memcpy same buffer void GetStudentDataString ( student * ps ) { const int bufferSize = 127 ; char buffer [bufferSize+1] = { 0 }; snprintf ( buffer, bufferSize, "%s, %d, %02d:%02d:%02d" , ps->name, ps->rollNumber, ps->yy, ps->mm, ps->dd ); } Permalink. Devices. A buffer overflow is a bug, among the generic class of bugs known as "the programmer is not fully aware of what he is doing". matri[boneids[0]] * weights[0]; Why do you use memcpy on an MSP? The maximum RAM size is 16k, so the maximum transfer size is 8k. Copy Code. I think beyond 64K, it counts for more than 50% of the execution time. 2)Same as (1), except that the following errors are detected at runtime and cause the entire destination range [dest, dest+destsz)to be zeroed out (if both destand destszare valid), as well as call the currently installed constraint memcpy(buffer [destination], reference to data struct [source], sizeof data struct [data source size]); 5. This can be resolved in this way. size ())); // return n_copy;} // An overload that fills in `max_copy` for us: size_t buffer_copy (mutable_buffer dest, mutable_buffer source) {return buffer_copy (dest, source, numeric_limits < size_t >:: max ());} We classify heap buffer over-read into three categories. If the objects overlap (which is a violation of the restrict contract) (since C99), the behavior is undefined. It is not a "competing" paper, but provides an alternative look at the same issues. GCC does only seem to translate memcpy to a function call if the size to copy is not constant. memcpy () method is the same as Clib. makeBuffer (bytesNoCopy:length:options:deallocator:) creates a MTLBuffer object that reuses an existing storage allocation and does not allocate any new Note that some memory controllers can hide unaligned access - they just force the core to wait extra wait states while the memory controller performs multiple memory accesses and then glues together the partial reads. The easiest way to see if the memcpy() is doing what you want is to use it to copy the buffer back into *another* object of the same class as was copied to the buffer. When an object implements this protocol, you can use the memoryview class constructor on it to build a new memoryview object that references the original object memory. 1)Copies countcharacters from the object pointed to by srcto the object pointed to by dest. 1000 M solutions of the weak acid and its conjugate base had been used and the same amount of NaOH had been added: The concentration of HCOOH would change from 0. But instead of holding it as 2 buffers, we will store it on one Instead, you want to write to GST_BUFFER_DATA (buffer). 14, a versioned symbol was added so that old binaries (i. 14) employed a memcpy() implementation that safely handles the overlapping buffers case (by providing an "older" memcpy() implementation that was aliased to memmove(3)). Here, this test program hasfreed the same block twice. Both objects are interpreted as arrays of unsigned char. At it's heart, all it does is copy a byte from one pointer to another and increment bo memcpy () buffer manipulation copies the "count" characters from the array block, "str2" to str1". There is a heap-based buffer over-read in a memcpy call of the parse_SST function. I would like this operation to be double buffered to ensure that the input is never stalled. g. Unbound memcpy with a failed length check at nfs_lookup_reply. familiar_name, strlen(user. */ /* Get the buffer */ buffsize = sizeof(int) + (strlen(user. The strcpy() function copies the string pointed to by src, including the terminating null byte ('\0'), to the buffer pointed to by dest. Ok, thank you. However, because the buffer that overflows during the call to memcpy resides in a previous stack frame, the return pointer for memcpy will have a numerically higher memory address than the buffer. "Stack Overflow" is often used to mean the same thing as stack-based buffer overflow, however it is also used on occasion to mean stack exhaustion, usually a result from an excessively recursive function call. There's not much to really look into, however, because C provides an alternative that does support overlapping memory: memmove(). The buffer number assignment is implemented this way, so that you can always jump to a buffer using the same buffer number. And the results: Figure 12 – Finding the source buffer size in memcpy “memcpy_location” – the location of the memcpy. SoBufferObject. dest New buffer. The “safe” version just includes an extra length parameter (of the target buffer). This paper relates to P1726: Pointer lifetime-end zap and provenance, too. An attacker can cause the program to crash, make data corrupt, steal some private information or run his/her own code. 4 these functions guarantee that if the destination buffer is 8 byte aligned, size is a multiple of 8 and application is interrupted (by crash / OS crash / power failure), then each 8-byte location has either new or old value, never a mix of the two. A language with bounds check (or even the use of memcpy_s()) will not remove such bugs; it will only make consequences a bit less dire (e. VALUE str = rb_str_new_static (buffer, buflen); /* no malloc or memcpy done here, just ownership change of buffer */ RUBY_FL_UNSET (str, STR_NOFREE); /* STR_NOFREE isn't actually defined in internal. Posted 8-Aug-17 10:41am. Siebel eScript protects data from being overwritten; therefore, in Siebel eScript Clib. I did try glEnable(GL_BLEND) but it didn't work. 15. If you are planning to use the same buffer object between multiple programs and/or program stages, it is a good idea to use the shared option. That code just replaces the vertices in place, updating two vertices at a time (2*i+0 and 2*i+1). It is used to initialize a specified number of bytes to null or any other value in the buffer. Share . MemoryCopy, performs better in most cases, more detail at the bottom of this post. g. I would expect 'A' and 'C' to produce the same results from Fortify. When “touching” the destination buffer of memcpy (memset(b2, 0, BUFFERSIZE )) then the first run of memcpy is also faster. buffer[3] should be 'B' after memcpy Is NULL same as 0? Basically, yes. I dug down into the FreeRTOS code and it looks like they use memcpy under the covers memcpy() vs memmove(), The memory in memcpy cannot overlap or you risk undefined behaviour, in memmove , the source memory of specified size is copied into buffer and then Overlapping buffers and use of memcpy causes problems in practice. Thanks to the benefit of the DMA, we don’t have to wait for each memory copy to be done before we issue another memcpy request. We use the VmaAllocation object to manage the buffer allocation itself. memcpy () It is used to copy a specified number of bytes from one memory to another. The video call looked like it was being fuzzed and crashed in roughly fifteen minutes. Security Note Make sure that the destination buffer is the same size or larger than the source buffer. @tbenson Interesting results: Initially changing memcpy to memmove produced the same results when built in release mode ~300ms. 35f [ ] }; glBindBuffer (GL_ARRAY_BUFFER, buffer); // get pointer void *ptr = glMapBuffer (GL_ARRAY_BUFFER, GL_WRITE_ONLY); // now copy data into memory memcpy(ptr, data, sizeof(data)); // make sure to tell OpenGL we're done with the pointer glUnmapBuffer (GL_ARRAY_BUFFER); The mutex is a mutual exclusive lock that's going to serialize the access to the whole