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#include "config.h"
#ifdef USE_STREAM_CACHE
// gcc cache2.c ../linux/shmem.o -o cache2
// Initial draft of my new cache system...
// includes some simulation code, using usleep() to emulate limited bandwith
// TODO: seeking, data consistency checking
#define READ_SPEED 20
#define FILL_SPEED 10
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include "../linux/shmem.h"
#include "stream.h"
int stream_fill_buffer(stream_t *s);
int stream_seek_long(stream_t *s,off_t pos);
typedef struct {
// constats:
unsigned char *buffer; // base pointer of the alllocated buffer memory
int buffer_size; // size of the alllocated buffer memory
int sector_size; // size of a single sector (2048/2324)
// Note: buffer_size should be N*sector_size, where N is integer...
int back_size; // we should keep back_size amount of old bytes for backward seek
int fill_limit; // we should fill buffer if space>fill_limit
// reader's pointers:
int read_filepos;
// filler's pointers:
int min_filepos; // buffer contain only a part of the file, from min-max pos
int max_filepos;
int offset; // filepos <-> bufferpos offset value (filepos of the buffer's first byte)
int eof;
// commands/locking:
int cmd_lock; // 1 if we will seek/reset buffer, 2 if we are ready for cmd
int fifo_flag; // 1 if we should use FIFO to notice cache about buffer reads.
// callback
stream_t* stream;
} cache_vars_t;
int min_fill=0;
int sleep_flag=0;
void cache_stats(cache_vars_t* s){
int newb=s->max_filepos-s->read_filepos; // new bytes in the buffer
printf("0x%06X [0x%06X] 0x%06X ",s->min_filepos,s->read_filepos,s->max_filepos);
printf("%3d %% (%3d%%)\n",100*newb/s->buffer_size,100*min_fill/s->buffer_size);
}
int cache_read(cache_vars_t* s,unsigned char* buf,int size){
int total=0;
while(size>0){
int pos,newb,len;
pos=s->read_filepos - s->offset;
if(pos<0) pos+=s->buffer_size; else
if(pos>=s->buffer_size) pos-=s->buffer_size;
newb=s->max_filepos-s->read_filepos; // new bytes in the buffer
if(newb<min_fill) min_fill=newb; // statistics...
if(newb<=0){
// eof?
if(s->eof) break;
// waiting for buffer fill...
usleep(10000); // 10ms
continue;
}
// printf("*** newb: %d bytes ***\n",newb);
if(newb>s->buffer_size-pos) newb=s->buffer_size-pos; // handle wrap...
if(newb>size) newb=size;
// len=write(mem,newb)
//printf("Buffer read: %d bytes\n",newb);
memcpy(buf,&s->buffer[pos],newb);
buf+=newb;
len=newb; //usleep(len*READ_SPEED*sleep_flag);
// ...
s->read_filepos+=len;
size-=len;
total+=len;
}
return total;
}
int cache_fill(cache_vars_t* s){
int read,back,newb,space,len,pos,endpos;
read=s->read_filepos;
// calc number of back-bytes:
back=read - s->min_filepos;
if(back<0) back=0; // strange...
if(back>s->back_size) back=s->back_size;
// calc number of new bytes:
newb=s->max_filepos - read;
if(newb<0) newb=0; // strange...
// calc free buffer space:
space=s->buffer_size - (newb+back);
// calc bufferpos:
pos=s->max_filepos - s->offset;
if(pos>=s->buffer_size) pos-=s->buffer_size; // wrap-around
if(space<s->fill_limit){
// printf("Buffer is full (%d bytes free, limit: %d)\n",space,s->fill_limit);
return 0; // no fill...
}
// printf("### read=0x%X back=%d newb=%d space=%d pos=%d\n",read,back,newb,space,pos);
// reduce space if needed:
if(space>s->buffer_size-pos) space=s->buffer_size-pos;
// if(space>32768) space=32768; // limit one-time block size
if(space>4*s->sector_size) space=4*s->sector_size;
s->min_filepos=read-back; // avoid seeking-back to temp area...
// ....
//printf("Buffer fill: %d bytes of %d\n",space,s->buffer_size);
//len=space; usleep(len*FILL_SPEED*sleep_flag);
//len=stream_fill_buffer(s->stream);
//memcpy(&s->buffer[pos],s->stream->buffer,len); // avoid this extra copy!
// ....
len=stream_read(s->stream,&s->buffer[pos],space);
if(!len) s->eof=1;
s->max_filepos+=len;
if(pos+len>=s->buffer_size){
// wrap...
s->offset+=s->buffer_size;
}
return len;
}
cache_vars_t* cache_init(int size,int sector){
int num;
cache_vars_t* s=shmem_alloc(sizeof(cache_vars_t));
memset(s,0,sizeof(cache_vars_t));
num=size/sector;
s->buffer_size=num*sector;
s->sector_size=sector;
s->buffer=shmem_alloc(s->buffer_size);
s->fill_limit=8*sector;
s->back_size=size/2;
return s;
}
static void exit_sighandler(int x){
// close stream
exit(0);
}
void stream_enable_cache(stream_t *s,int size){
int ss=(s->type==STREAMTYPE_VCD)?VCD_SECTOR_DATA:STREAM_BUFFER_SIZE;
s->cache_data=cache_init(size,ss);
((cache_vars_t*)s->cache_data)->stream=s; // callback
if((s->cache_pid=fork())) return; // parent exits
// cache thread mainloop:
signal(SIGTERM,exit_sighandler); // kill
while(1){
if(!cache_fill(s->cache_data)){
usleep(50000); // idle
}
// cache_stats(s->cache_data);
}
}
int cache_stream_fill_buffer(stream_t *s){
int len;
if(s->eof){ s->buf_pos=s->buf_len=0; return 0; }
if(!s->cache_pid) return stream_fill_buffer(s);
cache_stats(s->cache_data);
len=cache_read(s->cache_data,s->buffer, ((cache_vars_t*)s->cache_data)->sector_size);
if(len<=0){ s->eof=1; s->buf_pos=s->buf_len=0; return 0; }
s->buf_pos=0;
s->buf_len=len;
s->pos+=len;
// printf("[%d]",len);fflush(stdout);
return len;
}
int cache_stream_seek_long(stream_t *s,off_t pos){
if(!s->cache_pid) return stream_seek_long(s,pos);
printf("cache2 seek not implemented!!!!!!!!\n");
return 0;
}
#endif
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