Windows error 0x7FFFFFFF, 2147483647

Performance difference between Windows and Linux using Intel compiler: looking at the assembly

I am running a program on both Windows and Linux (x86-64). It has been compiled with the same compiler (Intel Parallel Studio XE 2017) with the same options, and the Windows version is 3 times faster than the Linux one. The culprit is a call to std::erf which is resolved [...] read more

Efficient integer floor function in C++

I want to define an efficient integer floor function, i.e. a conversion from float or double that performs truncation towards minus infinity. We can assume that the values are such that no integer overflow occurs. So far I have a few options * casting to int; this requires special handling [...] read more

Why is Int32's maximum value 0x7FFFFFFF?

I saw in MSDN documents that the maximum value of Int32 is 2,147,483,647, hexadecimal 0x7FFFFFFF. I think, if it's Int32 it should store 32-bit integer values that finally should be 4,294,967,295 and hexadecimal 0xFFFFFFFF. My question is why Int32 stores 31-bit integer values? read more

C macro to create a bit mask -- possible? And have I found a GCC bug?

I am somewhat curious about creating a macro to generate a bit mask for a device register, up to 64bits. Such that BIT_MASK(31) produces 0xffffffff. However, several C examples do not work as thought, as I get 0x7fffffff instead. It is as-if the compiler is assuming I want signed output, [...] read more

"Simulate" a 32-bit integer overflow in JavaScript

JavaScript can handle the following Math just fine: var result = (20000000 * 48271) % 0x7FFFFFFF; But in some programming languages, that first int*int multiplication results in a value too large to hold in a standard 32 bit integer. Is there any way to "simulate" this in JavaScript, and see [...] read more

Javascript function rewritten in Java gives different results

There is this Javascript function that I'm trying to rewrite in Java: function normalizeHash(encondindRound2) { if (encondindRound2 < 0) { encondindRound2 = (encondindRound2 & 0x7fffffff) + 0x80000000; } return encondindRound2 % 1E6; } My Java adaptation: public long normalizeHash(long encondindRound2) { if (encondindRound2 < 0) { encondindRound2 = (((int) encondindRound2) [...] read more

Clang 8 with MinGW-w64: How do I use address- & UB sanitizers?

Clang 8 release notes have this promising line: > * Allow using Address Sanitizer and Undefined Behaviour Sanitizer on MinGW. However, I unable to figure out how to use those properly. I'm using Clang 8.0.0 with MSYS2 MinGW GCC. Exact details are at the bottom of the question. I'm trying [...] read more

What is the value of ~0 in C?

I want to get the values of INT_MIN and INT_MAX. I've tried ~0 and ~0 >> 1 since the leftmost bit is a sign bit but I got -1 for both of them. It's so confused that why ~0 doesn't turn out to be 0xffffffff and ~0 >> 1 to [...] read more

QSpinBox with Unsigned Int for Hex Input

There are a variety of questions written here about QSpinBox's limitation of using an int as its datatype. Often people want to display larger numbers. In my case, I want to be able to show an unsigned 32bit integer in hexadecimal. This means I'd like my range to be [0x0, [...] read more

Maximum Product of Three Numbers

I am trying to solve this problem from leetcode, going to copy here for convenience Given an integer array, find three numbers whose product is maximum and output the maximum product. Example 1: Input: [1,2,3] Output: 6 Example 2: Input: [1,2,3,4] Output: 24 Note: The length of the given array [...] read more

JPanel in puzzle game not updating

I have a simple puzzle game. There is an image consisting of 16 tiles (randomly placed). Images are stored in an array and when game is launched they're added to main JPanel. alt text [https://i.stack.imgur.com/2JP85.gif] Game works in this way : Each image has atributes 'place' and 'number'. 'Place' is [...] read more

"Anomaly" in signed integer in C

I'm currently writing a lecture on ARM optimization, specifically on vector machines such as NEON as the final target. And since vector machines don't fare well with if-else slaloms, I'm trying to demonstrate how to get rid of them by bit-hacking. I picked the "saturating absolute" function as an example [...] read more

why floor, ceil implementation return x + x when x is NaN or inf?

I'm reading IEEE-754 math functions' implementation in glibc. Here is floor implementation. float __floorf(float x) { int32_t i0,j0; uint32_t i; GET_FLOAT_WORD(i0,x); j0 = ((i0>>23)&0xff)-0x7f; if(j0<23) { if(j0<0) { /* return 0*sign(x) if |x|<1 */ if(i0>=0) {i0=0;} else if((i0&0x7fffffff)!=0) { i0=0xbf800000;} } else { i = (0x007fffff)>>j0; if((i0&i)==0) return x; /* [...] read more

Assembly enter protected mode and jump back to real mode

I am developing a toy OS in assembly and I have a problem when switching from protected mode back to real mode. I have successfully switched to protected mode, called the kernel that writes text to [0xb8000] video memory, returned to the caller and (probably) switched back to real mode. [...] read more

How do I prevent ld from adding .note.gnu.property?

