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分享怎样设置数组元素的变化作为事件触发机制的事件
现在程序在内存中开辟一个数组，存放实时采集到的数据，一个线程相当于专门采集数据，放入数组中。
现在想实现，每隔20ms发送一次该数组中变化的数据
其实也就是基于事件驱动来传输变化数据
可是不知道，这个事件驱动（数组元素变化）应该怎么实现，难道是每隔20ms扫描一次所有元素？然后跟之前的进行对比么？
求帮忙，谢谢
现在想实现，每隔20ms发送一次该数组中变化的数据
其实也就是基于事件驱动来传输变化数据
可是不知道，这个事件驱动（数组元素变化）应该怎么实现，难道是每隔20ms扫描一次所有元素？然后跟之前的进行对比么？
求帮忙，谢谢
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lm_whales 2014-03-20
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如果是固件设计，基本上就是定时器或者直接用中断处理。
如果是硬件就是触发器，比较器了，可能还需要锁存器了。
如果是软件，定时器，线程，锁等等。
不知道楼主设计的是偏向那个方面的
derekrose 2014-03-20
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设置一个bool不就行了
赵4老师 2014-03-20
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参考C:\Program Files\Microsoft Visual Studio\VC98\CRT\SRC\Intel\MEMCMP.ASM
page ,132
title memcmp - compare to blocks of memory
;***
;memcmp.asm - compare two blocks of memory
;
; Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
;
;Purpose:
; defines memcmp() - compare two memory blocks lexically and
; find their order.
;
;*******************************************************************************
.xlist
include cruntime.inc
.list
page
;***
;int memcmp(buf1, buf2, count) - compare memory for lexical order
;
;Purpose:
; Compares count bytes of memory starting at buf1 and buf2
; and find if equal or which one is first in lexical order.
;
; Algorithm:
; int
; memcmp (buf1, buf2, count)
; char *buf1, *buf2;
; unsigned count;
; {
; if (!count)
; return(0);
; while (--count && *buf1 == *buf2)
; {
; buf1++;
; buf2++;
; }
; return(*buf1 - *buf2);
; }
;
;Entry:
; char *buf1, *buf2 - pointers to memory sections to compare
; unsigned count - length of sections to compare
;
;Exit:
; returns -1 if buf1 < buf2
; returns 0 if buf1 == buf2
; returns +1 if buf1 > buf2
;
;Uses:
;
;Exceptions:
;
;*******************************************************************************
CODESEG
public memcmp
memcmp proc
.FPO ( 0, 3, 0, 0, 0, 0 )
mov eax,[esp+0ch] ; eax = counter
test eax,eax ; test if counter is zero
jz short retnull ; return 0
mov edx,[esp+4] ; edx = buf1
push esi
push edi
mov esi,edx ; esi = buf1
mov edi,[esp+10h] ; edi = buf2
; Check for dword (32 bit) alignment
or edx,edi
and edx,3 ; edx=0 iff buf1 are buf2 are aligned
jz short dwords
; Strings are not aligned. If the caller knows the strings (buf1 and buf2) are
; different, the function may be called with length like -1. The difference
; may be found in the last dword of aligned string, and because the other
; string is misaligned it may cause page fault. So, to be safe. the comparison
; must be done byte by byte.
test eax,1
jz short main_loop
mov cl,[esi]
cmp cl,[edi]
jne short not_equal
inc esi
inc edi
dec eax
jz short done ; eax is already 0
main_loop:
mov cl,[esi]
mov dl,[edi]
cmp cl,dl
jne short not_equal
mov cl,[esi+1]
mov dl,[edi+1]
cmp cl,dl
jne short not_equal
add edi,2
add esi,2
sub eax,2
jnz short main_loop
done:
pop edi
pop esi
retnull:
ret ; _cdecl return
dwords:
mov ecx,eax
and eax,3 ; eax= counter for tail loop
shr ecx,2
jz short tail_loop_start
; counter was >=4 so may check one dword
rep cmpsd
jz short tail_loop_start
; in last dword was difference
mov ecx,[esi-4] ; load last dword from buf1 to ecx
mov edx,[edi-4] ; load last dword from buf2 to edx
cmp cl,dl ; test first bytes
jne short difference_in_tail
cmp ch,dh ; test seconds bytes
jne short difference_in_tail
shr ecx,10h
shr edx,10h
cmp cl,dl ; test third bytes
jne short difference_in_tail
cmp ch,dh ; they are different, but each one is bigger?
