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Path: ...!weretis.net!feeder6.news.weretis.net!i2pn.org!i2pn2.org!.POSTED!not-for-mail From: fir <fir@grunge.pl> Newsgroups: comp.lang.c Subject: Re: macro for fir list? Date: Sat, 30 Mar 2024 15:07:57 +0100 Organization: i2pn2 (i2pn.org) Message-ID: <uu96bo$3hjan$1@i2pn2.org> References: <uu3s0m$3av2s$1@i2pn2.org> <uu88uo$qv85$3@dont-email.me> <uu8k48$3gr5r$1@i2pn2.org> <uu8leu$3gsq5$1@i2pn2.org> <uu8lqk$3gtd0$1@i2pn2.org> <uu8nju$3gvnj$1@i2pn2.org> <uu8rl0$v2o8$1@dont-email.me> <uu92rd$3heoj$1@i2pn2.org> <uu934s$3hf4l$1@i2pn2.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Sat, 30 Mar 2024 14:07:54 -0000 (UTC) Injection-Info: i2pn2.org; logging-data="3722583"; mail-complaints-to="usenet@i2pn2.org"; posting-account="+ydHcGjgSeBt3Wz3WTfKefUptpAWaXduqfw5xdfsuS0"; User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:27.0) Gecko/20100101 Firefox/27.0 SeaMonkey/2.24 In-Reply-To: <uu934s$3hf4l$1@i2pn2.org> X-Spam-Checker-Version: SpamAssassin 4.0.0 Bytes: 5285 Lines: 125 fir wrote: > fir wrote: >> bart wrote: >>> On 30/03/2024 09:56, fir wrote: >>> >>>>> >>>> yet other example >>>> >>>> //bytes container >>>> char* bytes = NULL; int bytes_size = 0; >>>> void bytes_add(char val) { >>>> (bytes=(char*)realloc(bytes,++bytes_size*sizeof(char)))[bytes_size-1]=val; >>>> >>>> >>>> } >>>> void bytes_load(char* name) { FILE *f = fopen(name, "rb"); int >>>> c; while((c=getc(f))!=EOF) bytes_add(c); fclose(f); } >>> >>> This is pretty inefficient. Loading an 8MB file this way takes 3 >>> seconds, vs. 50ms to load it in one go. >>> >>> Loading the same 90KB file 10,000 times took 120 seconds, vs. 0.8 >>> seconds even using a scripting language. >>> >>> 80% of the inefficiency is growing the buffer one byte at a time. The >>> other 20% is reading the file one byte at a time. >>> >>> >> i know its inneficient but that was not the point - the point was more >> about composition and utility >> >> i may revrite but the example would be much longer >> >> char* bytes = NULL; int bytes_size = 0; >> char* bytes_resize(char size) {return >> bytes=(char*)realloc(bytes,(bytes_size=size)*sizeof(char)); } >> void bytes_add(char val) { >> (bytes=(char*)realloc(bytes,++bytes_size*sizeof(char)))[bytes_size-1]=val; >> >> } >> void bytes_save(char* name) { FILE* f =fopen(name, "wb"); int >> saved = fwrite (bytes , 1, bytes_size, f); fclose (f); } >> >> >> int GetFileSize2(char *filename) >> { >> struct stat st; >> if (stat(filename, &st)==0) return (int) st.st_size; >> // ERROR_EXIT("error obtaining file size for &s", filename); >> return -1; >> } >> >> void bytes_load(char* name) >> { >> int flen = GetFileSize2(name); >> FILE *f = fopen(name, "rb"); >> int loaded = fread(bytes_resize(flen), 1, flen, f); >> fclose(f); >> } >> >> generally if some uses this bytes microcintainer (i call it also list, >> though it is also resizable array) one may use thie add method which >> callst reallock or call resize(1000) and use it by bytes[i] so its not >> inefficient >> >> //@include "bytes.c" >> for(int i=0;i<1000;i++) bytes_add(rand()&0xff); >> >> bytes_resize(1000); >> for(int i=0;i<1000;i++) bytes[i]=rand()&0xff; >> > > yoy may check how much it last to say insert 1M of bytes by add compared > to resize and put it normall way - thic could measure overhead of this > reallock... i may add this variable say _cached_size or what to name it, > its a line of code ot wo and that will speed up but there still be a > cost of if i made some test with putting 1M by add it takes 160 ms 10M by cahced add 45 ms and 10M stright 7 ms, 10M by firs approch may take more than 10x 160 ms becouse i drwa a plot and if its plots so slow i dont wait, if so it seems that this reallock is badly designed or what becouse it shouldnt be so much slow imo - i vaguelly remember there was iek already talko on this here..meybe becouse some multithreading things or what (calling across dll barrier shouldnt be so slow per se - it also seems i got some slight bug in the test if(_1_pressed) { bytes_size=0; for(int i=0; i<1*1024*1024; i++) bytes_add(0x55); } if(_2_pressed) { bytes_size=0; for(int i=0; i<10*1024*1024; i++) bytes_add_cached(0x55); } if(_3_pressed) { bytes_resize(10*1024*1024); for(int i=0; i<10*1024*1024; i++) bytes[i]=0x55; } becouse all is okai untill i press 1 2 1 2 and now its segfault but my head hurts today a bot and im not sure i even want to search fr that bug now char* bytes = NULL; int bytes_size = 0; char* bytes_resize(int size) { return bytes=(char*) realloc(bytes, (bytes_size=size)*sizeof(char)); } void bytes_add(char val) { (bytes=(char*)realloc(bytes,++bytes_size*sizeof(char)))[bytes_size-1]=val; } void bytes_add_cached(char val) { static int cached_size = 0; bytes_size++; if(bytes_size<=cached_size); else bytes=(char*)realloc(bytes,(cached_size=(bytes_size+100)*10)*sizeof(char)); bytes[bytes_size-1]=val; return; }