I've got a toy x86 assembly program that I'm writing and compiling with as and ld: .text .global _start _start: movq $1, %rax movq $0x7FFFFFFF, %rbx L1: cmp %rbx, %rax je L2 addq $1, %rax jmp L1 L2: movq %rax, %rbx movq $1, %rax int $0x80 And then to build: [...] read more

i dont understand what is 0x7fffffff mean. is there any other way to code getHashValue method?

public int getHashValue(K key){ return (key.hashCode() & 0x7fffffff) % size; } i dont understand what is 0x7fffffff mean. is there any other way to code getHasValue method? read more

Why is the (signed) cast necessary only sometimes to represent the minimum integer (32 bit system)?

I recently found this code: for (i = 0; i < k; i ++) { b[i] = 0x80000000; // min integer s[i] = 0; } the above is part of this program: int _max(int a, int b) { return a > b ? a : b; } int all_profits(int* prices, [...] read more

32-bit / 16-bit signed integer division without 32-bit registers?

I'm trying to divide a 32-bit signed integer by a 16-bit signed integer to get a signed 32-bit quotient and 16-bit remainder. I'm targeting a 286 with no fpu. I've already written code in the past to do 32-bit unsigned division: DIV32 PROC ;DIVIDES A 32-BIT VALUE BY A 16-BIT [...] read more

**polygon.setfillcolor(Color)** not working for google map v2

I am adding a Polygon into Google Map v2 like this: for (int index = coordinats.size()-1; index >= 0; index--) { polygonOptions.add( new LatLng(latCoordinats.get(index), lngCoordinats.get(index))); } polygonOptions.strokeColor(0x7FFFFFFF); polygonOptions.strokeWidth((float) 5); polygonOptions.fillColor(Color.BLUE); polygon= mMap.addPolygon(polygonOptions); > polygonOptions.fillColor(Color.BLUE); is not working for me... What am i missing? read more

How can I diagnose and resolve a crash on WCSession sendMessage(_:replyHandler:errorHandler:)?

I'm building a watchOS app that needs to periodically request information from a companion iPhone app to refresh a complication. To achieve this, I have a WKApplicationRefreshBackgroundTask that runs periodically. It uses sendMessage(_:replyHandler:errorHandler:) from WatchConnectivity to request the information from the iPhone app, process the reply, and update the complication. [...] read more

Hashing in java hash table

I've been digging in hash table source code. And found how hashing occurs: int index = (hash & 0x7FFFFFFF) % tab.length; I don't understand why bitwise AND used here? if we turn 0x7FFFFFFF into binary we get = 111 1111 1111 1111 1111 1111 1111 1111‬ As I know bitwise [...] read more

Writing to /dev/mem on a 32-bit system

I'm currently working on a 32-bit architecture Xilinx SoC-FPGA board. A small C-program has to write some data into a specific physical memory region starting at the address 0x80000000. To access the physical memory, /dev/mem is used. The program opens the device file and sets the position indicator to the [...] read more

Why/how does gcc compile the undefined behaviour in this signed-overflow test so it works on x86 but not ARM64?

I was self-studying CSAPP and got a strange result when I ran into a strange issue during the run of a assertion test. I'm not sure what to start this question with, so let me get the code first (file name visible in comments): // File: 2.30.c // Author: iBug [...] read more

Recreating JS bitwise integer handling in Python3

I need to translate a hash function from JavaScript to Python. The function is as follows: function getIndex(string) { var length = 27; string = string.toLowerCase(); var hash = 0; for (var i = 0; i < string.length; i++) { hash = string.charCodeAt(i) + (hash << 6) + (hash << [...] read more

How >, >=, <, <= are implemented using only bitwise operations

I have seen this and this, from which at least the > is obtained as: int isGt(int a, int b) { int diff = a ^ b; diff |= diff >> 1; diff |= diff >> 2; diff |= diff >> 4; diff |= diff >> 8; diff |= diff [...] read more

What is special in gcc about a loop that iterates 999 times?