buffer. Several C++ compilers transform suitable memory-copying loops to std::memcpy calls. Using the ring buffer in the UART driver. benchmark seq_memcpy(uint64_t chunk_size, uint64_t buffer_size) { using namespace std::chrono_literals; // Allocate the whole buffer, 8 bytes-aligned uint64_t* buffer64 = new uint64_t[buffer_size / sizeof(uint64_t)]; uint8_t* buffer8 = reinterpret_cast<uint8_t*>(buffer64); // Trick the optimizer into not optimizing any copies away utils::escape(buffer8); // Fill the buffer with random data random_number_generator<uint64_t> rnd; for (uint i = 0 / sizeof(uint64_t); i < buffer_size / sizeof memcpy_s looks daft when the two size_t parameters are the same. Jitter can be quantified in the same terms as all time-varying signals, e. RE: KB rule to create "memcpy" and "read" functions equivalent? Hi Shai, These forums are not the primary method of interacting with Rogue Wave Klocwork Support, especially if you are a customer with valid support and maintenance. So it moves the current token text at the beginning of the buffer to be able to append more characters after it. This method is given access to other internal dlls and this close to release we do not want to change The nursery does not allocate an inline data buffer that has the same size as the slow path will do. You don't replace memcpy unless you do it right. Difference between memmove and memcpy is, overlap can happen on memmove whereas memcpy should be done in non-destructive way. bufsize = 0; png_set_write_fn(png_ptr, &memory_writer_state, write_data_memory, user_png_flush); // We will get png array at the buffer in memory_writer_state struct. You can work out the algorithm, you copy from source upwards if destination is less than source, and from source + N -1 downwards if destination is greater than source. If you change a, do you want and identical change in b? However you can't memcpy to a null. 00GB took 0ms READ_REGISTER_BUFFER_ULONG(). void* pointers are only used to transfer data across functions, threads, but not access them. Despite being specified "as if" a temporary buffer is used, actual implementations of this function do not incur the overhead or double copying or extra memory. memcpy () does not check for any terminating null character in source buffer. C++ (Cpp) memcpy_P - 30 examples found. The naive handmade memcpy is nothing more than this code (not to be the best implem ever but at least safe for any kind of buffer size): memcpy () function: memcpy function copies specified number of bytes from source buffer to destination buffer. One method to achieve buffer number reordering is to restart Vim. A version of ARR38-C also appears in ISO/IEC TS 17961:2013 This same buffer can be diluted to create buffers of 0. Memcheck keeps track of the blocks allocated by your program withmalloc/new, so it can know exactly whether or not the argument tofree/delete is legitimate or not. " ; char str2 [40]; char str3 [40]; memcpy (str2, str1, strlen (str1) + 1); memcpy (str3, "copy successful", 16); printf ( "str1= %s str2= %s str3= %s ", str1, str2, str3); return 0; } However, according to this other thread, "memcopy can only be used to transfer from bus to a memory (array) or vice versa of the same width datatype". I then wrote a library for Android which had the same parameters as memcpy, but fuzzed and copied the buffer instead of just copying it, and put it on the filesystem where it would be loaded by dlopen. This allows a user to cause an arbitrary amount of data to be written to the 64-byte buffer buf, potentially overflowing that buffer. The size of the destination buffer is the same user-controlled buffer used in instance 1, destbuf. 43 / 3572. id), sizeof(int)); bufflen = sizeof(int); memcpy(databuff + bufflen, user. (Another way is to have an extra variable to tell wether the buffer is full or empty when LP and CP point to the same address. The idea is to write one part of the buffer without restricting the consumer thread to read other parts of the same buffer. The small amount of code needed for a memcpy should be in the cache lines, so it should execute at max CPU speed. Method B takes ~1400 ms, for an array length of 52,428,800 (which is image size of 1280 x 1024 pixels). There are two other layout qualifiers that are worth mentioning: row_major and column_major. To copy overlapping you need to determine which piece of memory is located before and copy in either forward or reverse order. Using a single memory buffer has several advantages. For example, copying to system memory could be done with memcpy(), copying to I/O memory would be done with memcpy_toio(). 61 = 1. More Complex Programs. This function simply copies byte by byte characters of the block from the array. GCC translates every calls to std::copy with a call to memmove regardless of the buffer size, while Clang only does it for buffer sizes of 64 or more, same with memcpy. 3539 ms Rate: 3486. If the source and destination objects overlap, the behavior of memcpy is undefined. Try changing the declaration of Input to char Input[64]={'A', 'B', 'C', 'D'}; That would make it a bit easier to see what's doing on. I can use unchecked conversion, but my source is not necessarily the same size as my target, but is always smaller. The function prototype is. Guarantee that library functions do not form invalid pointers. The Mesh class The copy is only when new data cannot be pushed further into the current lexer buffer because the end of the buffer has been reached. I suggest merging only memcpy+memmove (whose implementations are exactly the same), and still leaving bcopy separate, though. Inventor. Here, you allocate sizeof (uint32_t) bytes, but you're writing zeroes to idLength bytes. ValueOf(value) dims, dataType, err := dimsAndDataTypeOf(val. , those linked against glibc versions earlier than 2. When memcpy_s() proceeds to copy the attacker-controlled buffer into the undersized stack buffer variable, a buffer overflow condition occurs. But there were some glitches while reading data and some data was lost. As with the first instance, the call to memcpy takes a user-supplied value for the size argument. And it is the same case for cudaMemcpy with cudaMemcpyDefault parameter. This means that the input would write to one buffer (Buff0), then when that buffer is filled, the input would write to a second buffer (Buff1) while the memcpy command is copying the data from Buff0 to external memory at the same time. The performance in this method is also the same as the ANativeWindow one. The async memcpy API wraps all DMA configurations and operations, the signature of esp_async_memcpy() is almost the same to the standard libc one. The subscriber node populates another sensor_msgs/Image by deserializing the received buffer. Then i debug the program and find i When running memcpy twice, then the second run is faster than the first one. I tried to copy a struct which does not have pointer value using memcpy. 