I'm using arduino for encoding the massage, i have tried for required and success for encoding and decoding back, but for repeated, after i encode it, the size of buffer is 0, so i cant send my buffer to other arduino
here is my code
file.ino
{
for(int i=0;i<7;i++)
message.header[i]=i+1;
//this is my variabel, i declare in .proto = repeated int32 header = 4 [(nanopb).max_count = 10, (nanopb).fixed_length = true];
stream = pb_ostream_from_buffer(buffer, sizeof(buffer));
bool status = pb_encode(&stream, Message_fields, &message);
Serial.println(stream.bytes_written);
//when i print this after encode, the data is loss, but when the field type is required, it will show some data bytes
}
Your header variable is fixed-length array of 10 entries. That should be ok. If it was not a fixed-length one there would be separate header_count field that you would have to set to the actual number of entries. You can look inside generated .pb.h to double-check that there is no header_count field.
Your code does not show the length of buffer you have allocated. Is it perhaps too short? Though that message should take only about 14 bytes.
You could also check whether status is true, i.e. whether encoding was successful. If it was not, you can find more information from stream.errmsg.
Related
I am trying to interface A71CH with raspberry PI 3 over i2c, the device requires repeated starts and when a read request is made the first byte the device sends, is always the length of the whole message. When I am trying to make a read, instead of reading a fixed sized message , I want to read the first byte then send NACK signal to the slave after certain amount of bytes have been received that is indicated with the first byte. I used to following code but could not get the results I expected because it only read one byte than sends a NACK signal as you can see below.
struct i2c_rdwr_ioctl_data packets;
struct i2c_msg messages[2];
int r = 0;
int i = 0;
if (bus != I2C_BUS_0) // change if bus 0 is not the correct bus
{
printf("axI2CWriteRead on wrong bus %x (addr %x)\n", bus, addr);
}
messages[0].addr = axSmDevice_addr;
messages[0].flags = 0;
messages[0].len = txLen;
messages[0].buf = pTx;
// NOTE:
// By setting the 'I2C_M_RECV_LEN' bit in 'messages[1].flags' one ensures
// the I2C Block Read feature is used.
messages[1].addr = axSmDevice_addr;
messages[1].flags = I2C_M_RD | I2C_M_RECV_LEN|I2C_M_IGNORE_NAK;
messages[1].len = 256;
messages[1].buf = pRx;
messages[1].buf[0] = 1;
// NOTE:
// By passing the two message structures via the packets structure as
// a parameter to the ioctl call one ensures a Repeated Start is triggered.
packets.msgs = messages;
packets.nmsgs = 2;
// Send the request to the kernel and get the result back
r = ioctl(axSmDevice, I2C_RDWR, &packets);
Is there any way that allows me to make variable sized i2c reads ? What can I do to make it work ? Thanks for looking.
Raspbery doesn't support SMBUS Block Reads, only way to overcome this is to do bitbanging on GPIO pins. As #Ian Abbott mentioned above, I managed to modify bbI2CZip function to fit my need by checking the first byte of the received message and updating the read length afterwards.
I had a similar issue with the rpi3. I wanted to read exactly 32 bytes of data from a register on a slave device, but i2c_smbus_read_block_data() was returning -71 and errno 71 EPROTO.
The solution was to use i2c_smbus_read_i2c_block_data() instead of i2c_smbus_read_block_data().
/* Until kernel 2.6.22, the length is hardcoded to 32 bytes. If you
ask for less than 32 bytes, your code will only work with kernels
2.6.23 and later. */
extern __s32 i2c_smbus_read_i2c_block_data(int file, __u8 command, __u8 length,
__u8 *values);
I would like to know how to read a binary file into memory (writing it to memory like an "Array Buffer" from JavaScript), and write to different parts of memory 8-bit, 16-bit, 32-bit etc. values, even 5 bit or 10 bit values.
extension Binary {
static func readFileToMemory(_ file) -> ArrayBuffer {
let data = NSData(contentsOfFile: "/path/to/file/7CHands.dat")!
var dataRange = NSRange(location: 0, length: ?)