BACKGROUND Using gcc 7.2 I found that the compiler output changes when a loop iterates 999 times. In particular this program (link to compiler explorer using gcc 7.2): int f() { int i=0x7fffffff-998; while (i+1>i) i++; return i; } compiles (using -O3 -fwrapv) to: f(): mov eax, 2147483647 ret but, [...] read more

Linux hexdump offset strangeness

I'm trying to hexdump some bytes near the end of a 1 TB hard disk drive. First, let's look near the beginning, 0x1000: % hexdump -n 16 -s 0x1000 -C /dev/sda2 00001000 08 70 b5 7c 20 4c 56 4d 32 20 78 5b 35 41 25 72 |.p.| LVM2 [...] read more

qemu-img: Could not open $FILE

I received a single-file VMDK from a vendor that has a virtual appliance for a particular product I'm interested in evaluating. We run a KVM solution (Proxmox) so I tried converting the file but on that system qemu-img blows up. (I was able to convert (multipart) VMDK files from bitnami [...] read more

Ubuntu 11.04 Server Crashing - failed command: READ FPDMA QUEUED

I have a new Ubuntu Server (11.04) that keeps crashing, especially during heavy disk I/O (like making a backup). It's drives are configures as a RAID 10 with 4 1TB Western Digital Caviar Black Hard Drives. The message I'm seeing via /proc/kmsg when it crashes is, "failed command: READ FPDMA [...] read more

How can I correctly check that integer underflow and overflow will not happen before subtraction?

I'm currently working on a safe integer library for C++. I've come across some issues when implementing subtraction. Here's what I start with: #include <limits> #include <stdexcept> template<typename I> class safe_int { I val; public: typedef I value_type; static constexpr I max = std::numeric_limits<I>::max(); static constexpr I min = std::numeric_limits<I>::min(); [...] read more

Why is 0x1 interpreted as less than 0xC0000000?

I'm learning about binary representation of integers and tried to write a function that returns an int multiplied by 2 using saturation. The thought process is if the value overflows positively the function returns INT_MAX, and conversely if it overflows negatively it returns INT_MIN. In all other cases the binary [...] read more

What do the parameters of stb_png_to_mem mean?

I am using the stb libraries to load textures on the fly for OpenGL. I'm trying to use the function from stb_image_write.h. I cannot find any documentation on how to properly use the function stbi_write_png_to_mem my code looks like the following #ifndef STB_IMAGE_WRITE_IMPLEMENTATION #define STB_IMAGE_WRITE_IMPLEMENTATION #include <stb/stb_image_write.h> int main( ) [...] read more

INT_FAST16_MAX does not reflect type size in MSVC 2010?

C99 defines int_fast16_t as an "integer types being usually fastest having at least the specified width", and Microsoft define it as a 32-bit integer in MSVC 2010: typedef char int_fast8_t; typedef int int_fast16_t; typedef int int_fast32_t; typedef unsigned char uint_fast8_t; typedef unsigned int uint_fast16_t; typedef unsigned int uint_fast32_t; Yet, Microsoft [...] read more

What is the error in code? This seems to run fine in my IDE but doesn't work on online terminal

I'm trying to solve the leetcode question 8String to integer(atoi). But I'm getting a Runtime Error. TypeError: 'str' object is not callable Line 9 in myAtoi (Solution.py) I understand it's due to a string object getting called but can't seem to figure out what to fix. class Solution: def myAtoi(self, [...] read more

Separate object fields into two files by serializing DataContract

I an using DataContractSerializer and i want to separate data of same object into multiple files. [DataContract] public class TestObj { [DataMember] protected double field1 = 0.0; [DataMember] protected double field2 = 0.0; } Specifically I want to save field1 in one XML file and field2 in a different XML [...] read more

I'm using std::bitset and trying to create two arrays std::bitset with size 100,000,000,000

I am using std::bitset and I try to create two arrays std::bitset with size 100,000,000,000. As a result, program fills only 298 MB of my RAM but must to fill ~24 GB. I have 32 GB RAM and now 26 GB are free. When I build my code for x86, [...] read more

2D perlin noise in C

I followed this tutorial. When I implement it in my code (Raytracing), and apply it on a sphere, I get a uni-color sphere, with one stripe of darker pixel on it. When I change the random float generator, I got the basic linear noise, which isn't my goal. Can you [...] read more

printf and gcc -O option change return value

i'm trying to understand how gcc -O option and printf can change return value. in the code below isTmax is my function that return 1 if the input is the largest int value. int isTmax(int x); int main(void) { printf("%d\n", isTmax(0x7fffffff)); } int isTmax(int x) { int temp = x [...] read more

My perlin noise looks like wrong, almost like grey t-shirt material (heather). Why?

