Re^2: How to use 'unsigned char' C data type with Win32::API

[sam_bakki]

Hi BrowserUk

For some reason, having 'int' and getting data from my DLL is not working well.

my $i2cGetDeviceAddressFunc = Win32::API->new('CrdI2C32', 'int i2cGetD
+eviceAddress()') or warn "\n ERROR: Can not import API:i2cGetDeviceAd
+dress ,  $^E ,";

my $ret = 0;

$ret = $i2cGetDeviceAddressFunc->Call();

print "\n RET: $ret";

Output

1. Run
 RET: 53113496

2. Run
RET: 52195992

3. Run
RET: 52851352

4. Run
RET: 52458136

5. Run
 RET: 51540632

Output is not what i expected and more over every run, it produce different output. But the C code which calls the i2cGetDeviceAddress() API produces same output always.

I don't have source code of the DLL (CRDI2C32.DLL) , We bought this from other company, They gave C, C++, VB & PASCAL example code which has API prototypes.

PASCAL Sample:

xx.pas

Function  i2cGetDeviceAddress : Byte;                                 
+               stdcall; external 'CrdI2C32.DLL';

C Sample:

xx.h
typedef unsigned char __stdcall i2cGetDeviceAddress_type();
extern i2cGetDeviceAddress_type *i2cGetDeviceAddress;

xx.c
i2cGetDeviceAddress_type *i2cGetDeviceAddress = NULL;
....
 i2cGetDeviceAddress = (i2cGetDeviceAddress_type*)GetProcAddress(hDll,
+"i2cGetDeviceAddress");
  if (i2cGetDeviceAddress == NULL) {
    FreeLibrary(hDll);
    return 22; // function not found in library
  }

VB Sample:

xx.bas

 Declare Function i2cGetDeviceAddress Lib "CrdI2C32.DLL" () As Byte