; jmp short difference_in_tail
difference_in_tail:
mov eax,0
; buf1 < buf2 buf1 > buf2
not_equal:
sbb eax,eax ; AX=-1, CY=1 AX=0, CY=0
pop edi ; counter
sbb eax,-1 ; AX=-1 AX=1
pop esi
ret ; _cdecl return
; in tail loop we test last three bytes (esi and edi are aligned on dword
; boundary)
tail_loop_start:
test eax,eax ; eax is counter%4 (number of bytes for tail
; loop)
jz short done ; taken if there is no tail bytes
mov edx,[esi] ; load dword from buf1
mov ecx,[edi] ; load dword from buf2
cmp dl,cl ; test first bytes
jne short difference_in_tail
dec eax ; counter--
jz short tail_done
cmp dh,ch ; test second bytes
jne short difference_in_tail
dec eax ; counter--
jz short tail_done
and ecx,00ff0000h ; test third bytes
and edx,00ff0000h
cmp edx,ecx
jne short difference_in_tail
dec eax
tail_done:
pop edi
pop esi
ret ; _cdecl return
memcmp endp
end
赵4老师 2014-03-20
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参考X86汇编指令
CMPS 串比较.( CMPSB 比较字符. CMPSW 比较字. )
？
ldxab 2014-03-19
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sendmessage函数，产生消息
赵4老师 2014-03-19
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无论如何都要调用memcmp函数吧。
无论如何都要加锁吧。
无论如何都要写日志吧。
仅供参考：
//循环向a函数每次发送200个字节长度（这个是固定的）的buffer,
//a函数中需要将循环传进来的buffer，组成240字节（也是固定的）的新buffer进行处理，
//在处理的时候每次从新buffer中取两个字节打印
#ifdef WIN32
#pragma warning(disable:4996)
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef WIN32
#include <windows.h>
#include <process.h>
#include <io.h>
#define MYVOID void
#define vsnprintf _vsnprintf
#else
#include <unistd.h>
#include <sys/time.h>
#include <pthread.h>
#define CRITICAL_SECTION pthread_mutex_t
#define MYVOID void *
#endif
//Log{
#define MAXLOGSIZE 20000000
#define MAXLINSIZE 16000
#include <time.h>
#include <sys/timeb.h>
#include <stdarg.h>
char logfilename1[]="MyLog1.log";
char logfilename2[]="MyLog2.log";
static char logstr[MAXLINSIZE+1];
char datestr[16];
char timestr[16];
char mss[4];
CRITICAL_SECTION cs_log;
FILE *flog;
#ifdef WIN32
void Lock(CRITICAL_SECTION *l) {
EnterCriticalSection(l);
}
void Unlock(CRITICAL_SECTION *l) {
LeaveCriticalSection(l);
}
void sleep_ms(int ms) {
Sleep(ms);
}
#else
void Lock(CRITICAL_SECTION *l) {
pthread_mutex_lock(l);
}
void Unlock(CRITICAL_SECTION *l) {
pthread_mutex_unlock(l);
}
void sleep_ms(int ms) {
usleep(ms*1000);
}
#endif
void LogV(const char *pszFmt,va_list argp) {
struct tm *now;
struct timeb tb;
if (NULL==pszFmt||0==pszFmt[0]) return;
vsnprintf(logstr,MAXLINSIZE,pszFmt,argp);
ftime(&tb);
now=localtime(&tb.time);
sprintf(datestr,"%04d-%02d-%02d",now->tm_year+1900,now->tm_mon+1,now->tm_mday);
sprintf(timestr,"%02d:%02d:%02d",now->tm_hour ,now->tm_min ,now->tm_sec );
sprintf(mss,"%03d",tb.millitm);
printf("%s %s.%s %s",datestr,timestr,mss,logstr);
flog=fopen(logfilename1,"a");
if (NULL!=flog) {
fprintf(flog,"%s %s.%s %s",datestr,timestr,mss,logstr);
if (ftell(flog)>MAXLOGSIZE) {
fclose(flog);