I tried a quick and dirty translation of the code here. However, my version outputs noise comparable to grey t-shirt material, or heather if it please you: #include <fstream> #include "perlin.h" double Perlin::cos_Interp(double a, double b, double x) { ft = x * 3.1415927; f = (1 - cos(ft)) * [...] read more

Perlin Noise 2D: turning static into clouds

I am trying to wrap my head around Perlin noise. This article has helped and I have been trying to recreate the cloud type images that it provides. My noise code is as follows: #include "terrain_generator.hpp" using namespace std; #define PI 3.1415927; float noise(int x, int y) { int n [...] read more

gcc takes much memory to compile c++ file with very large object on stack

I have a c++ file which uses a std::bitset<size>. When compiling using gcc on windows subsystem linux, if size = 1000000000 (1Gbit) cause about 1.6GB compile-time memory using, size = 10000000000 (10Gbit) cause about ~6GB memory and ~15GB virtual memory (my PC has 8GB memory in total). The memory is [...] read more

How to fix "Dispatcher has no subscribers" error for a simple message producer?

I'm trying to create a simple JMS producer using Spring Integration. Can any one help me to explain why I'm getting "Dispatcher has no subscribers" error? I'm using ActiveMQ locally and based on my ActiveMQ log, both queue and session are created when I run my test application. But there [...] read more

Scikit - SGDRegressor doesn't fit

Hello I am trying to fit a small set of data using scilearn. import numpy as np from sklearn import linear_model, model_selection X = np.array([[86.5999984741211, 9.10000038146973, 14.3000001907349,1], [66.9000015258789, 17.3999996185303, 11.5,1], [66.3000030517578, 20 , 10.6999998092651,1], [78.6999969482422, 15.3999996185303, 12.1000003814697,1], [76.1999969482422, 18.2000007629395, 12.5,1], [84.4000015258789, 9.89999961853027, 12.1000003814697,1], [79.1999969482422, 8.5 , 10.1000003814697,1], [77.5 , 10.1999998092651, [...] read more

Is my SSD failing?

I've started getting these messages intermittently (see below). I got a whole lot of them several days ago, then they stopped. They occurred again last night, and stopped after the last line below. My /dev/sda is a Samsung 850 EVO Series 120GB SSD and is under warranty. It still seems [...] read more

Linux root filesystem on custom hardware

I have a custom-designed SoC implemented on FPGA, based on an ARM-processor clone, on which I am trying to boot Linux (kernel 3.10). I have successfully added support to my custom peripherals (an USART, Interrupt Controller and Timer), allowing me to see the printk messages displayed by the kernel up [...] read more

Can't connect to AWS instance after import with stock Centos7

I am trying to import a Centos7 based VM into Amazon AWS. The VM was created with the Centos7 minimal ISO installed into VirtualBox. Networking in the VM works fine locally before trying to do the import. I am using the EC2 command line tools to do the import: ec2-import-instance [...] read more

CentOS Raid 1 drive fails on raid-check

I have a pair of HP DL320e servers configured identically with two WD Red 6TB drives in a software raid 1 array. The DL320e has an on board raid controller which is disabled in favour of linux software raid. Both machines seem to work fine and the raid arrays look [...] read more

Perlin noise glitch

I have an infinite map generator. It works well with positive coordinates. Positive coordinates generation 1 But on negative coordinates I have this trash:Negative coordinates broken generation2 void generateChunk(int x0, int y0) { Chunk chunk = new Chunk(x0, y0); for(int yTile = 0; yTile < Chunk.CHUNK_SIZE; yTile++) { for(int xTile [...] read more

React and rSocket REQUEST_CHANNEL error with Spring Boot

We have a working demo between React and Spring Boot Data Geode using rSocket for fire & forget, request response and request stream but when we try and use request channel we get error: org.springframework.messaging.MessageDeliveryException: Destination 'quotes' does not support REQUEST_CHANNEL. Supported interaction(s): [REQUEST_STREAM] So far on web it looks [...] read more

Does this code violate One Definition Rule?

Some code in AOSP10 seems to violate ODR: source 1: struct ExtentsParam { void init (const OT::cff1::accelerator_t *_cff) { path_open = false; cff = _cff; bounds.init (); } void start_path () { path_open = true; } void end_path () { path_open = false; } bool is_path_open () const { return [...] read more

Counting 1's and 0's in a bit sequence

These two methods are from Hacker's Delight. I wish to count the number of 0's and 1's in a bit sequence. For example, for the following sequence 00000000000000000011011100111101 , I thought after removing the leading zeros I would get: * 2 Ones * 1 Zero * 3 Ones * 2 [...] read more

What is source of IID 0x7ffffff error in CCES debugger, and how to fix it properly?