1, could result in a crash or read from other parts of process memory. Social media is a two-way conversation. The C++ is MemCpy logic is echoing the desired output. It will be working well. The memcpy() Function. Actually, it doesn’t care what content is there in the memory. When flags is Gst. As with the illegal read/write errors,Memcheck attempts to make sense of the address free'd. The pattern for asynchronously copying data is similar. memcpy, mempcpy, memmove, memset, strcpy, stpcpy, strncpy, strcat, strncat, sprintf, vsprintf, snprintf, vsnprintf, gets Although some of them accept an argument defining the length of the passed buffer, the functions must believe that the size is correct. /mem_test 64 10000 Memory Tester Num loops: 10000 Buffer size: 64 MB Duration: 18. Using union appears to work the same way, and since my example was not using structure elements, it seems to make more sense to do it that way. Since these two vulnerabilities share the same root cause, we will discuss ZDI-20-494 only. The documentation is not written "through an intermediate buffer", and "as if using an intermediate buffer". Then that second object should contain exactly the same data as the original object. By incrementing the index only at the end, even if an interrupt fires in the middle of the memcpy, ring_buffer_put called from the ISR would see the current tail as still being used and would not write into it. And in application layer,i use memcpy() to copy data from buffer. memcpy, strcpy, strncpy, strcat and strncat are all perfectly safe providing you check the length of the input to make sure it can fit into the buffer provided, and/or provide a correct length The map/unmap APIs map the underlying memory store of a buffer into the host address space and allows the host application to read and write directly from/to the buffer’s content. ms memcpy s memmove s vs memcpy memmove Hundred thousand 23 memcpy_s It is used to initialize a specified number of bytes to null or any other value in the buffer: 2: memcpy() It is used to copy a specified number of bytes from one memory to another: 3: memmove() It is used to copy a specified number of bytes from one memory to another or to overlap on same memory. The size of a structure is not always equal to the sum of the sizes of its members. About the undefined behavior: I thought the purpose of reinterpret_cast is to tell the compiler "shut Figure 11 – Finding the allocation function that allocated the memory block provided as the destination argument in a memcpy. memcpy doesn't know what a buffer is-- no, it really doesn't. 5. (1) memcpy-based. 4, as used in Google TensorFlow before 1. Outgoing packets are created directly into the same buffer. We can have multiple descriptors point into different parts of the same buffer. Let’s see how we can handle the overlapping scenario. #2 When you're allocating a buffer and initializing it with memset, make sure you use the exact same size parameters for both function calls. Important exception: If a consumer requests a buffer without the PyBUF_FORMAT flag, format will be set to NULL , but itemsize still has the value for the original format. Both tests are running on the same Windows 7 OS x64, same machine Intel Core I5 750 (2. 5 bytes. // On arm this method behaves like memcpy and does not handle overlapping buffers. 1000 M to 0. Often memcpy is used to move memory around inside larger buffers, which completely invalidates memcpy_s as a safe replacement. memcpy is still a little bit slower than memmove. Beware of buffer overruns! (See BUGS. CVE-2018-5766 Next, then memcpy function is defined and annotated with pre- and post-conditions, using liveness and disjointness predicates. This is allowed as long as they don't read/write the same element (byte). Then i later found i could just texture->draw on a created buffer. The interesting part is to run this test on a x86 and x64 mode. I'm trying to create a render target (buffer) and draw on it. I dual boot same box with Intel i7 4770 CPU and 16Gb RAM and run same c++ code compiled. - NEON version of memcpy(): copied to buffer in 885 usec [37 MB/s] - Linux version of memcpy(): copied to buffer in 908 usec [36 MB/s] Again this is still from advertised speeds! Then I also tested & replaced EP bare-metal OS with Linux (from NXP RC/EP validation example). data, not including the null character. Heavy DMA have been known to slow the CPU. See, for example, LWN. src Buffer to copy from. My understanding from Joseph's reply is that using a value higher than PTRDIFF_MAX for memcpy length is undefined behavior because either for automatic objects or by using memory allocation functions the allocation will fail. 2. This means we have effectively two copy operations, which may be vectorized Buffer. . If the code is plain C, then there are no reason why above code would be slower that calling memcpy manually. e. Some (most) programs are much more complex, and require a Makefile. The memcpy function may not work if the objects overlap. Often you'll use memcpy() to simply copy from an array of vertices you have into that buffer. That is, while a memcpy() is in flight the destination buffer might contain transient or ephemeral values which could be observed by other threads. 1) Copies count characters from the object pointed to by src to the object pointed to by dest. The CLR used for this is the Runtime v4. The input and output use the same buffer but are not linked together. In glibc 2. It parses 4 bytes and uses them as length for a memcpy in two different locations. One important fact, which will matter in a moment, is that since PMDK 1. void *memcpy(void *dest, void *src, size_t count); memcpy, memcpy_s. I have some troubles to find the buffer overflow vulnerability in this piece of code, it is with memcpy but I am confused on the result it gives : #include <stdio. Every element of a slice must have the same length so // that the resulting Tensor has a valid shape. memcpy(to, packetbuf + hdrptr, PACKETBUF_HDR_SIZE - hdrptr); where "to" is the destination address. cpp, there is a buffer overflow in function DirectoryListingParserTest::testIndividual(). You should use it if the regions might overlap, as it accounts for that possibility. Building the code in debug mode caused memmove to run ~160ms. what you expect)? 2) Are either of the pointers NULL? by Amlendra on. The implementation of memcpy uses a C-style for loop with a loop invariant and a It returns the same error message whether the host buffer is allocated through malloc, cudaMalloc, or cudaHostAlloc (with all different flags). 0. 1. But after a while,in application layer,i cann't receive the data sended from pc. Copy bytes to buffer from buffer: how to use memcpy. Asynchronous data movement enables multiple batches to be “in flight” at the same time. The C library function void *memcpy(void *dest, const void *src, size_t n) copies n characters from memory area src to memory area dest. memcpy vs strcpy: Comparison between memcpy and strcpy based on user comments from StackOverflow. In case of strcpy, strcpy function copies characters one by one until it find NULL or ‘\0’ character. The post-condition states that after calling memcpy src dst len, the destination and the source have the same contents up to index len. This can virtually eliminate the time to do the transfers. CELEBM15 /* CELEBM15 This example sets 10 bytes of the buffer to "A" and the next 10 bytes to "B". Abstracting buffer creation. The C# app using Buffer. Description. To create a buffer object in device memory call: void * gcl_malloc(size_t bytes, void *host_ptr, cl_malloc_flags flags) The gcl_malloc function is very similar to the C language malloc function. Also like other time-varying signals, jitter can be expressed in terms of spectral density. This allows for optimizations that won't work if the buffers do overlap. Please begin this series by watching Part 1, if you have not already done so! In this video, we