//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop

#include "Compress.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
//---------------------------------------------------------------------------
typedef int WINAPI (*TZLibCompress)(void *dest, DWORD *destLen, const void *source, DWORD sourceLen);
typedef int WINAPI (*TZLibUncompress)(void *dest, DWORD *destLen, const void *source, DWORD sourceLen);
//---------------------------------------------------------------------------
bool __fastcall TPCompress(HANDLE fh, void *data, int length, TCompressMethod cm)
{
  DWORD dwWrite;
  HINSTANCE hLibrary = NULL;
  TZLibCompress ZLibCompress;
  void *dst = NULL;
   DWORD ls, ld;
  int n, r;

  switch (cm) {
     case cmZLib:
       ld = ls = length;
      hLibrary = LoadLibrary("zlib.dll");
      if (hLibrary) {
        ZLibCompress = (TZLibCompress)GetProcAddress(hLibrary, "compress");
         if (ZLibCompress) {
           n = 4;
           while (1) {
             ld = ls/n;
             if ((dst = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, ld))==NULL) goto fail;
            r = ZLibCompress(dst, &ld, data, ls);
             if (r==0) break;
             HeapFree(GetProcessHeap(), 0, dst); dst = NULL;
             if (n==1) {
               ld = ls;
               break;
            } else n--;
          }
         }
        FreeLibrary(hLibrary); hLibrary = NULL;
      }
      if (ld<ls) {
        if (!WriteFile(fh, &ld, sizeof(DWORD), &dwWrite, NULL)) goto fail;
        if (!WriteFile(fh, dst, ld, &dwWrite, NULL)) goto fail;
      } else {
        if (!WriteFile(fh, &ls, sizeof(DWORD), &dwWrite, NULL)) goto fail;
        if (!WriteFile(fh, data, ls, &dwWrite, NULL)) goto fail;
      }
      if (dst) HeapFree(GetProcessHeap(), 0, dst);
       break;
    case cmLZW:
       return false;
     default:
      if (!WriteFile(fh, data, length, &dwWrite, NULL)) goto fail;
       break;
  }
  return true;
fail:
  if (hLibrary) {
    if (dst) HeapFree(GetProcessHeap(), 0, dst);
    FreeLibrary(hLibrary);
  }
  return false;
}
//---------------------------------------------------------------------------
bool __fastcall TPUncompress(HANDLE fh, void *data, int length, TCompressMethod cm)
{
  DWORD dwRead;
  HINSTANCE hLibrary = NULL;
  TZLibUncompress ZLibUncompress;
   DWORD ls, ld;
  void *src = NULL;

  switch (cm) {
     case cmZLib:
      if (!ReadFile(fh, &ls, sizeof(DWORD), &dwRead, NULL)) goto fail;
      ld = length;
      if (ls<ld) {
        if ((hLibrary = LoadLibrary("zlib.dll"))==0) goto fail;
        if ((ZLibUncompress = (TZLibUncompress)GetProcAddress(hLibrary, "uncompress"))==NULL) goto fail;
        if ((src = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, ls))==NULL) goto fail;
        if (!ReadFile(fh, src, ls, &dwRead, NULL)) goto fail;
        ZLibUncompress(data, &ld, src, ls);
        HeapFree(GetProcessHeap(), 0, src);
        FreeLibrary(hLibrary);
      } else {
        if (!ReadFile(fh, data, ld, &dwRead, NULL)) goto fail;
      }
       break;
    case cmLZW:
       return false;
     default:
      if (!ReadFile(fh, data, length, &dwRead, NULL)) goto fail;
      break;
  }
  return true;
fail:
  if (hLibrary) {
    if (src) HeapFree(GetProcessHeap(), 0, src);
    FreeLibrary(hLibrary);
  }
  return false;
}
//---------------------------------------------------------------------------