var ? = [Int32](count: ?, repeatedValue: ?)
data.getBytes(&?, range: dataRange)
}
static func writeToMemory(_ buffer, location, value) {
buffer[location] = value
}
static func readFromMemory(_ buffer, location) {
return buffer[location]
}
}
I have looked at a bunch of places but haven't found a standard reference.
https://github.com/nst/BinUtils/blob/master/Sources/BinUtils.swift
https://github.com/apple/swift/blob/master/stdlib/public/core/ArrayBuffer.swift
https://github.com/uraimo/Bitter/blob/master/Sources/Bitter/Bitter.swift
In Swift, how do I read an existing binary file into an array?
Swift - writing a byte stream to file
https://apple.github.io/swift-nio/docs/current/NIO/Structs/ByteBuffer.html
https://github.com/Cosmo/BinaryKit/blob/master/Sources/BinaryKit.swift
https://github.com/vapor-community/bits/blob/master/Sources/Bits/Data%2BBytesConvertible.swift
https://academy.realm.io/posts/nate-cook-tryswift-tokyo-unsafe-swift-and-pointer-types/
https://medium.com/#gorjanshukov/working-with-bytes-in-ios-swift-4-de316a389a0c
I would like for this to be as low-level as possible. So perhaps using UnsafeMutablePointer, UnsafePointer, or UnsafeMutableRawPointer.
Saw this as well:
let data = NSMutableData()
var goesIn: Int32 = 42
data.appendBytes(&goesIn, length: sizeof(Int32))
println(data) // <2a000000]
var comesOut: Int32 = 0
data.getBytes(&comesOut, range: NSMakeRange(0, sizeof(Int32)))
println(comesOut) // 42
I would basically like to allocate a chunk of memory and be able to read and write from it. Not sure how to do that. Perhaps using C is the best way, not sure.
Just saw this too:
let rawData = UnsafeMutablePointer<UInt8>.allocate(capacity: width * height * 4)
If you're looking for low level code you'll need to use UnsafeMutableRawPointer. This is a pointer to a untyped data. Memory is accessed in bytes, so 8 chunks of at least 8 bits. I'll cover multiples of 8 bits first.
Reading a File
To read a file this way, you need to manage file handles and pointers yourself. Try the the following code:
// Open the file in read mode
let file = fopen("/Users/joannisorlandos/Desktop/ownership", "r")
// Files need to be closed manually
defer { fclose(file) }
// Find the end
fseek(file, 0, SEEK_END)
// Count the bytes from the start to the end
let fileByteSize = ftell(file)
// Return to the start
fseek(file, 0, SEEK_SET)
// Buffer of 1 byte entities
let pointer = UnsafeMutableRawPointer.allocate(byteCount: fileByteSize, alignment: 1)
// Buffer needs to be cleaned up manually
defer { pointer.deallocate() }
// Size is 1 byte
let readBytes = fread(pointer, 1, fileByteSize, file)
let errorOccurred = readBytes != fileByteSize
First you need to open the file. This can be done using Swift strings since the compiler makes them into a CString itself.
Because cleanup is all for us on this low level, a defer is put in place to close the file at the end.
Next, the file is set to seek the end of the file. Then the distance between the start of the file and the end is calculated. This is used later, so the value is kept.
Then the program is set to return to the start of the file, so the application starts reading from the start.
To store the file, a pointer is allocated with the amount of bytes that the file has in the file system. Note: This can change inbetween the steps if you're extremely unlucky or the file is accessed quite often. But I think for you, this is unlikely.
The amount of bytes is set, and aligned to one byte. (You can learn more about memory alignment on Wikipedia.
Then another defer is added to make sure no memory leaks at the end of this code. The pointer needs to be deallocated manually.
The file's bytes are read and stored in the pointer. Do note that this entire process reads the file in a blocking manner. It can be more preferred to read files asynchronously, if you plan on doing that I'll recommend looking into a library like SwiftNIO instead.
errorOccurred can be used to throw an error or handle issues in another manner.
