如何将C++联合转换为Delphi

Question

我知道之前已经问过这个问题,但是我试图将一些C++结构/联合转换为Delphi以使用Hikvision SDK却没有成功.

我试图转换的C++结构/联合如下:

struct{
  BYTE                           byEnable;
  BYTE                           byRes1[3];
  DWORD                          dwTriggerType;
  NET_ITC_TRIGGER_PARAM_UNION    uTriggerParam;
  BYTE                           byRes[64];
}NET_ITC_SINGLE_TRIGGERCFG,*LPNET_ITC_SINGLE_TRIGGERCFG;

union{
  DWORD                              uLen[1070];
  NET_ITC_POST_IOSPEED_PARAM         struIOSpeed;
  NET_ITC_POST_SINGLEIO_PARAM        struSingleIO;
  NET_ITC_POST_RS485_PARAM           struPostRs485;
  NET_ITC_POST_RS485_RADAR_PARAM     struPostRadar;
  NET_ITC_POST_VTCOIL_PARAM          struVtCoil;
  NET_ITC_EPOLICE_IOTL_PARAM         struIOTL;
  NET_ITC_EPOLICE_RS485_PARAM        struEpoliceRs485;
  NET_ITC_EPOLICE_RS485_PARAM        struPERs485;
}NET_ITC_TRIGGER_PARAM_UNION,*LPNET_ITC_TRIGGER_PARAM_UNION;

我尝试过以下方法:

  PNetItcSingleTriggerCfg = ^TNetItcSingleTriggerCfg;
  TNetItcSingleTriggerCfg = record
    byEnable:      Byte;
    byRes1:        array [0..2] of Byte;
    dwTriggerType: DWord;
    uTriggerParam: TNetItcTriggerParamUnion;
    byRes:         array [0..63] of Byte;
  end;

  PNetItcTriggerParamUnion = ^TNetItcTriggerParamUnion;
  TNetItcTriggerParamUnion = record
    case integer of
      0: (uLen:             array [0..1069] of DWord);
      1: (struIOSpeed:      TNetItcPostIOSpeedParam);
      2: (struSingleIO:     TNetItcPostSingleIOParam);
      3: (struPostRs485:    TNetItcPostRS485Param);
      4: (struPostRadar:    TNetItcPostRS485RadarParam);
      5: (struVtCoil:       TNetItcPostVTCoilParam);
      6: (struHvt:          TNetItcPostHvtParam);
      7: (struIOTL:         TNetItcEPoliceIOTLParam);
      8: (struEpoliceRs485: TNetItcEPoliceRS485Param);
      9: (struPERs485:      TNetItcEPoliceRS485Param);          
      10:(struPostMpr:      TNetItcPostMprParam);
      11:(struViaVtCoil:    TNetDvrViaVtCoilParam);
      12:(struPostImt:      TNetItcPostImtParam);
      13:(struPostPrs:      TNetItcPostPrsParam);
      14:(struIpcHvt:       TNetIpcPostHvtParam);
      15:(struHvtV50:       TNetIpcPostHvtParamV50);
  end;

而且我也尝试将它作为嵌套记录(如http://rvelthuis.de/articles/articles-convert.html#unions中所述)

  PNetItcSingleTriggerCfg = ^TNetItcSingleTriggerCfg;
  TNetItcSingleTriggerCfg = record
    byEnable:      Byte;
    byRes1:        array [0..2] of Byte;
    dwTriggerType: DWord;
    uTriggerParam: record
      case integer of
        0: (uLen:             array [0..1069] of DWord);
        1: (struIOSpeed:      TNetItcPostIOSpeedParam);
        2: (struSingleIO:     TNetItcPostSingleIOParam);
        3: (struPostRs485:    TNetItcPostRS485Param);
        4: (struPostRadar:    TNetItcPostRS485RadarParam);
        5: (struVtCoil:       TNetItcPostVTCoilParam);
        6: (struHvt:          TNetItcPostHvtParam);
        7: (struIOTL:         TNetItcSingleIOTLParam);
        8: (struEpoliceRs485: TNetItcEPoliceRS485Param); 
        9: (struPERs485:      TNetItcEPoliceRS485Param);
        10:(struPostMpr:      TNetItcPostMprParam);
        11:(struViaVtCoil:    TNetDvrViaVtCoilParam);
        12:(struPostImt:      TNetItcPostImtParam);
        13:(struPostPrs:      TNetItcPostPrsParam);
        14:(struIpcHvt:       TNetIpcPostHvtParam);
        15:(struHvtV50:       TNetIpcPostHvtParamV50);
      end;
    byRes:         array [0..63] of Byte;
  end;

我在这里看到过类似的问题(即如何将C联合转换为Delphi？),但我的例子中的联合处于结构的中间,据我所知,case语句的'end'也结束了记录.

我想我理解一个变量记录背后的理论,它对case语句中的字段有相同的内存分配,所以使用的字段可能是/或,但是我无法解决的是如何判断DLL是如何访问的这些记录,无论是struName.unionName.fieldName还是struName.fieldName,以及如何定义联合(即case语句的选择器是什么,以及如何知道选择器是什么数据类型).

我有三个类似的结构要翻译,如果我可以破解一个,我可以将它们全部破解.

使用上述记录,我不断收到错误消息"参数错误.SDK API中的输入或输出参数为NULL',同时从DLL调用函数(如果您需要更多信息,请询问),这让我觉得我的记录没有正确转换.

我正在使用HCNetSDK.dll SDK版本5.0.3.20,如果有帮助,我的IDE是XE7.

任何帮助,将不胜感激.

Answer 1

假设结构对齐设置匹配,那么您转换联合的两次尝试都是正确的.你可以使用你喜欢的任何一个.对于它的价值,我更倾向于第一种方法,你声明一个类型来表示联合.

无论你的实际问题是什么,它似乎都不在于联合转换.测试这个的一个简单方法是检查C++和Delphi版本中类型的大小是否匹配,以及每个成员的偏移是否匹配.

用于测试sizeofC++和SizeOfDelphi中使用的类型的大小.对于偏移量,使用offsetofC++ 的宏和我在这里为Delphi 回答的技巧.