will look at how to exploit a simple buffer overflow caused by misuse of the memcpy function. memmove (). Then I tried to use memcpy and RtlCopyMemory instead of READ_REGISTER_BUFFER_ULONG() but had the same problem. Because of that there are lots of calculations involved in working out exactly where in the buffer to place the next character. This problem exists in the nfs_lookup_reply function that again parses an nfs reply coming from the network. The cast takes a couple of milliseconds, roughly the same as Method 1. A buffer amplifier (sometimes simply called a buffer) is one that provides electrical impedance transformation from one circuit to another, with the aim of preventing the signal source from being affected by whatever currents (or voltages, for a current buffer) that the load may be produced with. count Number of characters to copy. 66Ghz). #include <stdio. flags describe the desired access of the memory. front ()), b. It returns s1. However, the manual Method A, in the preceding example, takes ~1300 ms. Here is a simple implementation of memcpy() in C/C++ which tries to replicate some of the mechanisms of the function. These are the top rated real world C++ (Cpp) examples of memcpy_s extracted from open source projects. /big_memcpy_test To specify a custom buffer size: big_memcpy_test Using built in buffer size: 1. The readonly copy of the buffer memory will then also be replaced with this writable copy. std::copy(src, src+sizeof(value), m_buffer+m_offset); m_offset += sizeof(value); Note that if you switch to vector<char>, you won't need to test for overflow at all, and you'd still be able to do Because memcpy () assumes that the value is unsigned, it will be interpreted as MAXINT-1 (CWE-195), and therefore will copy far more memory than is likely available to the destination buffer (CWE-787, CWE-788). vector<char> b = memcpy (out, (b. AFAIK, memcpy is not a simple loop, in a way that it can align the copies to match the architecture. Both objects are interpreted as arrays of unsigned char. To do this, i have used memcpy(. . Introduction. Method 3: Transfer byte array by calling memcpy memcpy vs strcpy – Performance : Memcpy() function will be faster if we have to copy same number of bytes and we know the size of data to be copied. surname) + 1); bufflen += strlen(user. memcpy() copies bytes of data between memory blocks, sometimes called buffers. The C++ app using MemCpy is running on XP/x86. > the buffer or do i have > to somehow create a SharedPointer to the Buffer and use the copyPointCloud > method ? I don't know the specifics of your system. memcpy saves a test. 00GB malloc for 1. surname) + 1 A data strobe buffer and a memory system including the data strobe buffer are provided. At the same time, it can be viewed as a feature since the code > would be more clearly written simply as strcpy(p, "1"). 0. Buffer's separate app, Buffer Reply, is expensive, but it offers more tools than Hootsuite's basic package. Let’s say we want to have an uninitialized buffer of 1024 bytes which we plan to fill in later. If you have not written anything into the buffer I would not expect you to be able to read from the buffer (as there is nothing to read). surname) + 2); databuff = malloc(buffsize); memset(databuff, 0, buffsize); /* copy everything to the buffer */ memcpy(databuff, &(user. This method has the advantages of: Not requiring 2 storage areas containing the same data (one in Linux system memory and one in the Buffer in CMEM memory), and Input validation to avoid buffer issue, like overflow, un- call h APIll the same API. To remove the extra overhead we can also handle the overlapping scenario by putting some condition for source and destination buffer. In order to make copying memory to constant buffers fast it makes sense to use _aligned_malloc () to allocate memory that is aligned to 16 byte boundaries, as this speeds up the necessary memcpy () operation from application memory to the memory returned by Map (). Actually, programmer supply the size of data to be copied. . There are two ways to deal with that Hi all, I am working on a camera to collect data. Writing and reading the data records is To do this, I have a loop that does a memcpy from a pointer to the SAM flash memory into a buffer, and then writes the buffer to the SPI flash. Calling dma-buf’s vmap operation returns a pointer to the buffer’s memory. empty ? 0 : &b. When you do write I would only expect you to be able to read only what has written (no more). Example 2: Distance from field This example illustrates the buffer of a line feature class using a numeric field with values of 10, 20, and 30 for distance, an end type of FLAT , a side type of FULL , and a dissolve type of ALL . Output: Copied string is GeeksforGeeks Copied array is 10 20 30 40 50 What is memmove()?. buffer = NULL; memory_writer_state. Following is the declaration for memcpy() function. It does not check for overflow of any receiving memory area. It basically means to access any buffer outside of it’s alloted memory space. The best we can do is to have every byte initialized: I'm trying to copy input buffer values into the multiple output buffers. Its usage is identical to memcpy(). Unfortunately the driver may not immediately copy the data into the buffer memory, for example because of caching. It is an IMU so basically one write for a packet of acceleration data and one write for a packet of magnetic data. 30319. h unfortunately, it's currently same as FL_USER18, but could change. mempcpy: GNU a variant of memcpy returning a pointer to the byte following the last written byte strcasecmp: POSIX, BSD If one or both arrays are not at least the same size as the size you pass to memcpy, then you will get a segfault. Where this cutoff point is placed differs between the compilers though. The strings may not overlap, and the destination string dest must be large enough to receive the copy. The test is performing a series of memcpy with different size of block : from 4 bytes to 2Mo. This call to memcpy() violates ARR38-C. Upon success, buffer will point to the writable storage and num_bytes will indicate the size of the buffer there. So you need to have the size as a parameter with memcpy, but not with strcpy. @2of1 It isn’t the same as in memcpy(), look: “qqwer r uiopasdfghjklzxcvbnm” - memcpy() “qqwer t uiopasdfghjklzxcvbnm” - memmove() So, memmove() properly moved “qwert” part and memcpy() failed because it doesn’t support overlapping buffers (it basically doubled the “r” letter due to described optimization). We will add a “environment data” buffer, holding information like ambient tint and fog settings. The source code analyzer can handle these, but the procedure is a bit more complicated. ZDI-20-494 and ZDI-20-496. memcpy from GraphicBuffer to system memory takes much time, about 10s ~ 100ms(and average 20s ~ 30s ms) to copy 640*480*1. memmove () It is used to copy a specified number of bytes from one memory to another or to overlap on same memory. For my case, I have a stream of data coming in via DMA RX which fills a larger buffer, and right now I am using memcpy to concatenate the received data into that buffer. The performance of copying aligned to unaligned or unaligned to aligned buffers is much quicker with your memcpy() however, about 2x faster. On almost any platform memcpy is going to be faster than strcpy when copying the same number of bytes. The problem is that it takes an Array not our current IntPtr. Using a staging buffer. A Simple memcpy() Implementation. You mempcy the data to a sensor_msgs/Image message. Hootsuite and Buffer offer very different ways to respond to comments and messages on social media so you can manage that conversation. 