Programming Forums > Application Development > C++

Narue · Nov 20th, 2006, 12:27 PM

>Only know how to do it in Windows and Linux
Have your implementation define a name depending on the build. Then you don't have to know the tricks, or the exceptions (there are several for Linux):

(Toggle Plain Text)

#if IS_LINUX
  #include <unistd.h>
  #define delay(x) sleep(x)
#elif IS_WINDOWS
  #include <windows.h>
  #define delay(x) Sleep(x * 1000)
#else
  #define delay(x) std::cout << "Unknown OS" << std::endl;
#endif

Then on Linux you could build like so:

(Toggle Plain Text)

gcc -D IS_LINUX main.c

You'll notice that a lot of open source code does this, especially with assumptions about the standard library.

v0id · Nov 21st, 2006, 11:32 AM

Oh.. Thanks a lot for the tip, Narue!

Lesliect6 · Nov 24th, 2006, 7:54 AM

The delay function in Windows is simple to write, you only need the <time.h> library, which should be included with your compiler. Then, define the function delay :

(Toggle Plain Text)

void delay(int seconds)
{
  clock_t endwait;
  endwait = clock () + seconds * CLK_TCK ;
  while (clock() < endwait) {}
}

Narue · Nov 24th, 2006, 8:29 AM

>The delay function in Windows is simple to write, you only need the <time.h> library
Of course, a busy loop is extremely antisocial in a multitasking OS. If you're assuming Windows, then just use Sleep.

>which should be included with your compiler
Which will be included with your compiler unless you're on a freestanding implementation. And if you're on a freestanding implementation, you probably don't need help writing a delay function.

>CLK_TCK
The CLOCKS_PER_SEC macro is standard and does exactly the same thing. In fact, in every implementation I've seen that defines CLK_TCK, it's done like this:

(Toggle Plain Text)

#define CLK_TCK CLOCKS_PER_SEC

Why sacrifice portability when you don't have to?

grumpy · Nov 24th, 2006, 8:30 AM

The problem with that function, Lesliect6, is that the while loop thrashes and therefore starves other programs (and other threads within your program, if it is multithreaded) of processor time. It will therefore have a noticeable effect on the performance of the whole system --- and any other programs running at the same time.

The Sleep(x*1000) described by Narue will introduce a delay, without starving other processes or threads of CPU time. (Incidentally, the header file that declares Sleep() in the win32 API is <winbase.h>).

One approach, sometimes used in addition to the one described by Narue, goes something like;

(Toggle Plain Text)

#include "id_sys.h"

#if IS_LINUX
  #include <unistd.h>
  #define delay(x) sleep(x)
#elif IS_WINDOWS
  #include <windows.h>
  #define delay(x) Sleep(x * 1000)
#else
  #define delay(x) std::cout << "Unknown OS" << std::endl;
#endif

where id_sys.h includes macros to detect the compiler and target system. For example;

(Toggle Plain Text)

#if defined (__MSDOS__) && !defined(__GNUG__)
#define IS_MSDOS
#elif defined(_MSC_VER) || defined(__BCPLUSPLUS__) || defined(__WIN32__)
#define IS_WINDOWS
#elif defined(__vax__)
#define IS_VAX
#endif

This technique works by using predefined macros that are associated with each compiler. The down side is that compiler specific macros change quite significantly between compilers, and sometimes even between compiler versions. The benefit is that, if the code supports your compiler and target system, there is less need to reconfigure build scripts. Usually, I prefer to configure build scripts, but this is an alternate option.

Lesliect6 · Nov 24th, 2006, 8:33 AM

Quote:

>CLK_TCK
The CLOCKS_PER_SEC macro is standard and does exactly the same thing. In fact, in every implementation I've seen that defines CLK_TCK, it's done like this:
Code:

#define CLK_TCK CLOCKS_PER_SEC

Why sacrifice portability when you don't have to?

Why, thank you I didn't know that.

Nov 20th, 2006, 12:27 PM	#11
Narue Professional Programmer Join Date: Sep 2005 Posts: 419 Rep Power: 4	>Only know how to do it in Windows and Linux Have your implementation define a name depending on the build. Then you don't have to know the tricks, or the exceptions (there are several for Linux): (Toggle Plain Text) #if IS_LINUX #include <unistd.h> #define delay(x) sleep(x) #elif IS_WINDOWS #include <windows.h> #define delay(x) Sleep(x * 1000) #else #define delay(x) std::cout << "Unknown OS" << std::endl; #endif #if IS_LINUX #include <unistd.h> #define delay(x) sleep(x) #elif IS_WINDOWS #include <windows.h> #define delay(x) Sleep(x * 1000) #else #define delay(x) std::cout << "Unknown OS" << std::endl; #endif Then on Linux you could build like so: (Toggle Plain Text) gcc -D IS_LINUX main.c gcc -D IS_LINUX main.c You'll notice that a lot of open source code does this, especially with assumptions about the standard library. __________________ Even if the voices aren't real, they have some pretty good ideas.