if (rename(logfilename1,logfilename2)) {
remove(logfilename2);
rename(logfilename1,logfilename2);
}
} else {
fclose(flog);
}
}
}
void Log(const char *pszFmt,...) {
va_list argp;
Lock(&cs_log);
va_start(argp,pszFmt);
LogV(pszFmt,argp);
va_end(argp);
Unlock(&cs_log);
}
//Log}
#define ASIZE 200
#define BSIZE 240
#define CSIZE 2
char Abuf[ASIZE];
char Cbuf[CSIZE];
CRITICAL_SECTION cs_HEX ;
CRITICAL_SECTION cs_BBB ;
struct FIFO_BUFFER {
int head;
int tail;
int size;
char data[BSIZE];
} BBB;
int No_Loop=0;
void HexDump(int cn,char *buf,int len) {
int i,j,k;
char binstr[80];
Lock(&cs_HEX);
for (i=0;i<len;i++) {
if (0==(i%16)) {
sprintf(binstr,"%03d %04x -",cn,i);
sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
} else if (15==(i%16)) {
sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
sprintf(binstr,"%s ",binstr);
for (j=i-15;j<=i;j++) {
sprintf(binstr,"%s%c",binstr,('!'<buf[j]&&buf[j]<='~')?buf[j]:'.');
}
Log("%s\n",binstr);
} else {
sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
}
}
if (0!=(i%16)) {
k=16-(i%16);
for (j=0;j<k;j++) {
sprintf(binstr,"%s ",binstr);
}
sprintf(binstr,"%s ",binstr);
k=16-k;
for (j=i-k;j<i;j++) {
sprintf(binstr,"%s%c",binstr,('!'<buf[j]&&buf[j]<='~')?buf[j]:'.');
}
Log("%s\n",binstr);
}
Unlock(&cs_HEX);
}
int GetFromRBuf(int cn,CRITICAL_SECTION *cs,FIFO_BUFFER *fbuf,char *buf,int len) {
int lent,len1,len2;
lent=0;
Lock(cs);
if (fbuf->size>=len) {
lent=len;
if (fbuf->head+lent>BSIZE) {
len1=BSIZE-fbuf->head;
memcpy(buf ,fbuf->data+fbuf->head,len1);
len2=lent-len1;
memcpy(buf+len1,fbuf->data ,len2);
fbuf->head=len2;
} else {
memcpy(buf ,fbuf->data+fbuf->head,lent);
fbuf->head+=lent;
}
fbuf->size-=lent;
}
Unlock(cs);
return lent;
}
MYVOID thdB(void *pcn) {
char *recv_buf;
int recv_nbytes;
int cn;
int wc;
int pb;
cn=(int)pcn;
Log("%03d thdB thread begin...\n",cn);
while (1) {
sleep_ms(10);
recv_buf=(char *)Cbuf;
recv_nbytes=CSIZE;
wc=0;
while (1) {
pb=GetFromRBuf(cn,&cs_BBB,&BBB,recv_buf,recv_nbytes);
if (pb) {
Log("%03d recv %d bytes\n",cn,pb);
HexDump(cn,recv_buf,pb);
sleep_ms(1);
} else {
sleep_ms(1000);
}
if (No_Loop) break;//
wc++;
if (wc>3600) Log("%03d %d==wc>3600!\n",cn,wc);
}
if (No_Loop) break;//
}
#ifndef WIN32
pthread_exit(NULL);
#endif
}
int PutToRBuf(int cn,CRITICAL_SECTION *cs,FIFO_BUFFER *fbuf,char *buf,int len) {
int lent,len1,len2;
Lock(cs);
lent=len;
if (fbuf->size+lent>BSIZE) {
lent=BSIZE-fbuf->size;
}
if (fbuf->tail+lent>BSIZE) {
len1=BSIZE-fbuf->tail;
memcpy(fbuf->data+fbuf->tail,buf ,len1);
len2=lent-len1;
memcpy(fbuf->data ,buf+len1,len2);
fbuf->tail=len2;
} else {
memcpy(fbuf->data+fbuf->tail,buf ,lent);
fbuf->tail+=lent;
}
fbuf->size+=lent;
Unlock(cs);
return lent;
}
MYVOID thdA(void *pcn) {
char *send_buf;
int send_nbytes;
int cn;
int wc;
int a;
int pa;
cn=(int)pcn;
Log("%03d thdA thread begin...\n",cn);
a=0;
while (1) {
sleep_ms(100);
memset(Abuf,a,ASIZE);
a=(a+1)%256;