0f, -0. We are going to change the code a bit. . well thank to everybody but i just give up,i just wanted to send an uniform array to the shader,i mean if i have a vec3 for example i can access each index easily from the vertex buffer--> bonetransform = matpush. Copy block of memory Copies the values of num bytes from the location pointed to by source directly to the memory block pointed to by destination. $ numactl -m 0 -N 0 . High performance memcpy gotchas in C#, The memcpy protocol test in C#. h&gt; #include &lt;string. There’re so many ways to display image in Android NDK, with so many Android versions! So I have been using several different dynamic shared libraries for different methods and Android versions, and load a poper one at runtime. ellapsed CPU cycles for fast_memcpy: 111125098666 experiment 6: memcpy with buffer size 256 ellapsed CPU cycles for slow_memcpy: 2330 [-----registers-----] EAX: 0xf7fca000--> 0x0 EDX: 0x804d138--> 0x0 I am using FreeRTOS and writing to a StreamBuffer twice from within the same task. VkBuffer is a handle to a GPU side Vulkan buffer, and VmaAllocation holds the state that the VMA library uses, like the memory that buffer was allocated from, and its size. That takes time. g. Depending on the location of the buffer, users may have to access it with I/O operations or memory load/store operations. 66Ghz). Conclusion. The behavior is undefined if access occurs beyond the end of the dest array. This function doesn't care about the type of data being copied--it simply makes an exact byte-for-byte copy. The gcl_malloc function returns an opaque pointer to a device memory buffer. So better make sure your memcpy and other memory functions are optimized! However, some graphics cards have the ability to specify the address in memory where the buffer used for rendering is Makes sense. strncpy is a strcpy, just that you can’t Obviously this has a lot to do with the size of either allocated buffer, but it's not the same thing. 7. MapInfo of all merged memory blocks in buffer. 4. Example 3 This example applies an encoding procedure to an input string and stores it into a buffer. Due to the ambiguity of the term, use of stack overflow to describe either circumstance is discouraged. This is declared in “string. These define the ordering of data within the matrix type variables within the uniform block. In this case, it's walking around a circle in 50 steps, writing in the top and bottom vertex for that part of the cylinder. It could be your flash chip needs register addresses to be byte wide. Information - use memcpy as it s faster than strcpy and we know. It does not check overflow. OIV. Such mechanisms require code space and buffer memory, both of which are at a premium in a memory-constrained system. (packetbuf + hdrptr) is the address of the buffer entry which stores the first byte of the packet's header. A quick search finds that Buffer. Conclusion. e. 1 M, 0. size ()); The initialization of a buffer is also inconvenient and potentially inefficient. Or, it may mean that you have some bytes in the buffer, but not enough and have to transfer what you have, read the next 512 bytes, then copy the remaining needed bytes to the caller's buffer. It makes no checks, and it can't wrap around like a circular buffer. My argument is that in many ways pointers are already treated like bags of bits by the language, so we should be consistent, and treat them as such throughout. The data strobe buffer includes: a first input/output node; a first driver coupled to the first input/output node, the first driver configured to output a first data strobe signal to the first input/output node during a write operation; and a first receiver coupled to receive a second data strobe signal // We could modify our cached version of our vertex buffer here, or totally regenerate it procedurally or whatever, skys the limit! // instead lets just prove its still valid by drawing it out (badly! really we should also get the triangle index buffer the same way Apparently this is really slow compared to the old memcpy of the C++ C world. ) The data is then streamed from L1 cache through the CPU registers to the target system memory buffer. This means that the oldest entries are the first ones that are read. The memcpy() built-in function copies count bytes from the object pointed to by src to the object pointed to by dest. Overwriting an array with an exact copy of the array will be idempotent from the perspective of the caller after memcpy() completes, but concurrent observers of the array are permitted to see transient ephemeral "garbage" values. if( numBytes > readBytesAvail ) { numBytes = readBytesAvail; } // Simultaneously keep track of how many bytes we've read and our position in the outgoing buffer if(numBytes > _size - _readPtr) { int len = _size-_readPtr; memcpy(dataPtr,_data+_readPtr,len); memcpy(dataPtr+len, _data, numBytes-len); } else { memcpy(dataPtr, _data+_readPtr, numBytes); } _readPtr = (_readPtr + numBytes) % _size; _writeBytesAvail += numBytes; return numBytes; } // Write to the ring buffer. h” header file in C language. Introduction. In the fast path, the nursery will allocate another buffer that is directly behind the minimal JSObject. If memset goes first and loop goes second the memset speedup is 4-5 times again. 7. When the arrays overlap behaviour of this function is undefined, this also returns a pointer to "str1". It is like a safety belt: a safety belt does not prevent car accidents, it just tries to keep you alive while your car is mangled into oblivion. exe: 0xC0000005: Access violation reading location 0xd41dddcc. Syntax. Here are the results: implementing the C memcpy functionality in Ada? I have a variety of record structures, that need to be passed to an interface buffer that is being written to another machine. > memcpy() which copies from the end of the buffer to the start, rather > than the start to the end? > memmove for possibly overlapping copies. First, we have to allocate some memory for that buffer: #define BUFFER_LENGTH 256 static uint8_t tx_buffer[BUFFER_LENGTH]; Note that you can't use any arbitrary size; EFR32 creates a FIFO ring buffer on this memory area, and it can only handle buffer sizes of power of 2 between 64 and 4096 (i. For memcpy in that case, you will want to wait as long as possible so the data will be as fresh as possible in the cache. You can rate examples to help us improve the quality of examples. BlockCopy seems to be the same style of function as memCpy. net's On Breaking Things and Glibc Change Exposing bugs ; and the discussion of Adobe I noticed that memcpy is faster on Linux than Windows on the same hardware. Most C programmers will instantly recognize the idioms for memcpy(): // OK: copy data into a buffer char dest[64]; memcpy(dest, src, sizeof(dest)); // OK: as above, but using a struct complex_t foo; memcpy(&foo, &bar, sizeof(foo)); Likewise with memset(): // OK: clear a buffer char buf[128]; memset(buf, 0, sizeof(buf)); Don’t implement this protocol yourself; instead, use the following MTLDevice methods to create MTLBuffer objects: makeBuffer (length:options:) creates a MTLBuffer object with a new storage allocation. 