From here, your buffer is ready for manipulation. You can print the file if it's text using the following code:
print(String(cString: pointer.bindMemory(to: Int8.self, capacity: fileByteSize)))
From here, it's time to learn how to read manipulate the memory.
Manipulating Memory
The below demonstrates reading byte 20..<24 as an Int32.
let int32 = pointer.load(fromByteOffset: 20, as: Int32.self)
I'll leave the other integers up to you. Next, you can alos put data at a position in memory.
pointer.storeBytes(of: 40, toByteOffset: 30, as: Int64.self)
This will replace byte 30..<38 with the number 40. Note that big endian systems, although uncommon, will store information in a different order from normal little endian systems. More about that here.
Modifying Bits
As you notes, you're also interested in modifying five or ten bits at a time. To do so, you'll need to mix the previous information with the new information.
var data32bits = pointer.load(fromByteOffset: 20, as: Int32.self)
var newData = 0b11111000
In this case, you'll be interested in the first 5 bits and want to write them over bit 2 through 7. To do so, first you'll need to shift the bits to a position that matches the new position.
newData = newData >> 2
This shifts the bits 2 places to the right. The two left bits that are now empty are therefore 0. The 2 bits on the right that got shoved off are not existing anymore.
Next, you'll want to get the old data from the buffer and overwrite the new bits.
To do so, first move the new byte into a 32-bits buffer.
var newBits = numericCast(newData) as Int32
The 32 bits will be aligned all the way to the right. If you want to replace the second of the four bytes, run the following:
newBits = newBits << 16
This moves the fourth pair 16 bit places left, or 2 bytes. So it's now on position 1 starting from 0.
Then, the two bytes need to be added on top of each other. One common method is the following:
let oldBits = data32bits & 0b11111111_11000001_11111111_11111111
let result = oldBits | newBits
What happens here is that we remove the 5 bits with new data from the old dataset. We do so by doing a bitwise and on the old 32 bits and a bitmap.
The bitmap has all 1's except for the new locations which are being replaced. Because those are empty in the bitmap, the and operator will exclude those bits since one of the two (old data vs. bitmap) is empty.
AND operators will only be 1 if both sides of the operator are 1.
Finally, the oldBits and the newBits are merged with an OR operator. This will take each bit on both sides and set the result to 1 if the bits at both positions are 1.
This will merge successfully since both buffers contain 1 bits that the other number doesn't set.
I am basing my code off of Portaudio's paex_record_file.c example. One of the parameters in the callback is inputBuffer, and I wanted to use its data to calculate other numbers with the double/float type. I changed the file from a .raw to a .txt, but notepad still cannot read it, leading me to believe its data is not actually encoded as a number. How is the data stored in inputBuffer and how can I do arithmetic with it (add, multiply, divide, etc)?
This is how I initialized inputParameters:
inputParameters.device = Pa_GetDefaultInputDevice(); /* default input device */
if (inputParameters.device == paNoDevice) {
fprintf(stderr,"Error: No default input device.\n");
goto error;
}
inputParameters.channelCount = 2; /* stereo input */
inputParameters.sampleFormat = paFloat32;
inputParameters.suggestedLatency = Pa_GetDeviceInfo( inputParameters.device )->defaultLowInputLatency;
inputParameters.hostApiSpecificStreamInfo = NULL;
This question is somewhat related to print floats from audio input callback function (unanswered).
The inputBuffer parameter to the callback is a void*. The actual type of the underlying buffer depends on the parameters and the flags that you pass to Pa_OpenStream.
If you specified paFloat32 then there will be a float* in there somewhere. However the are two possibilities:
Interleaved: inputParameters.sampleFormat = paFloat32;
Non-Interleaved: inputParameters.sampleFormat = paFloat32|paNonInterleaved;
You specified the interleaved option. In this case, inputBuffer points to a single buffer of interleaved floats. So you can write:
float *samples = (float*)inputBuffer;
In a two channel stream samples will contain interleaved left and right samples, e.g.:
samples[0]; // first left sample
samples[1]; // first right sample
samples[2]; // second left sample
samples[3]; // second right sample
// etc.
