  {
    while ( 1 )
    {
      result = fhand->tmpbuf1_pos;
      if ( result >= 0xF80 )
        break;
      if ( fhand->reading_bitmask == 0x80 )
      {
        if ( !fhand->field_14 && fhand->tmpbuf2_pos >= v5 )
        {
          if ( fhand->tmpbuf2_pos < fhand->tmpbuf2_left )
            memcpy(fhand->tmpbuf_2, &fhand->tmpbuf_2[fhand->tmpbuf2_pos], fhand->tmpbuf2_left - fhand->tmpbuf2_pos);
          fhand->tmpbuf2_left -= fhand->tmpbuf2_pos;
          fhand->tmpbuf2_pos = 0;
          to_read_tmpbuf2 = 0x1000 - fhand->tmpbuf2_left;
          v6 = fread(&fhand->tmpbuf_2[fhand->tmpbuf2_left], 1u, to_read_tmpbuf2, fhand->real_fhand);
          if ( v6 != to_read_tmpbuf2 )
            fhand->field_14 = 1;
          fhand->tmpbuf2_left += v6;
          v5 = fhand->tmpbuf2_left - 128;
        }
        result = (int)fhand;
        if ( fhand->tmpbuf2_pos >= fhand->tmpbuf2_left )
          return result;
        fhand->last_read_tmpbuf2 = (uint8_t)fhand->tmpbuf_2[fhand->tmpbuf2_pos++];
      }
      bit_masked = fhand->reading_bitmask & fhand->last_read_tmpbuf2;
      fhand->reading_bitmask >>= 1;
      if ( !fhand->reading_bitmask )
        fhand->reading_bitmask = 0x80;
      if ( bit_masked )
      {
        v7 = decompress_helper_1(fhand, 8);
        fhand->tmpbuf_2[fhand->field_20 + 0x1000] = v7;
        fhand->tmpbuf_1[fhand->tmpbuf1_pos++] = v7;
        fhand->field_20 = ((uint16_t)fhand->field_20 + 1) & 0xFFF;
      }
      else
      {
        result = decompress_helper_1(fhand, 12);
        v10 = result;
        if ( !result )
        {
          fhand->field_18 = 1;
          return result;
        }
        v9 = decompress_helper_1(fhand, 4) + 1;
        for ( i = 0; i <= v9; ++i )
        {
          v8 = fhand->tmpbuf_2[(((uint16_t)i + v10) & 0xFFF) + 4096];
          fhand->tmpbuf_1[fhand->tmpbuf1_pos++] = v8;
          fhand->tmpbuf_2[fhand->field_20 + 4096] = v8;
          fhand->field_20 = ((uint16_t)fhand->field_20 + 1) & 0xFFF;
        }
      }
    }
  }
  return result;
}

size_t fread_wrap_compressed(void *a1, size_t a2, size_t a3, file_struct *a4)
{
    int v5; // [esp+8h] [ebp-10h]
    signed int i; // [esp+Ch] [ebp-Ch]
    signed int bytes_read; // [esp+10h] [ebp-8h]
    char *v8; // [esp+14h] [ebp-4h]

    v8 = (char *)a1;
    if ( !a4->is_compressed )
        return fread(a1, a2, a3, a4->real_fhand);

    v5 = 0;
    for ( i = a2 * a3; i; i -= bytes_read )
    {
        if ( a4->seek_pos_maybe >= a4->tmpbuf1_pos )
            file_decompressy_idk(a4);
        bytes_read = a4->tmpbuf1_pos - a4->seek_pos_maybe;
        
        //printf("read %x\n", bytes_read);
        
        if ( !bytes_read )
            return v5 / (int)a2;
        if ( bytes_read > i )
            bytes_read = i;
        memcpy(v8, &a4->tmpbuf_1[a4->seek_pos_maybe], bytes_read);
        v8 += bytes_read;
        a4->seek_pos_maybe += bytes_read;
        v5 += bytes_read;
    }
    return v5 / (int)a2;
}

int main(int argc, char **argv)
{
    if (argc < 2)
    {
        printf("Usage: %s [mapfile.b3d]\n", argv[0]);
        return 0;
    }
    
    char* open_fpath = argv[1];
    char* out_fpath = malloc(strlen(open_fpath) + 5);
    strcpy(out_fpath, open_fpath);
    strcat(out_fpath, ".dec");

    file_struct f2;
    FILE* f = fopen(open_fpath, "rb");
    FILE* fout = fopen(out_fpath, "wb");
    
    // Weird file struct
    memset(&f2, 0, sizeof(f2));
    f2.real_fhand = f;
    f2.is_compressed = 1;
    f2.reading_bitmask = 0x80;
    f2.field_20 = 1;
    
    // Read the header, edit compressed bit, and decompress as much as possible
    uint8_t tmp[0x10000];
    fread(tmp, 1, 0x8A4, f);
    tmp[0x328] = 0; // decompressed
    fwrite(tmp, 1, 0x8A4, fout);
    
    while (1)
    {
        size_t len = fread_wrap_compressed(tmp, 1, 0x10000, &f2);
        
        if (!len) break;
        fwrite(tmp, 1, len, fout);
    }
    
    printf("Decompressed to `%s`\n", out_fpath);
    
    fclose(fout);
    fclose(f);
}