1 of the C Standard states, "There may be unnamed padding within a structure object, but not at its beginning" [ISO/IEC 9899:2011]. But in other to do that, the structure Inside the union must be of the same type as the global structure. A length check happens to make sure it is not bigger than the allocated buffer. - sim commented on July 15th 19 at 21:57 memcpy is copying a memory block, that can consist of any data. Either way, anytime I call memcpy() from within a function and the input size is not very clearly defined in that scope Fortify throws a 'Critical Error'. - I want to copy it rather than just "cast" it, so I can continue to use the buffer for further readings - I could copy it long-hand, by going through each element of the struct and assigning the right bytes (or pairs of bytes, if the element is an int) but that requires a separate procedure for each structure, and is a pain to maintain. And if you have to move so much, you're doing something wrong and optimizing your concept would bring more benefits than any optimized memcpy code. The serial buffer is a circular buffer. h> #include <string. 1) Copies count characters from the object pointed to by src to the object pointed to by dest. 3 consecutive float as the coordinates + 1 float for SSE padding in the case of PointXYZ), there should be no problem. The buffer storage is provided to the function block via the input variables pBuffer / cbBuffer. 5f, 1. x (Windows 10 is not affected because it uses WDDM2), device is discrete AMD GPU, and memory type is the special 256 MiB pool of DEVICE_LOCAL + HOST_VISIBLE memory (selected when you use VMA_MEMORY_USAGE_CPU_TO_GPU), then whenever a memory block pmem_memmove (), pmem_memcpy () and pmem_memset () functions provide the same memory copying as their namesakes memmove (3), memcpy (3) and memset (3), and ensure that the result has been flushed to persistence before returning (unless PMEM_F_MEM_NOFLUSH flag was used). At first,everything is ok. The only problem i'm facing now is that if i try to draw another image with alpha over the first one, it draws it opaque. Buffer Manipulation _memccpy memcpy, wmemcpy memmove may be used to set the effective type of an object obtained by an allocation function. The underlying type of the objects pointed to by both the source and destination pointers are irrelevant for this function; The result is a binary copy of the data. familiar_name) + 1; memcpy(databuff + bufflen, user. Buffer overflow vulnerability. BlockCopy behavior/output, to match the MemCpy behaviour/output. I furthermore tested handwritten for-loops accessing 8,16,32 and 64-bit elements at a time and those got similar performance. memmove() is similar to memcpy() as it also copies data from a source to destination. text:74257509 call memcpy ; Nsec3RecordRead+0xD9. If the source and destination addresses overlap then copy from the end (backward copy). Thanks, I tried several configurations of the memcpy(), with or without indexes and pre incremented pointers and I'm only getting about 65% of the performance of the compiler built-in version. It does not work the opposite way. Declaration. 30319. Copies bytes between buffers. Syntax void *memcpy( void *dest, const void *src, size_t count ); wchar_t *wmemcpy( wchar_t *dest, const wchar_t *src, size_t count ); Parameters. BlockCopy is running on Win7/x64 and the platform target (Visual Studio Build Option) is set to x86. This means that instead of the return pointer for foo being overwritten, the return pointer for memcpy will be overwritten. void* Buffer; ///< Pointer to image buffer @ above buffer data is made by inside of library which is c++. A copy routine built along these lines using READ_REGISTER_BUFFER_ULONG could be used too: void memcpy_from_BUFFER(void *src, void *dest, size_t len) When loop and memset operate on the same array and loop is first in order (memset follows the loop), memset can be 10 times faster (probably due to cache usage). Each thread calls cuda::memcpy_async one or more times to submit an asynchronous copy operation for elements within a batch and then all threads wait for the submitted copy operations to complete. There's nothing forcing those two things to always be equal. 1020 M. 0980 M and the concentration of HCOO – would change from 0. Release Results $ . In my CAN driver executed by xgate,i use memcpy() to copy data to buffer. C / C++ Forums on Bytes. The behavior is undefined if access occurs beyond the end of the dest array. The return value is the number of bytes you have transferred to the caller's buffer. The first memcpy handles data copy till buffer end and second one handles data copy from buffer beginning (wrap-around). Both tests are running on the same Windows 7 OS x64, same machine Intel Core I5 750 (2. */ memcpy (&buf[5], "abcde", n); /* Destination is known and it is known at compile time there will be overflow. len is the length of entry. You need to malloc() a as well as b. // While on other platforms it behaves like memmove and handles overlapping buffers. calcsize() called on non-NULL format values. Memory Copy. ) inside the for loop. // Before this part is same upto step 3 except png_init_io function MEMORY_WRITER_STATE memory_writer_state; memory_writer_state. e. Buffer overflow is a vulnerability in low level codes of C and C++. If the source and destination addresses are the same then left as it is. It returns a pointer to the destination. When you publish the sensor_msgs/Image, ROS serializes its fields into a buffer for inter-process transport - another memcpy. If an overflow is anticipated, the function shall abort and the program calling it shall exit. It is usually more efficient than std::strcpy, which must scan the data it copies or std::memmove, which must take precautions to handle overlapping inputs. This paper relates to P1726: Pointer lifetime-end zap and provenance, too. However strcpy is not recommended because it does not check buffer size and can cause buffer overflow (however in this particular case it would be safe to use). This happens when the size argument of a memcpy function is accidentally or maliciously enlarged so that more information than necessary or allowed is copied memcpy, memcpy_s. The CLR used for this is the Runtime v4. At the receiving end, declare same struct and a buffer of chars it's size. For memcpy(), the source characters may be overlaid if copying takes place between objects that overlap. After pchang's help, we force the preview buffer from camera to be "cached". Type()) if err != nil { return nil, err } // TODO(ashankar): Remove the bytes. (PACKETBUF_HDR_SIZE - hdrptr) is the actual size of the header. The next step we make note that each triangle is typically re-using many elements of the previous triangle - so don't repeat yourself! This data is then passed as argument 2 to doMemCpy(), which in turn sends the data to argument 2 of memcpy(). g. buffer_t * buffer_slice(buffer_t *buf, size_t from, ssize_t to) { size_t len = strlen(buf->data); if (to < from) return NULL; // bad range if (to < 0) to = len - ~to; // relative to end if (to > len) to = len; // cap end size_t n = to - from; buffer_t *self = buffer_new_with_size(n); memcpy(self->data, buf->data + from, n); return self; } Perhaps, and in some cases memcpy_s can definitely provide peace of mind, but in a large number of invocations of memcpy (most?), the buffer size is either constant or always equal to the source size (because the buffer was just allocated with that size), and it would feel nannying to me to be required to write the same size twice. The memcpy () function operates as efficiently as possible on memory areas. The code must be rewritten in the following way: memcpy(&(*m_data)[0], buf, len); An alternative version: memcpy(m_data->data(), buf, len); This error also appears when using memset/memcpy with structures whose fields are non-PDS objects. Solving for the pH of the buffer solution if 0. If destBuf has not already been defined, it is created as a buffer. That does not seem to be the case here. 05 M, or anything in between. 