Nov 21st, 2006, 11:32 AM	#12
v0id Hobbyist Programmer Join Date: Apr 2006 Posts: 155 Rep Power: 3	Oh.. Thanks a lot for the tip, Narue! __________________ -- v0id

Nov 24th, 2006, 7:54 AM	#13
Lesliect6 Programmer Join Date: Aug 2005 Posts: 68 Rep Power: 4	The delay function in Windows is simple to write, you only need the <time.h> library, which should be included with your compiler. Then, define the function delay : (Toggle Plain Text) void delay(int seconds) { clock_t endwait; endwait = clock () + seconds * CLK_TCK ; while (clock() < endwait) {} } void delay(int seconds) { clock_t endwait; endwait = clock () + seconds * CLK_TCK ; while (clock() < endwait) {} }

Nov 24th, 2006, 8:29 AM	#14
Narue Professional Programmer Join Date: Sep 2005 Posts: 419 Rep Power: 4	>The delay function in Windows is simple to write, you only need the <time.h> library Of course, a busy loop is extremely antisocial in a multitasking OS. If you're assuming Windows, then just use Sleep. >which should be included with your compiler Which will be included with your compiler unless you're on a freestanding implementation. And if you're on a freestanding implementation, you probably don't need help writing a delay function. >CLK_TCK The CLOCKS_PER_SEC macro is standard and does exactly the same thing. In fact, in every implementation I've seen that defines CLK_TCK, it's done like this: (Toggle Plain Text) #define CLK_TCK CLOCKS_PER_SEC #define CLK_TCK CLOCKS_PER_SEC Why sacrifice portability when you don't have to? __________________ Even if the voices aren't real, they have some pretty good ideas.

Nov 24th, 2006, 8:30 AM	#15
grumpy Programming Guru Join Date: Jun 2005 Location: Adelaide, South Australia Posts: 1,254 Rep Power: 5	The problem with that function, Lesliect6, is that the while loop thrashes and therefore starves other programs (and other threads within your program, if it is multithreaded) of processor time. It will therefore have a noticeable effect on the performance of the whole system --- and any other programs running at the same time. The Sleep(x1000) described by Narue will introduce a delay, without starving other processes or threads of CPU time. (Incidentally, the header file that declares Sleep() in the win32 API is <winbase.h>). One approach, sometimes used in addition to the one described by Narue, goes something like; (Toggle Plain Text) #include "id_sys.h" #if IS_LINUX #include <unistd.h> #define delay(x) sleep(x) #elif IS_WINDOWS #include <windows.h> #define delay(x) Sleep(x 1000) #else #define delay(x) std::cout << "Unknown OS" << std::endl; #endif #include "id_sys.h" #if IS_LINUX #include <unistd.h> #define delay(x) sleep(x) #elif IS_WINDOWS #include <windows.h> #define delay(x) Sleep(x * 1000) #else #define delay(x) std::cout << "Unknown OS" << std::endl; #endif where id_sys.h includes macros to detect the compiler and target system. For example; (Toggle Plain Text) #if defined (__MSDOS__) && !defined(__GNUG__) #define IS_MSDOS #elif defined(_MSC_VER) \|\| defined(__BCPLUSPLUS__) \|\| defined(__WIN32__) #define IS_WINDOWS #elif defined(__vax__) #define IS_VAX #endif #if defined (__MSDOS__) && !defined(__GNUG__) #define IS_MSDOS #elif defined(_MSC_VER) \|\| defined(__BCPLUSPLUS__) \|\| defined(__WIN32__) #define IS_WINDOWS #elif defined(__vax__) #define IS_VAX #endif This technique works by using predefined macros that are associated with each compiler. The down side is that compiler specific macros change quite significantly between compilers, and sometimes even between compiler versions. The benefit is that, if the code supports your compiler and target system, there is less need to reconfigure build scripts. Usually, I prefer to configure build scripts, but this is an alternate option.

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Programming Forums > Application Development > C++

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