I have problems with MDMA transfer on ADSP-SC584. I work in CCES IDE 2.8.3 I take MDMA CrossCore example project ,and do changes towards ARM direction of data flow. So initialisation is the same(MCAPI addresses and SID of interrupt). I have complex problem with it: 1. When i run project [...] read more

Bitshift Causing Overflow When It Shouldn't

When I am bitshifting the max positive 2's complement, shouldn't shifting it 31 bits make an effective 0 because it starts as 0111 1111, etc. I have tried decreasing the shift but I am assuming it's just the computer reading it incorrectly. int main(void) { int x = 0x7FFFFFFF; int [...] read more

How could I optimise this for loop to run fast on PHP. Runs extremely fast on javascript

So I've been porting some code from Javascript to PHP which works now, however, the execution time is very poor. It takes about 26 seconds in PHP whereas in javascript it is extremely fast. I've been able to break it down to the for loop causing the issue. This is [...] read more

Perlin noise value range

I used perlin noise to generate a 2D height map. At first i tried some parameters manually and found a good combination of amplitude, persistence,... for my job. Now that i'm developing the program, i added the feature for user to change the map parameters and make a new map [...] read more

Can I do binary taint analysis?

I want to analyze the following binary. 4005e0: 55 push %rbp 4005e1: 48 89 e5 mov %rsp,%rbp 4005e4: 48 83 ec 10 sub $0x10,%rsp 4005e8: c7 45 fc 09 00 00 00 movl $0x9,-0x4(%rbp) 4005ef: c7 45 f8 00 00 00 00 movl $0x0,-0x8(%rbp) 4005f6: c7 45 f4 00 00 [...] read more

How to check value of variable is between MAX_INT and MIN_INT of 32 bit OS

I understand that all variables are of type strings. How can we check a variable value between MAX_INT(0x7FFFFFFF) and MIN_INT (-0x80000000) of 32 bit OS set var "12334" ...How to check var variable datatype and value range .. read more

How to use base32 in combination with hotp (one time passwords) in python?

for a university exercise I want to develop a simple hotp server-client system in python. In this case the client sends a password and a one time password to the server. The server knows the secret, calculates the current hotp and compares the values it receives. So far, so good. [...] read more

How to upload large files through filestack?

When I try to upload a large file (+5GB) with the client.upload function of filestack-js in nodejs it throws an error: RangeError: File size is greater than possible Buffer: 0x7fffffff bytes I was using this SDK because I read that this allows to upload a large files through chunks but [...] read more

Implementing noise function in python from C code

I want to play around with procedural content generation algorithms, and decided to start with noises (Perlin, value, etc) For that, I want have a generic n-dimensional noise function. For that I wrote a function that returns a noise generation function of the given dimension: small_primes = [1, 83, 97, [...] read more

SQL: Random sampling X% of samples(unique IDs) from duplicated ID table

I am using SQL and obtained the following table: userID| time | location A10 | 20130801| 1000 A10 | 20130802| 1002 A10 | 20130806| 1008 B21 | 20130803| 1000 B21 | 20130801| 1099 C11 | 20130802| 1000 D33 | 20130802| 1002 D33 | 20130806| 1877 E01 | 20130801| 1765 E01 [...] read more

SQL Query for Random 10% with a minimum of 20 rows

I have been tasked with generating a report that will randomly pick 10% of a unique ID, unless 10% is less than 20 items in which case the report would pick 20 random ID's. I have been using NewID to generate the 10%, but that really isn't the best as [...] read more

Reading SMART results for failing disk

I recently started having trouble with my Dell laptop and would appreciate any recommendations on the next steps for my issue. I have portions of the dmesg log below to show the errors I'm getting. My laptop has 6 GB RAM and 1 TB convential hard drive (no SSD) running [...] read more

Input/Output error while playing video

I am using Linux Mint 15. Nowadays I am getting Input/Output error while watching movies. Sometimes when I copy/paste, I get the same error. What should I do? I have a laptop so unable to check inside the machine. If the hard disk is corrupt, how to take the backup [...] read more

need help SolusVM Xen-pv error

I recently use Solusvm and xen and I have a problem with xen-pv there is a xen-pv template by default with the solusvm Centos-5.3-x86 I have created a machine to test it but I have this error : xm create -c vm103.cfg Using config file "./vm103.cfg". Started domain vm103 (id=45) [...] read more

SCSI error: return code = 0x08000002, sense key: Aborted Command

The kernel logs: ata2.00: exception Emask 0x0 SAct 0x7fffffff SErr 0x0 action 0x0 ata2.00: irq_stat 0x40000008 ata2.00: cmd 61/08:f0:6f:5b:97/00:00:00:00:00/40 tag 30 ncq 4096 out res 41/10:01:6f:5b:97/d5:00:00:00:00/40 Emask 0x481 (invalid argument) <F> ata2.00: status: { DRDY ERR } ata2.00: error: { IDNF } ata2.00: configured for UDMA/133 sd 1:0:0:0: SCSI error: [...] read more

python pandas iloc bug or a feature?