5 M, 0. If the length is not supplied, the entire contents of srcBuf are copied to d estBuf. memcpy_s's buffer size argument should be used for the actual size of the destination buffer. makeBuffer (bytes:length:options:) creates a MTLBuffer object by copying data from an existing storage allocation into a new allocation. an exception is thrown, usually implying immediate thread termination). If the objects overlap (which is a violation of the restrict contract) (since C99), the behavior is undefined. The memcpy function copies n characters from the source object to the destination object. What that piece of code up is doing is putting NULL values in the other cells of the buffer, not zero. In the latest source code /tests/dirparsertest. // This behavioral difference is unfortunate but intentional because // 1. This is a major type of buffer over-read vulnerabilities and possibly the most damage-causing (due to Heartbleed) one. For example, with the right conditions (aligned memory), it can copy 32 or 64 bits at a time for most of the loop, and the remaining through copies of 8 bits (not specifically in that order). Somehow the packets are stomping on each other. Specifically, memcpy () copies n bytes from memory area s2 to s1. Subclause 6. and copying data into the buffer (e. When dealing with 3D calculations, large buffers of textures, audio synthesizing or whatever requires a memcpy copies count bytes from src to dest; wmemcpy copies count wide characters (two bytes). If you restart Vim, it will re-assign numbers sequentially to all the buffers in the buffer list (assuming you have properly set 'viminfo' to save and Create a new buffer with the same properties as the current one. Copying to the serial buffer is not the same as memcpy(), no. You can rate examples to help us improve the quality of examples. The result is an over 50% improvement in the overall memcpy rate when compares to Example 3, and a more than 250% improvement when compared to Example 1. There are some exceptions though, when you should consider mapping memory only for a short period of time: When operating system is Windows 7 or 8. 64, 908 and 1024 bytes all the same. In the C Programming Language, the memcpy function copies n characters from the object pointed to by s2 into the object pointed to by s1. This clearly shows that reads from VRAM using memcpy are ~766x slower than memcpy reads from cacheable system memory and even non-cacheable system memory is ~91x slower than cacheable system memory. Because the buffer distance is a constant, all features are buffered to the same width. The resulting call to memcpy() can then copy the contents of memory past the end of the packet data and the packet itself, potentially exposing sensitive data to the attacker. Now that we understand how the ring buffer works, it must be integrated into the UART driver. The buffer operates as a FIFO; data records are read from it in the same sequence in which they were first written into the ring buffer. Buffer and endcode directly into // C Welcome to Part 2 of the Exploit Research Megaprimer. In the process one of the functions is throwing errors while copying the data from the buffer on board to local system buffer. I am wanting the Buffer. If the programmer knows both sizes, a good program will already check, and a bad program will just pass the same size as both lengths, or define a lazy workaround: #define memcpy (dst, src, len) memcpy_s (dst, len, src, len) The 'memcpy' function copies data to the object pointed to by 'm_data' instead of the container. Fills a buffer with zero bytes, deprecated by memset: memccpy: SVID, POSIX copies up to specified number of bytes between two memory areas, which must not overlap, stopping when a given byte is found. You want the same interface to ease the drop-in replacement of one with the other. . memcpy() leads to problems when source and destination addresses overlap as memcpy() simply copies data one by one from one location to another. We first typecast src and dst to char* pointers, since we cannot de-reference a void* pointer. First, there is no need for any complex buffer management mechanisms to be implemented. If local buffer overlapped with the memory map, memcpy() (as opposed to memmove()) could fill the target area with some of the first or last bytes of source. Memcpy Same as the value of struct. BlockCopy, which is working on managed array but is working with a byte size block copy. DXXXX: Zap the Zap: Pointers should just be bags of bits. Allocating Memory For A Buffer Object In Device Memory. I changed the function interface to match memmove / memcpy. There is no way to do that with vector<char>. MEMCPY, copying full frame buffer in one call: 90: Streaming load & store 64 byte cache lines in one loop, copying full frame buffer: 745: Streaming load & store, via 4K buffer, load pitch, store frame width: 945: Streaming load, MOVDQA store, via 4K buffer, load pitch, store frame width: 985 To me, there is a possible buffer-overflow if the input is shorter than BUFFER_LENGTH and is NOT null-terminated. Do you make any null checks on the pointers before trying to copy? I would check the following? 1) Is the size that you are passing to memcpy correct (i. The vertex buffer we have right now works correctly, but the memory type that allows us to access it from the CPU may not be the most optimal memory type for the graphics card itself to read from. PR Details Swaps native memcpy with dotnet's Buffer. This statement makes no sense. size_t buffer_copy (mutable_buffer dest, const_buffer source, size_t max_copy) {const size_t n_copy = min (max_copy, min (dest. memcpy is also often used to copy smaller buffers into larger ones, and accidentally copying the uninitialized (or carefully crafted by some exploit) data that comes after the source object can be just as dangerous. memcpy() doesn't support overlapping memory. If the objects overlap(which is a violation of the restrictcontract)(since C99), the behavior is undefined. Below is a sketch which accomplishes the same task as the three methods posted above using a call to memcpy(). Both objects are interpreted as arrays of unsignedchar. I found it is resulted from the GraphicBuffer callbacked from camera preview is uncached. You can now simply memcpy the vertex data to the mapped memory and unmap it again using vkUnmapMemory. One way : C++. 