clock | 易学教程

How datetime.datetime.now() works without internet connection?

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问题 In python, by importing datetime module and using various functions of class datetime.datetime we could get basic dates with formatting and even date arithmetic for deployment. For example, datetime.datetime.now() will return today's date. But, today when I run this program there was no internet connection in my computer but still it outputs today's date. So, how datetime.datetime.now() could return proper date? Is the algorithm automatically increment after 24 hours time ? 回答1: tl;dr

How to benchmark in Qemu i386 system using rdtsc

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问题 Currently I am trying to measure number of clock cycles taken to complete an operation by two different programming languages on same environment. (without using an OS) Currently I am using Qemu-i386 emulator and using rdtsc to measure the clock cycles. /* Return the number of CPU ticks since boot. */ static inline u64 rdtsc(void) { u32 hi, lo; // asm("cpuid"); asm("rdtsc" : "=a" (lo), "=d" (hi)); return ((u64) lo) | (((u64) hi) << 32); } Taking the difference between rdtsc before and after

How to benchmark in Qemu i386 system using rdtsc

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calculating time elapsed in C++

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问题 I need to calculated time elapsed of my function. Right now i am using std::clock and from what i understand this is measuring CPU time, which could be different from real time. std::clock_t start; double duration; start = std::clock(); someFunctionToMeasure(); duration = (std::clock() - start) / (double)CLOCKS_PER_SEC; So there are 2 things i'd like to know How does std::clock exactly work? is it just measuring CPU when its computing that function? Is there a better way to measure time

Producing a clock glitch in a Verilog design

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问题 I am designing a chip using Verilog. I have a 3-bit counter. I want that when the counter is in its 8th loop, there should be a clock glitch , and thereafter work normally. What could be the possible ways of producing a clock glitch in a Verilog design? 回答1: One way to inject glitches on a clock signal is to use force and release from your testbench: module tb; reg clk; reg [2:0] cnt; reg reset; always begin #5 clk <= 0; #5 clk <= 1; end always @(posedge clk or posedge reset) begin if (reset)

How to make edits on webpage that change display on another webpage

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问题 I am not using a database or sql. This is the HTML and Javascript for my current design. I want the ability to change the hours offset on another customization page and for those changes to apply to the display page that the clocks are on. I currently change the offsets from the display page by typing in the TimeZone database name or by typing in the correct timezone offset. So in simple terms I am trying to change the timezone input from another webpage and have it still displayed from my

对Linux系统中的时钟和时间的探讨

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概要 1）介绍Linux系统中时钟的基本概念 2）探讨hwclock命令的工作方式。 3）系统启动过程中Linux系统对系统时钟和硬件时钟的同步。主要术语和背景知识 UTC: Coordinated Universal Time，一种是件标准，用以规范世界各地的时间。 Time Zone: 时区，表示方式是：UTC-xx:xx, UTC+xx:xx。比如中国的时区表示是：UTC+08:00. 其他一些相关术语，比如CST，DST等，我们并不需要关心。典型Linux 对时钟和时间的管理一个典型的Linux系统主要有两种时钟：系统时钟（System Clock）和硬件时钟（Hardware Clock）。硬件时钟独立运行于操作系统之外，有自己的电源供给，即使当系统关机时，它也依然在跑。Hardware Clock有时也叫BIOS Clock, CMOS Clock, RTC 等。但是只有hardware clock这个词汇不容易引起误解。系统时钟就是由操作系统维护的一个时钟。在Linux系统中，是由kernel维护，由timer的中断进行驱动的一个时钟（因为它是由计时器的中断驱动的，所以可以认为是一个软件时钟）。有两个时钟，就需要有同步。这个同步功能由hwclock来实现。在此仅作简要介绍，详情请查询手册（man hwclock).

AIML Chatbot response differs at different times?

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问题 A separate question for the AIML bot in my previous post... How do you create a bot that responds at different times of the day? I feel like it will make him seem more "real." I can't make heads or tails about how the date and time display actually works. I assume you'd have to fiddle with that alongside the set/get functions... but that's all I know for sure. I would like my bot to do something like this. TIME: Noon USER: Hi, bot. BOT: Good afternoon, USER! It's about lunchtime for me. Where

VHDL Gated Clock how to avoid

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问题 I've received an advice to avoid gated clock because it may cause problems with slacks and timing costraints. But I want to ask what I can consider like a gated clock. For example: This code have gated clock because StopCount gate it. process(ModuleCLK) begin if (rising_edge(ModuleCLK) and StopCount = '0') then if ModuleEN = '0' then RESET <= '0'; POWER <= '1'; EN <= '0'; CLOCK <= '0'; SERIAL <= '0'; elsif This code have also gated clock? process(ModuleCLK) begin if ModuleEN = '0' then RESET

STM32 internal clocks

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问题 I am confused with the clock system on my STM32F7 device (Cortex-M7 microcontroller from STMicroelectronics). The reference manual does not clarify the differences between these clocks sufficiently: SYSCLK HCLK FCLK The reference manual reads in chapter << 5.2 Clocks >> "The RCC feeds the external clock of the Cortex System Timer (SysTick) with the AHB clock (HCLK) divided by 8." This statement contradicts the figure from CubeMX. Notice that in CubeMX I can choose myself the prescaler from