This is my function to merge 2 dataframes by matching field values. #allow you to merge (left join) 2 dataframes def levenstein_merge(dfa, dfb, left_on, right_on, limit = 0x7FFFFFFF): #0x7FFFFFFF is a max integer import pandas as pd import Levenshtein as l a = dfa[left_on] b = dfb[right_on] mindst = 0x7FFFFFFF [...] read more

Rounding 64 bit integers to 32 bit integers

I have a function that does rounding operation as shown below. It takes 64bit integer as input and gives 32bit integer as output. While converting, a factor of 0x40000000 is being added to the input. What is the reason behind it? int rounder(long long int in) { INT64 out; if [...] read more

how to print boost multiprecision 128 bit unsigned integer

I want to print integer value that converted from hexadecimal value but i only could print hexadecimal value. #include <iostream> #include <boost/multiprecision/cpp_int.hpp> using namespace boost::multiprecision; cpp_int dsa("0xFFFFFFFFFFFFFFFF"); cpp_int daa("9223372036854775807"); daa = ((daa * 64) + daa); cout << std::hex<<dsa <<std::showbase<< endl; cout <<dsa << endl; cout <<daa << endl; cout [...] read more

How to get the seed according to the MT19937 array in python's random module?

I use the random.seed() to set a seed for random module, for example: >>> import random >>> random.seed(123456) Then i use random.getstate() to get the MT19937 array, it should be 624 32-bit integers: >>> MT = random.getstate()[1][:-1] >>> len(MT) 624 But when i check the value of these 624 numbers, [...] read more

What's wrong with my implementation of 2 Factor Authorization?

I'm trying to implement my own PHP function to generate codes for Google Authenticator. I do it for fun and to learn something new. Here's what I did: function twoFactorAuthorizationCode(string $secretBase32, int $digitsCount): string { $counter = (int) (time() / 30); $secret = Base32::decode($secretBase32); $hash = hash_hmac('sha1', $counter, $secret, true); [...] read more

Printing out DWORD in hex returns 0x7FFFFFFF in win32 c++

I'm currently working on win32 application that uses sha1 hash on strings to generate keys for my map. I want to use the hash as DWORD, so I can compute some calculations between hashes. Since sha1 hash reproduces 160-bit hash values, I created a struct with 5 DWORD (32-bit * [...] read more

arithmetic right shift shifts in 0s when MSB is 1

As an exercise I have to write the following function: multiply x by 2, saturating to Tmin / Tmax if overflow, using only bit-wise and bit-shift operations. Now this is my code: // xor MSB and 2nd MSB. if diferent, we have an overflow and SHOULD get 0xFFFFFFFF. otherwise we [...] read more

Google Authenticator authenticates only the latest "user"

I have been messing with the Google Authentication on PHP for a week right now and I have stumbled upon the issue with multiple "user" authentication. Basically I have downloaded Authentication.php code and using it to generate and verify the codes. <?php class Authenticator { protected $length = 6; public [...] read more

TOTP python to postgreSQL function

I have simple TOTP python code: import sys, time, math, hashlib, hmac, struct, base64 def totp_gen(secret, time_range=30, i=0): tm = int(time.time() / time_range) b = struct.pack(">q", tm + i) hm = hmac.HMAC(secret, b, hashlib.sha1).digest() offset = ord(hm[-1]) & 0x0F truncatedHash = hm[offset:offset + 4] code = struct.unpack(">L", truncatedHash)[0] code &= [...] read more

Get the greater of two numbers with bitwise operations

I have to find the greater of two numbers using bit manipulation. These are the rules for the same: /* * isGreater - if x > y then return 1, else return 0 * Example: isGreater(4,5) = 0, isGreater(5,4) = 1 * Legal ops: ! ~ & ^ | + [...] read more

How to create digital persona FMD from byte[] in Android?

I am able to save FMD to SQLite in Android. However when I am trying to recreate FMD it is not working properly. Saving FMD in database. try { Fmd m_enrollmant_fmd = m_engine.CreateEnrollmentFmd(Fmd.Format.ANSI_378_2004, enrollThread); if (m_success = (m_enrollmant_fmd != null)) { byte[] fingerprintData = m_enrollmant_fmd.getData(); int fingerprintImageHeight = m_enrollmant_fmd.getHeight(); int [...] read more

any docker command gives error: bad symbol table

I installed the docker engine successfully and no error or warning is shown. But after that, whenever I try any docker command, even docker ps, I get this error: runtime: pcdata is -2 and 76 args stack map entries for net/http.(*Transport).dialConn (targetpc=0x55afd17107cb) fatal error: bad symbol table runtime stack: runtime.throw(0x55afd29a0fb2, [...] read more

Debian does not recognise RAM although BIOS does

My debian system seems not to use the full ram which is installed (6GB) in my mini-itx. Here is some output of dmesg, free and dmidecode that might help. In BIOS, I can see both (2GB + 4GB). root@debian-simon:/home/simon# dmesg | grep -i memory [ 0.016839] initial memory mapped: [mem [...] read more

How to keyboard interrupt user32.GetMessageW / user32.SetWinEventHook loop in python?