0. The function memcpy () is used to copy a memory block from one location to another. (End of Update) I’m just now wrapping my brain around this, trying to figure out how this approach could be used to avoid using memcpy() and pointers. Note that, this function should be used only for outgoing packet. familiar_name) + 1); bufflen += strlen(user. Dpends if you want a shallow copy (two pointers pointing to the same data) or a deep copy (two versions of the same data). The syntax for the memcpy function in the C Language is: void *memcpy(void *s1, const void *s2, size_t n); float data[] = { 0. More secure versions of these functions are available; see memcpy_s, wmemcpy_s. But iff your data layout is the same as the point cloud layout (e. It just does 4-byte at a time copies when the length, source and destination allows it (which in x86-case is as long as remaining length > 4 bytes). memcpy() just copies one block of memory directly over another. I did a time profile base on the size of data and anything beyond 64K, memcpy (buffer, source, size) simply dominates this process. Don't move the data, move the pointers to it. size (), source. In the slow path, the Typed Array Object stores the inline data in the allocated space that fits the AllocKind. In memcpy, we need to pass the address of source and destination buffer and the number of bytes (n) which you want to copy. Fills info with the Gst. familiar_name) + strlen(user. So, I assume that pointer value in struct causes this problem. h> int main () { char str1 []= "This is a line. And as we know, barring exceptional factors, memcpy / memmove code which demonstrates either a consistent forward--or reverse--copy direction is eligible to allow, with full correctness, exactly one out of the two possible cases of source/destination overlap. But we don’t need to have 1 descriptor point to 1 buffer. std::memcpy is meant to be the fastest library routine for memory-to-memory copy. FIGURE 4 - Disassembly showing population of copy size argument. My mcu is MC9S12X. I’m trying to bench memccpy with this code The buffer protocol is defined in PEP 3118, which explains the C API used to provide this protocol to various types, such as strings. One is source and another is destination pointed by the pointer. but if the element-count is 20, half way through a 2^20 buffer. This happens quite frequently in the case of arrays. There will be a warning and __memcpy_chk call that will abort the program at runtime. When buffer is writable but the memory isn't, a writable copy will automatically be created and returned. dll) in Camera. The best way to do this would be to modify the union like this: However, continuing to the next one (256), we see the same exact issue: gdb-peda $ c Continuing. Got your point. h&g memcpy a int to a char buffer ?. 1000 M to 0. With that said if you just want a new buffer with the same data, it would seem easier to just use the gst_buffer_copy() function. The answer to that thread seems to indicate that the only way for a transaction of data width different from the interface width to be done is by using an intermediate local buffer, but that The interface __memcpy_chk() shall function in the same way as the interface memcpy(), except that __memcpy_chk() shall check for buffer overflow before computing a result. What I have discovered is that after memcpy the contents of the buffer are not always the same as what is actually stored in the SAM flash memory. surname, strlen(user. The caller should then write some data into the memory region and release it ASAP, indicating the number of bytes actually written: memcpy (buffer, "hello", 6); MojoResult result = MojoEndWriteData (producer, 6, nullptr); You need to copy the back buffer to the front buffer every time the buffer needs to be swapped (in games with a frame-rate of 30, 30 times each second). WRITE, buffer should be writable (as returned from gst_buffer_is_writable (not introspectable)). The reason for keeping bcopy separate is that, once we have ifunc support for powerpc64, we'll be ready to just replace the functions in this file with the resolver functions for memcpy, memmove and bcopy. RBE = ring buffer end address (first byte which may not be consumed) RBS = ring buffer start address (first byte which MAY be consumed) The principle: CP never equals LP: there's always a 1 byte gap. Memcpy parameter overlap in Google Snappy library 1. These are the top rated real world C++ (Cpp) examples of memcpy_P extracted from open source projects. Then I read the data using direct assignment, as in, while ( Count--) *(pulBuffer++) = *(pFifoAddress++)//reading from the FIFO to IBM Docs Vladimir, my code performs essentially loads and stores: it is a sort of multicast memcpy where the same source buffer is replicated over several destination buffers. I then tried making a WhatsApp call with this setup. C++ (Cpp) memcpy_s - 30 examples found. (I guess the error message will be a different one, perhaps Invalid Direction if this direction parameter is the problem). CVE-2018-7437: An issue was discovered in FreeXL before 1. Here are two examples of how a phosphate buffer can be calculated, as described by Clive Dennison, Department of Biochemistry at the University of Natal, South Africa. , root mean square (RMS), or peak-to-peak displacement. I'm gaining some performance improvement but it results in wrong output buffer values. The best case is to use ping-pong buffers so you can be transferring one buffer's data while processing on the first buffer's data. passing the actual buffer size gives a *hint* to the heap manager (especially LFH) to find the header for checking. To get the better performance i have used the openmp construct outside of the for loop. Transfer queue. , 64, 128, 256, 512, 1024, 2048, or 4096). I will try __rdtscp() or QueryPerformanceCounter(), thanks for the suggestion. 99 MB/s Results 5711. MapFlags. The message which I am getting is Unhandled exception at 0x1026ef58 (msvcr90d. 59867 The exact same test on both configurations shows that the single socket configuration is ~60% faster. AllocatedBuffer is going to hold the buffer we allocate, alongside its allocation data. See Built-in functions for information about the use of built-in functions. Linux based EP now copies with memcpy() to the same RC's allocated buffer! Description The C library function void *memcpy (void *dest, const void *src, size_t n) copies n characters from memory area src to memory area dest. strcpy and strncpy does only copy strings that end with a zero. It shouldn't be variable based on user input / program flow, and can likely be determined at compile time. memcpy() usually uses the widest possible moves to do the copy. 3) Remove duplicate triangles (triangles which occur more than once in the same index buffer, even if in different orders) 4) Order the vertexes such that they appear in the same order as the index buffer itself. What is "warning: argument to ‘sizeof’ in ‘memcpy’ call is the same expression as the source; did you mean to dereference it?" really about in a generic, non-code-specific sense? P2188R1: Zap the Zap: Pointers are sometimes just bags of bits. Let’s have a look: [code]void * memcpy(void * dst, const void * src, size_t len) { char * p = (char *)dst; while (len > 0) { *p++ = *((char *)src++); --len . */ Perhaps a new ruby string creation function would be useful? Something like An additional method to complete the copy is a standard function which the Arduino environment includes, it is memcpy(). It is also possible that writes to the buffer are not visible in the mapped memory yet. If you really want to "go for it", you could code lines 100 to 120 in assembler, using LDM and STM with 4 registers to hold 4 32-bit values at once. func NewTensor(value interface{}) (*Tensor, error) { val := reflect. (In reply to Yves Younan from comment #2) > Joseph, the bug is in memcpy, not malloc. Here that's not the idea. memcpy same buffer