metaforce/Runtime/IOStreams.cpp

#include "IOStreams.hpp"
#include "hecl/hecl.hpp"

namespace urde {

#define DUMP_BITS 0

#if DUMP_BITS
static void PrintBinary(u32 val, u32 count) {
  for (int i = 0; i < count; ++i) {
    printf("%d", (val >> (count - i - 1)) & 0x1);
  }
}
#endif

/*!
 * \brief CBitStreamReader::ReadBit
 * Reads and decodes an encoded value from a bitstream.
 * \param bitCount How many bits to read
 * \return s32 The encoded value
 */
s32 CBitStreamReader::ReadEncoded(u32 bitCount) {
#if DUMP_BITS
  auto pos = position();
  auto boff = x20_bitOffset;
#endif

  u32 ret = 0;
  s32 shiftAmt = x20_bitOffset - s32(bitCount);
  if (shiftAmt < 0) {
    /* OR in remaining bits of cached value */
    u32 mask = bitCount == 32 ? 0xffffffff : ((1 << bitCount) - 1);
    ret |= (x1c_val << u32(-shiftAmt)) & mask;

    /* Load in exact number of bytes remaining */
    auto loadDiv = std::div(-shiftAmt, 8);
    if (loadDiv.rem)
      ++loadDiv.quot;
    readUBytesToBuf(reinterpret_cast<u8*>(&x1c_val) + 4 - loadDiv.quot, loadDiv.quot);
    x1c_val = hecl::SBig(x1c_val);

    /* New bit offset */
    x20_bitOffset = loadDiv.quot * 8 + shiftAmt;

    /* OR in next bits */
    mask = (1 << u32(-shiftAmt)) - 1;
    ret |= (x1c_val >> x20_bitOffset) & mask;
  } else {
    /* OR in bits of cached value */
    u32 mask = bitCount == 32 ? 0xffffffff : ((1 << bitCount) - 1);
    ret |= (x1c_val >> u32(shiftAmt)) & mask;

    /* New bit offset */
    x20_bitOffset -= bitCount;
  }

#if DUMP_BITS
  printf("READ ");
  PrintBinary(ret, bitCount);
  printf(" %d %d\n", int(pos), int(boff));
#endif

  return ret;
}

void CBitStreamWriter::WriteEncoded(u32 val, u32 bitCount) {
#if DUMP_BITS
  printf("WRITE ");
  PrintBinary(val, bitCount);
  printf(" %d %d\n", int(position()), int(x18_bitOffset));
#endif

  s32 shiftAmt = x18_bitOffset - s32(bitCount);
  if (shiftAmt < 0) {
    /* OR remaining bits to cached value */
    u32 mask = (1 << x18_bitOffset) - 1;
    x14_val |= (val >> u32(-shiftAmt)) & mask;

    /* Write out 32-bits */
    x14_val = hecl::SBig(x14_val);
    writeUBytes(reinterpret_cast<u8*>(&x14_val), 4);

    /* Cache remaining bits */
    x18_bitOffset = 0x20 + shiftAmt;
    x14_val = val << x18_bitOffset;
  } else {
    /* OR bits to cached value */
    u32 mask = bitCount == 32 ? 0xffffffff : ((1 << bitCount) - 1);
    x14_val |= (val & mask) << u32(shiftAmt);

    /* New bit offset */
    x18_bitOffset -= bitCount;
  }
}

void CBitStreamWriter::Flush() {
  if (x18_bitOffset < 0x20) {
    auto pos = std::div(0x20 - x18_bitOffset, 8);
    if (pos.rem)
      ++pos.quot;
    x14_val = hecl::SBig(x14_val);
    writeUBytes(reinterpret_cast<u8*>(&x14_val), pos.quot);
    x18_bitOffset = 0x20;
    x14_val = 0;
  }
}

class CZipSupport {
public:
  static void* Alloc(void*, u32 c, u32 n) { return new u8[c * n]; }
  static void Free(void*, void* buf) { delete[] static_cast<u8*>(buf); }
};

CZipInputStream::CZipInputStream(std::unique_ptr<CInputStream>&& strm)
: x24_compBuf(new u8[4096]), x28_strm(std::move(strm)) {
  x30_zstrm.next_in = x24_compBuf.get();
  x30_zstrm.avail_in = 0;
  x30_zstrm.zalloc = CZipSupport::Alloc;
  x30_zstrm.zfree = CZipSupport::Free;
  inflateInit(&x30_zstrm);
}

CZipInputStream::~CZipInputStream() { inflateEnd(&x30_zstrm); }

atUint64 CZipInputStream::readUBytesToBuf(void* buf, atUint64 len) {
  x30_zstrm.next_out = (Bytef*)buf;
  x30_zstrm.avail_out = len;
  x30_zstrm.total_out = 0;
  while (x30_zstrm.avail_out != 0) {
    if (x30_zstrm.avail_in == 0) {
      atUint64 readSz = x28_strm->readUBytesToBuf(x24_compBuf.get(), 4096);
      x30_zstrm.avail_in = readSz;
      x30_zstrm.next_in = x24_compBuf.get();
    }
    int inflateRet = inflate(&x30_zstrm, Z_NO_FLUSH);
    if (inflateRet != Z_OK)
      break;
  }
  return x30_zstrm.total_out;
}

} // namespace urde