I'm new to Oxygene and I want to read strings from a stream that was generated by Delphi. I receive this stream via TCP. Here is how I save strings to a stream on the client side:
procedure SaveStringToStream(AStream: TStream; AString: String);
var
StringSize: Integer;
StringToSave: AnsiString;
begin
StringToSave := Utf8Encode(AString);
StringSize := Length(StringToSave);
AStream.WriteBuffer(StringSize, SizeOf(StringSize));
AStream.WriteBuffer(Pointer(StringToSave)^, StringSize);
end;
As you can See I first add the size of the string to the stream and then the content. My existing method to load strings from a stream on the server side (Oxygene) looks like this:
function LoadStringFromStream(const aStream: NSInputStream): String;
begin
var buf: array[1024] of uint8_t;
var len: Integer:= 0;
len := aStream.&read(buf) maxLength(1024);
if len > 0 then
begin
nslog(len.stringValue);
var data: NSMutableData := NSMutableData.alloc().initWithLength(0);
data.appendBytes(@buf) length(buf[0]);
exit NSString.alloc().initWithData(data) encoding(NSStringEncoding.NSASCIIStringEncoding);
end;
end;
But this returns the hole content and not the current part.
EDIT: Oh, I had a mistake in the server application... Now I'm able to read strings, but not to read integer values (only upto 256 bit). For Objective-C I found this code
- (int32_t)readInt32
{
int32_t value = 0;
if ([self read:(uint8_t *)&value maxLength:4] != 4)
{
NSlog(@"***** Couldn't read int32");
}
return value;
}
Thats the Oxygene code:
function readInt32(const aStream: NSInputStream): Integer;
begin
var value: int32_t := 0;
var tmp:= uint8_t(@value);
if aStream.&read(@tmp) maxLength(4) <> 4 then
NSLog('***** Couldn''t read int32');
exit value;
end;
But something goes wrong, I don't get any value. Do you guys know what I have to do?
I think you have converted the Objective-C code (slightly, but significantly) incorrectly:
function readInt32(const aStream: NSInputStream): Integer;
begin
var value: int32_t := 0;
var tmp:= uint8_t(@value);
if aStream.&read(@tmp) maxLength(4) <> 4 then
NSLog('***** Couldn''t read int32');
exit value;
end;
In the above code tmp is declared as a single byte and initialised using a type cast of the address of the value variable.
So if the value variable is being stored at the memory address $12345678 (stupid example kept to 32-bit for brevity) then tmp will be initialised with the value $78. You then pass the address of the tmp variable to aStream.read() which tries to read 4 bytes into the location of the tmp variable. But tmp is only a 1 byte value!
I think you need to change the declaration of tmp to make it a pointer to unit8_t, and then pass this directly to aStream.read():
var value: int32_t := 0;
var tmp:= ^uint8_t(@value);
if aStream.&read(tmp) maxLength(4) <> 4 then
NSLog('***** Couldn''t read int32');
Or eliminate the tmp variable and pass the address of value directly, with an appropriate cast:
var value: int32_t := 0;
if aStream.&read(^uint8_t(@value)) maxLength(4) <> 4 then
NSLog('***** Couldn''t read int32');
This latter approach is more directly comparable to the Objective-C original.