if (16==a) {No_Loop=1;break;}//去掉这句可以让程序一直循环直到按Ctrl+C或Ctrl+Break或当前目录下存在文件No_Loop
send_buf=(char *)Abuf;
send_nbytes=ASIZE;
Log("%03d sending %d bytes\n",cn,send_nbytes);
HexDump(cn,send_buf,send_nbytes);
wc=0;
while (1) {
pa=PutToRBuf(cn,&cs_BBB,&BBB,send_buf,send_nbytes);
Log("%03d sent %d bytes\n",cn,pa);
HexDump(cn,send_buf,pa);
send_buf+=pa;
send_nbytes-=pa;
if (send_nbytes<=0) break;//
sleep_ms(1000);
if (No_Loop) break;//
wc++;
if (wc>3600) Log("%03d %d==wc>3600!\n",cn,wc);
}
if (No_Loop) break;//
}
#ifndef WIN32
pthread_exit(NULL);
#endif
}
int main() {
#ifdef WIN32
InitializeCriticalSection(&cs_log);
InitializeCriticalSection(&cs_HEX );
InitializeCriticalSection(&cs_BBB );
#else
pthread_t threads[2];
int threadsN;
int rc;
pthread_mutex_init(&cs_log,NULL);
pthread_mutex_init(&cs_HEX,NULL);
pthread_mutex_init(&cs_BBB,NULL);
#endif
Log("Start===========================================================\n");
BBB.head=0;
BBB.tail=0;
BBB.size=0;
#ifdef WIN32
_beginthread((void(__cdecl *)(void *))thdA,0,(void *)1);
_beginthread((void(__cdecl *)(void *))thdB,0,(void *)2);
#else
threadsN=0;
rc=pthread_create(&(threads[threadsN++]),NULL,thdA,(void *)1);if (rc) Log("%d=pthread_create %d error!\n",rc,threadsN-1);
rc=pthread_create(&(threads[threadsN++]),NULL,thdB,(void *)2);if (rc) Log("%d=pthread_create %d error!\n",rc,threadsN-1);
#endif
if (!access("No_Loop",0)) {
remove("No_Loop");
if (!access("No_Loop",0)) {
No_Loop=1;
}
}
while (1) {
sleep_ms(1000);
if (No_Loop) break;//
if (!access("No_Loop",0)) {
No_Loop=1;
}
}
sleep_ms(3000);
Log("End=============================================================\n");
#ifdef WIN32
DeleteCriticalSection(&cs_BBB );
DeleteCriticalSection(&cs_HEX );
DeleteCriticalSection(&cs_log);
#else
pthread_mutex_destroy(&cs_BBB);
pthread_mutex_destroy(&cs_HEX);
pthread_mutex_destroy(&cs_log);
#endif
return 0;
}
飞天御剑流 2014-03-19
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写者写入的时候，把数组的下标写入一个set中，另一个线程每隔20ms读取这个set，发送相应下标的元素。
要加锁。
mangoalx 2014-03-19
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这是正道。写入的时候判断要容易得多
JiMoKuangXiangQu 2014-03-19
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或者使用OS机制(互斥等等)实现生产者/消费者模式。
JiMoKuangXiangQu 2014-03-19
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可以试试ring buffer方式。
kiloyqp 2014-03-19
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另一个线程改变数组数据的时候，难道不能在其中加入PostMessage吗
碼上道 2014-03-19
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你的数组是多大，如果不是很大，什么办法估计差不多，直接扫描就可以了。
cnblackmamba 2014-03-19
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我想再细化一下问题，其实，数组元素的更新，不是全部更新的
当采集的数据往数组中对应的下标存放的时候，如果与原来的值不同的时候，就发送给客户端。如果与原来的值不同的时候，就不用发送。
事件驱动：当数组中某个元素值变了，就把它发送给客户端。
只是这个事件驱动应该怎么写啊，不知道应该怎么来实现，是我过一段时间扫描一下数组看看它变了哪些，然后发送出去？
turing-complete 2014-03-19
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使用条件变量，如果你编译器允许的话，可以使用std::condition_variable