I can't seem to figure out how to let Ctrl-C interrupt this code. It prints a KeyboardInterrupt exception to the console when you press Ctrl-C but never actually stops the program. How can I make it actually stop? import ctypes import ctypes.wintypes from random import random user32 = ctypes.windll.user32 ole32 [...] read more

Should i store data that need to be cast into variable first? or call Dictionary indexer more than once?

I don't really know how to phrase this well but I confused about performance I have variables that read from the dictionary. but sometimes it can contain null. For example, I have the following: Dictionary<string,object> DataRow = new Dictionary<string,object>(); The previous line is reading Row from database Table and fetch [...] read more

How to get rid of automatically added library provided by GCC?

I'm compiling main.c file by gcc with enabled sanitizer option. As a result, linker command contains "-lubsan" option in its arguments list. Need to say, that I haven't provided "-lubsan" option to gcc explicitly. Moreover, I'm against of using it. So, the question is: "How to get rid of such [...] read more

structure occurring C2148 when compiling

I have a very large structure, and it seems to be over the limit, what would be the best way to work this out? Error Message: total size of array must not exceed 0x7fffffff bytes structure occurring C2148 when compiling struct listen_instance { struct instance_l instance[2000]; }; I need all [...] read more

Linker error: Multiple definition of a function

I got stuck with this linker error: movecursor.cpp:(.text+0x0): multiple definition of 'random()' beep.cpp:(.text+0x0): first defined here [Error] ld returned 1 exit status What's going on? main.cpp: #include "beep.h" #include "movecursor.h" beep.h: #include <Windows.h> #include <mmsystem.h> DWORD WINAPI BeepSec(LPVOID parameters); beep.cpp: #include "beep.h" #include "random.h" DWORD WINAPI BeepSec(LPVOID parameters) { code... [...] read more

Getting memory location of C++ static variable in Visual Studio Community Debugger

In this simple C++ program: int main() { int n = 0xffffff12; static int q = 0x7fffffff; static int r = 0x10000000; static int R = 0x80000000; return 0; } I can retrieve the actual memory location of variable n in Visual Studio Community debugger by looking at the assembly [...] read more

Manual vectorization/SSE for a complex problem in C++

I want to speed up my algorithm which is an objective function f(x). The problem dimension is 5000. I have already introduced a lot of improvement in the code, but still the calculation time does not fit to my expectation. Most of the dataset are allocated dynamically as (float*)_mm_malloc(N_h*sizeof(float),16). In [...] read more

Install GYM openAI win 10/7

I am new here and following this guide ( https://towardsdatascience.com/how-to-install-openai-gym-in-a-windows-environment-338969e24d30 ) it is not possible to install the open AI, there is always an error when compiling. Tried different versions of anaconda ... python version ... adding compiler to path... Any help would be appreciated! Collecting git+https://github.com/Kojoley/atari-py.gitCloning https://github.com/Kojoley/atari-py.git to c:\users...\appdata\local\temp\pip-req-build-ppc4tb1g [...] read more

TelephoneManager.getAllCellInfo() on Android Emulator not emulated correctly

I am trying to access the CellInfo using TelephoneManager.getAllCellInfo() on an Android Emulator in Android Studio 3.5. Unfortunately it returns always the same values ... CellInfoGsm:{mRegistered=YES mTimeStamp=1111449158860ns mCellConnectionStatus=2147483647 CellIdentityGsm:{ mLac=3 mCid=91 mArfcn=0 mBsic=0x7fffffff mMcc=310 mMnc=260 mAlphaLong= mAlphaShort=} CellSignalStrengthGsm: rssi=-93 ber=0 mTa=2147483647 mLevel=3} ... independent of what network type and signal [...] read more

rand and rands implementation in python

I need an implementation of rand and rands from c++ in python to re-encrypt a bunch of files. But can't seem to get it right. I have a exe that un-encrypts a file into text, I also have to source code, after editing the file I need to encrypt it [...] read more

How to not calculate the hashcode each time value is inserted

I have implemented my own hashmap for study purposes. The key has a string and the value has an object of the class I created. By the way, I want to know if my hashcode method is appropriate, and how to not calculate the hashcode every time a value is [...] read more

type in vhdl corresponds to c-language: "uint32_t" or "unsigned long"

What's the closet data type in VHDL to the classic c-language data type "uint32_t", example: #include "stdint.h" void main() { uint32_t data = 0xFFFFFFFF; } From my understanding, VHDL's "positive" and "natural" types are just subsets of a signed "integer" type and are missing half of the range of c-langauge [...] read more

Divide by zero error from Colt OpenLongObjectHashMap

I saw this exception from Colt OpenLongObjectHashMap: java.lang.ArithmeticException: divide by zero at cern.colt.map.OpenLongObjectHashMap.indexOfKey(Unknown Source) at cern.colt.map.OpenLongObjectHashMap.get(Unknown Source) It's not reproduceable. This is indexOfKey: protected int indexOfKey(long key) { final long tab[] = table; final byte stat[] = state; final int length = tab.length; final int hash = HashFunctions.hash(key) & 0x7FFFFFFF; [...] read more

Work on an array of signed int as if it contained unsigned values

I've inherited some old code that assumes that an int can store values from -231 to 2^31-1, that overflow just wraps around, and that the sign bit is the high-order bit. In other words, that code should have used uint32_t, except that it wasn't. I would like to fix this [...] read more

Limit to size of array type, while there's not yet an instance

I have the following minimal test program: struct Test { double contents [1000000000]; }; int main () { return 0; } It refuses to compile, even though the compiler cannot know wether I will instantiate Test statically, on the stack or on the heap. Why does the compiler complain? Are [...] read more

How to declare a vector of data

I'm doing an Assembly program in ArmV8 that uses multiple constants (in floating point) that are therefore multiplied by the a certain value (also in floating point). For that, I want to develop a loop that just went trought a vector that contained the constants, incrementing the address each time [...] read more

How can I realize a Mars program while Extended (pseudo) instruction or format not permitted is deactivated using the Operation NOT, ADDI and ADDIU?

We have to extend our code. With these operations. Operations [https://i.stack.imgur.com/sWzCa.png] Ziel= destination register in line 14 im getting the error: line 14 column 2: Extended (pseudo) instruction or format not permitted. See Settings. When i comment line 14. (#not $9, $9) i get this errorline 27: Runtime exception at [...] read more

initializing values in Mars 4.5 getting an error

My homework is to initialize values in certain registers. We have to turn off Permit extended (pseudo) instructions and formats. When i try to assemble the code i get this error message for line 7,8,9 Extended (pseudo) instruction or format not permitted. Also is there a way to optimize the [...] read more

what does this 0x7fffffff mean in this function and where can i learn more about it

want to understand this and learn to implement it myself what does 0x7FFFFFF mean where can i look to learn more var secureRandom = function(count) { var rand = new Uint32Array(1) var skip = 0x7fffffff - 0x7fffffff % count var result if (((count - 1) & count) === 0) { [...] read more

Javascript - will this noise function work?

I have the following deterministic noise function which I've been using in a C# and C++ terrain generator for a while: float GridNoise(int x, int z, int seed) { int n = (1619*x + 31337*z + 1013*seed) & 0x7fffffff; n = (n >> 13) ^ n; return 1 - ((n*(n*n*60493 [...] read more

I don't know why ArrayIndexOutOfBoundsException occur in Separate Chaining

I have a problem implementing Separate Chaining Hash. I made hash function as follows and expected to made hash value that is smaller than M. private int hash(K key) { return (key.hashCode() & 0x7fffffff) & M; } I don't know why I'm getting ArrayIndexOutOfException. When I tried to debug, I [...] read more

Interval schedule question about choose the same length of time from each interval

I was struggle with an interval schedule question, the question description as follow: > Description: Lanran has N friends. Every Sunday, Lanran has to play with his friends. The i-th friend can play with Lanran from time a to time b (a and b are included). However, Lanran has to [...] read more

How to make the android.widget.Scroller stop scrolling at a specific item index?

I'm experimenting with this project: https://github.com/maarek/android-wheel/blob/master/wheel-demo/src/kankan/wheel/demo/extended/PasswActivity.java I've been trying to implement the following: 1) set the wheel to land on the number 5 (or any other number) 2) scroll the wheel for about 2 seconds 3) after spinning stops (could be any number of rotations through 0 to 9) the [...] read more

Compute Shader not compiling for specific (valid) code

I'm experiencing weird behavior with conditional loops, branches and updating the UAV with my compute shader (DX11), CS 5.0. I'm t esting a naive raymarching through Sparse Voxel Octtree bricks. The data is linearised by BFS. The structure (LWSVO = Light Weight SVO) looks like: struct LWSVO { int firstChild; [...] read more