Question

C数据结构：

typedef struct dpfpdd_dev_info {
        unsigned int         size;
        char                 name[MAX_DEVICE_NAME_LENGTH];
        DPFPDD_HW_DESCR      descr;
        DPFPDD_HW_ID         id;
        DPFPDD_HW_VERSION    ver;
        DPFPDD_HW_MODALITY   modality;
        DPFPDD_HW_TECHNOLOGY technology;
} DPFPDD_DEV_INFO;

typedef struct dpfpdd_hw_descr {
        char vendor_name[MAX_STR_LENGTH];
        char product_name[MAX_STR_LENGTH];
        char serial_num[MAX_STR_LENGTH];
} DPFPDD_HW_DESCR;

typedef struct dpfpdd_hw_id {
        unsigned short  vendor_id;
        unsigned short  product_id;
} DPFPDD_HW_ID;

typedef struct dpfpdd_hw_version {
        DPFPDD_VER_INFO hw_ver;
        DPFPDD_VER_INFO fw_ver;
        unsigned short bcd_rev;
} DPFPDD_HW_VERSION;

typedef struct dpfpdd_ver_info {
        int major;
        int minor;
        int maintenance;
} DPFPDD_VER_INFO;

typedef unsigned int DPFPDD_HW_MODALITY;
typedef unsigned int DPFPDD_HW_TECHNOLOGY;

上面的C代码的模拟JS代码：

const ref = require('ref');
const StructType = require('ref-struct');
const FixedBuffer = require('./FixedBuffer'); // from https://gist.github.com/TooTallNate/80ac2d94b950216a2705

const DPFPDD_DEV_INFO = StructType({
  size: ref.types.uint,
  name: FixedBuffer(MAX_DEVICE_NAME_LENGTH, 'utf-8'),
  descr: DPFPDD_HW_DESCR,
  id: DPFPDD_HW_ID,
  ver: DPFPDD_HW_VERSION,
  modality: DPFPDD_HW_MODALITY,
  technology: DPFPDD_HW_TECHNOLOGY
});

const DPFPDD_HW_DESCR = StructType({
  vendor_name: FixedBuffer(MAX_STR_LENGTH, 'utf-8'),
  product_name: FixedBuffer(MAX_STR_LENGTH, 'utf-8'),
  serial_num: FixedBuffer(MAX_STR_LENGTH, 'utf-8')
});

const DPFPDD_HW_ID = StructType({
  vendor_id: ref.types.ushort,
  product_id: ref.types.ushort
});

const DPFPDD_HW_VERSION = StructType({
  hw_ver: DPFPDD_VER_INFO,
  fw_ver: DPFPDD_VER_INFO,
  bcd_rev: ref.types.ushort
});

const DPFPDD_VER_INFO = StructType({
  major: ref.types.int,
  minor: ref.types.int,
  maintenance: ref.types.int
});

const DPFPDD_HW_MODALITY = ref.types.uint;
const DPFPDD_HW_TECHNOLOGY = ref.types.uint;

DLL API：

int DPAPICALL dpfpdd_query_devices (unsigned int *dev_cnt, DPFPDD_DEV_INFO *dev_infos)

上面的DLL API的

node-ffi代码：

const lib = ffi.Library('theDLL'), {
  'dpfpdd_init': [ 'int', [] ],
  'dpfpdd_query_devices': [ 'int', [ ref.refType('uint'), ref.refType(DPFPDD_DEV_INFO) ] ]
});

节点中的ffi函数调用：

lib.dpfpdd_init();
let deviceEntries = ref.alloc('uint');
let deviceInfo = ref.alloc(DPFPDD_DEV_INFO);
lib.dpfpdd_query_devices(deviceEntries, deviceInfo);
console.log(deviceInfo.deref());

控制台日志将返回以下内容：

{ size: 0,
  name: <Buffer@0x019572AC 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ... >,
  descr: { vendor_name: <Buffer@0x019576AC 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ... >,
  product_name: <Buffer@0x0195772C 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ... >,
  serial_num: <Buffer@0x019577AC 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ... >,
  'ref.buffer': <Buffer@0x019576AC 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ... > },
  id: { vendor_id: 0,
  product_id: 0,
  'ref.buffer': <Buffer@0x0195782C 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00> },
  ver: { hw_ver: { major: 0,
  minor: 0,
  maintenance: 0,
  'ref.buffer': <Buffer@0x01957830 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00> },
  fw_ver: { major: 0,
  minor: 0,
  maintenance: 0,
  'ref.buffer': <Buffer@0x0195783C 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00> },
  bcd_rev: 0,
  'ref.buffer': <Buffer@0x01957830 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00> },
  modality: 0,
  technology: 0,
  'ref.buffer': <Buffer@0x019572A8 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ... > }

从所有Buffer类型日志中，似乎我没有从OUT StructType参数中接收任何值。我不知道为什么会这样。我是使用node-ffi和node-ref的新手。我设法与另一个USB设备通信，但是数据结构更加简单，没有嵌套的结构和数组类型。但是我无法上班。有人启发我我做错了什么吗？

具有结构指针的类型的node-ffi OUT参数无法从DLL调用接收回值

0 个答案: