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#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
//int open(const char *pathname, int flags);
#define BUFFSIZE (4*65536)
#define NUM_BUFS (16)
unsigned char *buffer[NUM_BUFS];
unsigned int buf_read=0;
unsigned int buf_write=0;
unsigned int buf_read_pos=0;
unsigned int buf_write_pos=0;
int full_buffers=0;
int main(int argc,char* argv[]){
fd_set rfds;
fd_set wfds;
struct timeval tv;
int retval;
int i;
// int empty=1;
int can_read=1;
int eof=0;
int in_fd=0; // stdin
if(argc>1) in_fd=open(argv[1],O_RDONLY|O_NDELAY);
for(i=0;i<NUM_BUFS;i++) buffer[i]=malloc(BUFFSIZE);
while(1){
/* Watch stdin (fd 0) to see when it has input. */
FD_ZERO(&rfds); if(can_read){ FD_SET(in_fd, &rfds);}
FD_ZERO(&wfds); FD_SET(1, &wfds);
/* Wait up to five seconds. */
tv.tv_sec = 1;
tv.tv_usec = 0;
retval = select((in_fd<1?1:in_fd)+1, &rfds, &wfds, NULL, &tv);
/* Don't rely on the value of tv now! */
if (retval){
if(FD_ISSET(in_fd, &rfds) || !full_buffers){
fprintf(stderr,"\n%d r",full_buffers);fflush(stderr);
if(full_buffers==NUM_BUFS){
// buffer is full!
can_read=0;
fprintf(stderr,"\n%d full!\n",full_buffers);fflush(stderr);
} else {
// we can read input.
int len=BUFFSIZE-buf_read_pos;
fprintf(stderr,"R");fflush(stderr);
len=read(in_fd,buffer[buf_read]+buf_read_pos,len);
fprintf(stderr,"(%d)\n",len);fflush(stderr);
if(len>0){
buf_read_pos+=len;
if(buf_read_pos>=BUFFSIZE){
// block is full, find next!
buf_read=(buf_read+1)%NUM_BUFS;
++full_buffers;
buf_read_pos=0;
fprintf(stderr,"+");fflush(stderr);
}
} else {
eof=1;
}
}
}
if(FD_ISSET(1, &wfds)){
fprintf(stderr,"\n%d w",full_buffers);fflush(stderr);
if(full_buffers==0){
if(eof){
// flush buffer!
int pos=0;
int len;
fprintf(stderr,"\nf");fflush(stderr);
while((len=buf_read_pos-pos)>0){
len=write(1,buffer[buf_write]+pos,len);
fprintf(stderr,"(%d)",len);fflush(stderr);
if(len<=0) break;
pos+=len;
}
exit(1);
}
fprintf(stderr," empty");fflush(stderr);
//empty=1; // we must fill buffers!
} else {
// yeah, we can read from the buffer!
int len=BUFFSIZE-buf_write_pos;
fprintf(stderr,"W");fflush(stderr);
len=write(1,buffer[buf_write]+buf_write_pos,len);
fprintf(stderr,"(%d)",len);fflush(stderr);
if(len>0){
buf_write_pos+=len;
if(buf_write_pos>=BUFFSIZE){
// block is empty, find next!
buf_write=(buf_write+1)%NUM_BUFS;
--full_buffers;
buf_write_pos=0;
fprintf(stderr,"-");fflush(stderr);
can_read=1;
}
}
}
}
} else {
fprintf(stderr,".");fflush(stderr);
}
}
return 0;
}
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