C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  What are the codes doing?          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message Skyhorse Guest Posted: Fri Apr 16, 2004 6:18 am    Post subject: What are the codes doing? What are the following codes doing? What are the meaning of & 0xffe00000, & 3, 0xf, 0x3? Is there any difference between & 3 and & 0x3? inline BOOL CheckAudioHeader(DWORD dwHeader) { if ( (dwHeader & 0xffe00000) != 0xffe00000) return FALSE; if (!((dwHeader >> 17) & 3)) return FALSE; if ( ((dwHeader >> 12) & 0xf) == 0xf) return FALSE; if ( ((dwHeader >> 10) & 0x3) == 0x3) return FALSE; #ifdef _WIN32_WCE if ( ((dwHeader >> 12) & 0xf) == 0x0) return FALSE; #endif return TRUE; } Thanks [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Jakob Bieling Guest Posted: Fri Apr 16, 2004 5:06 pm    Post subject: Re: What are the codes doing? "Skyhorse" <victoryen (AT) cuhk (DOT) edu.hk> wrote Quote: What are the following codes doing? What are the meaning of & 0xffe00000, & 3, 0xf, 0x3? They are bitwise-AND operators, followed by integrals (written decimally or hexadecimally, see below). Quote: Is there any difference between & 3 and & 0x3? No, but there would be a difference between 0x10 and 10. The prefix 0x means, the following is a hexadecimal number (base 16), so 0x10 would be 16 in our decimal system (base 10). hth -- jb (replace y with x if you want to reply by e-mail) [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Gerhard Menzl Guest Posted: Fri Apr 16, 2004 6:35 pm    Post subject: Re: What are the codes doing? Skyhorse wrote: Quote: What are the following codes doing? The code tests whether certain bits are set in a value that has 32 bits on the Win32 platform. Quote: What are the meaning of & 0xffe00000, & 3, 0xf, 0x3? & is the bitwise or operator. The initial sequence 0x denotes a hexadecimal literal. If you are not familiar with these concepts, look up the terms in a C++ introductory text. Quote: Is there any difference between & 3 and & 0x3? No. Both fragments test whether the value of the expression left of them have the two lowermost bits set. 3 is the decimal, and 0x3 is the hexadecimal way of specifying the binary constant 00000011. Quote: inline BOOL CheckAudioHeader(DWORD dwHeader) { if ( (dwHeader & 0xffe00000) != 0xffe00000) return FALSE; if (!((dwHeader >> 17) & 3)) return FALSE; if ( ((dwHeader >> 12) & 0xf) == 0xf) return FALSE; if ( ((dwHeader >> 10) & 0x3) == 0x3) return FALSE; #ifdef _WIN32_WCE if ( ((dwHeader >> 12) & 0xf) == 0x0) return FALSE; #endif return TRUE; } Gerhard Menzl -- Humans may reply by replacing the obviously faked part of my e-mail address with "kapsch". [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Jakob Bieling Guest Posted: Sat Apr 17, 2004 10:10 pm    Post subject: Re: What are the codes doing? "Gerhard Menzl" <gerhard.menzl (AT) spambucket (DOT) net> wrote Quote: What are the meaning of & 0xffe00000, & 3, 0xf, 0x3? & is the bitwise or operator. Guess that is a typo | is the bitwise-or operator and & is the bitwise-and operator! regards -- jb (replace y with x if you want to reply by e-mail) [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Steve Folly Guest Posted: Sat Apr 17, 2004 10:44 pm    Post subject: Re: What are the codes doing? On 16/4/04 7:35 pm, in article 407fb09c$1 (AT) news (DOT) kapsch.co.at, "Gerhard Menzl" <gerhard.menzl (AT) spambucket (DOT) net> wrote: Quote: What are the meaning of & 0xffe00000, & 3, 0xf, 0x3? & is the bitwise or operator. No. It is, of course, the bit-wise AND operator. Picking a (fairly) random page from a google search, this might explain a few things about bitwise operators... http://cplus.about.com/library/weekly/aa042203a.htm Steve. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Gerhard Menzl Guest Posted: Mon Apr 19, 2004 6:43 pm    Post subject: Re: What are the codes doing? Jakob Bieling wrote: Quote: What are the meaning of & 0xffe00000, & 3, 0xf, 0x3? & is the bitwise or operator. Guess that is a typo | is the bitwise-or operator and & is the bitwise-and operator! More like a thinko. How deeply embarrassing. Gerhard Menzl -- Humans may reply by replacing the obviously faked part of my e-mail address with "kapsch". [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. 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