For completeness: If it had been a non-interleaved stream then inputBuffer points to an array of pointers to single-channel buffers. To extract the buffer pointers you would write something like:
float *left = ((float **) inputBuffer)[0];
float *right = ((float **) inputBuffer)[1];
Note that in all cases framesPerBuffer counts frames not samples. A frame includes one sample from each channel. For example, in a stereo stream, a frame includes both the left and right channel samples.
After having a detail review of WWDC2014,Session513, I try to write my app on IOS8.0 to decode and display one live H.264 stream. First of all, I construct a H264 parameter set successfully. When I get one I frame with a 4 bit start code,just like"0x00 0x00 0x00 0x01 0x65 ...", I put it into a CMblockBuffer. Then I construct a CMSampleBuffer using previews CMBlockBuffer. After that,I put the CMSampleBuffer into a AVSampleBufferDisplayLayer. Everything is OK(I checked the value returned ) except the AVSampleBufferDisplayLayer does not show any video image. Since these APIs are fairly new to everyone, I couldn't find any body who can resolve this problem.
I'll give the key codes as follows,and I do really appreciate it if you can help to figure out why the vide image can't be displayed. Thanks a lot.
(1) AVSampleBufferDisplayLayer initialised.
dsplayer is a objc instance of my main view controller.
#property(nonatomic,strong)AVSampleBufferDisplayLayer *dspLayer;
if(!_dspLayer)
{
_dspLayer = [[AVSampleBufferDisplayLayer alloc]init];
[_dspLayer setFrame:CGRectMake(90,551,557,389)];
_dspLayer.videoGravity = AVLayerVideoGravityResizeAspect;
_dspLayer.backgroundColor = [UIColor grayColor].CGColor;
CMTimebaseRef tmBase = nil;
CMTimebaseCreateWithMasterClock(NULL,CMClockGetHostTimeClock(),&tmBase);
_dspLayer.controlTimebase = tmBase;
CMTimebaseSetTime(_dspLayer.controlTimebase, kCMTimeZero);
CMTimebaseSetRate(_dspLayer.controlTimebase, 1.0);
[self.view.layer addSublayer:_dspLayer];
}
(2)In another thread, I get one H.264 I frame.
//construct h.264 parameter set ok
CMVideoFormatDescriptionRef formatDesc;
OSStatus formatCreateResult =
CMVideoFormatDescriptionCreateFromH264ParameterSets(NULL, ppsNum+1, props, sizes, 4, &formatDesc);
NSLog([NSString stringWithFormat:#"construct h264 param set:%ld",formatCreateResult]);
//construct cmBlockbuffer .
//databuf points to H.264 data. starts with "0x00 0x00 0x00 0x01 0x65 ........"
CMBlockBufferRef blockBufferOut = nil;
CMBlockBufferCreateEmpty (0,0,kCMBlockBufferAlwaysCopyDataFlag, &blockBufferOut);
CMBlockBufferAppendMemoryBlock(blockBufferOut,
dataBuf,
dataLen,
NULL,
NULL,
0,
dataLen,
kCMBlockBufferAlwaysCopyDataFlag);
//construct cmsamplebuffer ok
size_t sampleSizeArray[1] = {0};
sampleSizeArray[0] = CMBlockBufferGetDataLength(blockBufferOut);
CMSampleTiminginfo tmInfos[1] = {
{CMTimeMake(5,1), CMTimeMake(5,1), CMTimeMake(5,1)}
};
CMSampleBufferRef sampBuf = nil;
formatCreateResult = CMSampleBufferCreate(kCFAllocatorDefault,
blockBufferOut,
YES,
NULL,
NULL,
formatDesc,
1,
1,
tmInfos,
1,
sampleSizeArray,
&sampBuf);
//put to AVSampleBufferdisplayLayer,just one frame. But I can't see any video frame in my view
if([self.dspLayer isReadyForMoreMediaData])
{
[self.dspLayer enqueueSampleBuffer:sampBuf];
}
[self.dspLayer setNeedsDisplay];
Your NAL unit start codes 0x00 0x00 0x01 or 0x00 0x00 0x00 0x01 need to be replaced by a length header.
This was clearly stated in the WWDC session you are referring to that the Annex B start code needs to be replaced by a AVCC conform lengh header. You are basically remuxing to MP4 file format from Annex B stream format on the fly here (simplified description of course).
Your call when creating the Parameter Set is "4" for this, so you need to prefix your VCL NAL units with a 4 byte length prefix. That's why you specifiy it as in AVCC format the length header can be shorter.
Whatever you put inside CMSampleBuffer will be OK, there is no sanity check if the contents can be decoded, just that you met the required parameters for being arbitrary data combined with timing information and a parameter set.
Basically with the data you put in you said the the VCL NAL units are 1 byte long. The decoder doesn't get the full NAL unit and bails out on an error.
Also make sure that when you use create the parameter set that the PPS/SPS do not have a length byted added and that the Annex B start code is also stripped.
Also I recommend not to use AVSampleBufferDisplayLayer but go through a VTDecompressionSession, so you can do stuff like color correction or other things that are needed inside a pixel shader.
It might be an idea to use DecompressionSessionDecode Frame initially as this will give you some feedback on the success of the decoding. If there is an issue with the decoding the AVSampleBufferDisplay layer doesn't tell you it just doesn't display anything. I can give you some code to help with this if required, let me know how you get on as I am attempting the same thing :)
I can't write data at index above 128 in byte array.
code is given below.
private void Write1(APDU apdu) throws ISOException
{
apdu.setIncomingAndReceive();
byte[] apduBuffer = apdu.getBuffer();
byte j = (byte)apduBuffer[4]; // Return incoming bytes lets take 160
Buffer1 = new byte[j]; // initialize a array with size 160
for (byte i=0; i<j; i++)
Buffer1[(byte)i] = (byte)apduBuffer[5+i];
}
It gives me error 6F 00 (It means reach End Of file).
I am using:
smart card type = contact card
using java card 2.2.2 with jcop using apdu
Your code contains several problems:
As already pointed out by 'pst' you are using a signed byte value which works only up to 128 - use a short instead
Your are creating a new buffer Buffer1 on every call of your Write1 method. On JavaCard there is usually no automatic garbage collection - therefore memory allocation should only be done once when the app is installed. If you only want to process the data in the adpu buffer just use it from there. And if you want to copy data from one byte array into another better use javacard.framework.Util.arrayCopy(..).
You are calling apdu.setIncomingAndReceive(); but ignore the return value. The return value gives you the number of bytes of data you can read.
The following code is from the API docs and shows the common way:
short bytesLeft = (short) (buffer[ISO7816.OFFSET_LC] & 0x00FF);
if (bytesLeft < (short)55) ISOException.throwIt( ISO7816.SW_WRONG_LENGTH );
short readCount = apdu.setIncomingAndReceive();
while ( bytesLeft > 0){
// process bytes in buffer[5] to buffer[readCount+4];
bytesLeft -= readCount;
readCount = apdu.receiveBytes ( ISO7816.OFFSET_CDATA );
}
short j = (short) apdu_buffer[ISO7816.OFFSET_LC] & 0xFF
Elaborating on pst's answer. A byte has 2^8 bits numbers, or rather 256. But if you are working with signed numbers, they will work in a cycle instead. So, 128 will be actually -128, 129 will be -127 and so on.
Update: While the following answer is "valid" for normal Java, please refer to Roberts answer for Java Card-specific information, as well additional concerns/approaches.
In Java a byte has values in the range [-128, 127] so, when you say "160", that's not what the code is really giving you :)
Perhaps you'd like to use:
int j = apduBuffer[4] & 0xFF;
That "upcasts" the value apduBuffer[4] to an int while treating the original byte data as an unsigned value.
Likewise, i should also be an int (to avoid a nasty overflow-and-loop-forever bug), and the System.arraycopy method could be handy as well...
(I have no idea if that is the only/real problem -- or if the above is a viable solution on a Java Card -- but it sure is a problem and aligns with the "128 limit" mentioned.)
Happy coding.